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RAJ, Y. E. A., R. SURESH, P. V. SANKARAN, and B. AMUDHA. "Seasonal variation of 200 hPa upper tropospheric features over India in relation to performance of Indian southwest and northeast monsoons." MAUSAM 55, no. 2 (January 19, 2022): 269–80. http://dx.doi.org/10.54302/mausam.v55i2.1082.
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The relation between 200 hPa upper tropospheric parameters such as temperature, zonal and meridional winds over India with the Indian southwest and northeast monsoons has been studied, based on monthly and seasonal upper air data of 14 well-distributed Indian radiosonde stations for the 36 year period 1963-98. It has been found that by and large, positive temperature/height anomalies, negative zonal wind anomalies and northerly position of the sub-tropical ridge during the preceding months/seasons are associated with good southwest/poor northeast monsoons and that complement of the above with poor southwest/good northeast monsoons. The profiles of the above relationship display a double peak in May and September/October. A multiple regression forecast scheme for seasonal forecasting of northeast monsoon rainfall, based on October data has been derived which when tested in an independent sample of 5 years yielded nearly 50% correct forecasts. The southwest monsoon rainfall of India and the northeast monsoon rainfall of Tamil Nadu/Southern parts of India have been shown to share a negative relationship, though the relationship is discordant rather than decisive, which gets defined better when years of deficient southwest monsoon rainfall get excluded. The feature of good Indian northeast monsoon getting preceded by colder upper tropospheric temperatures as shown in the study tie in well with the accepted mechanism of Asian winter monsoon getting intensified due to cold surges from the Siberian High.
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Tardif, Delphine, Frédéric Fluteau, Yannick Donnadieu, Guillaume Le Hir, Jean-Baptiste Ladant, Pierre Sepulchre, Alexis Licht, Fernando Poblete, and Guillaume Dupont-Nivet. "The origin of Asian monsoons: a modelling perspective." Climate of the Past 16, no. 3 (May 8, 2020): 847–65. http://dx.doi.org/10.5194/cp-16-847-2020.
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Abstract. The Cenozoic inception and development of the Asian monsoons remain unclear and have generated much debate, as several hypotheses regarding circulation patterns at work in Asia during the Eocene have been proposed in the few last decades. These include (a) the existence of modern-like monsoons since the early Eocene; (b) that of a weak South Asian monsoon (SAM) and little to no East Asian monsoon (EAM); or (c) a prevalence of the Intertropical Convergence Zone (ITCZ) migrations, also referred to as Indonesian–Australian monsoon (I-AM). As SAM and EAM are supposed to have been triggered or enhanced primarily by Asian palaeogeographic changes, their possible inception in the very dynamic Eocene palaeogeographic context remains an open question, both in the modelling and field-based communities. We investigate here Eocene Asian climate conditions using the IPSL-CM5A2 (Sepulchre et al., 2019) earth system model and revised palaeogeographies. Our Eocene climate simulation yields atmospheric circulation patterns in Asia substantially different from modern conditions. A large high-pressure area is simulated over the Tethys ocean, which generates intense low tropospheric winds blowing southward along the western flank of the proto-Himalayan–Tibetan plateau (HTP) system. This low-level wind system blocks, to latitudes lower than 10∘ N, the migration of humid and warm air masses coming from the Indian Ocean. This strongly contrasts with the modern SAM, during which equatorial air masses reach a latitude of 20–25∘ N over India and southeastern China. Another specific feature of our Eocene simulation is the widespread subsidence taking place over northern India in the midtroposphere (around 5000 m), preventing deep convective updraught that would transport water vapour up to the condensation level. Both processes lead to the onset of a broad arid region located over northern India and over the HTP. More humid regions of high seasonality in precipitation encircle this arid area, due to the prevalence of the Intertropical Convergence Zone (ITCZ) migrations (or Indonesian–Australian monsoon, I-AM) rather than monsoons. Although the existence of this central arid region may partly result from the specifics of our simulation (model dependence and palaeogeographic uncertainties) and has yet to be confirmed by proxy records, most of the observational evidence for Eocene monsoons are located in the highly seasonal transition zone between the arid area and the more humid surroundings. We thus suggest that a zonal arid climate prevailed over Asia before the initiation of monsoons that most likely occurred following Eocene palaeogeographic changes. Our results also show that precipitation seasonality should be used with caution to infer the presence of a monsoonal circulation and that the collection of new data in this arid area is of paramount importance to allow the debate to move forward.
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Lim, Young-Kwon, and Kwang-Yul Kim. "ENSO Impact on the Space–Time Evolution of the Regional Asian Summer Monsoons." Journal of Climate 20, no. 11 (June 1, 2007): 2397–415. http://dx.doi.org/10.1175/jcli4120.1.
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Abstract This study investigates how ENSO affects the space–time evolution of the Asian summer monsoon (ASM) precipitation and synoptic variables on a 5-day resolution over the entire ASM area. Cyclostationary EOF and regression methods were used to investigate the detailed evolution features associated with ENSO during the prominent life cycle of the ASM (21 May–17 September). This ENSO mode is identified as the third largest component (next to the seasonal cycle and the intraseasonal oscillations with a 40–50-day period) of the ASM rainfall variation. The ENSO mode reveals that the individual regional monsoons over the ASM domain respond to ENSO in a complex manner. 1) Under the El Niño condition, the early monsoon stage over India, the Bay of Bengal, and the Indochina peninsula is characterized by rainfall deficit, along with a delayed monsoon onset by one or two pentads. This is the result of weakened diabatic heating over the Asian continent and meridional pressure gradient over the Indian Ocean, causing a weak low-tropospheric westerly monsoonal flow and the ensuing moisture transport decrease toward the regional monsoon areas. Onsets of the subsequent regional monsoons are delayed successively by this poorly developed ASM system in the early stage. 2) The Walker circulation anomaly persistently induces an enhanced subsidence over the Maritime Continent, resulting in a drought condition over this region for the entire ASM period. 3) The Hadley circulation anomaly linked to the Walker circulation anomaly over the Tropics drives a rising motion over the subtropical western Pacific, resulting in a wetter south China monsoon. The negative sea level pressure anomaly over the subtropical western Pacific associated with this anomalous Hadley circulation provides an unfavorable condition for the moisture transport toward East Asia, causing drier monsoons over north China, Japan, and Korea regions. 4) This negative sea level pressure anomaly intrudes into India, the Bay of Bengal, and the Indochina peninsula during late July and early August, developing a brief wet period over these regions. In contrast, the physical changes including the onset variation and the monsoon strength addressed above are reversed during La Niña events. In reality, the observed ASM rainfall anomaly does not necessarily follow the ENSO-related patterns addressed above because of other impacts contributing to the rainfall variations. Although the impact of ENSO is moderately important, a comparison with other impacts demonstrates that the rainfall variations are controlled more by regional-scale intraseasonal oscillations.
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Santhoshkumar, B., N. K. Sathyamoorthy, V. Geethalakshmi, Ga Dheebakaran, K. Boomiraj, and N. Manikandan. "Standardized Precipitation Index Based Drought Assessment over the North Western Zone of Tamil Nadu, India." International Journal of Environment and Climate Change 13, no. 10 (August 12, 2023): 1–9. http://dx.doi.org/10.9734/ijecc/2023/v13i102612.
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Drought is a natural disaster that tremendously affect the agriculture production and livelihood. Though the Tamil Nadu state is located at peninsular region of India and contributed from both the monsoons, the frequency of drought is high due to vagaries of monsoonal pattern. A study was conducted at Tamil Nadu Agricultural University to assess the drought characteristics across the north western Agro Climatic Zone (ACZ) of Tamil Nadu using Standardized Precipitation Index (SPI) during the past 30 years (1991-2020). The study clearly indicated that the Salem district had high vulnerability to drought followed by Dharmapuri and Namakkal districts during the South West Monsoon (SWM), whereas the Namakkal had high vulnerability followed by Salem and Dharmapuri during North East Monsoon (NEM).
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Zheng, Yangxing, M. M. Ali, and Mark A. Bourassa. "Contribution of Monthly and Regional Rainfall to the Strength of Indian Summer Monsoon." Monthly Weather Review 144, no. 9 (September 2016): 3037–55. http://dx.doi.org/10.1175/mwr-d-15-0318.1.
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Indian summer monsoon rainfall (ISMR; June–September) has both temporal and spatial variability causing floods and droughts in different seasons and locations, leading to a strong or weak monsoon. Here, the authors present the contribution of all-India monthly, seasonal, and regional rainfall to the ISMR, with an emphasis on the strong and weak monsoons. Here, regional rainfall is restricted to the seasonal rainfall over four regions defined by the India Meteorological Department (IMD) primarily for the purpose of forecasting regional rainfall: northwest India (NWI), northeast India (NEI), central India (CI), and south peninsula India (SPIN). In this study, two rainfall datasets provided by IMD are used: 1) all-India monthly and seasonal (June–September) rainfall series for the entire Indian subcontinent as well as seasonal rainfall series for the four homogeneous regions for the period 1901–2013 and 2) the latest daily gridded rainfall data for the period 1951–2014, which is used for assessment at the extent to which the four regions are appropriate for the intended purpose. Rainfall during July–August contributes the most to the total seasonal rainfall, regardless of whether it is a strong or weak monsoon. Although NEI has the maximum area-weighted rainfall, its contribution is the least toward determining a strong or weak monsoon. It is the rainfall in the remaining three regions (NWI, CI, and SPIN) that controls whether an ISMR is strong or weak. Compared to monthly rainfall, regional rainfall dominates the strong or weak rainfall periods.
