Log in

Relevant bibliographies by topics / Refractivity / Journal articles

To see the other types of publications on this topic, follow the link: Refractivity.

Journal articles on the topic 'Refractivity'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 July 2025

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Refractivity.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Bodine, David, Dan Michaud, Robert D. Palmer, et al. "Understanding Radar Refractivity: Sources of Uncertainty." Journal of Applied Meteorology and Climatology 50, no. 12 (2011): 2543–60. http://dx.doi.org/10.1175/2011jamc2648.1.

Full text

Abstract:

AbstractThis study presents a 2-yr-long comparison of Weather Surveillance Radar-1988 Doppler (WSR-88D) refractivity retrievals with Oklahoma Mesonetwork (“Mesonet”) and sounding measurements and discusses some challenges to implementing radar refractivity operationally. Temporal and spatial analyses of radar refractivity exhibit high correlation with Mesonet data; however, periods of large refractivity differences between the radar and Mesonet are observed. Several sources of refractivity differences are examined to determine the cause of large refractivity differences. One source for nonklys

APA, Harvard, Vancouver, ISO, and other styles

2

Weckwerth, Tammy M., Crystalyne R. Pettet, Frédéric Fabry, Shin Ju Park, Margaret A. LeMone, and James W. Wilson. "Radar Refractivity Retrieval: Validation and Application to Short-Term Forecasting." Journal of Applied Meteorology 44, no. 3 (2005): 285–300. http://dx.doi.org/10.1175/jam-2204.1.

Full text

Abstract:

Abstract This study will validate the S-band dual-polarization Doppler radar (S-Pol) radar refractivity retrieval using measurements from the International H2O Project conducted in the southern Great Plains in May–June 2002. The range of refractivity measurements during this project extended out to 40–60 km from the radar. Comparisons between the radar refractivity field and fixed and mobile mesonet refractivity values within the S-Pol refractivity domain show a strong correlation. Comparisons between the radar refractivity field and low-flying aircraft also show high correlations. Thus, the r

APA, Harvard, Vancouver, ISO, and other styles

3

Oyewole, Olayinka J., Christopher Sirola, Anwaoy Pandit, and Samson Ayo. "The Study of Altitudinal Refractivity and Refractivity Gradient Variations by Weather Parameters in Some Selected Locations in Nigeria." Physical Science International Journal 29, no. 3 (2025): 42–49. https://doi.org/10.9734/psij/2025/v29i3882.

Full text

Abstract:

Weather parameters such as pressure, temperature and humidity significantly affect the altitudinal refractivity and refractivity gradients which in return impact the propagation of the radio wave. The alteration in these parameters changes the atmospheric refractive index. Radio refractivity expresses the degree at which a radio signal bends when it travels through the atmosphere. This study examines weather parameters effects on the altitudinal refractivity and refractivity in some selected locations in Nigeria using existing mathematical models relating them with some meteorological paramete

APA, Harvard, Vancouver, ISO, and other styles

4

Feng, Ya-Chien, and Frédéric Fabry. "Quantifying the Error of Radar-Estimated Refractivity by Multiple Elevation and Dual-Polarimetric Data." Journal of Atmospheric and Oceanic Technology 35, no. 10 (2018): 1897–911. http://dx.doi.org/10.1175/jtech-d-18-0008.1.

Full text

Abstract:

AbstractTo properly use radar refractivity data quantitatively, good knowledge of its errors is required. The data quality of refractivity critically depends on the phase measurements of ground targets that are used for the refractivity estimation. In this study, the observational error structure of refractivity is first estimated based on quantifying the uncertainties of phase measurements, data processing, and the refractivity estimation method. New correlations between the time series of phase measurements at different elevation angles and between polarizations are developed to assess the b

APA, Harvard, Vancouver, ISO, and other styles

5

Feng, Ya-Chien, Frédéric Fabry, and Tammy M. Weckwerth. "Improving Radar Refractivity Retrieval by Considering the Change in the Refractivity Profile and the Varying Altitudes of Ground Targets." Journal of Atmospheric and Oceanic Technology 33, no. 5 (2016): 989–1004. http://dx.doi.org/10.1175/jtech-d-15-0224.1.

Full text

Abstract:

AbstractAccurate radar refractivity retrievals are critical for quantitative applications, such as assimilating refractivity into numerical models or studying boundary layer and convection processes. However, the technique as originally developed makes some simplistic assumptions about the heights of ground targets () and the vertical gradient of refractivity (). In reality, the field of target phases used for refractivity retrieval is noisy because of varying terrain and introduces estimation biases. To obtain a refractivity map at a constant height above terrain, a 2D horizontal refractivity

APA, Harvard, Vancouver, ISO, and other styles

6

Kirschenstein, Małgorzata, and Kamil Krasuski. "Designation of the Troposphere Radio Refractivity for the Area of the Military Aerodrome in Dęblin." Journal of KONBiN 49, no. 3 (2019): 137–58. http://dx.doi.org/10.2478/jok-2019-0054.

