Publication Abstracts

Jin 1997

Jin, Y., 1997: Investigation of Cirrus Cloud Climatology by Satellite Remote Sensing. Ph.D. thesis. Columbia University.

This thesis investigates cirrus cloud climatology and cirrus cloud formation scheme by satellite remote sensing, and is organized into three sections. The first section compares individually matched analyses of high-level cloudiness from ISCCP and HIRS for 4 months. The comparison shows that almost all of the difference in high-level cloud amount occurs as differences of optically thin cirrus, consistent with a previous comparison of SAGE II and ISCCP. From these two datasets and by analyzing the reasons for the differences in high-level cloud amount, it is concluded that about one-third of the earth is covered by high-level clouds and more than two-thirds of these clouds are cirrus, defined as those clouds that have a net radiative heating effect. About half of all cirrus clouds are optically very thin. Major features of cirrus clouds obtained by ISCCP and confirmed by HIRS are also presented. Supplemented by the comparison between ISCCP and SAGE II, this work gives confidence that the patterns of geographical and seasonal variations of cirrus clouds are well represented in both ISCCP and HIRS data except for differences in absolute high-level cloud amount. The second section proposes a multispectral method to detect cirrus overlapping low-level clouds which is easy to apply and applicable for global retrieval (excluding polar regions). This method uses the results from different HIRS channel combinations assuming a single cloud layer in the CO2-Slicing technique and is valid over both land and ocean. Two months of HIRS data have been analyzed using this method, which gives a first global survey of the possible impacts (in terms of frequency) of cirrus overlapping low-level clouds on the retrieval of high transmissive cloud properties. It is concluded that the fraction of cirrus overlapping low-level cloud would not significantly alter the patterns of cirrus geographical and seasonal variation patterns presented in current ISCCP and HIRS datasets. Globally averaged fraction and the global distribution patterns of such two-layer cloudiness for these two months are presented. Qualitative comparisons to surface and upper air observations are also provided and are very encouraging. Having confidence in the cirrus climatology in ISCCP, the third section studies temporal evolution patterns of high-level clouds with various τ categories for 6 months of ISCCP data to investigate the cirrus cloud formation processes over mid-latitudes. It is found that the temporal autocorrelations for thin cirrus are always higher than that of medium and thick high-level clouds and do not track the oscillation patterns of medium and thick high-level clouds, while medium and thick high-level clouds present similar oscillation features over each hemispheric land and ocean. These phenomena suggest that thin cirrus is standing while medium and thick high-level clouds propagate together, which means that thin cirrus are not produced by the same formation processes as are medium and thick high-level clouds.

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BibTeX Citation

  author={Jin, Y.},
  title={Investigation of Cirrus Cloud Climatology by Satellite Remote Sensing},
  school={Columbia University},
  address={New York, N.Y.},

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RIS Citation

ID  - ji05000n
AU  - Jin, Y.
PY  - 1997
BT  - Investigation of Cirrus Cloud Climatology by Satellite Remote Sensing
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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