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Chandel, Vikram, and Tejasvi Chauhan. "Attributing Vegetation Recovery During the Indian Summer Monsoon to Climate Drivers in Central India." Ecology, Economy and Society–the INSEE Journal 6, no. 1 (January 31, 2023): 109–22. http://dx.doi.org/10.37773/ees.v6i1.927.
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Increasing droughts and heat waves as a result of global warming pose a major threat to forests and croplands in India. Monitoring the dynamics of vegetation during a drought and its recovery is essential for the Indian socio-economy and biodiversity. We investigate vegetation recovery from a stressed state in the pre-monsoon (May) period to the end of the monsoon period (September). We then attribute net change during the monsoon period to climate drivers such as temperature, precipitation, and soil moisture. To delineate non-linear interactions, we use an information-theoretic metric to understand the relative association of climate variables with vegetation productivity on a daily scale. We found that pre-monsoon vegetation stress is influenced by soil moisture (r = 0.8, p < 0.01), which is driven by variations in temperature and precipitation. During the monsoons, precipitation contributes to vegetation recovery from pre-monsoon stress through soil moisture recharge while inhibiting vegetation productivity by limiting the amount of radiation available for photosynthesis. Linear regression shows the significant negative dependence of vegetation recovery on precipitation (β = –0.7, p < 0.01) and positive dependence on soil moisture (β = 0.4, p < 0.1) indicating radiation limitation on photosynthesis...
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JENAMANI, RAJENDRA KUMAR, S. R. KALSI, H. R. HATWAR, and S. K. SUBRAMANIAN. "Another deficient monsoon 2004 - A comparison with drought year 2002 and possible causes." MAUSAM 58, no. 2 (November 27, 2021): 161–76. http://dx.doi.org/10.54302/mausam.v58i2.1199.
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The rainfall over India as a whole during the summer monsoon season of 2004 was deficient with –13% below normal. Earlier in 2002, India has faced another worst situation when large-scale drought occurred and all India rainfall was below –19%. In the present study, we have compared briefly salient observational features of both the monsoons to find out their distinct characteristics. Comparisons show appearance of many similar as well as contrasting features. Though, both seasons were deficient, their dates of onset of monsoon over Kerala were either before or near the normal date. Progress up to central India was also normal in both the seasons. While Indian Summer Monsoon Rainfall (ISMR) during June was good, a few longest stagnation periods during advancing stage in July of both the years made unexpected delay of monsoon in covering entire India. Rainfall of July also suffered the most in both the seasons with a record lowest ISMR in 2002. Not a single depression formed in 2002 while in 2004, their frequency was less than half of normal. Analysis of other large-scale monthly anomalous ocean and atmospheric conditions over Indo-Pacific region including El-Nino conditions confirms that ENSO and Equatorial Indian Ocean Oscillation or EQUINOO have caused drought in July 2002, but not in July 2004. This is because very high typhoon formation and their recurvature with significantly higher than normal convection over northwest Pacific associated with record lowest ISMR in July, 2002 in contrast to occurrence of deficient ISMR in July 2004 which was associated with few typhoon formation and less convection. Also in 2002, Indian region was happened to fall exactly under the subsidence branch of Walker circulation with ascending branch over the western Pacific in the season in contrast to 2004, when subsidence was observed to be both over large part of western Pacific and adjoining Indian region.
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Fasullo, J. "Atmospheric Hydrology of the Anomalous 2002 Indian Summer Monsoon." Monthly Weather Review 133, no. 10 (October 1, 2005): 2996–3014. http://dx.doi.org/10.1175/mwr3014.1.
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Abstract The 2002 Indian summer monsoon season is unique because of its exceptional weakness, its association with a relatively weak El Niño, and its precedence by over a decade in which ENSO events fail to be associated with significant monsoon anomalies. In this study, atmospheric hydrology during the 2002 summer monsoon and its relationship to monsoon seasons accompanying El Niño events since 1948 are assessed using reanalysis and satellite fields. Strong hydrologic deficits are identified for July and September 2002. During July, the impact of the disturbed Hadley and Walker circulations in the African and Indian Ocean region on vertically integrated moisture transport (VIMT) in the Arabian Sea and India is found to be key to the Indian drought. Interhemispheric coherence in satellite-derived surface wind anomalies is also identified. During September, VIMT and surface wind anomalies, both to the east and west of India, contribute to anomalous moisture divergence in India. Bay of Bengal SST and Indian CAPE anomalies are found to act in response to the season’s major break episodes, contrary to other studies that suggest their role as instigators of break periods. The 2002 season is also found to exhibit characteristics that are common to other recent weak monsoons accompanying El Niño, such as strong westerly VIMT anomalies in the western Pacific Ocean and easterly VIMT anomalies in the Arabian Sea. Hydrologic anomalies that distinguish many recent normal monsoon seasons coinciding with El Niño from the El Niño distribution overall are not evident in 2002. In many respects, the 2002 season thus represents a reemergence of the hydrologic anomalies that have accompanied a strong monsoon–ENSO teleconnection over the past 50 yr and may present a challenge for perspectives that suggest a lasting decoupling of the monsoon–ENSO systems.
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Guha, Sukanya. "Echoing Tagore’s Love for the Monsoons." ASIAN-EUROPEAN MUSIC RESEARCH JOURNAL 6 (December 4, 2020): 101–4. http://dx.doi.org/10.30819/aemr.6-8.
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In India, Bengal’s most celebrated literary figure, Rabindranath Tagore, was specifically sensitive regarding the various seasons occurring in India. The monsoon and its relation with Tagore’s songs is the main focus of this paper. The monsoon, when Mother Nature spreads her beauty by unravelling her bounty treasures, is richly expressed by Tagore. In the composition for the khanika (poem) ‘Asho nai tumi phalgune’ [you did not come in the spring season] Tagore says: “when I awaited eagerly for your visit in the spring, you didn’t come. Please, don’t make me wait any longer and do come during the full monsoon”. In another of his songs he visualises on a cloudy sunless day, a person’s longing to share his or her deepest treasure of feeling for that particular important person ‘Emon ghonoghor boroshaye’ [in this heavy downpour] (Tagore 2002: 333, song 248). Through these poetic compositions and many more, one may understand the depth in Tagore’s understanding of the human’s emotional details regarding this specific season. The monsoon may also be disastrous. According to Tagore’s a composition ‘Bame rakho bhoyonkori’ [keep aside the destructions] (Tagore 2002: 394, song 58) he describes as well as wishes that the monsoon keeps away the damage or distress from people’s lives. His tunes blend with his words and emotions, not to mention the ragas that are believed to be related with rain that is popular to the Indian subcontinent such as Rag Megh or Rag Mian ki Malhar. These have been affluently used by Tagore to create emotional feelings through his words. He expresses being a philosopher with whom people can find a connection, irrespective of their regional background.
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Babu, J. Madhu, and S. Raja Rao. "Indian Press Coverage of Farmers’ Suicides in Andhra Pradesh: A Content Analysis." IRA-International Journal of Management & Social Sciences (ISSN 2455-2267) 14, no. 2 (March 5, 2019): 47. http://dx.doi.org/10.21013/jmss.v14.n2.p3.
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<p>India, consisting of 16 percent of world population subsists only on 2.4 percent land resources. Agriculture is the only source of livelihood to the two third of the population which gives employment to 57 percent of the workforce. Agriculture in India is often regarded as gambling with monsoons, because of its almost exclusive dependency on precipitation from monsoons. The failure of monsoons leading to a series of droughts, lack of better prices, exploitation by middlemen, and Gene Modified (GM) seed companies who are selling expensive cotton seeds and fertilizers, all of which have led to a series of suicides committed by farmers across India. Farmers' suicides are a complex phenomenon. Since the 1990s farmer suicides in India have made headlines. The journalist Palagummi Sainath highlighted that 17,500 farmers were suicides between 2002 to 2006. The government figures show 14,000 farmers took their own lives in 2011. The total number of farmers’ suicides crossed 3 lakh mark till in 2014. That most suicides occurred in the states of Andhra Pradesh, Maharashtra, Karnataka, Kerala and Punjab. This study seeks to investigate news items on farmers’ suicides in the Indian newspapers. A quantitative content analysis was adopted in this research. This study used two English dailies i.e. The Hindu and The New Indian Express and two Telugu dailies i.e. Eenadu and Andhrajyothi were taken for analysis. It is not a random sample. In this, a purposive sample method was adopted. The selection time period was one year i.e. from January 1, 2015, to December 31, 2015. Keeping in view ten subject categories have been mainly identified for this research. All the data collected were analyzed simple percentage and mean, standard deviation, ANOVA, Chi-square have been used for analysis. </p>
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Singh Mehra, Gajendra, Shivam Shrotriya, Deepa Bisht, Sarita Bisht, Harendra Singh Bargali, Tanveer Ahmad, Neha Verma, Nakulananda Mohanty, and Sushil Kumar Dutta. "Seasonal variations in the diversity of Amphibians and Reptiles in Western Terai arc landscape, India." International Journal of Zoology and Applied Biosciences 6, no. 4 (August 31, 2021): 194–202. http://dx.doi.org/10.55126/ijzab.2021.v06.i04.019.
