Cloudiness and its relationship to saturation pressure differences during a developing east coast winter storm

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Journal of Applied Meteorology

DOI:https://doi.org/10.1175/1520-0450(1995)034<2367:CAIRTS>2.0.CO;2· OSTI ID:273955

Alliss, R J; Raman, S ^[1]

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1. North Carolina State Univ., Raleigh, NC (United States)

Cloudiness derived from surface observations and the Geostationary Operational Environmental Satellite VISSR (Visible-Infrared Spin Scan Radiometer) Atmospheric Sounder (VAS) are compared with thermodynamic properties derived from upper-air soundings over the Gulf Stream locale during a developing winter storm. Cloud-top pressures are derived from VAS using the CO{sub 2} slicing technique and a simple threshold procedure. Cloud-base heights and cloud fractions are obtained from National Weather Service hourly reporting stations. Saturation pressure differences, defined as differences between air parcel pressure and saturation-level pressure (lifted condensation level), are derived from upper-air soundings. Collocated comparisons with VAS and surface observations are also made. Results indicate that cloudiness is observed nearly all of the time during the 6-day period, well above the 8-yr mean. High, middle, and low opaque cloudiness are found approximately equally. Of the high- and midlevel cloudiness observed, a considerable amount is semitransparent to terrestrial radiation. Comparisons of satellite-inferred cloudiness with surface observations indicate that the satellite can complement surface observations of cloud cover, particularly above 700 mb. Surface-observed cloudiness is segregated according to a composite cloud fraction and compared to the mean saturation pressure difference for a 1000-600-mb layer. The analysis suggests that this conserved variable may be a good indicator for estimating cloud fraction. Large negative values of saturation pressure difference correlate highly with clear skies, while those approaching zero correlate with overcast conditions. Scattered and broken cloud fractions are associated with increasing values of the saturation pressure difference. Furthermore, cloud fractions observed in this study are considerably higher than those reported in similar studies and by other cloud fraction formulations. 22 refs., 16 figs., 2 tabs.

• OSTI ID: 273955
• Journal Information: Journal of Applied Meteorology, Journal Name: Journal of Applied Meteorology Journal Issue: 11 Vol. 34; ISSN 0894-8763; ISSN JOAMEZ
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CLOUD COVER
CORRELATION FUNCTIONS
PRESSURE GRADIENTS
STORMS
US GULF COAST
VAPOR PRESSURE