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Artykuły w czasopismach na temat „Radio refractivity”

Autor: Grafiati

Data publikacji: 3 czerwca 2025

Data aktualizacji: 31 lipca 2025

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1

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.

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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

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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.

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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

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3

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.

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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

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4

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.

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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

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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.

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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

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6

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.

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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

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7

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.

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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

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8

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.

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<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

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9

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.

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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

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10

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.

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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

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11

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.

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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

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12

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.

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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

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13

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.

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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

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14

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.

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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

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15

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.

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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

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16

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.

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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

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17

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.

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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

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18

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.

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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

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19

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.

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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

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20

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.

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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

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21

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.

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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

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22

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.

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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

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23

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.

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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

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Akpootu, D. O., and A. M. Rabiu. "Empirical Models for Estimating Tropospheric Radio Refractivity Over Osogbo, Nigeria." Open Atmospheric Science Journal 13, no. 1 (2019): 43–55. http://dx.doi.org/10.2174/1874282301913010043.

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Background:Estimation of tropospheric radio refractivity is significant in the planning and design of terrestrial communication links.Methods: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 7.470N, Longitude 4.290E, and 302.0 m above sea level) were used to estimate the monthly tropospheric radio refractivity. The monthly average daily global solar radiation with other meteorological param

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Akpootu, D. O., and A. M. Rabiu. "Empirical Models for Estimating Tropospheric Radio Refractivity Over Osogbo, Nigeria." Open Atmospheric Science Journal 13, no. 1 (2019): 43–55. http://dx.doi.org/10.2174/1874282301913010055.

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Background:Estimation of tropospheric radio refractivity is significant in the planning and design of terrestrial communication links.Methods: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 7.470N, Longitude 4.290E, and 302.0 m above sea level) were used to estimate the monthly tropospheric radio refractivity. The monthly average daily global solar radiation with other meteorological param

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Okafor, Joyce Odu, Adeniyi .D. Adebayo, Bassey .E. Donatus, and Kelvin Benjamin Ayibapreye. "CHARACTERIZATION OF THE INFLUENCE OF RADIO WAVE REFRACTIVITY IN SOUTH SOUTH NIGERIA." International Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE) 11, no. 3 (2024): 12–21. https://doi.org/10.5281/zenodo.13740645.

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<strong>Abstract:</strong> This study clarifies the impact of radio wave refractivity on wireless communication systems with a focus on South-South Nigeria. Using a thorough methodology that combines computer models with empirical observations, the study looks into fluctuations in atmospheric conditions and how they affect radio signal transmission. The results highlight how important it is to take refractivity dynamics into consideration while building reliable communication infrastructures that are appropriate for the unique climate of this area. These abstracts are meant to capture the subs

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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.

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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

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S, Jamiyan, Battogtokh J, Tsendayush O, and Nyamjav J. "Seasonal Variations of Surface Radio Refractive Index in Mongolia." Физик сэтгүүл 24, no. 468 (2022): 65–69. http://dx.doi.org/10.22353/physics.v24i468.642.

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In this paper, the statistical analysis of surface radio refractivity in Mongolia is studied. Themethod proposed in the recommendation of the International Telecommunication Union ITU has been used. Meteorological data derived from fifty nine weather stations which cover the most populated areas in Mongolia. A total of more than five million refractivitymeasurements was considered in this analysis. The result showed that the highest averagevalues of the radio refractivity were observed in January while the lowest values wereobserved in April and May. The annual refractivity values were higher

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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.

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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

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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.

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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

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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.

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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

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Ladan, Muhammad, Oyedum David, Jibrin Yabagi, et al. "Study of Seasonal Surface Refractivity over North-Central Nigeria." Physics Access 01, no. 02 (2021): 5–13. http://dx.doi.org/10.47514/phyaccess.2020.1.2.002.

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Tropospheric radio wave signals experience loss due to multipath effect, scattering and other forms of attenuation through the atmospheric medium, primarily due to variations in weather conditions with time. The knowledge of surface refractivity profile is important for optimal planning of Very High Frequency/Ultra High Frequency (VHF/UHF) terrestrial radio links in a region. The study of surface refractivity (Ns) over the North-Central Nigeria was carried out using meteorological data from seven locations in North-Central zone of Nigeria. The seasonal variations of Ns were also derived using

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KULSHRESTHA, SM, and K. CHATTERJEE. "Radio-Climatology of India : I V. Vertical structure of Radio Refractive Index distribution in the lower troposphere." MAUSAM 18, no. 3 (2022): 335–48. http://dx.doi.org/10.54302/mausam.v18i3.4615.

