Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties
Improvements to climate model results in polar regions require improved knowledge of cloud properties. Surface-based infrared (IR) radiance spectrometers have been used to retrieve cloud properties in polar regions, but measurements are sparse. Reductions in cost and power requirements to allow more...
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ftunivpugetsound:oai:soundideas.pugetsound.edu:faculty_pubs-4412 2023-05-15T15:11:40+02:00 Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties Rowe, Penny M. Cox, Christopher J. Neshyba, Steven Walden, Von P. 2019-09-23T07:00:00Z text/html https://soundideas.pugetsound.edu/faculty_pubs/3403 https://soundideas.pugetsound.edu/context/faculty_pubs/article/4412/type/native/viewcontent unknown Sound Ideas https://soundideas.pugetsound.edu/faculty_pubs/3403 https://soundideas.pugetsound.edu/context/faculty_pubs/article/4412/type/native/viewcontent All Faculty Scholarship text 2019 ftunivpugetsound 2022-07-27T18:36:38Z Improvements to climate model results in polar regions require improved knowledge of cloud properties. Surface-based infrared (IR) radiance spectrometers have been used to retrieve cloud properties in polar regions, but measurements are sparse. Reductions in cost and power requirements to allow more widespread measurements could be aided by reducing instrument resolution. Here we explore the effects of errors and instrument resolution on cloud property retrievals from downwelling IR radiances for resolutions of 0.1 to 20 cm-1. Retrievals are tested on 336 radiance simulations characteristic of the Arctic, including mixed-phase, vertically inhomogeneous, and liquid-topped clouds and a variety of ice habits. Retrieval accuracy is found to be unaffected by resolution from 0.1 to 4 cm-1, after which it decreases slightly. When cloud heights are retrieved, errors in retrieved cloud optical depth (COD) and ice fraction are considerably smaller for clouds with bases below 2 km than for higher clouds. For example, at a resolution of 4 cm-1, with errors imposed (noise and radiation bias of 0.2 mW/(m2 sr cm-1) and biases in temperature of 0.2K and in water vapor of -3 %), using retrieved cloud heights, root-mean-square errors decrease from 1.1 to 0.15 for COD, 0.3 to 0.18 for ice fraction (fice), and 10 to 7 μm for ice effective radius (errors remain at 2 μm for liquid effective radius). These results indicate that a moderately low-resolution, surface-based IR spectrometer could provide cloud property retrievals with accuracy comparable to existing higher-resolution instruments and that such an instrument would be particularly useful for low-level clouds. Text Arctic University of Puget Sound: Sound Ideas Arctic |
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University of Puget Sound: Sound Ideas |
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Improvements to climate model results in polar regions require improved knowledge of cloud properties. Surface-based infrared (IR) radiance spectrometers have been used to retrieve cloud properties in polar regions, but measurements are sparse. Reductions in cost and power requirements to allow more widespread measurements could be aided by reducing instrument resolution. Here we explore the effects of errors and instrument resolution on cloud property retrievals from downwelling IR radiances for resolutions of 0.1 to 20 cm-1. Retrievals are tested on 336 radiance simulations characteristic of the Arctic, including mixed-phase, vertically inhomogeneous, and liquid-topped clouds and a variety of ice habits. Retrieval accuracy is found to be unaffected by resolution from 0.1 to 4 cm-1, after which it decreases slightly. When cloud heights are retrieved, errors in retrieved cloud optical depth (COD) and ice fraction are considerably smaller for clouds with bases below 2 km than for higher clouds. For example, at a resolution of 4 cm-1, with errors imposed (noise and radiation bias of 0.2 mW/(m2 sr cm-1) and biases in temperature of 0.2K and in water vapor of -3 %), using retrieved cloud heights, root-mean-square errors decrease from 1.1 to 0.15 for COD, 0.3 to 0.18 for ice fraction (fice), and 10 to 7 μm for ice effective radius (errors remain at 2 μm for liquid effective radius). These results indicate that a moderately low-resolution, surface-based IR spectrometer could provide cloud property retrievals with accuracy comparable to existing higher-resolution instruments and that such an instrument would be particularly useful for low-level clouds. |
format |
Text |
author |
Rowe, Penny M. Cox, Christopher J. Neshyba, Steven Walden, Von P. |
spellingShingle |
Rowe, Penny M. Cox, Christopher J. Neshyba, Steven Walden, Von P. Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
author_facet |
Rowe, Penny M. Cox, Christopher J. Neshyba, Steven Walden, Von P. |
author_sort |
Rowe, Penny M. |
title |
Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
title_short |
Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
title_full |
Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
title_fullStr |
Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
title_full_unstemmed |
Toward autonomous surface-based infrared remote sensing of polar clouds: Retrievals of cloud optical and microphysical properties |
title_sort |
toward autonomous surface-based infrared remote sensing of polar clouds: retrievals of cloud optical and microphysical properties |
publisher |
Sound Ideas |
publishDate |
2019 |
url |
https://soundideas.pugetsound.edu/faculty_pubs/3403 https://soundideas.pugetsound.edu/context/faculty_pubs/article/4412/type/native/viewcontent |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
All Faculty Scholarship |
op_relation |
https://soundideas.pugetsound.edu/faculty_pubs/3403 https://soundideas.pugetsound.edu/context/faculty_pubs/article/4412/type/native/viewcontent |
_version_ |
1766342497113473024 |