Retrieval of Cirrus Cloud Optical Depth under Day and Night Conditions from MODIS Collection 6 Cloud Property Data

Andrew Heidinger,Yue Li,Steven Platnick,Ping Yang,Robert Holz,Bryan Baum

doi:10.3390/rs70607257

Andrew Heidinger, Yue Li + Show 4 more

Open Access

https://doi.org/10.3390/rs70607257

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Abstract

This paper presents a technique to generate cirrus optical depth and particle effective size estimates from the cloud emissivities at 8.5, 11 and 12 μm contained in the Collection-6 (C6) MYD06 cloud product. This technique employs the latest scattering models and scattering radiative transfer approximations to estimate cloud optical depth and particle effective size using efficient analytical formulae. Two scattering models are tested. The first is the same scattering model as that used in the C6 MYD06 solar reflectance products. The second model is an empirical model derived from radiometric consistency. Both models are shown to generate optical depths that compare well to those from constrained CALIPSO retrievals and MYD06. In terms of effective radius retrievals, the results from the radiometric empirical model agree more closely with MYD06 than those from the C6 model. This analysis is applied to AQUA/MODIS data collocated with CALIPSO/CALIOP during January 2010.

Highlights

The recently released MYD06 Collection 6 (C6) cloud products have been expanded in several ways compared to the Collection 5 (C5) data [1]
General Method for Optical Depth Retrieval. The step in this analysis is the estimation of the cirrus cloud optical depth, which can be derived after effective particle size is retrieved
The CALIPSO/Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) QC filtering was not applied in the comparisons to C6 MYD06 or CALIPSO/Imaging Radiometer (IIR)

Summary

Introduction

The recently released MYD06 Collection 6 (C6) cloud products have been expanded in several ways compared to the Collection 5 (C5) data [1]. One of the new features of C6 MYD06 is the inclusion of cloud emissivity values in three InfraRed (IR) channels located in the longwave. The emissivities are a natural byproduct of the MYD06 cloud top height approach [2]. The addition of the emissivity values provides the basis for an accurate and computationally efficient estimation of the optical and microphysical properties of semitransparent cirrus clouds. These IR products can be generated both day and night and complement the suite of optical and microphysical properties in MYD06 derived during the day

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Conclusion