Full text

Abstract:

Abstract The radio refractivity is one of major parameters in troposphere monitoring over a selected military aerodrome. The paper makes an in-depth analysis and description of the results of radio refractivity of the troposphere zone. The radio refractivity of the troposphere zone was estimated for the area of the military aerodrome EPDE in Dęblin, Poland. The radio refractivity of the troposphere zone was calculated using empirical troposphere models for the GNSS satellite technique as well as real meteorological data from the SYNOP message. In the paper, the authors demonstrate the results

APA, Harvard, Vancouver, ISO, and other styles

7

VENKATRAMAN, SQN LDR C. N. "Radio climatology of Gauhati." MAUSAM 23, no. 4 (2022): 537–42. http://dx.doi.org/10.54302/mausam.v23i4.5316.

Full text

Abstract:

An attempt has been made to study the pattern of radio refractivity of air over Gauhati from the surface to the 700.mb level. It is noticed that the variations in the surface values of refractivity do not reflect and are not correlated with the changes in the, ertioal profile of refractivity. Fluctuations in refractivity are not always the highest at the surface, stoadily decreasing upwards. Ideas about models of refractivity derived from studies in the temperate countries need to be modified before they can find application in tropical countries like India. The occurrence of super-refraction

APA, Harvard, Vancouver, ISO, and other styles

8

Sabiru, Aminu Yar`adua, Akinbolati Akinsanmi, and Florence N. Ikechiamaka. "Temporal Analysis of Radio Refractivity Variation over Kaduna: Implications for Radio Wave Communication Systems." UMYU Scientifica 4, no. 2 (2025): 100–108. https://doi.org/10.56919/usci.2542.012.

Full text

Abstract:

Study’s Excerpt:• Refractivity in Nigeria’s savannah is stable yearly (±13 N) but swings monthly (112 N) with wet/dry seasons.• Humidity, not temperature, drives refractivity peaks (391 N) in October rains, setting a new regional record.• ERA5 data is valid for West African refractivity, bridging ground data gaps for climate-based models.• Guides adaptive systems (antenna/power tuning) to boost telecom planning in Nigeria’s savannah zones.• Kaduna’s refractivity aligns with rainforest, not savannah, challenging assumptions on regional propagation.Full Abstract: Surface radio refractivity is a

APA, Harvard, Vancouver, ISO, and other styles

9

Usman, S. L., F. N. Ikechiamaka, A. Akinbolati, J. A. Owolabi, and C. O. Akusu. "Exploring vertical gradients of radio refractivity and their significance for radio wave propagation in Abuja, Jos and Makurdi of North-Central Nigeria." Science World Journal 19, no. 1 (2024): 58–63. http://dx.doi.org/10.4314/swj.v19i1.8.

Full text

Abstract:

Vertical radio refractivity gradients are essential for monitoring propagation conditions when designing and planning terrestrial radio links for communications in the lower atmosphere. Average data gathered from meteorological factors such as temperature, pressure, and relative humidity was used from 1980 to 2020 n this study. This study focuses on the vertical gradient of radio refractivity within the lower atmospheric layer, investigating its influence on factors like signal propagation, route clearance, and line-of-sight communication. The analysis encompasses three cities - Abuja, Makurdi

APA, Harvard, Vancouver, ISO, and other styles

10

Sa’adu, L., Bawa, M., and Bello, M. "A Review on the Effects of Radio Refractivity and Atmospheric Parameters on Signal Quality at Ultra High Frequency (UHF)." International Journal of Science for Global Sustainability 6, no. 2 (2020): 9. http://dx.doi.org/10.57233/ijsgs.v6i2.112.

Full text

Abstract:

Refractivity is an important factor in predicting the performance of radio link. The structures of the refractive index of the troposphere are responsible for many complicated mechanisms such as, multipath effects, absorption, scattering of radio signals, etc. and these mechanisms can cause a lot of propagation impairment such as, loss of signal for mobile communication, the accuracy of tracking radio source (such as stars) with radio telescopes, radar system etc. Understanding the effects of the weather on radio wave propagation will help to improve the quality of radio signals, as the Weathe

APA, Harvard, Vancouver, ISO, and other styles

11

Zhao, Xiaofeng. "“Refractivity-from-clutter” based on local empirical refractivity model." Chinese Physics B 27, no. 12 (2018): 128401. http://dx.doi.org/10.1088/1674-1056/27/12/128401.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Sani Otto, Muhammed, O. J. Abimbola, O. A. Falaiye, F. U. Muhammad, and A. A. Sule. "QUARTERLY VARIATION OF TROPOSPHERIC SURFACE REFRACTIVITY IN ILORIN, NIGERIA." Malaysian Journal of Science 42, no. 3 (2023): 85–91. http://dx.doi.org/10.22452/mjs.vol42no3.11.

Full text

Abstract:

To construct a radio communication system, there is need for extensive knowledge of the refractivity and its variations. This work aims to determine the change in season with tropospheric surface refractivity of Ilorin, Kwara, Nigeria. The refractivity for both dry (1st quarter) and rainy (3rd quarter) seasons for 2000 - 2002 have been calculated using the meteorological data obtained from the Nigerian Meteorological Agency, Ilorin. The result shows that there is a variation between tropospheric surface refractivity during the dry and rainy seasons. High refractivity during the rainy season th

APA, Harvard, Vancouver, ISO, and other styles

13

Adegboyega, Gabriel Adisa, and Temitope Sadiq. "Diurnal Variation of Surface Radio Refractivity Over Three Meteorological Stations in Nigeria." Journal of Communications Technology, Electronics and Computer Science 6 (June 27, 2016): 6. http://dx.doi.org/10.22385/jctecs.v6i0.104.

