Comparison of Tropospheric Water Vapour over Antarctica Derived from AMSU-B Data, Ground-Based GPS Data and the NCEP/NCAR Reanalysis

ABSTRACT:The diurnal and semi-diurnal variability of the integrated precipitable water vapour (IPWV) was studied by using Global Positioning System (GPS) data (1998)(1999)(2000)(2001)(2002)(2003)(2004)) from 14 International GNSS Service (IGS) stations located between latitudes 20°S and 20°N, and longitudes 70°-170°E. The phases and amplitudes of the IPWV are compared to the corresponding estimates from two numerical weather models (NWMs). Results reveal that there are diurnal amplitudes of more than 0.4 mm for most sites, except sites on small islands in the ocean. The maximum diurnal amplitude is 3 mm at Bakosurtanal, Indonesia. The estimated semi-diurnal signals are in general small. The maximum of the IPWV typically occurs between 1200 and 2400 local solar time. The results suggest that GPS data are useful for high-temporal-resolution studies of IPWV. The accuracy of the estimated diurnal amplitudes is limited by the use of a simple model for the mean temperature of the wet refractivity, and the accuracy of the estimated semi-diurnal amplitudes is likely to be improved by a higher temporal resolution of the ground pressure data at the GPS sites.

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“…the Advanced Microwave Sounding Unit (AMSU-B). These techniques provide good spatial but poor temporal resolution (Vey et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Sensing of diurnal and semi‐diurnal variability in the water vapour content in the tropics using GPS measurements

Pramualsakdikul

Haas

Elgered

et al. 2007

Meteorological Applications

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“…Above this value two of the 183.31 GHz band channels become saturated and the sensor fails to "see" down to the ground anymore. This limit is sufficient for the central Arctic region for most of the year and it shows good agreement with retrievals based on the analysis of GPS signals taken at stations around Antarctica (Vey et al, 2004). However, because of the limited TWV retrieval range, this method alone cannot ensure year-long monitoring of TWV values (Selbach et al, 2003).…”

Section: Introductionmentioning

confidence: 72%

Retrieval of total water vapour in the Arctic using microwave humidity sounders

2018

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Abstract. Quantitative retrievals of atmospheric water vapour in the Arctic present numerous challenges because of the particular climate characteristics of this area. Here, we attempt to build upon the work of Melsheimer and Heygster (2008) to retrieve total atmospheric water vapour (TWV) in the Arctic from satellite microwave radiometers. While the above-mentioned algorithm deals primarily with the icecovered central Arctic, with this work we aim to extend the coverage to partially ice-covered and ice-free areas. By using modelled values for the microwave emissivity of the icefree sea surface, we develop two sub-algorithms using different sets of channels that deal solely with open-ocean areas. The new algorithm extends the spatial coverage of the retrieval throughout the year but especially in the warmer months when higher TWV values are frequent. The high TWV measurements over both sea-ice and open-water surfaces are, however, connected to larger uncertainties as the retrieval values are close to the instrument saturation limits.This approach allows us to apply the algorithm to regions where previously no data were available and ensures a more consistent physical analysis of the satellite measurements by taking into account the contribution of the surface emissivity to the measured signal.

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“…Above this value two of the 15 183.31 GHz band channels become saturated and the sensor fails to 'see' down to the ground anymore. This limit is sufficient for the central Arctic region for most of the year and it shows good agreement with retrievals based on the analysis of GPS signals taken at stations around Antarctica (Vey et al, 2004). However this AMSU-B based method alone cannot ensure a year long monitoring of TWV values (Selbach et al, 2003).…”

mentioning

confidence: 86%

Retrieval of Total Water Vapour in the Arctic Using Microwave Humidity Sounders

Scarlat¹,

Melsheimer²,

Heygster³

2017

Preprint

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Quantitative retrievals of atmospheric water vapour in the Arctic are faced with numerous challenges because of the particular climate characteristics of this area. Here, we attempt to build upon the work of Melsheimer and Heygster (2008) to retrieve total atmospheric water vapour (TWV) in the Arctic from satellite microwave radiometers. While the above mentioned al-5 gorithm deals primarily with the ice-covered central Arctic, with this work we are aiming to extend the coverage to low ice cover and ice-free areas. By using modeled values for the microwave emissivity of the ice-free sea surface, we develop two sub-algorithms using different sets of channels that deal solely with open ocean areas. This approach allows us to apply the algorithm to regions where previously no data were available and ensures a more consistent 10 physical analysis of the satellite measurements by taking into account the contribution of the surface emissivity to the measured signal.

show abstract

Comparison of Tropospheric Water Vapour over Antarctica Derived from AMSU-B Data, Ground-Based GPS Data and the NCEP/NCAR Reanalysis

Cited by 34 publications

References 23 publications

Sensing of diurnal and semi‐diurnal variability in the water vapour content in the tropics using GPS measurements

Sensing of diurnal and semi‐diurnal variability in the water vapour content in the tropics using GPS measurements

Retrieval of total water vapour in the Arctic using microwave humidity sounders

Retrieval of Total Water Vapour in the Arctic Using Microwave Humidity Sounders

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