Cargando…
Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives
The cloud droplet number concentration (N (d)) is of central interest to improve the understanding of cloud physics and for quantifying the effective radiative forcing by aerosol‐cloud interactions. Current standard satellite retrievals do not operationally provide N (d), but it can be inferred from...
Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2018
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099364/ https://www.ncbi.nlm.nih.gov/pubmed/30148283 http://dx.doi.org/10.1029/2017RG000593 |
_version_ | 1783348648312045568 |
---|---|
author | Grosvenor, Daniel P. Sourdeval, Odran Zuidema, Paquita Ackerman, Andrew Alexandrov, Mikhail D. Bennartz, Ralf Boers, Reinout Cairns, Brian Chiu, J. Christine Christensen, Matthew Deneke, Hartwig Diamond, Michael Feingold, Graham Fridlind, Ann Hünerbein, Anja Knist, Christine Kollias, Pavlos Marshak, Alexander McCoy, Daniel Merk, Daniel Painemal, David Rausch, John Rosenfeld, Daniel Russchenberg, Herman Seifert, Patric Sinclair, Kenneth Stier, Philip van Diedenhoven, Bastiaan Wendisch, Manfred Werner, Frank Wood, Robert Zhang, Zhibo Quaas, Johannes |
author_facet | Grosvenor, Daniel P. Sourdeval, Odran Zuidema, Paquita Ackerman, Andrew Alexandrov, Mikhail D. Bennartz, Ralf Boers, Reinout Cairns, Brian Chiu, J. Christine Christensen, Matthew Deneke, Hartwig Diamond, Michael Feingold, Graham Fridlind, Ann Hünerbein, Anja Knist, Christine Kollias, Pavlos Marshak, Alexander McCoy, Daniel Merk, Daniel Painemal, David Rausch, John Rosenfeld, Daniel Russchenberg, Herman Seifert, Patric Sinclair, Kenneth Stier, Philip van Diedenhoven, Bastiaan Wendisch, Manfred Werner, Frank Wood, Robert Zhang, Zhibo Quaas, Johannes |
author_sort | Grosvenor, Daniel P. |
collection | PubMed |
description | The cloud droplet number concentration (N (d)) is of central interest to improve the understanding of cloud physics and for quantifying the effective radiative forcing by aerosol‐cloud interactions. Current standard satellite retrievals do not operationally provide N (d), but it can be inferred from retrievals of cloud optical depth (τ (c)) cloud droplet effective radius (r (e)) and cloud top temperature. This review summarizes issues with this approach and quantifies uncertainties. A total relative uncertainty of 78% is inferred for pixel‐level retrievals for relatively homogeneous, optically thick and unobscured stratiform clouds with favorable viewing geometry. The uncertainty is even greater if these conditions are not met. For averages over 1° ×1° regions the uncertainty is reduced to 54% assuming random errors for instrument uncertainties. In contrast, the few evaluation studies against reference in situ observations suggest much better accuracy with little variability in the bias. More such studies are required for a better error characterization. N (d) uncertainty is dominated by errors in r (e), and therefore, improvements in r (e) retrievals would greatly improve the quality of the N (d) retrievals. Recommendations are made for how this might be achieved. Some existing N (d) data sets are compared and discussed, and best practices for the use of N (d) data from current passive instruments (e.g., filtering criteria) are recommended. Emerging alternative N (d) estimates are also considered. First, new ideas to use additional information from existing and upcoming spaceborne instruments are discussed, and second, approaches using high‐quality ground‐based observations are examined. |
format | Online Article Text |
id | pubmed-6099364 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-60993642018-08-24 Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives Grosvenor, Daniel P. Sourdeval, Odran Zuidema, Paquita Ackerman, Andrew Alexandrov, Mikhail D. Bennartz, Ralf Boers, Reinout Cairns, Brian Chiu, J. Christine Christensen, Matthew Deneke, Hartwig Diamond, Michael Feingold, Graham Fridlind, Ann Hünerbein, Anja Knist, Christine Kollias, Pavlos Marshak, Alexander McCoy, Daniel Merk, Daniel Painemal, David Rausch, John Rosenfeld, Daniel Russchenberg, Herman Seifert, Patric Sinclair, Kenneth Stier, Philip van Diedenhoven, Bastiaan Wendisch, Manfred Werner, Frank Wood, Robert Zhang, Zhibo Quaas, Johannes Rev Geophys Review Articles The cloud droplet number concentration (N (d)) is of central interest to improve the understanding of cloud physics and for quantifying the effective radiative forcing by aerosol‐cloud interactions. Current standard satellite retrievals do not operationally provide N (d), but it can be inferred from retrievals of cloud optical depth (τ (c)) cloud droplet effective radius (r (e)) and cloud top temperature. This review summarizes issues with this approach and quantifies uncertainties. A total relative uncertainty of 78% is inferred for pixel‐level retrievals for relatively homogeneous, optically thick and unobscured stratiform clouds with favorable viewing