Full text

Abstract:

Analysis and study of the vertical variation of refractivity in the troposphere is required for radio systems planning in order to achieve successful operation. The diurnal variation of surface radio refractivity over three meteorological stations in Nigeria is presented. The stations include Lagos-Ikeja (6⁰35’N, 3⁰40’E), Akure (7⁰15’09”N, 5⁰11’35”E) and Minna (9⁰37’N, 6⁰32’E). Monthly mean values of temperature, pressure and relative humidity were used to compute refractivity for three stations. The surface refractivity also shows latitudinal and seasonal variation. The maximum refractivity v

APA, Harvard, Vancouver, ISO, and other styles

14

Enice Sanyaolu, Modupe, and Sanyaolu Olufemi. "Seasonal and latitudinal variations of surface radio refractivity over Nigeria." Indonesian Journal of Electrical Engineering and Computer Science 28, no. 3 (2022): 1548. http://dx.doi.org/10.11591/ijeecs.v28.i3.pp1548-1553.

Full text

Abstract:

Refractivity is a significant challenge of radio signal propagation. As it often distorts or leads to loss of signals. The seasonal and latitudinal variations of surface refractivity at three Nigerian tropospheric Observatory stations in Nigeria, namely Port-Harcourt, Lagos, and Makurdi, are presented in this paper. Values of monthly averages of pressure, temperature, relative humidity, and water vapour from the stations were used to compute surface refractivity at each station. The results show that the values of surface refractivity increase from the arid region in the north to the coastal a

APA, Harvard, Vancouver, ISO, and other styles

15

Akpootu, D. O., Z. Aminu, I. Nouhou, et al. "Assessment of Tropospheric Radio Refractivity and Its Variation with Climatic Variables Over Zaria, Nigeria." Dutse Journal of Pure and Applied Sciences 10, no. 1b (2024): 243–55. http://dx.doi.org/10.4314/dujopas.v10i1b.25.

Full text

Abstract:

To achieve optimal performances, radio link/system planning and design must take radio refractivity estimation very seriously. This study utilizes measured average daily temperature, relative humidity, and atmospheric pressure for forty-one-year period (1981–2021) obtained from the National Aeronautics and Space Administration (NASA) archives for Zaria (latitude 11.100 N, longitude 7.680 E) strategically located in Nigeria’s midland climate zone to calculate the monthly tropospheric radio refractivity and look into how it varies with other meteorological factors and radio refractive index. The

APA, Harvard, Vancouver, ISO, and other styles

16

Akpootu, Davidson Odafe, Z. Aminu, A. Yusuf, et al. "INVESTIGATION OF TROPOSPHERIC RADIO REFRACTIVITY AND OTHER RELEVANT PARAMETERS USING METEOROLOGICAL VARIABLES OVER BAUCHI, NIGERIA." FUDMA JOURNAL OF SCIENCES 8, no. 2 (2024): 306–14. http://dx.doi.org/10.33003/fjs-2024-0802-2366.

Full text

Abstract:

The National Aeronautics and Space Administration (NASA) archives were used in this work to obtain the measured monthly average daily temperature, relative humidity, and atmospheric pressure over a 41-years period (1981–2021) for Bauchi (latitude , longitude ) to calculate the monthly tropospheric radio refractivity. The site is located in Nigeria's midland climate zone. We also looked into the variation with other factors, the refractivity gradient, and the percentage contribution of the dry term (Ndry) and wet term (Nwet) radio refractivity. The results showed that during the rainy and dry s

APA, Harvard, Vancouver, ISO, and other styles

17

Eunice, Sanyaolu Modupe, and Sanyaolu Olufemi. "Seasonal and latitudinal variations of surface radio refractivity over Nigeria." Indonesian Journal of Electrical Engineering and Computer Science 28, no. 3 (2022): 1548–53. https://doi.org/10.11591/ijeecs.v28.i3.pp1548-1553.

Full text

Abstract:

Refractivity is a significant challenge of radio signal propagation. As it often distorts or leads to loss of signals. The seasonal and latitudinal variations of surface refractivity at three Nigerian tropospheric Observatory stations in Nigeria, namely Port-Harcourt, Lagos, and Makurdi, are presented in this paper. Values of monthly averages of pressure, temperature, relative humidity, and water vapour from the stations were used to compute surface refractivity at each station. The results show that the values of surface refractivity increase from the arid region in the north to the coastal a

APA, Harvard, Vancouver, ISO, and other styles

18

Zhao, Xiaofeng, and Sixun Huang. "Estimation of Atmospheric Duct Structure Using Radar Sea Clutter." Journal of the Atmospheric Sciences 69, no. 9 (2012): 2808–18. http://dx.doi.org/10.1175/jas-d-12-073.1.