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Based on the 5-year averages of the values of pressure, temperature and relative humidity at the ground surface,850-mb level (about 5000ft a.s.l.) and 700-mb level (about l0,000 ft a.s.l.) , the corresponding values of modified radio-refractive index (or radio-refractivity) have been computed for these three levels for each month at various stations in India. These data have been utilised to describe and discuss the vertical structure of radio refractivity distribution in the lower troposphere upto an approximate height of 10,000 ft a.s.l. Various radio climatic charts have been prepared and t

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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.

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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

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O. O., Fashade, Akinwumi S. A., Omotosho T. V., et al. "Evaluation of Refractivity Gradient and k-factor within the Lower Troposphere of Maiduguri and Enugu under Two Climatic Zones in Nigeria." International Journal on Applied Physics and Engineering 2 (April 5, 2023): 1–6. http://dx.doi.org/10.37394/232030.2023.2.1.

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Estimation of radio refractivity is important in the planning and design of terrestrial radio communication links for the availability and accessibility of strong networks and signals. This paper investigates the refractivity gradient, effective earth radius factor (k), and the geo-climatic factor K in the first 1km of the troposphere of two selected stations (Maiduguri and Enugu) under different climatic zones in Nigeria. The indirect method of measuring radio refractivity was employed in this study to take measurements over the two selected stations. Vertical profile values of pressure (hPa)

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Kingsley, Eghonghon Ukhurebor, and Nwankwo Wilson. "Estimation of the refractivity gradient from measured essential climate variables in Iyamho-Auchi, Edo State, South-South Region of Nigeria." Indonesian Journal of Electrical Engineering and Computer Science (IJEECS) 19, no. 1 (2020): 276–84. https://doi.org/10.11591/ijeecs.v19.i1.pp276-284.

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Meteorological variables are crucial constituents in the estimation of refractivity disseminations and the uncharacteristic radio wave propagation situations of the troposphere as a result of their impact on radio wave communication relations over the atmosphere. In this study the measurement and assessment of air temperature, relative humidity and atmospheric pressure was carried out for a period of one year; 2018, so as to estimate the refractivity gradient over Iyamho-Auchi, Edo State, Nigeria using a self-implemented inexpensive portable meteorological monitoring device. The measurements o

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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.

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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

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Onujagbe, IP, F. Ahmed-Ade, M. Mopah, and AJ David. "Surface Radio Refractivity of Akure and Ondo town, Southwest Nigeria." NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES 4, no. 1 (2021): 212–19. http://dx.doi.org/10.46912/napas.173.

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The surface radio refractivity, refractivity gradient at 1km above ground surface and the effective earth radius factor, K over Akure and Ondo town of South west Nigeria has been investigated using Ten (10) years daily data of the meteorological parameters of Pressure, air temperature and humidity. The result showed that the mean monthly value of the surface refractivity at the Ondo station is generally slightly higher than that of Akure. The monthly mean value of refractivity at the two stations was found to be strongly correlated with a value of 0.915. The most negative refractive gradient v

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Zou, X., S. Yang, and P. S. Ray. "Impacts of Ice Clouds on GPS Radio Occultation Measurements." Journal of the Atmospheric Sciences 69, no. 12 (2012): 3670–82. http://dx.doi.org/10.1175/jas-d-11-0199.1.

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Abstract Mathematical solutions accounting for the effects of liquid and ice clouds on the propagation of the GPS radio signals are first derived. The percentage contribution of ice water content (IWC) to the total refractivity increases linearly with the amount of IWC at a rate of 0.6 (g m−3)−1. Measurements of coincident profiles of IWC from CloudSat in deep convection during 2007–10 are then used for estimating the ice-scattering effects on GPS radio occultation (RO) measurements from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC). The percentage contrib

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Wee, Tae-Kwon. "A variational regularization of Abel transform for GPS radio occultation." Atmospheric Measurement Techniques 11, no. 4 (2018): 1947–69. http://dx.doi.org/10.5194/amt-11-1947-2018.

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Abstract. In the Global Positioning System (GPS) radio occultation (RO) technique, the inverse Abel transform of measured bending angle (Abel inversion, hereafter AI) is the standard means of deriving the refractivity. While concise and straightforward to apply, the AI accumulates and propagates the measurement error downward. The measurement error propagation is detrimental to the refractivity in lower altitudes. In particular, it builds up negative refractivity bias in the tropical lower troposphere. An alternative to AI is the numerical inversion of the forward Abel transform, which does no

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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.

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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

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Wang, Sungsik, Tae Heung Lim, Kyoungsoo Oh, Chulhun Seo, and Hosung Choo. "Prediction of Wide Range Two-Dimensional Refractivity Using an IDW Interpolation Method from High-Altitude Refractivity Data of Multiple Meteorological Observatories." Applied Sciences 11, no. 4 (2021): 1431. http://dx.doi.org/10.3390/app11041431.

