Joint cloud water path and rainwater path retrievals from airborne ORACLES observations
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Published:2021-04-09
Issue:7
Volume:21
Page:5513-5532
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ISSN:1680-7324
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Container-title:Atmospheric Chemistry and Physics
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language:en
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Short-container-title:Atmos. Chem. Phys.
Author:
Dzambo Andrew M.ORCID, L'Ecuyer TristanORCID, Sinclair KennethORCID, van Diedenhoven BastiaanORCID, Gupta SiddhantORCID, McFarquhar GregORCID, O'Brien Joseph R., Cairns Brian, Wasilewski Andrzej P., Alexandrov Mikhail
Abstract
Abstract. This study presents a new algorithm that combines W-band reflectivity
measurements from the Airborne Precipitation Radar – third generation
(APR-3) passive radiometric cloud optical depth and effective radius
retrievals from the Research Scanning Polarimeter (RSP) to estimate total
liquid water path in warm clouds and identify the contributions from cloud
water path (CWP) and rainwater path (RWP). The resulting CWP estimates are
primarily determined by the optical depth input, although reflectivity
measurements contribute ∼10 %–50 % of the uncertainty due to
attenuation through the profile. Uncertainties in CWP estimates across all
conditions are 25 % to 35 %, while RWP uncertainty estimates frequently
exceed 100 %. Two-thirds of all radar-detected clouds observed during the ObseRvations of
Aerosols above CLouds and their intEractionS (ORACLES) campaign that took
place from 2016–2018 over the southeast Atlantic Ocean have CWP between 41
and 168 g m−2 and almost all CWPs (99 %) between 6 to 445 g m−2.
RWP, by contrast, typically makes up a much smaller fraction of total liquid
water path (LWP), with more than 70 % of raining clouds having less than 10 g m−2 of rainwater. In heavier warm rain (i.e., rain rate exceeding 40 mm h−1 or 1000 mm d−1), however, RWP is observed to exceed 2500 g m−2. CWP (RWP) is found to be approximately 30 g m−2 (7 g m−2) larger in unstable environments compared to stable environments.
Surface precipitation is also more than twice as likely in unstable
environments. Comparisons against in situ cloud microphysical probe data
spanning the range of thermodynamic stability and meteorological conditions
encountered across the southeast Atlantic basin demonstrate that the
combined APR-3 and RSP dataset enable a robust joint cloud–precipitation
retrieval algorithm to support future ORACLES precipitation susceptibility
and cloud–aerosol–precipitation interaction studies.
Publisher
Copernicus GmbH
Subject
Atmospheric Science
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