Applying of helicity in an analysis of severe sandstorm

摘要

The helicity of a severe sandstorm happened in Northwest China was analyzed by using global reanalysis grid data of NCEP/NCAR for 4 times a day. As an important physical parameter in analyzing and predicting severe convective weather, the helicity also has good indication in the forecasting of sandstorm. The distribution of helicity over the sandstorm area was negative at higher levels and positive at lower levels. There was definite relationship between the evolvement of helicity's negative value at higher levels and the occurrence of sandstorm.