Full text

Abstract:

Abstract Retrieving atmospheric refractivity profiles from the sea surface backscattered radar clutter is known as the refractivity-from-clutter (RFC) technique. Because the relationship between refractivity and radar sea clutter is clearly nonlinear and ill posed, it is difficult to get analytical solutions according to current theories. Previous works treat this problem as a model parameter estimation issue and some optimization algorithms are selected to get approximate solutions. Two main factors that limit the accuracy of the estimation are that 1) the refractive environments are describe

APA, Harvard, Vancouver, ISO, and other styles

19

Heinselman, P. L., B. L. Cheong, R. D. Palmer, D. Bodine, and K. Hondl. "Radar Refractivity Retrievals in Oklahoma: Insights into Operational Benefits and Limitations." Weather and Forecasting 24, no. 5 (2009): 1345–61. http://dx.doi.org/10.1175/2009waf2222256.1.

Full text

Abstract:

Abstract The 2007 and 2008 spring refractivity experiments at KTLX investigated the potential utility of high-resolution, near-surface refractivity measurements to operational forecasting. During these experiments, forecasters at the Norman, Oklahoma, National Weather Service Forecast Office (NWSFO) assessed refractivity and scan-to-scan refractivity change fields retrieved from the Weather Surveillance Radar-1988 Doppler weather radar near Oklahoma City—Twin Lakes, Oklahoma (KTLX). Both quantitative and qualitative analysis methods were used to analyze the 41 responses from seven forecasters

APA, Harvard, Vancouver, ISO, and other styles

20

Bello, Gazali, Davidson Odafe Akpootu, and Salihu Bolaji Sharafa. "Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria." European Journal of Theoretical and Applied Sciences 2, no. 3 (2024): 88–104. http://dx.doi.org/10.59324/ejtas.2024.2(3).10.

Full text

Abstract:

In studies involving terrestrial atmospheric electromagnetic propagation, such as point-to-point microwave communication, terrestrial radio, television radio, television broadcast, and mobile communication systems, radio refractivity—the bending of a radio signal as it propagates through media—is crucial. In this study, the seasonal tropospheric radio refractivity was estimated and its variations with other meteorological parameters and refractive index were investigated using the measured monthly climatic data of atmospheric pressure, relative humidity, and temperature obtained from the Natio

APA, Harvard, Vancouver, ISO, and other styles

21

Gazali, Bello, Odafe Akpootu Davidson, and Bolaji Sharafa Salihu. "Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria." European Journal of Theoretical and Applied Sciences 2, no. 3 (2024): 88–104. https://doi.org/10.59324/ejtas.2024.2(3).10.

Full text

Abstract:

In studies involving terrestrial atmospheric electromagnetic propagation, such as point-to-point microwave communication, terrestrial radio, television radio, television broadcast, and mobile communication systems, radio refractivity—the bending of a radio signal as it propagates through media—is crucial. In this study, the seasonal tropospheric radio refractivity was estimated and its variations with other meteorological parameters and refractive index were investigated using the measured monthly climatic data of atmospheric pressure, relative humidity, and temperature obtained fr

APA, Harvard, Vancouver, ISO, and other styles

22

Modupe Eunice, Sanyaolu. "Evaluation of Vertical Refractivity Profile over Microwave Link in Mowe, Nigeria." International Journal of Microwave Engineering 6, no. 4 (2021): 1–6. http://dx.doi.org/10.5121/jmicro.2021.6401.

Full text

Abstract:

The radio refractive index structure of the lower section of the atmospheric boundary layer is critical in the planning and construction of microwave communication connections. This study analyses the refractivity profile carried out in Mowe (6.8085° N, 3.4367° E) South – Western Nigeria. Ground measurements of air pressure, temperature, and relative humidity used in this investigation were collected from the rain gauge of the Tropospheric Observatory Data Acquisition Network (TRODAN). The radio refractivity, associated refractivity gradient and climatic factor were computed using data from Ja

APA, Harvard, Vancouver, ISO, and other styles

23

Nielsen, Johannes K., Hans Gleisner, Stig Syndergaard, and Kent B. Lauritsen. "Estimation of refractivity uncertainties and vertical error correlations in collocated radio occultations, radiosondes, and model forecasts." Atmospheric Measurement Techniques 15, no. 20 (2022): 6243–56. http://dx.doi.org/10.5194/amt-15-6243-2022.

Full text

Abstract:

Abstract. Random uncertainties and vertical error correlations are estimated for three independent data sets. The three collocated data sets are (1) refractivity profiles of radio occultation measurements retrieved from the Metop-A and B and COSMIC-1 missions, (2) refractivity derived from GRUAN-processed RS92 sondes, and (3) refractivity profiles derived from ERA5 forecast fields. The analysis is performed using a generalization of the so-called three-cornered hat method to include off-diagonal elements such that full error covariance matrices can be calculated. The impacts from various sourc

APA, Harvard, Vancouver, ISO, and other styles

24

Jang, Doyoung, Jongmann Kim, Yong Bae Park, and Hosung Choo. "Study of an Atmospheric Refractivity Estimation from a Clutter Using Genetic Algorithm." Applied Sciences 12, no. 17 (2022): 8566. http://dx.doi.org/10.3390/app12178566.

