Inter-calibrating SMMR brightness temperatures over continental surfaces
<p>Microwave remote sensing can be used to monitor the time evolution of some key parameters over land, such as land surface temperature or surface water extent. Observations are made with instruments, such as the Scanning Microwave Multichannel Radiometer (SMMR) before 1987, the Special Senso...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/13/5481/2020/amt-13-5481-2020.pdf |
| Summary: | <p>Microwave remote sensing can be used to monitor the time evolution of
some key parameters over land, such as land surface temperature or
surface water extent. Observations are made with instruments, such as
the Scanning Microwave Multichannel Radiometer (SMMR) before 1987, the
Special Sensor Microwave/Imager (SSM/I) and the subsequent Special
Sensor Microwave Imager/Sounder (SSMIS) from 1987 and still
operating, and the more recent Global Precipitation Measurement Microwave Imager (GMI). As these instruments differ on some of their
characteristics and use different calibration schemes, they need to be
inter-calibrated before long-time-series products can be derived from
the observations. Here an inter-calibration method is designed to
remove major inconsistencies between the SMMR and other microwave
radiometers for the 18 and 37 <span class="inline-formula">GHz</span> channels over continental
surfaces. Because of a small overlap in observations and a
<span class="inline-formula">∼6</span> <span class="inline-formula">h</span> difference in overpassing times between SMMR and
SSM/I, GMI was chosen as a reference despite the lack of a common
observing period. The diurnal cycles from 3 years of GMI
brightness temperatures are first calculated and then used to
evaluate SMMR differences. Based on a statistical analysis of the
differences, a simple linear correction is implemented to calibrate
SMMR on GMI. This correction is shown to also reduce the biases
between SMMR and SSM/I, and can then be applied to SMMR observations
to make them more coherent with existing data records of microwave
brightness temperatures over continental surfaces.</p> |
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| ISSN: | 1867-1381 1867-8548 |