Toward Developing an Objective 4DVAR BDA Scheme for Hurricane Initialization Based on TPC Observed Parameters

Abstract This study aims to make the four-dimensional variational (4DVAR) bogus data assimilation (BDA) scheme for hurricane initialization first proposed by Zou and Xiao more objective. The BDA scheme consists of two steps: (i) specifying a bogus sea level pressure (SLP) field based on parameters observed by the Tropical Prediction Center (TPC) and (ii) assimilating the bogus SLP field under a forecast model constraint adjusting all model variables. In previous studies, specification of the bogus SLP was based on Fujita's formula, requiring the central SLP pressure (Pc), the radius of the outermost closed isobar (Rout), and the radius of the maximum SLP gradient (R0) as inputs. Although the parameters Pc and Rout are provided directly by the TPC, R0 is not. In this research, an empirical linear model designed to determine the value of R0 (the size of the bogus vortex) from the TPC observed radius of 34-kt wind (R34kt) is developed. Numerical experiments are carried out for the initialization and predicti...

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