October 1, 2017.
Over the past decade, California has experienced a serious drought. Using the National Center for Atmospheric Research Command Language (NCL), we first analyzed the changes in temperature and the water budgets including precipitation, river runoff, evapotranspiration, and terrestrial water storage (TWS), and snow cover over California. Results show that there were decreasing trends in precipitation and runoff, more apparently in snow cover and TWS, and an increasing trend in temperature over California from 2002-2015, indicating a “hot” drought. In addition, we analyzed the satellite data of leaf area index (LAI) and normalized difference vegetation index (NDVI) to investigate how ecosystems respond to the hot drought. Either LAI or NDVI does not show as much decreasing trends as TWSA and snow cover. There was even an increasing trend in both LAI and NDVI in the forest ecosystem over the mountainous region with very little decreasing trend or no change in LAI and NDVI in many desert areas of California. This may be caused by the elevated CO2 level, which facilitates plant photosynthesis, and adaption of vegetation to the drought, for instance, through deeper roots, or increased groundwater pumping. There are also some patches of forest ecosystems showing a significant trend, possibly related to the tree “die-off” occurring worldwide caused by the hot drought.
Biosphere 2 (B2)
The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the California State University Office of the Chancellor, and California Polytechnic State University, in partnership with Biosphere 2.