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Amphibian and reptiles are weather sensitive, poikilothermic group of animals, and their occurrence varies with the change in seasons. Present study was conducted in Ramnagar Forest Division of Uttarakhand state of India. Ramnagar Forest Division is the western part of Terai Arc Landscape which is an important ecoregion of the world. Sampling was done with Visual Encounter Surveys along with other methods, in all the seasons of a year. A total of 47 species of herpetofauna was recorded in the study, including 10 species of frogs, 13 species of lizards, 20 species of snakes and 4 species of testudines. The maximum number of herpetofauna species was observed during monsoon season, while the least number species were found in winters. The general pattern of herpetofauna species richness that observed in Ramnagar Forest Division was, found to be highest in monsoons, which then started decreasing in autumns and a rapid decrease was noticed in pre-winter and reached minimum in winters. In springs it started rising again and continue to rise in summers to reached maximum in monsoons
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Sirisena, Jeewanthi, Denie Augustijn, Aftab Nazeer, and Janaka Bamunawala. "Use of Remote-Sensing-Based Global Products for Agricultural Drought Assessment in the Narmada Basin, India." Sustainability 14, no. 20 (October 12, 2022): 13050. http://dx.doi.org/10.3390/su142013050.
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Droughts exert severe impacts on the environment, economy, and society. The south Asian region is vulnerable to droughts and the Indian sub-continent is one of the most vulnerable in the region to frequent drought disasters. This study assesses the agricultural droughts in the Narmada River Basin (NRB), India, where more than 50% of the area is utilized for agriculture, through freely available local and global remote-sensing-based data focusing on long-term rainfall trends (1989–2018) and recently weakened monsoons in 2017 and 2018. In this study, some of the widely used indices to characterize droughts (viz., Standardized Precipitation Index (SPI), simplified Rainfall Index (RIs), Normalized Difference Vegetation Index (NDVI)), soil moisture content, and reservoir surface areas were used to assess the drought conditions in the Narmada River Basin over the study period. Our analysis shows that the NRB has experienced a decreasing trend in monsoon rainfall over the past three decades. The SPI captured most of the basin’s historical droughts. The weakened monsoons during 2017–2018 show that different parts of the NRB have experienced severe or moderate drought conditions. A clear difference does not show in the NDVI and in the soil moisture contents of the basin over three hydrological years (2015/16, 2016/17, and 2017/18), except for July to September 2017/18. The estimated water area depletion using the Normalized Difference Water Index (NDWI) follows the actual water levels in three selected reservoirs in the basin, of which, two show a decline in the maximum surface area, likely due to the weakened monsoons in 2017 and 2018. This research indicates that the freely available data can be beneficial for local authorities to monitor and understand the drought conditions to support water resources management and planning for agricultural activities.
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Desai, Dattesh V., and A. C. Anil. "Recruitment of the barnacle Balanus amphitrite in a tropical estuary: implications of environmental perturbation, reproduction and larval ecology." Journal of the Marine Biological Association of the United Kingdom 85, no. 4 (June 27, 2005): 909–20. http://dx.doi.org/10.1017/s0025315405011884.
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Phytoplankton blooms are known to influence barnacle recruitment and in boreal regions spring blooms work as an important trigger. Close to the west coast of the sub-continent of India, blooms tend to be triggered by breaks in the monsoon and the recurrence of the monsoon after a short break can stress the new recruits. The recruitment of Balanus amphitrite, an acorn barnacle, at Dona Paula Bay at the mouth of Zuari estuary, Goa, India was studied. Observations included variations in recruitment, larval abundance, development and reproduction. Adult conditioning and inter-brood variations were important factors in the larval ecology of this organism. The results indicate that the impulsive release of larvae during breaks between monsoons could be a short-sighted luxury for Balanus amphitrite in these waters. Temporal variations or recruitment failure in such environments can be attributed to inappropriate cue synchronization.
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Anderson, R. Charles. "Do dragonflies migrate across the western Indian Ocean?" Journal of Tropical Ecology 25, no. 4 (July 2009): 347–58. http://dx.doi.org/10.1017/s0266467409006087.
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Abstract:In the tropical Indian Ocean, the Maldive Islands lack surface freshwater, so are unsuitable for dragonfly reproduction. Nevertheless, millions of dragonflies (Insecta, Odonata; mostly globe skimmer, Pantala flavescens) appear suddenly every year starting in October. Arrival dates in the Maldives and India demonstrate that the dragonflies travel from southern India, a distance of some 500–1000 km. Dates of arrival and occurrence coincide with the southward passage of the Inter-tropical Convergence Zone (ITCZ). Circumstantial evidence suggests that the dragonflies fly with north-easterly tail winds, within and behind the ITCZ, at altitudes over 1000 m. It is proposed that this massive movement of dragonflies is part of an annual migration across the western Indian Ocean from India to East Africa. Arrival dates in the Seychelles support this hypothesis. Dragonflies also appear (in smaller numbers) in the Maldives in May, with the onset of the southwest monsoon, suggesting a possible return migration from Africa. These proposed migrations of dragonflies, regularly crossing 3500 km or more of open ocean, were previously unknown. It is known that these dragonflies exploit ephemeral rain pools for reproduction; the monsoons and ITCZ bring not only alternating, seasonal rains to India and Africa, but also appropriate winds for dragonflies to follow those rains. Several bird species migrate from India across the western Indian Ocean to wintering grounds in Africa. They do so at the same time as the dragonflies, presumably taking advantage of the same seasonal tail winds. Many of these birds also eat dragonflies; the possible significance of this was not previously appreciated.
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Kochhar, Rajesh. "Modern Astronomical Developments in India." Highlights of Astronomy 11, no. 2 (1998): 894–97. http://dx.doi.org/10.1017/s1539299600019055.
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Modern astronomy came to India in tow with the Europeans and was institutionalized more than 200 years ago by the (English) East India Company with the establishment in 1790 of Madras Observatory for assistance in navigational and geographical surveys. One hundred years later, in 1899, it was replaced by a solar observatory at Kodaikanal set up by the government to meet the European scientists’ demand for sunny skies and in the hope that a study of the Sun would help predict the failure of monsoons, the key factor then as now in Indian economy. It is mildly interesting to note that, when the scientific agenda was laid down by the Royal Society, no mention was made of climate or rains [1].
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Gupta, Raj, DK Benbi, and IP Abrol. "Indian Agriculture needs a Strategic Shift for Improving Fertilizer Response and Overcome Sluggish Foodgrain Production." Journal of Agronomy Research 4, no. 3 (December 25, 2021): 1–16. http://dx.doi.org/10.14302/issn.2639-3166.jar-21-4018.
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In India, loss of fertility through soil erosion is primarily a summer monsoons mediated phenomenon. Reversing the land degradation processes contribute to water availability, soil fertility maintenance, adapting to climate change and overall food security. Whereas kharif (monsoon/rainy season crop) foodgrain production largely depends on summer monsoons, the rabi season (post-rainy season/winter crop) rainfall is too little to exert a direct influence. In spite of larger acreage under kharif foodgrain crops, total fertiliser consumption during kharif and rabi seasons is comparable. Negative rainfall anomalies (deficit) adversely affected total fertiliser consumption and their use efficiency. Despite significant differences in fertiliser application rates, the response to applied fertiliser nutrients is almost similar in the two seasons. This implies that nutrient use efficiency (NUE) has a ‘manageable’ and an ‘unmanageable’ component wherein 4R practices are difficult to implement under unfavourable kharif weather conditions. Partial factor productivity of fertilizer nutrients (PFPF) has continuously declined over decades mainly because of depletion of soil organic carbon, imbalanced use of nutrients and inability to maintain soil moisture supplies. These observations plus yield-gap analysis permitted us to conclude that past trends of declining NUE can only be reversed through a shift either in sustainable land management practices or enhancing the genetic yield potential/ biomass of crop cultivars or by combining both and making kharif crop planting independent of monsoons rains through direct dry seeding.
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Jagadheesha, D., and R. Ramesh. "Past monsoons : A review of proxy data and modelling." MAUSAM 52, no. 1 (December 29, 2021): 275–84. http://dx.doi.org/10.54302/mausam.v52i1.1694.
