Improvement of stratospheric aerosol extinction retrieval from OMPS/LP using a new aerosol model
<p>The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been flying on the Suomi National Polar-orbiting Partnership (S-NPP) satellite since October 2011. It is designed to produce ozone and aerosol vertical profiles at ∼ 2 km vertical resolution over the entire sunl...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-12-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/11/6495/2018/amt-11-6495-2018.pdf |
| Summary: | <p>The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been flying
on the Suomi National Polar-orbiting Partnership (S-NPP) satellite since
October 2011. It is designed to produce ozone and aerosol vertical profiles
at ∼ 2 km vertical resolution over the entire sunlit globe. Aerosol
extinction profiles are computed with Mie theory using radiances measured at
675 nm. The operational Version 1.0 (V1.0) aerosol extinction retrieval
algorithm assumes a bimodal lognormal aerosol size distribution (ASD) whose
parameters were derived by combining an in situ measurement of aerosol
microphysics with the Stratospheric Aerosol and Gas Experiment (SAGE II)
aerosol extinction climatology. Internal analysis indicates that this bimodal
lognormal ASD does not sufficiently explain the spectral dependence of
LP-measured radiances. In this paper we describe the derivation of an
improved aerosol size distribution, designated Version 1.5 (V1.5), for the LP
retrieval algorithm. The new ASD uses a gamma function distribution that is
derived from Community Aerosol and Radiation Model for Atmospheres
(CARMA)-calculated results. A cumulative distribution fit derived from the
gamma function ASD gives better agreement with CARMA results at small
particle radii than bimodal or unimodal functions. The new ASD also explains
the spectral dependence of LP-measured radiances better than the V1.0 ASD. We
find that the impact of our choice of ASD on the retrieved extinctions varies
strongly with the underlying reflectivity of the scene. Initial comparisons
with collocated extinction profiles retrieved at 676 nm from the SAGE III
instrument on the International Space Station (ISS) show a significant
improvement in agreement for the LP V1.5 retrievals. Zonal mean extinction
profiles agree to within 10  % between 19 and 29 km, and regression
fits of collocated samples show improved correlation and reduced scatter
compared to the V1.0 product. This improved agreement will motivate
development of more sophisticated ASDs from CARMA results that incorporate
latitude, altitude and seasonal variations in aerosol properties.</p> |
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| ISSN: | 1867-1381 1867-8548 |