Validation of INSAT-3D sounder data with in situ measurements and other similar satellite observations over India
To date, several satellites measurements are available which can provide profiles of temperature and water vapour with reasonable accuracies. However, the temporal resolution has remained poor, particularly over the tropics, as most of them are polar orbiting. At this juncture, the launch of INSAT-3...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/9/5735/2016/amt-9-5735-2016.pdf |
| Summary: | To date, several satellites measurements are available which can
provide profiles of temperature and water vapour with reasonable accuracies.
However, the temporal resolution has remained poor, particularly over the
tropics, as most of them are polar orbiting. At this juncture, the launch of
INSAT-3D (Indian National Satellite
System) by the Indian Space Research
Organization (ISRO) on 26 July 2013 carrying a multi-spectral imager covering
visible to long-wave infrared made it possible to obtain profiles of
temperature and water vapour over India with higher temporal and vertical
resolutions and altitude coverage, besides other parameters. The initial
validation of INSAT-3D data is made with the high temporal (3 h) resolution
radiosonde observations launched over Gadanki (13.5° N,
79.2° E) during a special campaign and routine evening soundings
obtained at 12:00 UTC (17:30 LT). We also compared INSAT-3D data with the
radiosonde observations obtained from 34 India Meteorological Department
stations. Comparisons were also made over India with data from other
satellites like AIRS, MLS and SAPHIR and from ERA-Interim and NCEP reanalysis
data sets. INSAT-3D is able to show better coverage over India with high
spatial and temporal resolutions as expected. Good correlation in temperature
between INSAT-3D and in situ measurements is noticed except in the upper
tropospheric and lower stratospheric regions (positive bias of 2–3 K).
There is a mean dry bias of 20–30 % in the water vapour mixing ratio.
Similar biases are noticed when compared to other satellites and reanalysis
data sets. INSAT-3D shows a large positive bias in temperature above
25° N in the lower troposphere. Thus, caution is advised when using
these data for tropospheric studies. Finally it is concluded that temperature
data from INSAT-3D are of high quality and can be directly assimilated for
better forecasts over India. |
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| ISSN: | 1867-1381 1867-8548 |