![]() Correlation, covariance and variance matrices of daily and monthly rainfall amounts were calculated at monthly steps. Thus only data from 1990 to 2004 (208 weather stations) were used to avoid the detected changes in climate in the region. Differences in rainfall were found between the most recent 15-year period and all others occurring during the 90-year period of record. ![]() Rainfall data from 523 weather stations (National Climate Data Center) were obtained for the period 1915–2004 and divided into 15-year subsets for comparisons. We first determined the historical record length that is stationary followed by an analysis of the monthly spatial characteristics of rainfall variables. Monthly spatial statistics are needed to improve downscaling from climate models producing seasonal rainfall forecasts, and spatial correlation of daily rainfall is needed to inform spatial weather generators used in climate risk analysis. This study seeks to understand the spatial variability of monthly and daily rainfall in Alabama, Georgia, and Florida, USA. They are modified by mesoscale and continental circulation patterns as the annual shift of pressure cells, the east Andean low-level Jet and katabatic flows. They are characterized by specific combinations of local and regional atmospheric processes and interactions with the topographical configuration. ![]() This leads to complex patterns of rainfall in space and time.Several types of characteristic weather situations are revealed by the study. Several processes interact like small and large-scale convective cloud systems, local and regional valley/mountain breeze systems and terrain-lines of preferred moisture transport interact on various time scale. The typical form is light to heavy drizzle with long duration but lower rain rates.However, in contrast to former knowledge there is no single mechanism of rain formation for any given place. A blending method encompassing geostatistical tools allows to derive a comprehensive rainfall climatology for the study area.Precipitation is predominantly of the advective type, associated with humid air masses from the Amazon basin transported by the tropical easterlies. ![]() ![]() By using a cost-efficient rain radar and a network of high-resolution rain gauges, the real complexity of the rainfall distribution and the meteorological processes of rainfall formation can be assessed. The existing operational network of the national weather service is not capable of reproducing these complex patterns. The Andes of Ecuador show an extreme heterogeneity of spatial and temporal distribution of precipitation. ![]()
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