RAPID: The Mechanisms Driving Extreme Precipitation in Atmospheric Rivers with an Integrated Stable Isotope and Aerosol Chemistry Approach

Santa Clara University, Santa Clara CA

Investigators

Abstract

This Rapid Response Research (RAPID) award is for the collection of precipitation data in California during the 2015-16 strong El Nino event. Researchers will study atmospheric rivers, which are plumes of moisture from the tropics that enhance storms and bring substantial precipitation to the west coast of the United States. This project will complement an ongoing study of these events by adding additional measurement locations for stable isotopes of precipitation data. Isotopic analysis of rainfall can provide insight into the source and the phase change history of water, which gives scientists a better idea of how and why heavy rainfall events are initiated. A better understanding of the precipitation during atmospheric river events should help improve weather and climate models. The work will also help to train the next generation of scientists by including a diverse group of undergraduate students in the collection and analysis of data. The research team plans to quantitatively evaluate the origin and rainout of moisture with the stable isotopes of water and water vapor, and address three main scientific questions: 1) What are the relationships between aerosols and precipitation amount, efficiency and phase? 2) What are the stable isotope signatures of extreme precipitation events and which macro-and micro-scale dynamics are responsible for producing them? and 3) What are the moisture sources of extreme precipitation events and how do these sources change within storms? This RAPID project will complement an existing observational effort related to the CALWATER-2 field program by including additional measurement sites and an instrument to measure real-time stable isotopes of water vapor. After the campaign the PI team will analyze around 1500 water samples while collaborators will analyze ice and cloud condensation nuclei chemistry. Synoptic scale and backtrajectory analysis will also be performed with the WRF model.