Assessing Arctic low-level clouds and precipitation from above – a radar perspective
Most Arctic clouds occur below 2 km altitude, as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clou...
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ftdoajarticles:oai:doaj.org/article:67307f9c504f44248a335387c1cd10a7 2023-10-09T21:48:35+02:00 Assessing Arctic low-level clouds and precipitation from above – a radar perspective I. Schirmacher P. Kollias K. Lamer M. Mech L. Pfitzenmaier M. Wendisch S. Crewell 2023-09-01T00:00:00Z https://doi.org/10.5194/amt-16-4081-2023 https://doaj.org/article/67307f9c504f44248a335387c1cd10a7 EN eng Copernicus Publications https://amt.copernicus.org/articles/16/4081/2023/amt-16-4081-2023.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-16-4081-2023 1867-1381 1867-8548 https://doaj.org/article/67307f9c504f44248a335387c1cd10a7 Atmospheric Measurement Techniques, Vol 16, Pp 4081-4100 (2023) Environmental engineering TA170-171 Earthwork. Foundations TA715-787 article 2023 ftdoajarticles https://doi.org/10.5194/amt-16-4081-2023 2023-09-17T00:38:46Z Most Arctic clouds occur below 2 km altitude, as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clouds. We investigate the impact of these limitations on the Arctic low-level cloud fraction, which is the number of cloudy points with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved vertical profiles of low-level cloud fraction derived from down-looking Microwave Radar/radiometer for Arctic Clouds (MiRAC) radar reflectivity measurements. MiRAC was operated during four aircraft campaigns that took place in the vicinity of Svalbard during different times of the year, covering more than 25 000 km . This allows us to study the dependence of CloudSat limitations on different synoptic and surface conditions. A forward simulator converts MiRAC measurements to synthetic CloudSat radar reflectivities. These forward simulations are compared with the original CloudSat observations for four satellite underflights to prove the suitability of our forward-simulation approach. Above CloudSat's blind zone of 1 km and below 2.5 km , the forward simulations reveal that CloudSat would overestimate the MiRAC cloud fraction over all campaigns by about 6 percentage points ( pp ) due to its horizontal resolution and by 12 pp due to its range resolution and underestimate it by 10 pp due to its sensitivity. Especially during cold-air outbreaks over open water, high-reflectivity clouds appear below 1.5 km , which are stretched by CloudSat's pulse length causing the forward-simulated cloud fraction to be 16 pp higher than that observed by MiRAC. The pulse length merges multilayer clouds, whereas thin low-reflectivity clouds remain undetected. Consequently, 48 % of clouds observed by MiRAC belong to multilayer clouds, which reduces by a factor of 4 for the ... Article in Journal/Newspaper Arctic Svalbard Directory of Open Access Journals: DOAJ Articles Arctic Svalbard Atmospheric Measurement Techniques 16 17 4081 4100 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
spellingShingle |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 I. Schirmacher P. Kollias K. Lamer M. Mech L. Pfitzenmaier M. Wendisch S. Crewell Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
topic_facet |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
description |
Most Arctic clouds occur below 2 km altitude, as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clouds. We investigate the impact of these limitations on the Arctic low-level cloud fraction, which is the number of cloudy points with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved vertical profiles of low-level cloud fraction derived from down-looking Microwave Radar/radiometer for Arctic Clouds (MiRAC) radar reflectivity measurements. MiRAC was operated during four aircraft campaigns that took place in the vicinity of Svalbard during different times of the year, covering more than 25 000 km . This allows us to study the dependence of CloudSat limitations on different synoptic and surface conditions. A forward simulator converts MiRAC measurements to synthetic CloudSat radar reflectivities. These forward simulations are compared with the original CloudSat observations for four satellite underflights to prove the suitability of our forward-simulation approach. Above CloudSat's blind zone of 1 km and below 2.5 km , the forward simulations reveal that CloudSat would overestimate the MiRAC cloud fraction over all campaigns by about 6 percentage points ( pp ) due to its horizontal resolution and by 12 pp due to its range resolution and underestimate it by 10 pp due to its sensitivity. Especially during cold-air outbreaks over open water, high-reflectivity clouds appear below 1.5 km , which are stretched by CloudSat's pulse length causing the forward-simulated cloud fraction to be 16 pp higher than that observed by MiRAC. The pulse length merges multilayer clouds, whereas thin low-reflectivity clouds remain undetected. Consequently, 48 % of clouds observed by MiRAC belong to multilayer clouds, which reduces by a factor of 4 for the ... |
format |
Article in Journal/Newspaper |
author |
I. Schirmacher P. Kollias K. Lamer M. Mech L. Pfitzenmaier M. Wendisch S. Crewell |
author_facet |
I. Schirmacher P. Kollias K. Lamer M. Mech L. Pfitzenmaier M. Wendisch S. Crewell |
author_sort |
I. Schirmacher |
title |
Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
title_short |
Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
title_full |
Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
title_fullStr |
Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
title_full_unstemmed |
Assessing Arctic low-level clouds and precipitation from above – a radar perspective |
title_sort |
assessing arctic low-level clouds and precipitation from above – a radar perspective |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/amt-16-4081-2023 https://doaj.org/article/67307f9c504f44248a335387c1cd10a7 |
geographic |
Arctic Svalbard |
geographic_facet |
Arctic Svalbard |
genre |
Arctic Svalbard |
genre_facet |
Arctic Svalbard |
op_source |
Atmospheric Measurement Techniques, Vol 16, Pp 4081-4100 (2023) |
op_relation |
https://amt.copernicus.org/articles/16/4081/2023/amt-16-4081-2023.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-16-4081-2023 1867-1381 1867-8548 https://doaj.org/article/67307f9c504f44248a335387c1cd10a7 |
op_doi |
https://doi.org/10.5194/amt-16-4081-2023 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
16 |
container_issue |
17 |
container_start_page |
4081 |
op_container_end_page |
4100 |
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1779311667874627584 |