By using the objective similaritymethod, A short - range forecastmodel of hail in Gannan Plateau was comp leted. The system comp iled by four parts, including a history database of hail, similar case and judgment, viewing history weathermap and comparing with intraday actually happening, adding new hail data. The result shows that the model has a good effect in short - range forecast of hail, and it is an effective method of short - range forecast.

An abrup t severe storm occurred on August 30 - 31 of 2006 in the Gannan Plateau was analyzed. Results show that the combination of convective clouds from the southeast of Qinghai and the local convective cloud ismain cause resulting in this p rocess, and the severe storm and hail occurred on the front of right side of the convective cloud. The development of airflow leaning east at the height of 600 - 700 hPa over the eastern part of Gannan p lateau is very important to the severe storm’s occurring and develop ing. The distributions ofθse high energy center at 700 hPa level,θse departure between 500 hPa and 700 hPa, the helicity and vapor flux divergency fields at 700 hPa level are meaningful to estimate the occurring region of this severe storm.

The variations of the accumulated temperature and the sunlight hours inMaqu grassland in recent 40 yearswere analyzed by using a non - parameterMann - Kendall testmethod and wavelet analysis. The results show that annual variation of accumulated temperature tended to increase, and the tendency rate of ≥ 0 ℃ accumulated temperature is 59. 5 ℃/10 a, and 33. 7 ℃/10 a for ≥ 10 ℃ accumulated temperature. The period corresponding to high oscillation center of ≥10 ℃ accumulated temperature is two yearsmore than that of ≥0 ℃ accumulated temperature; the low and high frequency oscillation tended to increase at the same time. The annual trend of sunlight hours is also increasing, and the tendency rate is 40. 2 h /10 a. By Spearman’s order correlation analysis, we know that the positive matching characteristic of light, heat and water is remarkable; the synchronous changes p resented inMay to Sep tember forwater and heat, and June to July for light and water. The app rop riate p recip itation, higher air temperature and the adequate sunshine are helpful to pasture’s growth ofMaqu grassland.