The Salton Sea lake level in California is expected to transition in 2018 from a period of gradual decline to a new era of rapid decline that will expose about 40% of the year 2000 lakebed to wind erosion by 2030. The newly exposed Playa substrate can emit large amounts of particulate matter (PM) and thus degrade regional air quality. We use the Weather Research Forecast model (WRF-Chem) to estimate changes in dust aerosol emission and distribution in the Salton Sea region from 2000 to 2030. First, we evaluate simulations of present day wind speed, mineral dust emission, concentration, and optical depth over the region. WRF-Chem at 4 km spatial resolution satisfactorily reproduces the present-day spatio-temporal pattern of dust emission. With an estimated 38% exposure of the Salton Sea by 2030, the domain-averaged PM10 in the 2 × 2 degree domain enclosing the Sea increases on average by 11% and by nearly a factor of ten in localized source areas. The simulated increases in dust emission are consistent with earlier empirical estimates although our estimates are comparatively lower. Our regional model provides more spatially detailed and quantitative attribution of the projected air quality degradation. For example, our model suggests that newly exposed playa emissions will emanate more from the southwest than southeast side of the lake, even though most of the new playa will be on the southeast side. These results may inform decisions that affect trade-offs between environmental quality, human health, and water-use issues in the Salton Sea region.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Station winds and PM10 data were downloaded from Air Quality and Meteorological Information System (AQMIS) of Air Resources Board (ARB), California from the website https://www.arb.ca.gov/aqmis2/aqmis2.php. MODIS AOD data were downloaded from http://ladsweb.nascom.nasa.gov/data/. We gratefully acknowledge Hyunglok Kim of Universtiy of South Carolina for the help in processing MODIS AOD data. The first author is thankful to Martina Klose of Barcelona Supercomputing Center and Qinjian Jin of Massachusetts Institute of Technology for their kind help in WRF-Chem modeling. A copy of the data and maps presented in this study can be obtained by contacting the first author by email at email@example.com. Supported by NASA ACCESS NNX14AH55A, DOE ACME DE-SC0012998, and the Borrego Valley Endowment Fund.