The core of lightning density appears in front of the hail zone.

31, the yearly, seasonal and diurnal lightning number and their change with the longitude and latitude, the lightning density distribution and lightning climatic feature were calculated and analyzed in this paper.

Using lightning data detected by the TRMM satellite between 18～30 °N and 74～123 °E from 1998 Jan , 1 to 2003 Dec, 31, the yearly, seasonal and diurnal lightning number and their change with the longitude and latitude, the lightning density distribution and lightning climatic feature were calculated and analyzed in this paper.

In order to draw and study the cloud-to-ground flash density map,the monitoring lightning data in 2004-2006 of Zhejiang Lightning Location System is selected as study samples,and the method--Grid Method for drawing high resolution cloud-to-ground flash density map using vast automatic monitoring data is presented.

In order to test the validity and availability of the cloud-to-ground flash density(GFD) map from the lighting location systems(LLS) for the application of lightning protection of transmission lines,we studied on the correlation between the GFD and the practical operating experience of lines,taking some regions such as south of Hebei province and Yunnan province as the analytical examples.

The special distribution of ground flash density has a strong regularity,and it also has a close relationship with elevation.

The results show that the value of the ground flash density of transmission lines of high thunderstorm area,the shielding failure rates calculated by the paper are much higher than the results calculated with the parameters recommended by regular method,can well meet the operational experience.