Characteristics Of Global Lighting Activities And Its Relationship With The Atmospheric Environment Parameters

Based on space-borne lightning observation data from Lightning Imaging Sensor (LIS) on the Optical Transient Detector (OTD), reanalysis data of NCEP/NCAR and ERA-Interim in Almost 20 -year period from 1995 to 2014, and ground-based lightning detection network in a 3 -year period from 2007 to 2009, the global lightning activity and its associations with atmospheric environmental factors are investigated. The results are as follows:Global lightning frequency is approximately 46.23fl· s-1, nearly 86.25% of global lightning flashes occur in the region of 35°S-35°N, nearly71.80% of ocean lightning flashes occur in the offshore areas o Land and oceans lightning densities are 7.01 fl km-2a-1、0.63 fl ? km-2a-1 respectively ,its lightning density ratio is approximated at 11.3: 1. Variation in global and land lightning frequency with longitude is represented by triplet peaks. Variation in ocean lightning frequency with longitude is represented by two peaks. Variation in land lightning frequency with latitude is represented by convex. The land lightning activities show strong seasonal variabilities with 58.87 fl·s-1 high frequency of lightning events in summer(August).The most lightning activities occur in July in the northern (southern) hemisphere.The land and offshore areas lightning densities are 4.44 flkm-2a-1、5.04 fl-km-2a-1 respectively in China. The lightning density distribution has obvious regional differences. Lightning density is larger in southeast China where the altitude is lower. Lightning density is smaller in western China inland areas where the altitude is higher. The lightning activities show strong seasonal variabilities with high frequency of lightning events in spring and summer, over southeastern China (17.5-30°N, 100-122.5°E). On the inter-annual time scale, the El Nino-Southern Oscillation (ENSO) has a significant impact on the lightning variability. The El Nino events can significantly intensify the lightning activities in winter and spring.Seasonal average lightning activities in different areas of temperature and wet bulb temperature changes have different response characteristics in the region of 35°S- 35°N. Seasonal average lightning activities function as the sensitive indicator of the temperature change in the northern hemisphere land(EQ-35°N)、Tropical ocean and Africa. The lightning activity is positive correlation with atmospheric thermodynamic parameters, such as surface temperature、surface wet bulb temperature、700-400hPa averaged relative humidity、850hPa potential temperature、850hPa potential equivalent temperature and 850hPa potential pseudo-equivalent temperature. Lightning activity and the thermodynamic parameters in the total heat flux, sensible heat flux, latent heat flux, bowen ratio correlation is obviously regional differences, different regions have different positive and negative correlation. The lightning activity is positive correlation with atmospheric stability parameters, such as CAPE, DCI, K index, modified K index, PII,700-400 hPa average vertical water vapor flux and precipitation rate. The lightning activity is negative correlation with atmospheric stability parameters, such as LI, SI, HI, KO.The high frequency of lightning events in southeastern China is associated with the increase of thermodynamic parameters, such as surface air temperature,700-400hPa averaged relative humidity and 850hPa potential temperature. The atmospheric stability parameters are also closely related to lightning activities, and a larger unstable atmospheric layer is associated with a stronger lightning activities. Furthermore, multivariate step linear regression is applied to establish the relationship between predictor variables (e.g., surface air temperature, Convective Available Potential Energy, Bowen Ratio, Lifted index and Showalter Index) and prediction (averaged lightning activity concentration). The multiple stepwise linear regression equation is beneficial for regional lightning activities forecast.The frequency of lightning events in Beijing is associated with the atmospheric parameters. The atmospheric stability parameters are also more closely related to lightning activities than thermodynamic parameters. The regression equation established had a unideal fitting effect. The quantitative analysis of regional lighting activity has mang difficulties, it needs to be studied further...