Ground geotemperature characteristics of fog and haze days and the possible effects of seismic activities in Langfang City

According to the meteorological observation data about fog, haze, shallow geotemperature, wind direction, wind speed and relative humidity and seismic data of magnitude Ms2.0 or above in Langfang City from 2009 to 2018, the deep analysis was carried out on the characteristics of shallow geotemperature of fog and haze days, and the effects of seismic activities by Yamamoto statistical analysis and mathematical statistics. The results showed that: 1)The occurrence and distribution of fog and haze in Langfang City had both similarities and differences. The distribution of fog fluctuated in a single peak, with peak value in December, while that of haze was bimodal, with peak value in July and January, and July had the biggest value. 2)The distribution and formation of fog and haze were greatly connected with high shallow geotemperature. Once the fog and haze were highly severe at the same time, the characteristics of high geotemperature would be very significant. The average proportion of positive anomalies in geotemperature of 0, 10, 20 and 40 cm under the ground reached over 70%, and the surface temperature was above 80%. 3)There were differences in daily geotemperature characteristics on fog, haze days and their mixture days. The average proportion of positive anomalies in daily geotemperature of mixture of fog and haze was the highest, and the geothermal layers were relatively thick. There was a continuously increase in geotemperature before the formation of haze. And the average proportion of positive anomalies in geotemperature on fog days was higher than that on haze days. 4)The geotemperature was relatively high before and after the earthquake. The more seismicity, the more persistent the characteristic of relatively high geotemperature. The seismicity in 50 km of Langfang City was related to the increase of geotemperature, fog, haze and abnormal distribution of them. The increase of geotemperature caused by seismicity provided beneficial conditions for the formation of fog and haze, and also provided certain basic thermodynamic conditions for the formation of weathers including rainfall and snowfall. The rainfall and snowfall could lead to the decrease of geotemperature for some time.