Distant dust and atmospheric rivers increase flooding in California
Overseas dust increases the Sierra Nevada Mountains snowpack and atmospheric rivers cause it to rapidly melt, according to scientists at DOE's Pacific Northwest National Laboratory and their colleagues. The team reached this finding by modeling two cloud conditions under the influence of atmospheric rivers, narrow bands of moisture transported from the tropics, during a field experiment called CalWater 2011. Atmospheric rivers are the primary cause of flooding in California by dumping rain and accelerating snowmelt in the mountainous terrain. Dust blown in possibly from Asia and Africa increases the formation of snow in winter clouds over California and increases rain- and snowfall by 10 to 20 percent. However, local pollution from California cities and the Central Valley has little impact on snowfall. Further, local pollution's influence on rain from warm clouds heavily depends on cloud conditions and the strength of a low level jet, often associated with atmospheric rivers, that...