The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations
Observations collected over 3 months by the beam-matched second-generation Ka/W band Scanning Cloud Radar located at the Atmospheric Radiation Measurement Program Eastern North Atlantic observatory are used to advance existing liquid water content (LWC) retrieval techniques, quantify retrieval uncer...
Published in: | Journal of Geophysical Research: Atmospheres |
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Online Access: | http://www.osti.gov/servlets/purl/1802498 https://www.osti.gov/biblio/1802498 https://doi.org/10.1029/2019jd031188 |
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ftosti:oai:osti.gov:1802498 2023-07-30T04:05:35+02:00 The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations Zhu, Zeen Lamer, Katia Kollias, Pavlos Clothiaux, Eugene E. 2021-08-23 application/pdf http://www.osti.gov/servlets/purl/1802498 https://www.osti.gov/biblio/1802498 https://doi.org/10.1029/2019jd031188 unknown http://www.osti.gov/servlets/purl/1802498 https://www.osti.gov/biblio/1802498 https://doi.org/10.1029/2019jd031188 doi:10.1029/2019jd031188 54 ENVIRONMENTAL SCIENCES 2021 ftosti https://doi.org/10.1029/2019jd031188 2023-07-11T10:04:50Z Observations collected over 3 months by the beam-matched second-generation Ka/W band Scanning Cloud Radar located at the Atmospheric Radiation Measurement Program Eastern North Atlantic observatory are used to advance existing liquid water content (LWC) retrieval techniques, quantify retrieval uncertainty, and subsequently characterize the impact of cloud dynamics and rain rates on the vertical distribution of LWC in boundary layer clouds both precipitating and broken. A threefold technique is proposed that involves (1) temporally averaging measured radar reflectivities collected at two wavelengths to 30-s resolution, (2) smoothing via fitting a second-degree polynomial to their dual-wavelength ratios within 187.5-m vertical overlapping sliding windows, and (3) averaging the multiple LWC estimates produced at each height. It is estimated that this technique reduced LWC retrieval uncertainty to 0.10–0.65 g/m 3 , depending on cloud thickness. Although individual retrievals remained noisy, statistics on subgroups of height-normalized LWC profiles show that, on average, the vertical distributions of LWC in most of the observed clouds followed a linear relationship with a degree of adiabaticity ranging from 0.6 to 0.2 for 200- to 600-m thick clouds. However, nonlinear LWC profiles were present in subgroups of cloud segments presenting intense (0.1–0.5 mm/hr) drizzle rates where LWC was observed to pool near cloud base and in subgroups of cloud segments within strong (0.6 m/s) downdrafts near cloud top where LWC was coincidently reduced. This nonlinearity is inconsistent with the use of adiabatic cloud assumptions for process studies and supports further development of retrievals like the one proposed. Other/Unknown Material North Atlantic SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Journal of Geophysical Research: Atmospheres 124 24 14184 14197 |
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Open Polar |
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SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
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ftosti |
language |
unknown |
topic |
54 ENVIRONMENTAL SCIENCES |
spellingShingle |
54 ENVIRONMENTAL SCIENCES Zhu, Zeen Lamer, Katia Kollias, Pavlos Clothiaux, Eugene E. The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
topic_facet |
54 ENVIRONMENTAL SCIENCES |
description |
Observations collected over 3 months by the beam-matched second-generation Ka/W band Scanning Cloud Radar located at the Atmospheric Radiation Measurement Program Eastern North Atlantic observatory are used to advance existing liquid water content (LWC) retrieval techniques, quantify retrieval uncertainty, and subsequently characterize the impact of cloud dynamics and rain rates on the vertical distribution of LWC in boundary layer clouds both precipitating and broken. A threefold technique is proposed that involves (1) temporally averaging measured radar reflectivities collected at two wavelengths to 30-s resolution, (2) smoothing via fitting a second-degree polynomial to their dual-wavelength ratios within 187.5-m vertical overlapping sliding windows, and (3) averaging the multiple LWC estimates produced at each height. It is estimated that this technique reduced LWC retrieval uncertainty to 0.10–0.65 g/m 3 , depending on cloud thickness. Although individual retrievals remained noisy, statistics on subgroups of height-normalized LWC profiles show that, on average, the vertical distributions of LWC in most of the observed clouds followed a linear relationship with a degree of adiabaticity ranging from 0.6 to 0.2 for 200- to 600-m thick clouds. However, nonlinear LWC profiles were present in subgroups of cloud segments presenting intense (0.1–0.5 mm/hr) drizzle rates where LWC was observed to pool near cloud base and in subgroups of cloud segments within strong (0.6 m/s) downdrafts near cloud top where LWC was coincidently reduced. This nonlinearity is inconsistent with the use of adiabatic cloud assumptions for process studies and supports further development of retrievals like the one proposed. |
author |
Zhu, Zeen Lamer, Katia Kollias, Pavlos Clothiaux, Eugene E. |
author_facet |
Zhu, Zeen Lamer, Katia Kollias, Pavlos Clothiaux, Eugene E. |
author_sort |
Zhu, Zeen |
title |
The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
title_short |
The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
title_full |
The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
title_fullStr |
The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
title_full_unstemmed |
The Vertical Structure of Liquid Water Content in Shallow Clouds as Retrieved From Dual-Wavelength Radar Observations |
title_sort |
vertical structure of liquid water content in shallow clouds as retrieved from dual-wavelength radar observations |
publishDate |
2021 |
url |
http://www.osti.gov/servlets/purl/1802498 https://www.osti.gov/biblio/1802498 https://doi.org/10.1029/2019jd031188 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://www.osti.gov/servlets/purl/1802498 https://www.osti.gov/biblio/1802498 https://doi.org/10.1029/2019jd031188 doi:10.1029/2019jd031188 |
op_doi |
https://doi.org/10.1029/2019jd031188 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
124 |
container_issue |
24 |
container_start_page |
14184 |
op_container_end_page |
14197 |
_version_ |
1772817599582699520 |