Global evaluation of Doppler velocity errors of EarthCARE cloud-profiling radar using a global storm-resolving simulation
<p>The cloud-profiling radar (CPR) on the Earth Clouds, Aerosol, and Radiation Explorer (EarthCARE) satellite (EC-CPR) is the first satellite-borne Doppler radar. In a previous study, we examined the effects of horizontal (along-track) integration and simple unfolding methods on the reduction...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-06-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/16/3211/2023/amt-16-3211-2023.pdf |
| Summary: | <p>The cloud-profiling radar (CPR) on the Earth Clouds,
Aerosol, and Radiation Explorer (EarthCARE) satellite (EC-CPR) is the first
satellite-borne Doppler radar. In a previous study, we examined
the effects of horizontal (along-track) integration and simple unfolding
methods on the reduction of Doppler errors in the EC-CPR observations, and
those effects were evaluated using two limited scenes in limited-latitude
and low-pulse-repetition-frequency (PRF) settings. In this study, the amount
of data used was significantly increased, and the area of the data used was
extended globally. Not only low-PRF but also high-PRF settings were
examined. We calculated the EC-CPR-observed Doppler velocity from pulse-pair
covariances using the radar reflectivity factor and Doppler velocity
obtained from a satellite data simulator and a global storm-resolving
simulation. The global data were divided into five latitudinal zones, and
each standard deviation of Doppler errors for 5 dB<span class="inline-formula"><i>Z</i><sub>e</sub></span> after 10 km
integration was calculated. In the case of the low-PRF setting, the error
without unfolding correction for the tropics reached a maximum of 2.2 m s<span class="inline-formula"><sup>−1</sup></span> and then decreased toward the poles (0.43 m s<span class="inline-formula"><sup>−1</sup>)</span>. The error
with unfolding correction for the tropics became much smaller at 0.63 m s<span class="inline-formula"><sup>−1</sup></span>. In the case of the high-PRF setting, the error without unfolding
correction for the tropics reached a maximum of 0.78 m s<span class="inline-formula"><sup>−1</sup></span> and then
decreased toward the poles (0.19 m s<span class="inline-formula"><sup>−1</sup>)</span>. The error with unfolding
correction for the tropics was 0.29 m s<span class="inline-formula"><sup>−1</sup></span>, less than half the value
without the correction. The results of the analyses of the simulated data
indicated that the zonal mean frequency of precipitation echoes was highest
in the tropics and decreased toward the poles. Considering a limitation of
the unfolding correction for discrimination between large upward velocity
and large precipitation falling velocity, the latitudinal variation in the
standard deviation of Doppler error can be explained by the precipitation
echo distribution.</p> |
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| ISSN: | 1867-1381 1867-8548 |