Relationship between Tropical Diabatic Heating and Atmospheric Rivers under the Indian summer monsoon system

Tropical heating anomalies associated with organized convection can impact weather systems in the mid-latitude region by interacting with extratropical regions. These anomalies can affect the formation of atmospheric rivers (ARs) and their moisture supply from various sources. Our study investigates the relationship between tropical diabatic heating and cross-Pacific ARs under the Indian summer monsoon system, focusing on the Indian Monsoon region (ISM) and the Philippine Sea-Western North Pacific region (PWNP). These regions are characterized by maximum intraseasonal diabatic heating variability, with different combinations of heating anomalies (heating or cooling sources) that accompanied by the subseasonal features (onset/peak/withdrawal) of the Indian summer monsoon. Our findings reveal that the different combinations of heating anomalies act as precursors for AR activity, affecting the landfall location, length, strength, and duration of ARs across the Pacific during the boreal summer. The dipolar heating anomaly in the ISM and PWNP is identified as a strong signal positively correlated with long cross-Pacific ARs that make landfall on the West Coast of North America. Furthermore, we investigate the variabilities of moisture sources and transport for ARs under different abnormal tropical heat sources by applying the three-dimensional Lagrangian FLEXible PARTicle dispersion model (FLEXPART). The atmospheric circulation pattern triggered by the tropical perturbation creates favorable atmospheric conditions for moisture transport and influences the landfall location of ARs. Our study highlights the importance of considering tropical heating in forecasting AR activity in the North Pacific and mitigating associated risks.