Mind-the-gap part I: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars
Ground-based radar observations show that, in the eastern north Atlantic, 50% of warm marine boundary layer (WMBL) hydrometeors occur below 1.2km and have reflectivities < -17dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface cl...
| Published in: | Atmospheric Measurement Techniques |
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| Main Authors: | , , , |
| Language: | unknown |
| Published: |
2023
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| Subjects: | |
| Online Access: | http://www.osti.gov/servlets/purl/1609092 https://www.osti.gov/biblio/1609092 https://doi.org/10.5194/amt-13-2363-2020 |
| Summary: | Ground-based radar observations show that, in the eastern north Atlantic, 50% of warm marine boundary layer (WMBL) hydrometeors occur below 1.2km and have reflectivities < -17dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface clutter limits the CloudSat-Cloud Profiling Radar (CPR)'s ability to observe true cloud base in ~52% of the cloudy columns it detects and true virga base in ~80%, meaning the CloudSat-CPR often provides an incomplete view of even the clouds it does detect. Using forward-simulations, we determine that a 250-m resolution radar would most accurately capture the boundaries of WMBL clouds and precipitation; that being said, because of sensitivity limitations, such a radar would suffer from cloud cover biases similar to those of the CloudSat-CPR. Overpass observations and forward-simulations indicate that the CloudSat-CPR fails to detect 29-43% of the cloudy columns detected by the ground-based sensors. Out of all configurations tested, the 7 dB more sensitive EarthCARE-CPR performs best (only missing 9.0% of cloudy columns) indicating that improving radar sensitivity is more important than decreasing the vertical extent of surface clutter for observing cloud cover. However, because 50% of WMBL systems are thinner than 400 m, they tend to be artificially stretched by long sensitive radar pulses; hence the EarthCARE-CPR overestimation of cloud top height and hydrometeor fraction. Thus, it is recommended that the next generation of space-borne radars targeting WMBL science shall operate interlaced pulse modes including both a highly sensitive long-pulse and a less sensitive but clutter limiting short-pulse mode. |
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