Data from the GARP Atlantic Tropical Experiment (GATE) was analysed
in an exploratory manner to discover the characteristics of mesoscale
organization of convection and it's relationship to large-scale wind profiles.
Automated methods were developed to identify the convective cells and their
linear organization. These automated methods use a median high-pass filter
to identify enhanced cells and a simple pattern recognition technique to ascertain
the linear organization between them. Due to the simplified nature
of the algorithm, the whole data set of the 21 day period from the phase
3 of GATE was processed in an economical manner obtaining a large data
base which was used in the investigation of clusters and other associated phenomena.
The mesoscale organization of convective cells and the widespread
areas of lighter precipitation associated with them showed expected characteristics
and compared satisfactorily with previous results. A large fraction
of the rainfall (64%) fell from the widespread area. The total precipitation
had a correlation of 0.94 with the fractional area of the widespread and a
correlation of 0.89 with the fractional area of the clusters. The widespread
precipitation had a correlation index of 0.97 with it's fractional area and
the cluster precipitation had a strong linear relationship to it's area with
a correlation of 0.99. These factors argue well for the parameterization of
rainfall rate in tropical regions to a high accuracy by the area covered by
organized convective cells and widespread areas. It was also seen that there
was a good correlation with the number of clusters and number of cores with
the total precipitation rate in a given area. These factors create a strong
argument for identifying mesoscale systems consisting of convective cells and
widespread precipitation as basic units of precipitation in tropical regions,
having a characteristic life cycle of their own. The widespread and total
precipitation showed very good correlation with upper-level vertical motion.
Clusters tended to align parallel with the horizontal low-level wind shear and
the degree of alignment appears to depend on the strength of the wind shear. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28794 |
| Date | 06 December 1990 |
| Creators | De Silva, Sirilath J. |
| Contributors | Esbensen, Steven K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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