Publication Abstracts

Cho et al. 2015

Cho, H.-M., Z. Zhang, K. Meyer, M. Lebsock, S. Platnick, A.S. Ackerman, L. Di Girolamo, L.C. Labonnote, C. Cornet, J. Riedi, and R.E. Holz, 2015: Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans. J. Geophys. Res. Atmos., 120, no. 9, 4132-4154, doi:10.1002/2015JD023161.

Moderate Resolution Imaging Spectroradiometer (MODIS) retrieves cloud droplet effective radius (re) and optical thickness (τ) by projecting observed cloud reflectances onto a precomputed look-up table (LUT). When observations fall outside of the LUT, the retrieval is considered "failed" because no combination of τ and re within the LUT can explain the observed cloud reflectances. In this study, the frequency and potential causes of failed MODIS retrievals for marine liquid phase (MLP) clouds are analyzed based on 1 year of Aqua MODIS Collection 6 products and collocated CALIOP and CloudSat observations. The retrieval based on the 0.86 µm and 2.1 µm MODIS channel combination has an overall failure rate of about 16% (10% for the 0.86 µm and 3.7 µm combination). The failure rates are lower over stratocumulus regimes and higher over the broken trade wind cumulus regimes. The leading type of failure is the "re too large" failure accounting for 60%-85% of all failed retrievals. The rest is mostly due to the "re too small" or τ retrieval failures. Enhanced retrieval failure rates are found when MLP cloud pixels are partially cloudy or have high subpixel inhomogeneity, are located at special Sun-satellite viewing geometries such as sunglint, large viewing or solar zenith angles, or cloudbow and glory angles, or are subject to cloud masking, cloud overlapping, and/or cloud phase retrieval issues. The majority (more than 84%) of failed retrievals along the CALIPSO track can be attributed to at least one or more of these potential reasons. The collocated CloudSat radar reflectivity observations reveal that the remaining failed retrievals are often precipitating. It remains an open question whether the extremely large re values observed in these clouds are the consequence of true cloud microphysics or still due to artifacts not included in this study.

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BibTeX Citation

  author={Cho, H.-M. and Zhang, Z. and Meyer, K. and Lebsock, M. and Platnick, S. and Ackerman, A. S. and Di Girolamo, L. and Labonnote, L. C. and Cornet, C. and Riedi, J. and Holz, R. E.},
  title={Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans},
  journal={J. Geophys. Res. Atmos.},

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RIS Citation

ID  - ch06110m
AU  - Cho, H.-M.
AU  - Zhang, Z.
AU  - Meyer, K.
AU  - Lebsock, M.
AU  - Platnick, S.
AU  - Ackerman, A. S.
AU  - Di Girolamo, L.
AU  - Labonnote, L. C.
AU  - Cornet, C.
AU  - Riedi, J.
AU  - Holz, R. E.
PY  - 2015
TI  - Frequency and causes of failed MODIS cloud property retrievals for liquid phase clouds over global oceans
JA  - J. Geophys. Res. Atmos.
VL  - 120
IS  - 9
SP  - 4132
EP  - 4154
DO  - 10.1002/2015JD023161
ER  -

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