geometry. The uncertainty is even greater if these conditions are not met. For averages over 1° ×1° regions the uncertainty is reduced to 54% assuming random errors for instrument uncertainties. In contrast, the few evaluation studies against reference in situ observations suggest much better accuracy with little variability in the bias. More such studies are required for a better error characterization. N (d) uncertainty is dominated by errors in r (e), and therefore, improvements in r (e) retrievals would greatly improve the quality of the N (d) retrievals. Recommendations are made for how this might be achieved. Some existing N (d) data sets are compared and discussed, and best practices for the use of N (d) data from current passive instruments (e.g., filtering criteria) are recommended. Emerging alternative N (d) estimates are also considered. First, new ideas to use additional information from existing and upcoming spaceborne instruments are discussed, and second, approaches using high‐quality ground‐based observations are examined. John Wiley and Sons Inc. 2018-06-27 2018-06 /pmc/articles/PMC6099364/ /pubmed/30148283 http://dx.doi.org/10.1029/2017RG000593 Text en ©2018. The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Review Articles Grosvenor, Daniel P. Sourdeval, Odran Zuidema, Paquita Ackerman, Andrew Alexandrov, Mikhail D. Bennartz, Ralf Boers, Reinout Cairns, Brian Chiu, J. Christine Christensen, Matthew Deneke, Hartwig Diamond, Michael Feingold, Graham Fridlind, Ann Hünerbein, Anja Knist, Christine Kollias, Pavlos Marshak, Alexander McCoy, Daniel Merk, Daniel Painemal, David Rausch, John Rosenfeld, Daniel Russchenberg, Herman Seifert, Patric Sinclair, Kenneth Stier, Philip van Diedenhoven, Bastiaan Wendisch, Manfred Werner, Frank Wood, Robert Zhang, Zhibo Quaas, Johannes Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title | Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title_full | Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title_fullStr | Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title_full_unstemmed | Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title_short | Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives |
title_sort | remote sensing of droplet number concentration in warm clouds: a review of the current state of knowledge and perspectives |
topic | Review Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099364/ https://www.ncbi.nlm.nih.gov/pubmed/30148283 http://dx.doi.org/10.1029/2017RG000593 |
work_keys_str_mv | AT grosvenordanielp remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT sourdevalodran remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT zuidemapaquita remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT ackermanandrew remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT alexandrovmikhaild remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT bennartzralf remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT boersreinout remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT cairnsbrian remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT chiujchristine remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT christensenmatthew remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT denekehartwig remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT diamondmichael remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT feingoldgraham remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT fridlindann remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT hunerbeinanja remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT knistchristine remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT kolliaspavlos remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT marshakalexander remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT mccoydaniel remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT merkdaniel remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT painemaldavid remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT rauschjohn remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT rosenfelddaniel remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT russchenbergherman remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT seifertpatric remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT sinclairkenneth remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT stierphilip remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT vandiedenhovenbastiaan remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT wendischmanfred remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT wernerfrank remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT woodrobert remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT zhangzhibo remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives AT quaasjohannes remotesensingofdropletnumberconcentrationinwarmcloudsareviewofthecurrentstateofknowledgeandperspectives |