Mind the gap – Part 1: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars
<p>Ground-based radar observations show that, over the eastern North Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities of < <span class="inline-formula">−17</span>&thinsp...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-05-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/13/2363/2020/amt-13-2363-2020.pdf |
| Summary: | <p>Ground-based radar observations show that, over the eastern North Atlantic,
50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km
and have reflectivities of < <span class="inline-formula">−17</span> dBZ, thus making their detection from
space susceptible to the extent of surface clutter and radar sensitivity.</p>
<p>Surface clutter limits the ability of the CloudSat cloud profiling radar (CPR) to
observe the true cloud base in <span class="inline-formula">∼52</span> % of the cloudy columns it
detects and true virga base in <span class="inline-formula">∼80</span> %, 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.</p>
<p>Observations and forward simulations indicate that the CloudSat CPR
fails to detect 29 %–43 % of the cloudy columns detected by 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 measuring 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.</p>
<p>Thus, it is recommended that the next generation of space-borne radars
targeting WMBL science should operate interlaced pulse modes including both a
highly sensitive long-pulse mode and a less sensitive but clutter-limiting
short-pulse mode.</p> |
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| ISSN: | 1867-1381 1867-8548 |