Rainfall regime prevalence and water phase partition in atmospheric river systems observed offshore
Abstract
Wintertime storms having high impact on West Coast of North America are often a result of landfalling Atmospheric Rivers (ARs). Significant uncertainties in annual precipitation and extreme precipitation events in California result from uncertainties in the representation of ARs offshore. CalWater research objectives include improvements in model representations of ARs. Predictions of the rainfall regime prevalence (e.g., warm rain versus the bright band - BB rain) and water substance partitioning were identified as issues where models need improvements. In this study, CloudSat spaceborne radar measurements were used to analyze the AR vertical cross sections over ocean. Based on the one cold season CloudSat measurements, observational statistics of the rainfall regime prevalence were obtained. For BB rainfall, independent retrievals of total ice amount and mean rain rate were performed within the AR structures. It was shown that there is significant correlation between mean values of ice amount and resultant rainfall in AR BB precipitating events. Generally, the ice component becomes more abundant as a result of an AR landfall. Over ocean, the identifiable bright band was present in more than half of all observed AR cross sections. These observational findings can be used for model tuning purposes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A11A0041M
- Keywords:
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- 0320 ATMOSPHERIC COMPOSITION AND STRUCTURE / Cloud physics and chemistry;
- 3310 ATMOSPHERIC PROCESSES / Clouds and cloud feedbacks;
- 3354 ATMOSPHERIC PROCESSES / Precipitation;
- 3360 ATMOSPHERIC PROCESSES / Remote sensing