Document Type

Article

Abstract

The influence of land–atmosphere interactions on the variability of the North American monsoon system(NAMS) is investigated using the Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder(TOVS) Pathfinder, the Climate Prediction Center (CPC) gauge precipitation, and observed snow water equivalent(SWE). Three hypotheses are tested regarding the connection between land surface variables and precipitationin the NAMS region. First, there is a weak negative correlation between 1 April SWE and subsequent surfacetemperature in the southern Rocky Mountains (SRM) region. However, this connection persists only until Juneand, therefore, cannot directly influence monsoon rainfall in July and August. Second, there is a negativecorrelation between SRM surface temperature and NAMS precipitation during the monsoon season, rather thanthe positive correlation previously proposed. Third, there is a highly significant negative correlation betweenrainfall and surface temperature within the NAMS region. On the monthly timescale, surface temperature decreasesby ~4 K per 1 mm day21 increase in rainfall, consistent with a positive soil moisture–rainfall feedback.The substantial variability of SRM skin temperature (~10 K) may modulate the temperature gradient betweenland and ocean. However, these skin temperature anomalies persist only for ~1 month, so their effects arevariable throughout the monsoon season.

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