Developing and Testing Water Cycle Intensification Indicator (WCI) over the United States

Abstract:

Is the water cycle intensifying in response to global warming due to temperature-driven changes in atmospheric water holding capacity? To address this question, we are developing and testing Water Cycle Intensification Indicator (WCI) to quantify the current and future change in the strength of the water cycle across the conterminous U.S. in support of the National Climate Assessment (NCA). The WCI consists of a suite of primary water cycle trend and extreme composites that are spatially- and temporally-scalable for summarizing how the climate changes results in stronger or more extreme water cycling over the nation. We calculated trend and extreme in water cycle components using NASA-produced data and modeling products. Six water cycle variables are chosen, including precipitation, evaporation, runoff, moisture convergence flux, terrestrial storage and water vapor. Our preliminary results showed that the strength of water cycle depends on specific regions and variables, even different datasets. For instance, precipitation from MERRA-Land offline simulation is consistent with the CPC unified precipitation dataset in showing positive trend over the northeastern, northwestern and west north central, but negative trend over the western and central regions. However, negative trends are observed in MERRA-land over the southern Texas and some parts of the southern coast, contrary to the positive trend revealed by the unified dataset in the same area. Next, we are going to integrate and combine the trends and extremes of these water cycle components to develop a suite of climate indicators to monitor the changes of water cycle as result of climate change. These indicators will be implemented and tested over the nation for further optimization. Moreover, we will also be developing innovative WCI visualization, documentation and distribution methods to disseminate WCI products to the public and stakeholders.