Full text

Abstract:

In this paper, a method for estimating atmospheric refractivity from sea and land clutters is proposed. To estimate the atmospheric refractivity, clutter power spectrums based on an artificial tri-linear model are calculated using an Advanced Refractive Prediction System (AREPS) simulator. Then, the clutter power spectrums are again obtained based on the measured atmospheric refractivity data using the AREPS simulator. In actual operation, this spectrum from measured reflectivity can be replaced with real-time clutter spectrums collected from radars. A cost function for the genetic algorithm (

APA, Harvard, Vancouver, ISO, and other styles

25

Chen, Shu-Ya, Ching-Yuang Huang, Ying-Hwa Kuo, and Sergey Sokolovskiy. "Observational Error Estimation of FORMOSAT-3/COSMIC GPS Radio Occultation Data." Monthly Weather Review 139, no. 3 (2011): 853–65. http://dx.doi.org/10.1175/2010mwr3260.1.

Full text

Abstract:

Abstract The Global Positioning System (GPS) radio occultation (RO) technique is becoming a robust global observing system. GPS RO refractivity is typically modeled at the ray perigee point by a “local refractivity operator” in a data assimilation system. Such modeling does not take into account the horizontal gradients that affect the GPS RO refractivity. A new observable (linear excess phase), defined as an integral of the refractivity along some fixed ray path within the model domain, has been developed in earlier studies to account for the effect of horizontal gradients. In this study, the

APA, Harvard, Vancouver, ISO, and other styles

26

López, Rubén Nocelo, Verónica Santalla del Rio, and Brais Sánchez-Rama. "Refractivity Observations from Radar Phase Measurements: The 22 May 2002 Dryline Case during IHOP Project." Atmosphere 15, no. 1 (2023): 33. http://dx.doi.org/10.3390/atmos15010033.

Full text

Abstract:

The dryline, often associated with the development of severe storms in the Southern Great Plains of the United States of America, is a boundary layer phenomenon that occurs when a warm and moist air mass from the Gulf of Mexico meets a hot and dry air mass from the southwest desert area. An accurate knowledge of the water vapor spatio-temporal variability in the lower part of the atmosphere is crucial for a better understanding of the evolution of the dryline. The tropospheric refractivity, directly related to water vapor content, is a proxy for the water vapor content of the troposphere. It h

APA, Harvard, Vancouver, ISO, and other styles

27

Familusi, T. O., T. Ewetumo, K. D. Adedayo, and J. S. Ojo. "Assessment of Radio Refractivity and Frequency Modulated Radio Signal Strength Variability with Time in Broadcasting System using Osun State Broadcasting Cooperation (OSBC), FM 104.5 MHz as a Reference Station." International Journal of Innovative Science and Research Technology 7, no. 4 (2022): 1479–89. https://doi.org/10.5281/zenodo.6655115.

Full text

Abstract:

Radio Refractivity and frequency modulated radio signal strength were simultaneously synchronized through a self-developed frequency modulated radio signal Strength (FMRSS) and radio refractivity (RF) Meter to acquire data for this research work. The meter was tuned to Osun State Broadcasting Cooperation (OSBC) at FM 104.5 MHz to acquire data over period of 66 days from 23/11/2021 to 05/12/2021, 17/12/2021to 31/12/2021 and 01/01/2022 to 05/02/2022 respectively. The data were processed and the result viewed to infer the relationship between radio refractivity and frequency modulated radio signa

APA, Harvard, Vancouver, ISO, and other styles

28

Sokolovskiy, S., Y.-H. Kuo, and W. Wang. "Evaluation of a Linear Phase Observation Operator with CHAMP Radio Occultation Data and High-Resolution Regional Analysis." Monthly Weather Review 133, no. 10 (2005): 3053–59. http://dx.doi.org/10.1175/mwr3006.1.

Full text

Abstract:

Abstract In this study a nonlocal, linear observation operator for assimilating radio occultation data is evaluated. The operator consists of modeling the excess phase, that is, integrating the refractivity along straight lines tangent to rays, below a certain height. The corresponding observable is the excess phase integrated through the Abel-retrieved refractivity, along the same lines, below the same height. The operator allows very simple implementation (computationally efficient) while accurately accounting for the horizontal refractivity gradients. This is due to significant cancellation

APA, Harvard, Vancouver, ISO, and other styles

29

Gasperoni, Nicholas A., Ming Xue, Robert D. Palmer, and Jidong Gao. "Sensitivity of Convective Initiation Prediction to Near-Surface Moisture When Assimilating Radar Refractivity: Impact Tests Using OSSEs." Journal of Atmospheric and Oceanic Technology 30, no. 10 (2013): 2281–302. http://dx.doi.org/10.1175/jtech-d-12-00038.1.

Full text

Abstract:

Abstract The Advanced Regional Prediction System (ARPS) three-dimensional variational (3DVAR) system is enhanced to include the analysis of radar-derived refractivity measurements. These refractivity data are most sensitive to atmospheric moisture content and provide high-resolution information on near-surface moisture that is important to convective initiation (CI) and precipitation forecasting. Observing system simulation experiments (OSSEs) are performed using simulated refractivity data. The impacts of refractivity on CI and subsequent forecasts are investigated in the presence of varying

APA, Harvard, Vancouver, ISO, and other styles

30

Xie, Feiqin, Stig Syndergaard, E. Robert Kursinski, and Benjamin M. Herman. "An Approach for Retrieving Marine Boundary Layer Refractivity from GPS Occultation Data in the Presence of Superrefraction." Journal of Atmospheric and Oceanic Technology 23, no. 12 (2006): 1629–44. http://dx.doi.org/10.1175/jtech1996.1.