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Recent modelling studies have given insight into the role of internal feedback processes among components of the climate system on the evolution of monsoon strength since the Last Glacial Maximum (21,000 years ago). Here we present an overview of these modelling studies related to the summer monsoon over India and northern Africa. These studies indicate that the seasonal insolation changes alone do not explain the observed extent of hydrological changes during the early and middle Holocene over northern Africa. To simulate the extent of observed changes during this period incorporation of vegetation as an active component in climate models appears to be necessary. Over the Indian region, model results show that precipitation-soil moisture feedbacks play an important role in determining the response of the monsoon to changes in insolation and glacial-age surface boundary conditions. Indian monsoon strength from proxy records during the early and middle. Holocene have also been used in conjunction with coupled ocean atmosphere general circulation model experiments to refute the suggestion that semi-permanent warm surface conditions prevailed over equatorial Pacific ocean from 11 to 5ka.
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Parker, Sarah E., Sandy P. Harrison, Laia Comas-Bru, Nikita Kaushal, Allegra N. LeGrande, and Martin Werner. "A data–model approach to interpreting speleothem oxygen isotope records from monsoon regions." Climate of the Past 17, no. 3 (June 4, 2021): 1119–38. http://dx.doi.org/10.5194/cp-17-1119-2021.
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Abstract. Reconstruction of past changes in monsoon climate from speleothem oxygen isotope (δ18O) records is complex because δ18O signals can be influenced by multiple factors including changes in precipitation, precipitation recycling over land, temperature at the moisture source, and changes in the moisture source region and transport pathway. Here, we analyse >150 speleothem records of the Speleothem Isotopes Synthesis and AnaLysis (SISAL) database to produce composite regional trends in δ18O in monsoon regions; compositing minimises the influence of site-specific karst and cave processes that can influence individual site records. We compare speleothem δ18O observations with isotope-enabled climate model simulations to investigate the specific climatic factors causing these regional trends. We focus on differences in δ18O signals between the mid-Holocene, the peak of the Last Interglacial (Marine Isotope Stage 5e) and the Last Glacial Maximum as well as on δ18O evolution through the Holocene. Differences in speleothem δ18O between the mid-Holocene and the Last Interglacial in the East Asian and Indian monsoons are small, despite the larger summer insolation values during the Last Interglacial. Last Glacial Maximum δ18O values are significantly less negative than interglacial values. Comparison with simulated glacial–interglacial δ18O shows that changes are principally driven by global shifts in temperature and regional precipitation. Holocene speleothem δ18O records show distinct and coherent regional trends. Trends are similar to summer insolation in India, China and southwestern South America, but they are different in the Indonesian–Australian region. Redundancy analysis shows that 37 % of Holocene variability can be accounted for by latitude and longitude, supporting the differentiation of records into individual monsoon regions. Regression analysis of simulated precipitation δ18O and climate variables show significant relationships between global Holocene monsoon δ18O trends and changes in precipitation, atmospheric circulation and (to a lesser extent) source area temperature, whereas precipitation recycling is non-significant. However, there are differences in regional-scale mechanisms: there are clear relationships between changes in precipitation and δ18O for India, southwestern South America and the Indonesian–Australian regions but not for the East Asian monsoon. Changes in atmospheric circulation contribute to δ18O trends in the East Asian, Indian and Indonesian–Australian monsoons, and a weak source area temperature effect is observed over southern and central America and Asia. Precipitation recycling is influential in southwestern South America and southern Africa. Overall, our analyses show that it is possible to differentiate the impacts of specific climatic mechanisms influencing precipitation δ18O and use this analysis to interpret changes in speleothem δ18O.
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Ball, Philip. "India: a turbulent tale of rivers, floods and monsoons." Nature 564, no. 7735 (December 2018): 186–88. http://dx.doi.org/10.1038/d41586-018-07678-2.
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Hasan, Mohd Sayeed Ul, Mufti Mohammad Saif, Nehal Ahmad, Abhishek Kumar Rai, Mohammad Amir Khan, Ali Aldrees, Wahaj Ahmad Khan, Mustafa K. A. Mohammed, and Zaher Mundher Yaseen. "Spatiotemporal Analysis of Future Trends in Terrestrial Water Storage Anomalies at Different Climatic Zones of India Using GRACE/GRACE-FO." Sustainability 15, no. 2 (January 13, 2023): 1572. http://dx.doi.org/10.3390/su15021572.
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This work is a climatological evaluation of terrestrial water storage anomalies (TWSAs), which act as driving forces for sustainable development, in one of the most populous countries of the world. The objective of this work is to evaluate RL06 mascon data from the GRACE and GRACE-FO satellite missions over India to explore seasonal and interannual changes in terrestrial water storage, encompassing an area of ~3.29 million km2 with 285 grid points, from 2002 through to 2020. Several statistical tests are performed to check the homogeneity (i.e., Pettitt’s test, the BRT, the SNHT, and the VNRT). Most of the homogeneous data are found in winter, pre-monsoon, and post-monsoon, approximately above 42% to 47%, and the least are found in monsoons and annual with only 33%, at a 95% significance level. According to Pettitt’s test, the majority of the breakpoints are present in 2014 for winter, 2012 for pre-monsoon, 2011 for monsoons and post-monsoon, and 2008 as well as 2011 for annual. Furthermore, to detect trends and magnitudes we employed the nonparametric MK test, the MMK test, Sen’s slope estimator, and the parametric SLR test. According to the MK and MMK tests, the most significant negative and positive trends indicate the chances of droughts and floods, respectively. The Indo–Gangetic region shows the highest declination. According to Sen’s slope and the SLR test, the most declining magnitude is found in Delhi, Panjab, Uttrakhand, the northern part of Rajasthan, and Uttar Pradesh. Based on our findings, the average declining rate of yearly terrestrial water storage data from the MK, MMK, and SLR tests is −0.0075 m (−0.75 cm/year) from 2002 to 2020. Koppen–Geiger climate zones are also used to depict the seasonal and interannual descriptive statistics of TWSA trends. Interestingly, the annual means of arid desert cold (−0.1788 cm/year) and tropical savanna (−0.1936 cm/year) have the smallest declining trends when compared to other climatic zones. Northern Indian regions’ temperate dry winter, hot/warm summer, and dry arid steppe hot regions show the maximum declining future trend. This study could be useful in planning and managing water resources, agriculture, and the long-term growth of the country by using an intelligent water delivery system.
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Seo, S. Niggol. "Untold Tales of Goats in Deadly Indian Monsoons: Adapt or Rain-Retreat under Global Warming?" Journal of Extreme Events 03, no. 01 (March 2016): 1650001. http://dx.doi.org/10.1142/s2345737616500019.
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This paper examines the unique characteristics of the monsoon climate system and whether Indian farmers can adapt to an even deadlier monsoon climate caused by global climatic shifts. This paper shows that the monsoon climate system can be best captured by the Monsoon Variability Index (MVI) constructed by the present author which is defined as the coefficient of variation in the ratio of monsoon rainfall over non-monsoon rainfall for the 40-year period from 1971 to 2010. Monthly precipitation data are based on the observations at 304 weather stations located across India. This paper shows that the traditional measures of the monsoon climate such as monsoon precipitation do not explain the Indian farmers’ behaviors in response to the climate system. Second, this paper shows that the number of goats owned by farm households increases as the MVI increases, that is, as the monsoon climate intensifies. This paper finds that 50% increase in the MVI leads to 23% increase in the number of goats owned by farms. This means that farmers adapt to even the deadliest climate system, i.e., the monsoon system which often leaves millions of people homeless or dead in a single year. Third, this paper finds that the number of sheep owned declines as monsoon rainfall intensifies but increases if the non-monsoon season temperature warms up. The sheep number is not sensitive to changes in the MVI. This paper shows for the first time the ways farmers adapt to the deadly monsoon climate system. Past studies of climate change and agriculture in India are re-evaluated based on the results and policy implications are described.
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PATTANAIK, D. R., AJIT TYAGI, and ARUN KUMAR. "Dynamical-Empirical forecast for the Indian monsoon rainfall using the NCEP Coupled Modelling System – Application for real time monsoon forecast." MAUSAM 63, no. 3 (January 1, 2022): 433–48. http://dx.doi.org/10.54302/mausam.v63i3.1237.
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The performance of the National Centre for Environmental Prediction’s (NCEP) operational coupled modeling system known as the Climate Forecast System (CFS) is evaluated for the prediction of all India summer monsoon rainfall (AISMR) during June to September (JJAS). The evaluation is based on the hindcast initialized during March, April and May with 15 ensemble members each for 25 years period from 1981 to 2005.The CFS’s hindcast climatology during JJAS of March (lag-3), April (lag-2) and May (lag-1) initial conditions show mostly an identical pattern of rainfall similar to that of observed climatology with both the rainfall maxima (over the west-coast of India and over the head Bay of Bengal region) well captured, with a signification correlation coefficient between the forecast and observed climatology over the Indian monsoon region (bounded by 50°E-110°E and 10°S-35°N) covering Indian land mass and adjoining oceanic region. Although the CFS forecast rainfall is overestimated over the Indian monsoon region, the land only rainfall amount is underestimated compared to observation. The skill of the prediction of monsoon rainfall over the Indian land mass is found to be relatively weak, although it is significant at 95% with a correlation coefficient (CC) of 0.44 with April ensembles.By using CFS predicted JJAS rainfall over the regions of significant CCs, a hybrid dynamical-empirical model is developed for the real time prediction of AISMR, whose skill is found to be much higher (CC significant above 99% level) than the raw CFS forecasts. The dynamical-empirical hybrid forecast applied on real time for 2009 and 2010 monsoons are found to be much closer to the observed AISMR. Thus, when the hybrid model is used there is a correction not only to the sign of the actual forecast as in the case of 2009 monsoon but also to its magnitude and hence can be used as a better tool for the real time prediction of AISMR.
