Cloud base height retrieval from multi-angle satellite data

<p>Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base height (<span class="inline-formula">...

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Main Authors: C. Böhm, O. Sourdeval, J. Mülmenstädt, J. Quaas, S. Crewell
Format: Article
Language:English
Published: Copernicus Publications 2019-03-01
Series:Atmospheric Measurement Techniques
Online Access:https://www.atmos-meas-tech.net/12/1841/2019/amt-12-1841-2019.pdf
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author C. Böhm
O. Sourdeval
O. Sourdeval
J. Mülmenstädt
J. Quaas
S. Crewell
author_facet C. Böhm
O. Sourdeval
O. Sourdeval
J. Mülmenstädt
J. Quaas
S. Crewell
author_sort C. Böhm
collection DOAJ
description <p>Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base height (<span class="inline-formula"><i>z</i><sub>base</sub></span>) from satellite measurements. This study presents a new approach to retrieve cloud base heights using the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite. It can be applied if some cloud gaps occur within the chosen distance of typically <span class="inline-formula">10</span>&thinsp;km. The MISR cloud base height (MIBase) algorithm then determines <span class="inline-formula"><i>z</i><sub>base</sub></span> from the ensemble of all MISR cloud top heights retrieved at a <span class="inline-formula">1.1</span>&thinsp;km horizontal resolution in this area. MIBase is first calibrated using 1 year of ceilometer data from more than 1500 sites within the continental United States of America. The 15th percentile of the cloud top height distribution within a circular area of <span class="inline-formula">10</span>&thinsp;km radius provides the best agreement with the ground-based data. The thorough evaluation of the MIBase product <span class="inline-formula"><i>z</i><sub>base</sub></span> with further ceilometer data yields a correlation coefficient of about <span class="inline-formula">0.66</span>, demonstrating the feasibility of this approach to retrieve <span class="inline-formula"><i>z</i><sub>base</sub></span>. The impacts of the cloud scene structure and macrophysical cloud properties are discussed. For a 3-year period, the median <span class="inline-formula"><i>z</i><sub>base</sub></span> is generated globally on a 0.25<span class="inline-formula"><sup>∘</sup></span>&thinsp;<span class="inline-formula">×</span>&thinsp;0.25<span class="inline-formula"><sup>∘</sup></span> grid. Even though overcast cloud scenes and high clouds are excluded from the statistics, the median <span class="inline-formula"><i>z</i><sub>base</sub></span> retrievals yield plausible results, in particular over ocean as well as for seasonal differences. The potential of the full 16 years of MISR data is demonstrated for the southeast Pacific, revealing interannual variability in <span class="inline-formula"><i>z</i><sub>base</sub></span> in accordance with reanalysis data. The global cloud base data for the 3-year period (2007–2009) are available at <a href="https://doi.org/10.5880/CRC1211DB.19">https://doi.org/10.5880/CRC1211DB.19</a>.</p>
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spelling doaj.art-2c46da7deba64d0fbc9d664fdfe483bd2022-12-22T01:17:18ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482019-03-01121841186010.5194/amt-12-1841-2019Cloud base height retrieval from multi-angle satellite dataC. Böhm0O. Sourdeval1O. Sourdeval2J. Mülmenstädt3J. Quaas4S. Crewell5Institute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute of Meteorology, University of Leipzig, Leipzig, GermanyLaboratoire d'Optique Atmosphérique, Université de Lille, Villeneuve-d'Ascq, FranceInstitute of Meteorology, University of Leipzig, Leipzig, GermanyInstitute of Meteorology, University of Leipzig, Leipzig, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, Germany<p>Clouds are a key modulator of the Earth energy budget at the top of the atmosphere and at the surface. While the cloud top height is operationally retrieved with global coverage, only few methods have been proposed to determine cloud base height (<span class="inline-formula"><i>z</i><sub>base</sub></span>) from satellite measurements. This study presents a new approach to retrieve cloud base heights using the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite. It can be applied if some cloud gaps occur within the chosen distance of typically <span class="inline-formula">10</span>&thinsp;km. The MISR cloud base height (MIBase) algorithm then determines <span class="inline-formula"><i>z</i><sub>base</sub></span> from the ensemble of all MISR cloud top heights retrieved at a <span class="inline-formula">1.1</span>&thinsp;km horizontal resolution in this area. MIBase is first calibrated using 1 year of ceilometer data from more than 1500 sites within the continental United States of America. The 15th percentile of the cloud top height distribution within a circular area of <span class="inline-formula">10</span>&thinsp;km radius provides the best agreement with the ground-based data. The thorough evaluation of the MIBase product <span class="inline-formula"><i>z</i><sub>base</sub></span> with further ceilometer data yields a correlation coefficient of about <span class="inline-formula">0.66</span>, demonstrating the feasibility of this approach to retrieve <span class="inline-formula"><i>z</i><sub>base</sub></span>. The impacts of the cloud scene structure and macrophysical cloud properties are discussed. For a 3-year period, the median <span class="inline-formula"><i>z</i><sub>base</sub></span> is generated globally on a 0.25<span class="inline-formula"><sup>∘</sup></span>&thinsp;<span class="inline-formula">×</span>&thinsp;0.25<span class="inline-formula"><sup>∘</sup></span> grid. Even though overcast cloud scenes and high clouds are excluded from the statistics, the median <span class="inline-formula"><i>z</i><sub>base</sub></span> retrievals yield plausible results, in particular over ocean as well as for seasonal differences. The potential of the full 16 years of MISR data is demonstrated for the southeast Pacific, revealing interannual variability in <span class="inline-formula"><i>z</i><sub>base</sub></span> in accordance with reanalysis data. The global cloud base data for the 3-year period (2007–2009) are available at <a href="https://doi.org/10.5880/CRC1211DB.19">https://doi.org/10.5880/CRC1211DB.19</a>.</p>https://www.atmos-meas-tech.net/12/1841/2019/amt-12-1841-2019.pdf
spellingShingle C. Böhm
O. Sourdeval
O. Sourdeval
J. Mülmenstädt
J. Quaas
S. Crewell
Cloud base height retrieval from multi-angle satellite data
Atmospheric Measurement Techniques
title Cloud base height retrieval from multi-angle satellite data
title_full Cloud base height retrieval from multi-angle satellite data
title_fullStr Cloud base height retrieval from multi-angle satellite data
title_full_unstemmed Cloud base height retrieval from multi-angle satellite data
title_short Cloud base height retrieval from multi-angle satellite data
title_sort cloud base height retrieval from multi angle satellite data
url https://www.atmos-meas-tech.net/12/1841/2019/amt-12-1841-2019.pdf
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