Full text

Abstract:

Abstract The global positioning system (GPS) radio occultation (RO) technique has demonstrated the ability to precisely probe earth’s atmosphere globally with high vertical resolution. However, the lowermost troposphere still presents some challenges for the technique. Over moist marine areas, especially in subtropical regions, a very large negative moisture gradient often exists across the thermal inversion capping the marine boundary layer (MBL), which frequently causes superrefraction (SR), or ducting. In the presence of SR, the reconstruction of refractivity from RO data becomes an ill-pos

APA, Harvard, Vancouver, ISO, and other styles

31

Xu, Xiaoze, Wei Han, Jincheng Wang, et al. "Quality assessment of YUNYAO radio occultation data in the neutral atmosphere." Atmospheric Measurement Techniques 18, no. 6 (2025): 1339–53. https://doi.org/10.5194/amt-18-1339-2025.

Full text

Abstract:

Abstract. Global Navigation Satellite System (GNSS) radio occultation (RO) data are an important component of numerical weather prediction (NWP) systems. To incorporate more GNSS-RO data into NWP systems, commercial RO data have become an excellent option. Tianjin Yunyao Aerospace Technology Co., Ltd. (YUNYAO) plans to launch a meteorological constellation of 90 satellites equipped with GNSS-RO instruments, which will significantly increase the amount of GNSS-RO data in NWP systems. This study evaluates the quality of neutral atmospheric refractivity and bending angle profiles from YUNYAO sate

APA, Harvard, Vancouver, ISO, and other styles

32

Sarma, S. B. S. S., and B. M. Reddy. "Development and evaluation of airborne microwave refractometer for studies on atmospheric tropical boundary layer radiorefractive index." Annales Geophysicae 12, no. 8 (1994): 785–93. http://dx.doi.org/10.1007/s00585-994-0785-x.

Full text

Abstract:

Abstract. Observations of high-resolution data on radio refractivity were obtained by the airborne microwave refractometer over the Indian sub-continent (a tropical country) from 1971 to 1988. Detailed vertical and horizontal distributions of radio refractivity on a near-real-time basis in the atmospheric boundary layer were determined . Radiosonde observations cannot detect the thin refractivity gradients which characterize the propagation environment in this low-altitude region. This knowledge is required to design reliable and efficient communication systems for strategic, tactical and oper

APA, Harvard, Vancouver, ISO, and other styles

33

Liu, Hui, Jeffrey Anderson, and Ying-Hwa Kuo. "Improved Analyses and Forecasts of Hurricane Ernesto’s Genesis Using Radio Occultation Data in an Ensemble Filter Assimilation System." Monthly Weather Review 140, no. 1 (2012): 151–66. http://dx.doi.org/10.1175/mwr-d-11-00024.1.

Full text

Abstract:

Abstract Radio occultation (RO) refractivity observations provide information about tropospheric water vapor and temperature in all weather conditions. The impact of using RO refractivity observations on analyses and forecasts of Hurricane Ernesto’s genesis (2006) using an ensemble Kaman filter data assimilation system is investigated. Assimilating RO refractivity profiles in the vicinity of the storm locally moistens the analysis of the lower troposphere and also adjusts the wind analysis in both the lower and upper troposphere through forecast multivariate correlations of RO refractivity and

APA, Harvard, Vancouver, ISO, and other styles

34

Rao, V. V. M. Jagannadha, M. Venkat Ratnam, Y. Durga Santhi, M. Roja Raman, M. Rajeevan, and S. Vijaya Bhaskara Rao. "On the Detection of Onset and Activity of the Indian Summer Monsoon Using GPS RO Refractivity Profiles." Monthly Weather Review 141, no. 6 (2013): 2096–106. http://dx.doi.org/10.1175/mwr-d-12-00180.1.

Full text

Abstract:

Abstract Global positioning system (GPS) radio occultation (RO) data available during 2001–10 have been used to examine the variations in the refractivity during the onset of Indian summer monsoon (ISM) over the east Arabian Sea (5°–15°N, 65°–75°E). An enhancement of 5–10 N-units in the refractivity is observed around 4.8 km (~600 hPa) a few days (9.23 ± 3.6 days) before onset of the monsoon over Kerala, India. This is attributed to moisture buildup over the Arabian Sea during the monsoon onset phase. A sudden increase (1.5–2 K) in mean upper-tropospheric temperature at the time of onset and d

APA, Harvard, Vancouver, ISO, and other styles

35

D., O. Akpootu. "Performance Analysis of Tropospheric Radio Refractivity on Radio Field Strength and Radio Horizon Distance and Its Variation with Meteorological Parameters over Osogbo, Nigeria." International Journal of Advances in Scientific Research and Engineering (ijasre) 5, no. 10 (2019): 81–92. https://doi.org/10.31695/IJASRE.2019.33545.

Full text

Abstract:

<em>Radio refractivity estimation is paramount in the planning and design of radio link/systems for the purpose of achieving optimal performances. In this study, the monthly average daily atmospheric pressure, relative humidity and temperature data obtained from the National Aeronautics and Space Administration (NASA) during the period of twenty two years (July 1983 – June 2005) for Osogbo (Latitude </em><em>7.47 <sup>0</sup>N, Longitude 4.29 <sup>0</sup>E, and 302.0 m above sea level</em><em>) were used to estimate the monthly tropospheric radio refractivity and to investigate its varia

APA, Harvard, Vancouver, ISO, and other styles

36

Akinbolati, A., Idris Adamu, and Tunde Davide Adache. "The Investigation of Surface Radio Refractivity Over Lokoja, Kogi State Nigeria." UMYU Scientifica 3, no. 1 (2024): 144–56. http://dx.doi.org/10.56919/usci.2431.016.

