Cloud clusters and superclusters over the oceanic warm pool
- Univ. of Washington, Seattle (United States)
Infrared satellite images of the oceanic warm-pool region (80[degrees]E-160[degrees]W) have been processed to reveal tropical [open quotes]cloud clusters[close quotes] with temperatures colder than a given threshold. Cloud clusters span a lognormal distribution of sizes. The cloudiness per unit size interval peaks at small size, but half of the very cold (<208K) cloudiness is contributed by cloud clusters greater than 20,000 km[sup 2] in size, while half of the moderately cold (<235 K) cloudiness is contributed by cloud clusters greater than 100,000 km[sup 2] in size. The diurnal cycle of cold cloudiness is primarily a sun-synchronous process within large and giant clusters, not a modulation of populations of isolated convective clouds. Deep convection in these clusters peaks before dawn and decreases through the morning. The moderately cold cloud area suddenly expands in the afternoon. Over the maritime continent, an additional diurnal cycle of small clusters is present, with an afternoon pulse of convection over land and a lesser peak in small-cluster convection over the surrounding seas at night. The eastward-propagating intraseasonal variation (ISV) is apparent in fractional cold cloudiness integrated across the entire tropical latitude belt. The ISV modulates cloud clusters of all sizes, but larger clusters are proportionately more affected than smaller clusters. Cloud clusters have been tracked in time to reveal [open quotes]time clusters[close quotes], which spatially overlap from one frame of imagery to the next. In some cases, convection is so interconnected that these time clusters last for more than two days. These cases are called [open quotes]superclusters.[close quotes] Although they may exist at any given instant as several distinct cloud clusters, these superclusters are apparently real physical entities, as defined by spacetime continuity of very cold-topped cloud (proxy for precipitation) area. 33 refs., 21 figs.
- OSTI ID:
- 6070033
- Journal Information:
- Monthly Weather Review; (United States), Vol. 121:5; ISSN 0027-0644
- Country of Publication:
- United States
- Language:
- English
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CLOUDS
FORECASTING
REMOTE SENSING
TROPICAL REGIONS
ATMOSPHERIC CIRCULATION
ATMOSPHERIC PRECIPITATIONS
CONVECTION
DAILY VARIATIONS
ENERGY BUDGETS
INDIAN OCEAN
METEOROLOGY
PACIFIC OCEAN
SATELLITES
TEMPERATURE MONITORING
ENERGY TRANSFER
HEAT TRANSFER
MASS TRANSFER
MONITORING
SEAS
SURFACE WATERS
VARIATIONS
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