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Science Goals

Science Goals

The overarching goal of CalWater is to make combined aerosol-meteorology measurements to quantify the role of aerosols in suppressing mixed-phase orographic precipitation.


CalWater investigators intend to validate and/or evaluate the following hypotheses through direct measurements:

Uncertainty regarding the magnitude of potential anthropogenic impacts of aerosols on precipitation in California results from a lack of understanding of the fundamental physics of precipitation generation in ARs.

Advancement of numerical model representations of precipitation founded on observations are needed to properly represent key precipitation mechanisms associated with aerosols and black carbon.

Transport of dust from Asia aloft may have a substantial impact on precipitation type (rain/snow) and amount.


These further hypotheses may be evaluated through subsequent analysis and inter-comparison:

Aerosols will impact precipitation derived from shallow cloud events or shallow portions of mixed events but will have little impact on Atmospheric River (AR) events with deep vertical structure.

Anthropogenic aerosols suppress orographic precipitation by slowing the autoconversion rate, and hence decrease the amount of precipitation from the shallow and short living orographic clouds.


The role of black carbon deposition on snow could have an important impact on snow melt, and thus represents an important element of regional hydrology.