Full text

Abstract:

This research investigated the variation of Surface Radio Refractivity and its propagation effects on radio signals over Lokoja, Kogi State, Nigeria. The study used six years (2015-2020) of satellite data on temperature, pressure, relative humidity and rainfall at the surface (12 km) above ground level. The data retrieved were used to determine the monthly, seasonal, and annual Surface Radio Refractivity value for Lokoja Kogi State. Results show that high Surface Radio Refractivity values were recorded generally during the wet season months compared to the dry season months in all Six years (2

APA, Harvard, Vancouver, ISO, and other styles

37

Akinbolati, Akinsanmi, and Bolanle T. Abe. "The effect of secondary atmospheric parameters on radio wave propagation in a typical Sahel Savannah environment." Edelweiss Applied Science and Technology 9, no. 3 (2025): 7–16. https://doi.org/10.55214/25768484.v9i3.5105.

Full text

Abstract:

The need for radio scientists and engineers to consider the atmospheric dynamics of a region is key in the design of communication links. This study was carried out over Katsina City, in the Sahel parts of Nigeria, using mean monthly atmospheric data covering 1980 to 2020. The data were retrieved from the European Centre for Medium-Range Weather Forecast ERA-5 Reanalysis. Refractivity at the surface, 100 m, and 250 m, refractivity gradient (G), and effective earth radius factor (k-factor) were determined using the International Telecommunications Union-Radio Study Group (ITU-R) Recommendation

APA, Harvard, Vancouver, ISO, and other styles

38

O, Akpootu, D., Bello, G, and Sharafa, S. B. "Investigation of Tropospheric Radio Refractivity and other Relevant Parameters across Some Selected Locations in the Sahelian Region of Nigeria." Saudi Journal of Engineering and Technology 9, no. 11 (2024): 492–508. http://dx.doi.org/10.36348/sjet.2024.v09i11.001.

Full text

Abstract:

The troposphere's internal processes are complex and exhibit nonlinear trends, which have a significant impact on the transmission and reception of high-quality signals worldwide. This study used measured monthly climatic data of temperature, relative humidity, and atmospheric pressure for Maiduguri and Sokoto from the National Aeronautic and Space Administration (NASA) over a forty-two-years period (1981 to 2022) to estimate the seasonal tropospheric radio refractivity and examine its variations with other meteorological parameters and refractive index. The refractivity gradiant, effective ea

APA, Harvard, Vancouver, ISO, and other styles

39

Sokolovskiy, Sergey, Ying-Hwa Kuo, and Wei Wang. "Assessing the Accuracy of a Linearized Observation Operator for Assimilation of Radio Occultation Data: Case Simulations with a High-Resolution Weather Model." Monthly Weather Review 133, no. 8 (2005): 2200–2212. http://dx.doi.org/10.1175/mwr2948.1.

Full text

Abstract:

Abstract Assimilation into numerical weather models of the refractivity, Abel-retrieved from radio occultations, as the local refractivity at ray tangent point may result in large errors in the presence of strong horizontal gradients (atmospheric fronts, strong convection). To reduce these errors, other authors suggested modeling the Abel-retrieved refractivity as a nonlocal linear function of the 3D refractivity, which can be used as a linear observation operator for assimiliation. The authors of this study introduce their approach for the nonlocal linear observation operator, which consists

APA, Harvard, Vancouver, ISO, and other styles

40

Falaiye, O. A., O. J. Abimbola, J. Omojola, and D. S. Akinyanju. "SPACIO-TEMPORAL VARIATION OF RADIO REFRACTIVITY IN LAFIA, NASARAWA STATE USING CM SAF ATOVS SATELLITE DATA." FULafia Journal of Science and Technology 2, no. 1 (2016): 111–16. http://dx.doi.org/10.62050/fjst2016.v2n1.40.

Full text

Abstract:

Communications using radio waves propagates through the atmosphere and plays a major role in civilization. Vertical variation of radio refractivity in Lafia( 8.492°N and 8.517°E ) Nigeria, was investigated with a five-year (2010 – 2014) monthly mean atmospheric layered data from the ATOVS (Advanced TIROS (Television InfraRed Observation Satellite) Operational Vertical Sounders) instruments flying onboard the NOAA and Metop-A satellites; this data is provided by the EUMETSAT’s Climate Monitoring Satellite Application Facilities (CM SAF). Using the CM SAF data, at six pressure levels (1000hPa, 8

APA, Harvard, Vancouver, ISO, and other styles

41

Liu, Hui, Jeffrey Anderson, Ying-Hwa Kuo, Chris Snyder, and Alain Caya. "Evaluation of a Nonlocal Quasi-Phase Observation Operator in Assimilation of CHAMP Radio Occultation Refractivity with WRF." Monthly Weather Review 136, no. 1 (2008): 242–56. http://dx.doi.org/10.1175/2007mwr2042.1.

