Abstract: Based on the conventional surface meteorological observational data and sounding data obtained from Chinese Meteorological Administration (CMA) as well as the GD05 numerical forecasting data over Jiangxi province from 2000 to 2012,the characteristics of spatiotemporal distribution,weather situation and major meteorological parameters of three kinds of regional heavy fog in Jiangxi province were comparatively analyzed.The results show that a total of 259 regional heavy fog events occur in Jiangxi province from 2000 to 2012,and the radiative fog events occur most frequently.The radiative fog events mainly occur from late autumn to early spring,and the advective-radiative fog events mainly occur in winter.The advection fog events usually occur in late winter and early spring but not in summer.Overall,the spatial distribution of regional heavy fog in Jiangxi province is characterized by a high frequency in the middle region and low frequency in the northern and southeastern regions.A radiative fog event can cover a wide area,while the advection fog events usually occur within a narrow area.Among the regional heavy fog events in Jiangxi province,the radiative fog events are the most common type.The temperature inversion intensity is the strongest for advection-radiation fog events and is the weakest for advection fog events.The temperature inversion layer mainly exists near and under 1000 hPa level,and dry air at upper levels and wet air at lower levels.Multi-inversion layers can be found in advection-radiation fog and occur under 1000 hPa level and near 925 hPa level with high moist area.The advection fog has deep moist layer and with the thermal inversion layer near 925 hPa level.As a radiation fog event occurs,the surface pressure field is uniform and the lower levels are controlled by an anticyclone circulation over Jiangxi province.During advection-radiaiton fog events,Jiangxi province is mostly controlled by the southerly flows at the back of weak high pressures,and a wide southerly current prevails at the lower levels.When an advection radiation fog occurs,the foggy area is located near the surface depression inverted trough and is controlled by the warm and moist southerly flows within 2-latitudes distance to the south of the shear line at 925 hPa.

Key words: Regional heavy fog, Temperature inversion layer, Dew-point depression of temperature