A Self-Adaptive Approach to Analyze Weather-within-Climate Rainfall Characteristics

Abstract:

Rainfall characteristics such as onset, duration, and demise provide important insight for the agriculture, health, disaster, and energy industry. However, forecasts on the temporal characteristics of the annual rainfall cycle are not readily available by local weather or climate services. The lack of forecasts on temporal characteristics of rainfall is likely attributed to its lack of attention and how the broader scientific understanding of these temporal characteristics, which the efficacy of forecasts is relied upon, is an ongoing investigation for many regions. Several methods have attempted to calculate temporal characteristics of rainfall; however, these methods are configured based on their region of interest. In addition, there are issues when applying these methods for complex rainfall regimes, or regions that have one or more of the following: (1) multiple rainfall seasons in a given year, (2) an unclear dry season, (3) an intermittent less wet season. This study aims at developing a new and comprehensive method for calculating rainfall characteristics, especially for regions that have complex annual rainfall cycles. The method consists of three steps: (1) creating the annual cycle climatology of rainfall, (2) identifying seasonal windows of the rainfall cycle based on its climatological modality, and (3) calculate rainfall characteristics for each year. Given the complexity of the Caribbean rainfall pattern, 34 Caribbean rainfall stations with daily data are used to showcase this method. The method can be used to investigate subseasonal-to-interannual variability, precipitation trends, and rainfall prediction. The method can also be applied under an agronomical or meteorological lens.