Full text

Abstract:

Abstract A nonlocal quasi-phase radio occultation (RO) observation operator is evaluated in the assimilation of Challenging Minisatellite Payload (CHAMP) radio occultation refractivity using a Weather Research and Forecasting (WRF) ensemble data assimilation system at 50-km resolution. The nonlocal operator calculates the quasi phase through integration of the model refractivity along the observed ray paths. As a comparison, a local refractivity operator that calculates the model refractivity at the observed ray perigee points is also evaluated. The assimilation is done over North America duri

APA, Harvard, Vancouver, ISO, and other styles

42

Lawal, Yusuf Babatunde, Pius Adewale Owolawi, Chunling Tu, Etienne Van Wyk, and Joseph Sunday Ojo. "Machine learning-based models for forecasting radio refractivity over the coastal area of South Africa." Edelweiss Applied Science and Technology 9, no. 1 (2024): 72–80. http://dx.doi.org/10.55214/25768484.v8i6.3109.

Full text

Abstract:

Surface refractivity is a crucial parameter that determines the bending of radio signals as they propagate within the troposphere. It is greatly influenced by the atmospheric weather conditions and changes rapidly, especially in the coastal areas. This research utilized 50 years (1974-2023) surface temperature, pressure, and humidity data from six coastal stations in South Africa to forecast radio refractivity in the Mediterranean climate. Five machine learning models: Gated Recurrent Unit (GRU), Light Gradient Boosting Machine (LightGBM), Long-Short Term Memory (LSTM), Prophet, and Random For

APA, Harvard, Vancouver, ISO, and other styles

43

Bawa, Musa, Afam Uzorka, Living Ounyesiga, and Rabiu Tukur. "Investigating tropospheric radio refractivity variation with weather parameters in Kampala, Uganda: implications for communication systems." International Journal of Physical Research 12, no. 2 (2024): 116–22. http://dx.doi.org/10.14419/10qp7q48.

Full text

Abstract:

The tropospheric radio refractivity plays an important role in the propagation of radio waves and significantly affecting the performance of radio communication systems. This study aims to investigate the influence of weather parameters on tropospheric radio refractivity variation and the implication for communication system in Kampala, Uganda. Through a comprehensive dataset of temperature, humidity and pressure obtained from the National Aeronautics and Space Administration (NASA) archives for Kampala over a period of one year (January 2023 to December 2023). Using the International Telecomm

APA, Harvard, Vancouver, ISO, and other styles

44

Emmanuel, I., K. D. Adedayo, B. Adeyemi, and O. S. Ojo. "Meteorological parameter anomalies and anomalous radio propagation over Nigeria." Nigeria Journal of Pure and Applied Physics 9, no. 1 (2020): 34–50. http://dx.doi.org/10.4314/njpap.v9i1.7.

Full text

Abstract:

Distribution and variation of anomalous radio propagation, temperature and relative humidity anomalies were obtained and analyzed using six years (2010-2015) Era interim data. Seasonal spatial distribution of refractivity gradient and its components were analyzed. The result showed that about 90% of wet component contributed to the variation of refractivity gradient. Highest range of refractivity gradients and its wet components were obtained during the wet season. The result of correlation between ducting occurrence and temperature showed strong negative correlation except in Lagos where posi

APA, Harvard, Vancouver, ISO, and other styles

45

Otto, Muhammed S., Adeniran F. Oluwasesan, OLADIRAN JOHNSON ABIMBOLA, et al. "Quarterly hour variation of surface refractivity and its relation to some atmospheric parameters in Ilorin, North-central Nigeria." Equity Journal of Science and Technology 11, no. 1 (2025): 1–10. https://doi.org/10.4314/equijost.v11i1.1.

Full text

Abstract:

The study investigated the quarterly variations in surface refractivity for Ilorin, North-Central Nigeria. Meteorological data, including air temperature, atmospheric pressure, and relative humidity, were collected from January 2000 to December 2002 at NIMET, Ilorin Airport. These meteorological parameters were averaged over three-hour intervals to determine specific time periods: sunrise (6-8 AM local time), midday (12-2 PM local time), sunset (5-7 PM local time), and midnight (11 PM-1 AM local time). The refractivity was then computed using the collected data. Notably, the quarterly surface

APA, Harvard, Vancouver, ISO, and other styles

46

Sasagawa, Katsuyoshi. "High-Refractivity Optical Material." Kobunshi 43, no. 4 (1994): 290. http://dx.doi.org/10.1295/kobunshi.43.290.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Vaughan, D. J. "Crystal Chemistry and Refractivity." Physics of the Earth and Planetary Interiors 64, no. 1 (1990): 103–4. http://dx.doi.org/10.1016/0031-9201(90)90009-m.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Annersten, Hand Hans. "Crystal chemistry and refractivity." Chemical Geology 90, no. 1-2 (1991): 169. http://dx.doi.org/10.1016/0009-2541(91)90041-o.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

A.D. "Crystal chemistry and refractivity." Journal of Molecular Structure 213 (October 1989): 325–26. http://dx.doi.org/10.1016/0022-2860(89)85138-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Sclar, Charles B. "Crystal chemistry and refractivity." Geochimica et Cosmochimica Acta 53, no. 7 (1989): 1713. http://dx.doi.org/10.1016/0016-7037(89)90261-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!