A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra
A new retrieval scheme for cloud optical thickness, effective radius, and thermodynamic phase was developed for ground-based measurements of cloud shortwave solar spectral transmittance. Fifteen parameters were derived to quantify spectral variations in shortwave transmittance due to absorpt...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/8/1361/2015/amt-8-1361-2015.pdf |
| _version_ | 1818000327102693376 |
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| author | S. E. LeBlanc P. Pilewskie K. S. Schmidt O. Coddington |
| author_facet | S. E. LeBlanc P. Pilewskie K. S. Schmidt O. Coddington |
| author_sort | S. E. LeBlanc |
| collection | DOAJ |
| description | A new retrieval scheme for cloud optical thickness, effective
radius, and thermodynamic phase was developed for ground-based
measurements of cloud shortwave solar spectral transmittance. Fifteen
parameters were derived to quantify spectral variations in shortwave
transmittance due to absorption and scattering of liquid water and
ice clouds, manifested by shifts in spectral slopes, curvatures,
maxima, and minima. To retrieve cloud optical thickness and
effective particle radius, a weighted least square fit that matched
the modeled parameters was applied. The measurements for this
analysis were made with the ground-based Solar Spectral Flux
Radiometer in Boulder, Colorado, between May 2012 and
January 2013. We compared the cloud optical thickness and effective
radius from the new retrieval to two other retrieval methods. By
using multiple spectral features, we find a closer fit (with a root
mean square difference over the entire spectra of 3.1% for
a liquid water cloud and 5.9% for an ice cloud) between
measured and modeled spectra compared to two other retrieval
methods which diverge by a root mean square of up to 6.4%
for a liquid water cloud and 22.5% for an ice cloud. The new
retrieval introduced here has an average uncertainty in effective
radius (± 1.2 μm) smaller by factor of at least 2.5
than two other methods when applied to an ice cloud. |
| first_indexed | 2024-04-14T03:20:24Z |
| format | Article |
| id | doaj.art-edd5ba5c94e24ecea7250a67c5b1e49b |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-04-14T03:20:24Z |
| publishDate | 2015-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-edd5ba5c94e24ecea7250a67c5b1e49b2022-12-22T02:15:19ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482015-03-01831361138310.5194/amt-8-1361-2015A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectraS. E. LeBlanc0P. Pilewskie1K. S. Schmidt2O. Coddington3University of Colorado, Department of Atmospheric and Oceanic Sciences, Boulder, CO, USAUniversity of Colorado, Department of Atmospheric and Oceanic Sciences, Boulder, CO, USAUniversity of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, USAUniversity of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, USAA new retrieval scheme for cloud optical thickness, effective radius, and thermodynamic phase was developed for ground-based measurements of cloud shortwave solar spectral transmittance. Fifteen parameters were derived to quantify spectral variations in shortwave transmittance due to absorption and scattering of liquid water and ice clouds, manifested by shifts in spectral slopes, curvatures, maxima, and minima. To retrieve cloud optical thickness and effective particle radius, a weighted least square fit that matched the modeled parameters was applied. The measurements for this analysis were made with the ground-based Solar Spectral Flux Radiometer in Boulder, Colorado, between May 2012 and January 2013. We compared the cloud optical thickness and effective radius from the new retrieval to two other retrieval methods. By using multiple spectral features, we find a closer fit (with a root mean square difference over the entire spectra of 3.1% for a liquid water cloud and 5.9% for an ice cloud) between measured and modeled spectra compared to two other retrieval methods which diverge by a root mean square of up to 6.4% for a liquid water cloud and 22.5% for an ice cloud. The new retrieval introduced here has an average uncertainty in effective radius (± 1.2 μm) smaller by factor of at least 2.5 than two other methods when applied to an ice cloud.http://www.atmos-meas-tech.net/8/1361/2015/amt-8-1361-2015.pdf |
| spellingShingle | S. E. LeBlanc P. Pilewskie K. S. Schmidt O. Coddington A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra Atmospheric Measurement Techniques |
| title | A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| title_full | A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| title_fullStr | A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| title_full_unstemmed | A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| title_short | A spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| title_sort | spectral method for discriminating thermodynamic phase and retrieving cloud optical thickness and effective radius using transmitted solar radiance spectra |
| url | http://www.atmos-meas-tech.net/8/1361/2015/amt-8-1361-2015.pdf |
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