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Sunilkumar, K., T. Narayana Rao, and S. Satheeshkumar. "Assessment of small-scale variability of rainfall and multisatellite precipitation estimates using a meso-rain gauge network measurements from southern peninsular India." Hydrology and Earth System Sciences Discussions 12, no. 10 (October 13, 2015): 10389–429. http://dx.doi.org/10.5194/hessd-12-10389-2015.
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Abstract. This paper describes the establishment of a dense rain gauge network and small-scale variability in rain storms (both in space and time) over a complex hilly terrain in southeast peninsular India. Three years of high-resolution gauge measurements are used to evaluate 3 hourly rainfall and sub-daily variations of four widely used multisatellite precipitation estimates (MPEs). The network consists of 36 rain gauges arranged in a near-square grid area of 50 km × 50 km with an intergauge distance of ~ 10 km. Morphological features of rainfall in two principal monsoon seasons (southwest monsoon: SWM and northeast monsoon: NEM) show marked seasonal differences. The NEM rainfall exhibits significant spatial variability and most of the rainfall is associated with large-scale systems (in wet spells), whereas the contribution from small-scale systems is considerable in SWM. Rain storms with longer duration and copious rainfall are seen mostly in the western quadrants in SWM and northern quadrants in NEM, indicating complex spatial variability within the study region. The diurnal cycle also exhibits marked spatiotemporal variability with strong diurnal cycle at all the stations (except for 1) during the SWM and insignificant diurnal cycle at many stations during the NEM. On average, the diurnal amplitudes are a factor 2 larger in SWM than in NEM. The 24 h harmonic explains about 70 % of total variance in SWM and only ~ 30 % in NEM. The late night-mid night peak (20:00–02:00 LT) observed during the SWM is attributed to the propagating systems from the west coast during active monsoon spells. Correlograms with different temporal integrations of rainfall data (1, 3, 12, 24 h) show an increase in the spatial correlation with temporal integration, but the correlation remains nearly the same after 12 h of integration in both the monsoons. The 1 h resolution data shows the steepest reduction in correlation with intergauge distance and the correlation becomes insignificant after ~30 km in both monsoons. Evaluation of high-resolution rainfall estimates from various MPEs against the gauge rainfall indicates that all MPEs underestimate the weak and heavy rain. The MPEs exhibit good detection skills of rain at both 3 and 24 h resolutions, however, considerable improvement is observed at 24 h resolution. Among different MPEs, Climate Prediction Centre morphing technique (CMORPH) performs better at 3 hourly resolution in both monsoons. The performance of TRMM multisatellite precipitation analysis (TMPA) is much better at daily resolution than at 3 hourly, as evidenced by better statistical metrics than the other MPEs. All MPEs captured the basic shape of diurnal cycle and the amplitude quite well, but failed to reproduce the weak/insignificant diurnal cycle in NEM.
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VERMA, R. K. "Variability of Indian summer monsoon: Relationship with surface air temperature anomalies over northern hemisphere." MAUSAM 44, no. 2 (January 1, 2022): 191–98. http://dx.doi.org/10.54302/mausam.v44i2.3820.
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Thirty year (1950-79) time series of Monsoon Index (MI) is correlated with the gridded surface air temperature data over northern hemisphere land at various time lags of months (i.e., months preceding concurrent and succeeding to the monsoon season) to identify tele-connections of monsoon with the northern hemisphere surface air temperature anomalies. .
Out of three key regions identified which show statistically significant relationship of monsoon rainfall, two regions are in the higher latitudinal belt of 40oN- 70oN over North America and Eurasia which show positive correlations with temperatures during northern winter particularly during January and February. The third region is located over northwest India and adjoining Pakistan, where the maximum positive correlation is observed to occur during the pre-li1onsoon months of April and May. These relationships suggest that cooler northern hemisphere during the preceding seasons of winter/spring over certain key regions are generally associated with below normal summer monsoon rainfall over India and vice-versa which could be useful predictors for long-range forecasting of monsoon.
There are two large regions in the northern tropics, namely, Asian and African monsoons whose temperatures reveal strong negative correlations with monsoon rainfall during the seasons concurrent and subsequent to the summer monsoon season. However, persistence of this relationship for longer period of about two seasons after the monsoon, suggests the dominant influence of ENSO (El. Nino-Southern Oscillation) on tropical climate.
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Recchia, Lucy G., and Valerio Lucarini. "Modelling the effect of aerosol and greenhouse gas forcing on the South Asian and East Asian monsoons with an intermediate-complexity climate model." Earth System Dynamics 14, no. 3 (June 30, 2023): 697–722. http://dx.doi.org/10.5194/esd-14-697-2023.
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Abstract. The South Asian and East Asian summer monsoons are globally significant meteorological features, creating a strongly seasonal pattern of precipitation, with the majority of the annual precipitation falling between June and September. The stability the monsoons is of extreme importance for a vast range of ecosystems and for the livelihoods of a large share of the world's population. Simulations are performed with an intermediate-complexity climate model in order to assess the future response of the South Asian and East Asian monsoons to changing concentrations of aerosols and greenhouse gases. The radiative forcing associated with absorbing aerosol loading consists of a mid-tropospheric warming and a compensating surface cooling, which is applied to India, Southeast Asia, and eastern China both concurrently and independently. The primary effect of increased absorbing aerosol loading is a decrease in summer precipitation in the vicinity of the applied forcing, although the regional responses vary significantly. The decrease in precipitation is not ascribable to a decrease in the precipitable water and instead derives from a reduction in the precipitation efficiency due to changes in the stratification of the atmosphere. When the absorbing aerosol loading is added in all regions simultaneously, precipitation in eastern China is most strongly affected, with a quite distinct transition to a low precipitation regime as the radiative forcing increases beyond 60 W m−2. The response is less abrupt as we move westward, with precipitation in southern India being least affected. By applying the absorbing aerosol loading to each region individually, we are able to explain the mechanism behind the lower sensitivity observed in India and attribute it to remote absorbing aerosol forcing applied over eastern China. Additionally, we note that the effect on precipitation is approximately linear with the forcing. The impact of doubling carbon dioxide levels is to increase precipitation over the region while simultaneously weakening the circulation. When the carbon dioxide and absorbing aerosol forcings are applied at the same time, the carbon dioxide forcing partially offsets the surface cooling and reduction in precipitation associated with the absorbing aerosol response. Assessing the relative contributions of greenhouse gases and aerosols is important for future climate scenarios, as changes in the concentrations of these species has the potential to impact monsoonal precipitation.
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Kumaran, K. P. N., K. M. Nair, Mahesh Shindikar, Ruta B. Limaye, and D. Padmalal. "Stratigraphical and Palynological Appraisal of the Late Quaternary Mangrove Deposits of the West Coast of India." Quaternary Research 64, no. 3 (November 2005): 418–31. http://dx.doi.org/10.1016/j.yqres.2005.08.015.
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AbstractThe organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 14C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540 14C yr B.P.) and the Late Holocene (<4000 14C yr B.P.). Pollen analyses confirm that the deposits are mostly derived from the mangrove vegetation. Peat accumulation during the period 40,000–28,000 14C yr B.P. can be correlated with the excess rainfall, 40–100% greater than modern values, of the Asian summer monsoon. The low occurrence of mangrove between 22,000 and 18,000 14C yr B.P. can be attributed to the prevailing aridity and/or reduced precipitation associated worldwide with Last Glacial Maximum, because exposure surfaces and ferruginous layers are commonly found in intervals representing this period. The high rainfall of 11,000–4000 14C yr B.P. is found to be the most significant as the mangrove reached an optimum growth around 11,000 14C yr B.P. but with periods of punctuated weaker monsoons. From the present and previous studies, it has been observed that after about 5000 or 4000 14C yr B.P., the monsoons became gradually reduced leading to drying up of many of the marginal marine mangrove ecosystems. A case study of Hadi profile provided an insight to the relevance of magnetic susceptibility (χ) to record the ecological shift in Late Holocene.
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TODMAL, RAHUL S., and VISHWAS S. KALE. "Monsoon rainfall variability and rainfed agriculture in the water-scarce Karha Basin, western India." MAUSAM 67, no. 4 (October 1, 2016): 927–38. http://dx.doi.org/10.54302/mausam.v67i4.1421.
