Radiometric estimation of water vapor content over Brazil

Karmakar, P. K.; Maiti, Manabendra; Sett, Susmita; Angelis, Carlos Frederico de; Machado, Luiz A. T.

doi:10.1016/j.asr.2011.06.032

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…30 GHz lies in weak water vapour attenuation region. It has also been found that the choice of this frequency pair is optimal (4,20) for the measurement of vapour and liquid water.…”

Section: Methodsmentioning

confidence: 99%

“…A ground based microwave radiometer (1,2) has proved its utility to monitor the atmosphere up to 10 Km continuously by measuring very low level microwave radiation at some specific frequency channels in the microwave bands dominated by atmospheric water vapor, cloud liquid water and molecular oxygen emissions. Geophysical observables such as the total amount of water vapor (PWV), the non-precipitating cloud liquid content (LWC) and rain are have frequently been used to develop models (3,4) .…”

Section: Introductionmentioning

confidence: 99%

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Determination of sky status by ground based radiometric data analysis

Maiti¹,

Bhattacharyya²,

Biswas³

et al. 2021

IJST

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Objectives: To predict meteorological phenomena such as rain events from sky status during rainy and non-rainy periods. Methods: The method used here is based on brightness temperature ratio measurement at two different frequencies, namely 23.8 GHz and 30 GHz respectively, using ground based dual frequency radiometric data. The ratios of brightness temperature readings obtained by the dual-frequency radiometer at the two above mentioned frequencies are calculated for each simultaneously-taken pair of measurements. Data obtained by the authors for the year 2009 at Cachoeira Paulista in Brazil has been used for analysis. Findings: The major results obtained from the analysis of data collected over a continuous period of seven months are used to construct corresponding histograms and cumulative count graphs of brightness temperature ratios. The histograms and graphs clearly show three peak values that could be interpreted as thresholds between clear sky, cloudy sky and rainy sky conditions respectively. Novelty: The study implements detection of rain events from sky status during rainy and non-rainy periods using peak brightness temperature values obtained from graphs generated using the observation data. The outlined technique can therefore be used to clearly determine sky conditions and accurately predict rain phenomena. The ratio of brightness temperatures at the two frequencies is a unique parameter which is critical to the successful estimation of rain from sky status. The results agree well with multi-channel radiometric data obtained by other researchers at lower frequencies.

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“…30 GHz lies in weak water vapour attenuation region. It has also been found that the choice of this frequency pair is optimal (4,20) for the measurement of vapour and liquid water.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of sky status by ground based radiometric data analysis

Maiti¹,

Bhattacharyya²,

Biswas³

et al. 2021

IJST

View full text Add to dashboard Cite

show abstract

“…As for the PWV measurement methods, the groundbased GPS [7], Sun photometer [8], microwave radiometer [9], and radiosonde [10] can accurately measure the atmospheric water vapor. Since the number of observation station is limited, and its distribution is uneven, the instrument measurements on ground cannot be applied to properly study the of PWV spatial distribution characteristics.…”

Section: Introductionmentioning

confidence: 99%

Analysis on Precipitable Water Vapor over the Tibetan Plateau Using FengYun-3A Medium Resolution Spectral Imager Products

2019

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The Tibetan Plateau is the largest and highest plateau in the world, and its complex terrain affects the distribution of precipitable water vapor (PWV) in the atmosphere, which plays an important role in the weather and climate of East Asia. In this paper, the characteristics of PWV over the Tibetan Plateau are studied using the FengYun-3A Medium Resolution Spectral Imager (MERSI) water vapor products, which are retrieved from the MERSI raw images of Chinese second-generation polar orbit meteorological satellite. Firstly, the accuracy of the MERSI 5-minute water vapor product is validated using three referenced water vapor data from TERRA/MODIS, ground-based GPS, and AERONET sun photometer over the Tibetan Plateau. Then, the spatial distribution and seasonal variation of PWV over the plateau are analyzed, and the effects of topographic factors on PWV are discussed. The results indicate that the MERSI 5-minute water vapor product has a good accuracy over the Tibetan Plateau, which the mean absolute error of MERSI water vapor product is in the range of 28.91%-37.54%, the mean absolute error range between 1.87 and 2.76 millimeter (mm), and the mean bias is between -1.14 and 0.64 mm comparing three referenced data. The PWV content appears as a typical spatial pattern over the Tibetan Plateau where there is a decrease from east to west of the Tibetan Plateau with increasing elevation, with the highest values over the south of Tibet. A second pattern also appears over the eastern part of the Tibetan Plateau, where the PWV content in the Qaidam Basin and the south of Tarim Basin are also considerably high. The seasonal variation of PWV content over the Tibetan Plateau presents to be highest in summer, followed by autumn and spring, and lowest in winter. The PWV content changes periodically during the year, which fits with a quadratic polynomial over monthly scales. The topographical factors of the Tibetan Plateau were found to affect the water vapor, where the altitude and latitude are negatively correlated with water vapor, while the slope and longitude show a positive correlation with water vapor; however, the aspect does not appear to have any significant influence on water vapor.

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Cloud and rain liquid water statistics in the CHUVA campaign

Calheiros

Machado

2014

Atmospheric Research

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Radiometric estimation of water vapor content over Brazil

Cited by 10 publications

References 29 publications

Determination of sky status by ground based radiometric data analysis

Determination of sky status by ground based radiometric data analysis

Analysis on Precipitable Water Vapor over the Tibetan Plateau Using FengYun-3A Medium Resolution Spectral Imager Products

Cloud and rain liquid water statistics in the CHUVA campaign

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