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{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,10,11]],"date-time":"2023-10-11T05:03:00Z","timestamp":1697000580369},"reference-count":72,"publisher":"Copernicus GmbH","issue":"17","license":[{"start":{"date-parts":[[2023,9,11]],"date-time":"2023-09-11T00:00:00Z","timestamp":1694390400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["268020496 - TRR 172"]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Atmos. Meas. Tech."],"abstract":"<jats:p>Abstract. Most Arctic clouds occur below 2\u2009km altitude, as revealed by CloudSat satellite observations. However, recent studies suggest that the\nrelatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively\ndocument low-level clouds. We investigate the impact of these limitations on the Arctic low-level cloud fraction, which is the number of cloudy\npoints with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved\nvertical profiles of low-level cloud fraction derived from down-looking Microwave Radar\/radiometer for Arctic Clouds (MiRAC) radar reflectivity\nmeasurements. MiRAC was operated during four aircraft campaigns that took place in the vicinity of Svalbard during different times of the year,\ncovering more than 25\u2009000\u2009km. 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\nCloudSat observations for four satellite underflights to prove the suitability of our forward-simulation approach. Above CloudSat's blind zone of\n1\u2009km and below 2.5\u2009km, the forward simulations reveal that CloudSat would overestimate the MiRAC cloud fraction over all campaigns\nby about 6\u00a0percentage points (pp) due to its horizontal resolution and by 12\u2009pp due to its range resolution and underestimate it by\n10\u2009pp due to its sensitivity. Especially during cold-air outbreaks over open water, high-reflectivity clouds appear below 1.5\u2009km,\nwhich are stretched by CloudSat's pulse length causing the forward-simulated cloud fraction to be 16\u2009pp higher than that observed by\nMiRAC. The pulse length merges multilayer clouds, whereas thin low-reflectivity clouds remain undetected. Consequently, 48\u2009% of clouds observed\nby MiRAC belong to multilayer clouds, which reduces by a factor of\u00a04 for the forward-simulated CloudSat counterpart. Despite the overestimation\nbetween\u00a01 and\u00a02.5\u2009km, the overall low-level cloud fraction is strongly reduced due to CloudSat's blind zone that misses a cloud fraction of\n32\u2009% and half of the total (mainly light) precipitation amount.\n <\/jats:p>","DOI":"10.5194\/amt-16-4081-2023","type":"journal-article","created":{"date-parts":[[2023,9,11]],"date-time":"2023-09-11T08:20:55Z","timestamp":1694420455000},"page":"4081-4100","source":"Crossref","is-referenced-by-count":0,"title":["Assessing Arctic low-level clouds and precipitation from above \u2013 a radar perspective"],"prefix":"10.5194","volume":"16","author":[{"ORCID":"http:\/\/orcid.org\/0000-0003-4438-3077","authenticated-orcid":false,"given":"Imke","family":"Schirmacher","sequence":"first","affiliation":[]},{"given":"Pavlos","family":"Kollias","sequence":"additional","affiliation":[]},{"ORCID":"http:\/\/orcid.org\/0000-0002-8328-5704","authenticated-orcid":false,"given":"Katia","family":"Lamer","sequence":"additional","affiliation":[]},{"ORCID":"http:\/\/orcid.org\/0000-0001-6229-9616","authenticated-orcid":false,"given":"Mario","family":"Mech","sequence":"additional","affiliation":[]},{"ORCID":"h
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