Evaluating the influence of antecedent soil moisture on variability of the North American monsoon precipitation in the Coupled MM5/VIC Modeling System

摘要: The influence of antecedent soil moisture on North American monsoon system (NAMS) precipitation variability was explored using the MM5 mesoscale model coupled with Variable Infiltration Capacity (VIC) land surface model. Sensitivity experiments were performed extreme wet and dry initial conditions for both 1984 year 1989 year. MM5-VIC reproduced key features NAMS in especially over northwestern Mexico. Our modeling results indicate that has memory wetness prescribed at onset persists most region well into season (e.g. until August). However, contrast to classical thermal concept, where wetter soils lead cooler temperatures, less land-sea contrast, weaker circulations precipitation, consistently demonstrated a positive – feedback. Specifically, anomalously premonsoon always enhanced reverse also true. temperature changes induced by differences energy flux partitioning associated pre-monsoon anomalies changed pressure consequently flow field model, which inmore » turn convergence and, accordingly, patterns. Both largescale circulation change local land-atmospheric interactions response play important roles model’s former may be sensitive strength location anomalies, thus leaving open possibility negative feedbacks.« less