Validation of GPS atmospheric water vapor with WVR data in satellite tracking mode
Slant-integrated water vapor (SIWV) data derived from GPS STDs (slant total delays), which provide the spatial information on tropospheric water vapor, have a high potential for assimilation to weather models or for nowcasting or reconstruction of the 3-D humidity field with tomographic technique...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-01-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/33/55/2015/angeo-33-55-2015.pdf |
| Summary: | Slant-integrated water vapor (SIWV) data derived from GPS STDs (slant total delays), which provide
the spatial information on tropospheric water vapor, have a high potential
for assimilation to weather models or for nowcasting or reconstruction of the
3-D humidity field with tomographic techniques. Therefore, the accuracy of
GPS STD is important, and independent observations are needed to estimate the
quality of GPS STD. In 2012 the GFZ (German Research Centre for Geosciences)
started to operate a microwave radiometer in the vicinity of the Potsdam GPS
station. The water vapor content along the line of sight between a ground
station and a GPS satellite can be derived from GPS data and directly
measured by a water vapor radiometer (WVR) at the same time. In this study we
present the validation results of SIWV observed by a ground-based GPS
receiver and a WVR. The validation covers 184 days of data with dry and wet
humidity conditions. SIWV data from GPS and WVR generally show good agreement
with a mean bias of −0.4 kg m<sup>−2</sup> and an rms (root mean square) of
3.15 kg m<sup>−2</sup>. The differences in SIWV show an elevation dependent
on an rms of 7.13 kg m<sup>−2</sup> below 15° but of 1.76 kg m<sup>−2</sup>
above 15°. Nevertheless, this elevation dependence is not observed
regarding relative deviations. The relation between the differences and
possible influencing factors (elevation angles, pressure, temperature and
relative humidity) are analyzed in this study. Besides the elevation,
dependencies between the atmospheric humidity conditions, temperature and the
differences in SIWV are found. |
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| ISSN: | 0992-7689 1432-0576 |