Mesoscale Observation and Modeling of the Atmospheric River during CalWater2

The CalWater2 is a multi-agency supported field campaign conducted during the January-March 2015 period over the Northern California coast to study the Atmospheric River (AR). To assess the air-sea interaction on the AR evolution, we deployed 148 Airborne eXpendable BathyThermographs (AXBTs) from the NOAA P-3 in order to investigate the upper-ocean temperature changes that arise before, during, and after the AR events. These AXBT deployments are released in tandem with co-located atmosphere dropsondes. Together, the AXBT and dropsondes provided a four dimensional depiction of the atmosphere and ocean boundary layer, which can be used to validate and study the impact of the coupled air-ocean model forecast of the AR. We will discuss the comparisons of the AXBT profiles as well as very high resolution (90 m) sea surface temperature observations from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) before and after the AR passage. The ocean data assimilation sensitivity experiments using the Navy Coupled Ocean Data Assimilation System (NCODA) and the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) show the COAMPS forecast AR rainbands are more distinctive and the local peak precipitation magnitudes are higher with than without from assimilation of these special AXBT and ASTER observations.