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This article proposes a method for the prediction of wide range two-dimensional refractivity for synthetic aperture radar (SAR) applications, using an inverse distance weighted (IDW) interpolation of high-altitude radio refractivity data from multiple meteorological observatories. The radio refractivity is extracted from an atmospheric data set of twenty meteorological observatories around the Korean Peninsula along a given altitude. Then, from the sparse refractive data, the two-dimensional regional radio refractivity of the entire Korean Peninsula is derived using the IDW interpolation, in c

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Ilori, Abolaji Okikiade, Kamoli Akinwale Amusa, Tolulope Christiana Erinosho, and Olumayowa Ayodeji Idowu. "Investigation of the Effects of Weather Variability on Surface Radio Refractivity and Digital Terrestrial Television Signal Strength in the UHF Band." Journal of High-Frequency Communication Technologies 03, no. 03 (2025): 339–48. https://doi.org/10.58399/mvsd5314.

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This study examines the impact of atmospheric variables on the propagation of digital terrestrial television signals from Ogun State Television, located in Abeokuta, Ogun State, Nigeria, with a focus on the relationship between weather parameters and surface radio refractivity. Data on received signal strength and meteorological factors such as temperature, relative humidity, and atmospheric pressure were collected over 12 months. The analysis revealed significant seasonal variations, with higher relative humidity and surface refractivity observed during the rainy season (April to October) com

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Ukhurebor, Kingsley Eghonghon, and Wilson Nwankwo. "Estimation of the refractivity gradient from measured essential climate variables in Iyamho-Auchi, Edo State, South-South Region of Nigeria." Indonesian Journal of Electrical Engineering and Computer Science 19, no. 1 (2020): 276. http://dx.doi.org/10.11591/ijeecs.v19.i1.pp276-284.

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<p>Meteorological variables are crucial constituents in the estimation of refractivity disseminations and the uncharacteristic radio wave propagation situations of the troposphere as a result of their impact on radio wave communication relations over the atmosphere. In this study the measurement and assessment of air temperature, relative humidity and atmospheric pressure was carried out for a period of one year; 2018, so as to estimate the refractivity gradient over Iyamho-Auchi, Edo State, Nigeria using a self-implemented inexpensive portable meteorological monitoring device. The measu

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Ibrahim, U., Bawa Musa, and M. Lawal. "Estimating the Variability of Tropospheric Radio Refractivity and Field Strength over Enugu, South-East Nigeria." International Journal of Science for Global Sustainability 10, no. 2 (2024): 251–57. http://dx.doi.org/10.57233/ijsgs.v10i2.678.

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The field strength variability (FSV) assessment highlights the significant impact of atmospheric conditions on radio signal propagation. A diurnal variation in radio refractivity is the primary driver of FSV, with local topography and environmental factors also playing important roles. This study investigated the variation of tropospheric radio refractivity and field strength in Enugu, South-East Nigeria. Through a comprehensive measurement of temperature, humidity and pressure obtained from the network of Vantage Pro 2 automatic weather station installed at the study location for a period of

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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.

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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

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Balarabe, M., O. D. Oyedum, and K. C. Igwe. "Radio refractivity computations in Kano, Northwestern Nigeria." Journal of Physics: Conference Series 2034, no. 1 (2021): 012029. http://dx.doi.org/10.1088/1742-6596/2034/1/012029.

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Kufre. M., Udofia, Ogungbemi Emmanuel Oluropo, and Etokebe Iniobong Jackson. "Determination and Comparative Analysis of Refractivity Profile and Fade Depth for Microwave Links in Lagos." International Journal of Information and Communication Sciences 1, no. 3 (2017): 59–62. http://dx.doi.org/10.11648/j.ijics.20160103.15.

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The concept of radio link design and planning remain very vital to a radio link engineer and so the need to have a clear information outlook of the refractivity profile and fade depth of that location. In this study, radiosonde data from 2012 to 2014 was used to estimate the point refractivity gradient and fade depth for Lagos located 6.4531° N, 3.3958°E South West of Nigeria. The refractivity gradient for Lagos from the distribution table showed the highest occurrence in December with dN1 of -56.4268.1N units and February with the lowest dN1 having -398.5034N units while the fade depth for th

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Xia, Pengfei, Shirong Ye, Kecai Jiang, and Dezhong Chen. "Estimation and evaluation of COSMIC radio occultation excess phase using undifferenced measurements." Atmospheric Measurement Techniques 10, no. 5 (2017): 1813–21. http://dx.doi.org/10.5194/amt-10-1813-2017.

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Abstract. In the GPS radio occultation technique, the atmospheric excess phase (AEP) can be used to derive the refractivity, which is an important quantity in numerical weather prediction. The AEP is conventionally estimated based on GPS double-difference or single-difference techniques. These two techniques, however, rely on the reference data in the data processing, increasing the complexity of computation. In this study, an undifferenced (ND) processing strategy is proposed to estimate the AEP. To begin with, we use PANDA (Positioning and Navigation Data Analyst) software to perform the pre

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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.

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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

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