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Recent climate projection models indicate that the semi-arid regions of the world are most vulnerable to the impact of climate change. Hence, the understanding of rainfall variability and availability of water resources in water-scarce regions is crucial for planners to formulate annual plan for judicious utilization and distribution of water. In the present study, an attempt is made to evaluate the hydro-meteorological characteristics of the Karha Basin, located in the rain shadow zone of the Western Ghat. Trends in monsoon rainfall, dam storage and the area under some principal crops were analyzed to ascertain their interrelationship. The analyses indicate high inter-annual variability in monsoon rainfall and distinct episodes of above - and below-average monsoon rainfall. There is enough evidence for enhanced monsoon variability during the recent decades and a tendency for weaker monsoons to be associated with El Niño events. The study also provides evidence of changes in the area under major crops with the multi-year fluctuations in monsoon rainfall and dam water storage. The relationship, however, is not as strong as expected and the pattern gets more erratic and confusing in the most recent decades, partly on account of increasing dependence on irrigation. The Karha Basin is already suffering from severe water scarcity. Increasing monsoon variability, seasonality and dependence on groundwater is likely to threaten agriculture and food security. Climate change related impacts are likely to further add to already difficult water management challenges in the basin. It is therefore necessary to plan for new challenges under climate change scenarios.
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Chen, Junming, Ping Zhao, Song Yang, Ge Liu, and Xiuji Zhou. "Simulation and Dynamical Prediction of the Summer Asian–Pacific Oscillation and Associated Climate Anomalies by the NCEP CFSv2." Journal of Climate 26, no. 11 (May 31, 2013): 3644–56. http://dx.doi.org/10.1175/jcli-d-12-00368.1.
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Abstract The Asian–Pacific Oscillation (APO) is a dominant teleconnection pattern linking the climate anomalies over Asia, the North Pacific, and other regions including North America. The National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2) successfully simulates many summer-mean features of the upper-tropospheric temperature, the South Asian high, the westerly and easterly jet streams, and the regional monsoons over Asia and Africa. It also well simulates the interannual variability of the APO and associated anomalies in atmospheric circulation, precipitation, surface air temperature (SAT), and sea surface temperature (SST). Associated with a positive APO are a strengthened South Asian high; a weakened extratropical upper-tropospheric westerly jet stream over North America; strengthened subtropical anticyclones over the Northern Hemisphere oceans; and strengthened monsoons over North Africa, India, and East Asia. Meanwhile, increased precipitation is found over tropical North Africa, South Asia, northern China, and tropical South America; decreased precipitation is seen over subtropical North Africa, the Middle East, central Asia, southern China, Japan, and extratropical North America. Low SAT occurs in North Africa, India, and tropical South America and high SAT appears in extratropical Eurasia and North America. SST increases in the extratropical Pacific and the North Atlantic but decreases in the tropical Pacific. The summer APO and many of the associated climate anomalies can be predicted by the NCEP CFSv2 by up to 5 months in advance. However, the CFSv2 skill of predicting the SAT in the East Asian monsoon region is low.
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Spicer, Robert, Jian Yang, Alexei Herman, Tatiana Kodrul, Galina Aleksandrova, Natalia Maslova, Teresa Spicer, et al. "Paleogene monsoons across India and South China: Drivers of biotic change." Gondwana Research 49 (September 2017): 350–63. http://dx.doi.org/10.1016/j.gr.2017.06.006.
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Reynolds, Mary Bernadette. "Book Review: Fifty Monsoons: Ministry of Change through Women of India." International Bulletin of Missionary Research 25, no. 1 (January 2001): 46. http://dx.doi.org/10.1177/239693930102500124.
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Valsala, Vinu, Yogesh K. Tiwari, Prasanth Pillai, Mathew Roxy, Shamil Maksyutov, and Raghu Murtugudde. "Intraseasonal variability of terrestrial biospheric CO2fluxes over India during summer monsoons." Journal of Geophysical Research: Biogeosciences 118, no. 2 (May 28, 2013): 752–69. http://dx.doi.org/10.1002/jgrg.20037.
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Sinha, Nitesh, Naveen Gandhi, S. Chakraborty, R. Krishnan, MG Yadava, and R. Ramesh. "Abrupt climate change at ~2800 yr BP evidenced by a stalagmite record from peninsular India." Holocene 28, no. 11 (August 2, 2018): 1720–30. http://dx.doi.org/10.1177/0959683618788647.
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This study presents an analysis of the Indian summer monsoon (ISM) rainfall variations for a 1460-year period (1720–3180, Before Present BP: 1950 AD), based on a long record of stable isotopic variations (δ18O) with high temporal resolution (~annual) obtained from a U-Th dated stalagmite from the Kadapa cave in peninsular India. This stalagmite proxy record captures variations associated with wet and dry monsoons on decadal to centennial time-scales, together with a general declining trend in the ISM during the 1460-year period. It is noted that the declining trend of the ISM follows the northern hemispheric summer insolation, which is known to influence the location and strength of the Inter tropical convergence zone (ICTZ). The stalagmite record also indicates an abrupt climate change, characterized by the decline of ISM around 2800 yr BP, as manifested in the enrichment of 18O values. Furthermore, the enriched 18O values around 2800 yr BP are corroborated by changes in the stalagmite growth rate, its trace elemental ratios (Sr/Ca, Ba/Ca and U/Ca) and crystallographic structure. In addition, the decline of ISM around 2800 yr BP coincides with a sudden rise in the atmospheric Δ14C, indicative of reduced solar activity. This period around 2800 yr BP is widely reported as the cold European climate associated with ice debris events in the North Atlantic (also known as the Iron Age Cold Epoch), which were reportedly forced by low solar activity. Syntheses of other available stalagmite records from the Indian region, during the common time-frame, show coherent variations with the Kadapa stalagmite and also the Dongge cave stalagmite (southern China), pointing to synchronous variations of the Indian and the East Asian monsoon systems.
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Zheng, Yangxing, Mark A. Bourassa, and M. M. Ali. "The Impact of Rainfall on Soil Moisture Variability in Four Homogeneous Rainfall Zones of India during Strong, Weak, and Normal Indian Summer Monsoons." Water 14, no. 18 (September 8, 2022): 2788. http://dx.doi.org/10.3390/w14182788.
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This observational study mainly examines the impact of rainfall on Indian soil moisture (SM) variability in four homogeneous rainfall zones (i.e., central India (CI), northwest India (NWI), south peninsula India (SPIN), and northeast India (NEI)) as defined by India Meteorological Department (IMD) during strong, weak, and normal Indian summer monsoons (ISMs), which are determined regionally for each homogeneous rainfall zone separately. This study uses the daily gridded (0.25° × 0.25°) rainfall data set provided by IMD and the daily gridded (0.25° × 0.25°) SM combined product version 06.1 from European Space Agency Climate Change Initiative (ESA CCI) over the period 1992–2020. Results reveal that monthly and seasonal mean SM in NWI, CI, and SPIN are overall higher during strong than during weak ISMs. The daily SM and its dependence on rainfall appear to be region-locked in space and phase-locked in time: Strong correlation and large response to rainfall generally occur in most parts of SPIN and NWI during June (June–July) of strong (weak) ISMs where SM values are relatively small; Weak correlation and small response generally occur in CI and NEI in July-September (August–September) of strong (weak) ISMs where SM values are relatively large. The phase-locked feature is associated with the features of ISMs. The region-locked feature is presumably associated with the local features, such as soil and vegetation types and/or environmental conditions. Both region-locked and phase-locked features cause regional distinct features in SM persistence.
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Namboodiri, K. V. S., P. K. Dileep, and Koshy Mammen. "Climatic Variation at Thumba Equatorial Rocket Launching Station, India." Journal of Climatology 2013 (November 10, 2013): 1–16. http://dx.doi.org/10.1155/2013/680565.
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Long-term (45 years) diversified surface meteorological records from Thumba Equatorial Rocket Launching Station (TERLS), India, were collected and analysed to study the long-term changes in the overall climatology, climatology pertained to a particular observational time, mean daily climatology in temperature, inter-annual variability in temperature, interannual variability in surface pressure, and rainfall for the main Indian seasons—South West and North East monsoons and inter-annual mean monthly anomaly structure in temperature. Results on various analyses show strong and vivid features contributed by climate change for this South Peninsular Indian Arabian Sea Coastal Station, and this paper may be a first time venture which discusses climate change imparted perturbations in several meteorological parameters in different time domains, like a specific time, daily, monthly, and interannually over a station. Being a coastal rocket launching station, climatic change information is crucial for long-term planning of its facilities as well as for various rocket range operational demands.
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Wijesekera, Hemantha W., Emily Shroyer, Amit Tandon, M. Ravichandran, Debasis Sengupta, S. U. P. Jinadasa, Harindra J. S. Fernando, et al. "ASIRI: An Ocean–Atmosphere Initiative for Bay of Bengal." Bulletin of the American Meteorological Society 97, no. 10 (October 1, 2016): 1859–84. http://dx.doi.org/10.1175/bams-d-14-00197.1.
