Using three meteorological factors such as temperature, average wind speed, relative humiditymeasured by automatic weather station in real - time as the basic parameters, the critical meteorological index for freezing and melting of wind sensor in automatic weather station was established. The wind - driven sensor antifreezing heating device was controlled for automatic operation through the PC - RS232 communication interface, ATmega8 - based single - chip and op toelectronic isolation circuit, which would realize the goal of the wind sensor antifreezeing p rotection in automatic weather station.

After  giving  observational  precipitation  and  forecasting  evaluation  in summer  nver Gansu  province since 1991.  the influencing factors on precipitation in summer were analyzed generally. Results show that the main influencing factors nn  summer precipitation are Northern Hemisphere polar vortex activity, sea surface temperature of Pacific Ocean, subtropical high nVel WeFtel'n Pacific Ocean, disembarking tropical storm number, the air current through equator and monsoon, blocking high  in easterm.  In summer. The stage developing characteristic is significant about influencing of subtropical high over western ific  Ocean COntlnlle  hlgheT  SltllatlOn  Of  the     helght  Held  In  SLnnnleT  haS  Weakened  1tS  Slgnal  effect.  The  1T1f1LlenCe  Of  the  Slln   aCtlVlty  1S COmpllCated.   and Illnl'e