Atmospheric River Contributions to Extra-Tropical Moisture Transports and Atmospheric Water Cycle

Atmospheric Rivers (ARs) are narrow, long, water vapor rich corridors of the atmosphere that are responsible for over 90% of the poleward moisture transport across mid-latitudes and into high latitudes. This suggests a crucial role for ARs in establishing the extra-tropical atmospheric water budget. However, there are still questions regarding the contribution of ARs to the extra-tropical atmospheric water budget, including impacts on water vapor transport and storage, and precipitation. This study quantifies the relationships between atmospheric integrated vapor transport (IVT), including the specific contribution from ARs, to the extratropical atmospheric water budget using the combination of multiple data sources. These sources include integrated water vapor (IWV), IVT, precipitation and evaporation derived from the MERRA2 reanalysis, the global atmospheric river catalog based on MERRA2 IVT (Guan and Waliser 2015), as well as additional precipitation products from the Global Precipitation Climatology Project version 2.3. The study period is from 1997 to 2014, the overlapping period of the various data sources. Results show that poleward water vapor transport of ARs is strongly related to changes in water vapor storage, precipitation, and evaporation in higher latitudes in both poles, indicating the important role of the episodic, extreme moisture transports associated with ARs for extratropical water budget.