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Abstract Air–Sea Interactions in the Northern Indian Ocean (ASIRI) is an international research effort (2013–17) aimed at understanding and quantifying coupled atmosphere–ocean dynamics of the Bay of Bengal (BoB) with relevance to Indian Ocean monsoons. Working collaboratively, more than 20 research institutions are acquiring field observations coupled with operational and high-resolution models to address scientific issues that have stymied the monsoon predictability. ASIRI combines new and mature observational technologies to resolve submesoscale to regional-scale currents and hydrophysical fields. These data reveal BoB’s sharp frontal features, submesoscale variability, low-salinity lenses and filaments, and shallow mixed layers, with relatively weak turbulent mixing. Observed physical features include energetic high-frequency internal waves in the southern BoB, energetic mesoscale and submesoscale features including an intrathermocline eddy in the central BoB, and a high-resolution view of the exchange along the periphery of Sri Lanka, which includes the 100-km-wide East India Coastal Current (EICC) carrying low-salinity water out of the BoB and an adjacent, broad northward flow (∼300 km wide) that carries high-salinity water into BoB during the northeast monsoon. Atmospheric boundary layer (ABL) observations during the decaying phase of the Madden–Julian oscillation (MJO) permit the study of multiscale atmospheric processes associated with non-MJO phenomena and their impacts on the marine boundary layer. Underway analyses that integrate observations and numerical simulations shed light on how air–sea interactions control the ABL and upper-ocean processes.
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Trott, Corinne B., and Bulusu Subrahmanyam. "Eddy Characteristics and Vertical Structure in the Bay of Bengal during Different Monsoon Regimes." Remote Sensing 15, no. 4 (February 16, 2023): 1079. http://dx.doi.org/10.3390/rs15041079.
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The evolution of mesoscale eddies in the Bay of Bengal (BoB) and their characteristics (number of eddies, radius, amplitude, and eddy kinetic energy) are addressed during all strong, normal, and weak monsoon regimes from 1993 to 2019. Their impacts on the 3–7-day synoptic oscillations of atmospheric precipitation and upper ocean heat content are also assessed. In the western Bay, eddies are located in the meandering East India Coastal Current (EICC). The propagation of coastally trapped Kelvin waves into the Andaman Sea varies with monsoon intensity. Eddies with smaller radii, weaker amplitudes, increased vertical mixing, and deeper vertical extents were found during weak monsoons. Eddy kinetic energy (EKE) of EICC anticyclonic eddies is high (1200–2000 cm2 s−2) in May and November-December during weak and normal monsoon regimes, and EKE attains a maximum off the Sri Lanka coast during the strong monsoon regime. Throughout the Bay, density anomalies at ~100 m depth are influenced by subsurface temperature anomalies, while those at the surface more closely follow salinity anomalies. Wavelet coherence analysis for all three monsoon regimes reveals stronger coherence between eddy amplitude, atmospheric precipitation, and ocean heat content than the number of eddies for both anticyclonic and cyclonic eddies.
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Ravi Kumar, K., Vinu Valsala, Yogesh K. Tiwari, J. V. Revadekar, Prasanth Pillai, Supriyo Chakraborty, and Raghu Murtugudde. "Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons." Atmospheric Environment 142 (October 2016): 229–37. http://dx.doi.org/10.1016/j.atmosenv.2016.07.023.
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Goswami, Kartika, Mahadev Rawat, Manoj K. Jaiswal, and Vishwas S. Kale. "Luminescence chronology of late-Holocene palaeofloods in the upper Kaveri basin, India: An insight into the climate–flood relationship." Holocene 29, no. 6 (March 5, 2019): 1094–104. http://dx.doi.org/10.1177/0959683619831436.
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Instrumental/historic records have helped to understand the extreme flood–climate relationship in the modern environment; however, few studies are available to understand their long-term relation (102–103 years) due to the poor preservation and lack of dating techniques. It remains uncertain whether extreme flooding is linked with long-term wet phases of climate or a random event caused by an unusual downpour irrespective of climate. Luminescence analysis of quartz grains from river/floodplain sediments in the Kaveri basin, southern India, showed heterogeneous bleaching. We demonstrated the successful application of various statistical age models in estimating ages of heterogeneously bleached young sediments. This study shows distinct flood clusters occurred during the times of major shifts in the monsoon climate, from fluvial dormancy to sudden outburst of monsoons (~2 ka), from warmer to colder (onset of ‘Little Ice Age’ (LIA) ~ 14th century), from colder to warmer (end of LIA ~ 19th century) and ~20th century, indicating that climatic pattern can be associated with more frequent occurrences of extreme flood events. The study also shows that the two major flood events of the 20th century reported from the upper Kaveri were produced by high intensity short duration storms, suggesting that not all wet phases are associated with major floods and all dry phases with low floods/droughts. The excellent match of the chronology with the historical data, instrumental data and published literature based on proxy data on the Indian summer monsoon validates the chronology and the potential of sedimentary archives for future palaeoenvironmental reconstruction of the study area.
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Sharma, O. P., H. Le Treut, G. Sèze, L. Fairhead, and R. Sadourny. "Interannual Variations of Summer Monsoons: Sensitivity to Cloud Radiative Forcing." Journal of Climate 11, no. 8 (August 1, 1998): 1883–905. http://dx.doi.org/10.1175/1520-0442-11.8.1883.
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Abstract The sensitivity of the interannual variations of the summer monsoons to imposed cloudiness has been studied with a general circulation model using the initial conditions prepared from the European Centre for Medium-Range Forecasts analyses of 1 May 1987 and 1988. The cloud optical properties in this global model are calculated from prognostically computed cloud liquid water. The model successfully simulates the contrasting behavior of these two successive monsoons. However, when the optical properties of the observed clouds are specified in the model runs, the simulations show some degradation over India and its vicinity. The main cause of this degradation is the reduced land–sea temperature contrast resulting from the radiative effects of the observed clouds imposed in such simulations. It is argued that the high concentration of condensed water content of clouds over the Indian land areas will serve to limit heating of the land, thereby reducing the thermal contrast that gives rise to a weak Somali jet. A countermonsoon circulation is, therefore, simulated in the vector difference field of 850-hPa winds from the model runs with externally specified clouds. This countermonsoon circulation is associated with an equatorial heat source that is the response of the model to the radiative effects of the imposed clouds. Indeed, there are at least two clear points that can be made: 1) the cloud–SST patterns, together, affect the interannual variability; and 2) with both clouds and SST imposed, the model simulation is less sensitive to initial conditions. Additionally, the study emphasizes the importance of dynamically consistent clouds developing in response to the dynamical, thermal, and moist state of the atmosphere during model integrations.
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MANOHAR, G. K., and A. P. KESARKAR. "Climatology of thunderstorm activity over the Indian region : II. Spatial distribution." MAUSAM 55, no. 1 (January 19, 2022): 31–40. http://dx.doi.org/10.54302/mausam.v55i1.854.
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Thunderstorms play important roles in many areas of information about earth-atmosphere relationship. Inspite of this awareness of importance of thunderstorms, it is noted that studies about thunderstorms over India received little attention in the past. Latest (IMD, 1999) climatological monthly data of number of thunderstorm days (Thn), rainy days (Tnr), and rainfall amount (Trr) for 276 Indian observatory stations are analyzed, over 11 geographic regions comprising India, to examine relationship between these parameters. Analysis of Thn and Tnr data sets showed that in the premonsoon season major part of India is strongly dominated by frequent and widespread thunderstorms but with occasional rainy days. However, in the monsoon season on account of very large increase in the rainy days over the thunderstorm days, the Thn-Tnr relationship is reversed. The climatological feature of India in the premonsoon season is noted as a characteristic of cumulonimbus regime of continental convection, and the one in the monsoon season is termed as cumulonimbus regime of monsoonsal convection. The prominence of monsoonal convective regime is therefore very important in deciding the performance of Indian southwest monsoon. The analysis between Trr and Thn was carried out over 11 geographic regions of India in the four seasons of the annual period. Results pertaining to monsoon season showed that the contribution of thunderstorms to rainfall is highest among the other three seasons. It is inferred that thunderstorm’s rain contribution to monsoonal rainfall is significant.
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Pattanaik, D. R., A. K. Sahai, R. Phani Muralikrishna, Raju Mandal, and Avijit Dey. "Active-Break Transitions of Monsoons Over India as Predicted by Coupled Model Ensembles." Pure and Applied Geophysics 177, no. 9 (May 25, 2020): 4391–422. http://dx.doi.org/10.1007/s00024-020-02503-2.
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Pattanaik, D. R., and V. Satyan. "Fluctuations of Tropical Easterly Jet during contrasting monsoons over India: A GCM study." Meteorology and Atmospheric Physics 75, no. 1-2 (November 16, 2000): 51–60. http://dx.doi.org/10.1007/s007030070015.
