Variation of arctic cloud cover in summer. Progress report, April 15, 1981-October 1, 1982
The largest impact of increasing CO/sub 2/ should occur in the high latitudes according to climate models. However, an appropriate data base on cloud distribution and optical thickness is needed in order to improve and test the models as well as to enable the future detection of the CO/sub 2/ climate impact in high latitudes. Cloud cover over the Arctic Basin in late spring and summer of 1979 was charted in three day intervals based on NOAA and DMSP imagery. Three cloud types were recognized based on visually determined optical thickness. They are thick opaque stratus, thin transparent stratus, through which surface features are identifiable, and thin cirrus or fog. While 50 to 60% of the Arctic Basin was found to have stratus cloud, only about half this amount was of the optically thick type. This differs considerably from earlier estimates. Moreover, the day to day variability of cloud cover was found to be large. A comparison of cloud distribution with reconstructed pressure patterns show that the cloud distribution can be used to improve the charts. Ratios determined for cloud and cloud free conditions over both snow and open water were found to be useful in making numerical estimates of the optical thickness of clouds. Calibration of cloud type with the mean optical thickness is underway. Also tested was the detection of the cloud height from the width of the shadow. If the 1979 conditions were typical of recent years, substantial revisions will be needed in climate models assessing the CO/sub 2/ impact on climate.
- Research Organization:
- Columbia Univ., Palisades, NY (USA). Lamont-Doherty Geological Observatory
- DOE Contract Number:
- AC02-81EV10665
- OSTI ID:
- 6854822
- Report Number(s):
- DOE/EV/10665-2; ON: DE83002174
- Country of Publication:
- United States
- Language:
- English
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Variation of arctic cloud cover in summer: results through February 1983
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