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Surianarayanan, S., S. Jaya kumar, and S. Jeyaprakash. "Monsoon Agriculture - Suggestieve Methods Using Dependable Inflow & Rainfall for a Command Area." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 729. http://dx.doi.org/10.14419/ijet.v7i3.12.16489.
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In the recent trend of changing environment, the rainfall and the inflow to the reservoir are getting reduced year by year respectively in agricultural field and in river basins. In this paper the dependable inflow into the reservoir and the rainfall in the command area is estimated with the past 30 years data. The statistical methods and formulae (Variance, Mann- Kendall method) are used to determine the dependable inflow and rainfall for both the monsoons. It is found that the inflow is not dependable for South –West monsoon, to do the agriculture, for a normal crop, with medium water requirement.. For the North - East monsoon both the inflow and rainfall are dependable hence the agriculture can be carried out with a single crop (paddy) having more water requirement (or) possible multi-crops, according to the storage in the reservoir and prediction of rainfall in that season. The deductions for other requirements of the dam, losses for evaporation, conveyance etc has been taken into account. The case study is done with the data for 30 years (1982-2012)for a dam in Tamil Nadu, India.
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Smith, Monica L., and Rabindra Kumar Mohanty. "Monsoons, rice production, and urban growth: The microscale management of ‘too much’ water." Holocene 28, no. 8 (May 10, 2018): 1325–33. http://dx.doi.org/10.1177/0959683618771497.
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In discussions of human-environmental dynamics and climate change, treatments of water usually focus on the problem of drought. Monsoon environments constitute a different set of parameters for landscape interactions because of seasonal episodes of water abundance. In this paper, we evaluate the microscale management of routine and anticipated high-water events for the ancient Indian subcontinent, where people used the monsoon cycle to engage in rice farming that in turn supported the growth of cities. Rice production would have encompassed two fluctuating inputs: rural labor, which may have become scarce when villagers left farmlands to become city dwellers; and water, the quantity of which varies dramatically on both a seasonal basis because of the monsoon and on an occasional basis because of tropical cyclones. The abundance of water (even with its risks of overabundance) encompassed numerous logistical challenges but also permitted high productivity within short distances of urban centers. The case study of the ancient city of Sisupalgarh in eastern India illustrates that high levels of productivity per land area enabled city residents to engage in short-distance economies for food production, while maintaining regional contacts through durable-goods trade to mitigate occasional episodes of crop failure in times of major flooding.
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RAO, GAPPA. "Moisture flux and vergence of water vapour over India during drought and good monsoons." MAUSAM 36, no. 1 (April 5, 2022): 97–100. http://dx.doi.org/10.54302/mausam.v36i1.1817.
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Water vapour flux and vergence of moisture during drought and good monsoon seasons over India have been computed. The net moisture vergence over the country have been obtained. The diurnal variations in the fluxes and vergence based on 00 and 12 GMT observations have been evaluated. The contrasting features between the two years are discussed.
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Gu, Dejun, Tim Li, Zhongping Ji, and Bin Zheng. "On the Phase Relations between the Western North Pacific, Indian, and Australian Monsoons*." Journal of Climate 23, no. 21 (November 1, 2010): 5572–89. http://dx.doi.org/10.1175/2010jcli2761.1.
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Abstract The phase relationships of the western North Pacific (WNP) summer monsoon (WNPM) with the Australian monsoon (AM) and Indian monsoon (IM) are investigated using observational rainfall, SST, and NCEP reanalysis data for the period of 1979–2005. It is found that a strong WNPM often follows a strong AM but leads a weak AM, and a significant simultaneous negative correlation appears between WNPM and IM. The in-phase relationship from AM to the succeeding WNPM occurs often during the El Niño decaying phase when the warm eastern Pacific SST anomaly (SSTA) weakens AM through anomalous Walker circulation and the persistence of an anomalous WNP anticyclone from the boreal winter to summer leads to a weak WNPM. The out-of-phase relation from WNPM to the succeeding AM occurs either during the El Niño early onset year when the warm SSTA in June–August (JJA) is strong enough to force a low-level cyclonic flow anomaly in WNP and in December–February (DJF) the same warm SSTA forces a weak AM, or during the El Niño decaying phase when the persistence of the WNP anomalous anticyclone causes a weak WNPM and the transition of a warm to a cold episode causes a strong AM in DJF. The simultaneous negative correlation between WNPM and IM often appears either during the El Niño early onset years when the warm eastern Pacific SSTA induces the cyclonic wind shear that strengthens WNPM but suppresses convection over India, or during the El Niño decaying summer when a weak WNPM results from the persistence of the local anomalous anticyclone and a strong IM results from the El Niño-to-La Niña transition or a basin-wide Indian Ocean warming.
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Hao, Yuqian, Boqi Liu, Congwen Zhu, and Shuangmei Ma. "The Interannual Dominant Covariation Mode of Boreal Summer Monsoon Rainfall during 1979–2014." Journal of Climate 31, no. 11 (May 1, 2018): 4193–213. http://dx.doi.org/10.1175/jcli-d-17-0423.1.
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Abstract The boreal summer monsoon (BSM), which includes the monsoons over India (IND), the western North Pacific (WNP), East Asia (EA), North America (NAM), and North Africa (NAF), shows prominent interannual variation (IAV) in summer precipitation and affects the areas with the largest populations in the world. In the present, the EOF analysis is used to extract the BSM dominant covariation mode during 1979–2014. This mode is featured by the out-of-phase rainfall IAV over the WNP compared with the other BSM members. The BSM covariation mode is closely associated with the upper- and lower-level coupled circulations, which are characterized by two anomalous zonal circulations over the tropical oceans coupled near the date line and an abnormal meridional cell over the WNP and EA regions, respectively. Furthermore, the strength of this mode depends on the phase relationship of rainfall IAV between the WNP and NAM monsoon regions, which is modulated by the seasonal evolution of ENSO events and the resultant SST anomalies (SSTAs) in the tropical Indian Ocean (TIO). The weaker mode is accompanied by the in-phase rainfall IAV between these two regions, along with the persisting ENSO events and stronger SSTAs in the TIO from winter to summer. In the years with fast-decaying ENSO events and the related weaker TIO SSTA, the out-of-phase rainfall IAV between the WNP and NAM region takes place to enhance this mode. A series of AGCM sensitivity experiments could reproduce the anomalies of atmospheric circulation related to the distinct seasonal evolution of ENSO events.
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DE, U. S., and J. C. NATU. "LOW FREQUENCY OSCILLATIONS IN TROPOSPHERIC WINDS DURING CONTRASTING SUMMER MONSOON OVER INDIA." MAUSAM 45, no. 3 (January 1, 2022): 261–66. http://dx.doi.org/10.54302/mausam.v45i3.2486.
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TIle'low frequency Iluctu atio ns in the troposphe ric wind field over India has been studied by spec tnuu~ na l l"i, tech nique. duri ng con trasting mon soons. namely, d rought and good monsoons ba sed on rainfall3cti\il)·. Si~ lliflc ant spectral peaks d urin g these years ha ve bee n iden tified.Zon al wind shea r in the lower tropospher ehan' also bern examin ed and the periodici ty in th e near 4()..day mode have bee n documented . Th e interannual, 'n.riill1i1ily of the mode and its potential as medium range predicti on tool has been examined in therrnpn perspect ive.
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Das, Gaurab Nandi, Zdenek Faltynek Fric, Shristee Panthee, Jatishwor Singh Irungbam, and Martin Konvicka. "Geography of Indian Butterflies: Patterns Revealed by Checklists of Federal States." Insects 14, no. 6 (June 13, 2023): 549. http://dx.doi.org/10.3390/insects14060549.
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Butterflies are widely used to analyze biogeographical patterns, both at the global and regional scales. Thus far, most of the latter originated from well-surveyed northern regions, while the species-rich tropical areas lag due to a lack of appropriate data. We used checklists of 1379 butterfly species recorded in 36 federal states of the Republic of India (1) to explore the basic macroecological rules, and (2) to relate species richness and the distribution of endemics and geographic elements to geography, climate, land covers and socioeconomic conditions of the states. The area, land covers diversity and latitude did not affect species richness, whereas topographic diversity and the precipitation/temperature ratio (energy availability) were positive predictors. This is due the geographic and climatic idiosyncrasies of the Indian subcontinent, with its highest species richness in the small, densely forested mountainous northeast that receives summer monsoons. The peninsular effect that decreases the richness towards the tip of subcontinent is counterbalanced by the mountainous forested Western Ghats. Afrotropical elements are associated with savannahs, while Palearctic elements are associated with treeless habitats. The bulk of Indian butterfly richness, and the highest conservation priorities, overlap with global biodiversity hotspots, but the mountainous states of the Western Himalayas and the savannah states of peninsular India host distinctive faunas.
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Paul, S. K., S. K. Bartarya, Piyoosh Rautela, and A. K. Mahajan. "Catastrophic mass movement of 1998 monsoons at Malpa in Kali Valley, Kumaun Himalaya (India)." Geomorphology 35, no. 3-4 (November 2000): 169–80. http://dx.doi.org/10.1016/s0169-555x(00)00032-5.
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