Abstract:

Usingthe water vapor pressure data from 1960 to 2019 and the 6-hour ECWMF reanalysis data from 2013 to 2019， the characteristics of the spatial distribution of water vapor and water condensate in the Gansu were analyzed， and the transmission， renewal cycle and precipitation efficiency of water vapor and water condensate were also diagnosed. Furthermore， the causes of the spatial distribution pattern of precipitation in Gansu were analyzed to provide the basis for seeking the sensitive areas and time periods for artificial rainfall enhancement. The results show that： （1） The annual total amount of atmospheric water storage in Gansu （accumulated daily during the year） was about 4×10¹⁵ kg， of which the atmospheric water condensate was about 4.5×10¹⁴ kg， the cloud water content was about 3×10¹⁴ kg， and the water vapor condensation efficiency was 11.8 %. The total water substance precipitation efficiency was 4.1%， water vapor precipitation efficiency was 4.0%， and water condensate precipitation efficiency was 35.1%. The annual water vapor input was 3.79×10¹⁵ kg， output was 3.89×10¹⁵ kg， net output was 9.77×10¹³ kg， water condensate input was 1.24×10¹⁴ kg， the output was 1.39×10¹⁴ kg， and the net output was 1.47×10¹³ kg. （2） During a year， water vapor and water condensate transmission were larger in the west Gansu than in the east Gansu. The water condensate was net output in the total province except in Qilian Mountains， and water vapor was net output in the total province except Qilian Mountains and West Qinling Mountains. The water vapor transmission in the Qilian Mountains was much larger than its instantaneous stock. （3） The daily transmission intensity of water vapor obviously showed a single peak， and the difference between the maximum and minimum transmission of a single day was more than 10 times， and the high transmission phase was concentrated in June-September （the transportation volume accounts for 55.4% of the year）. The daily input and output of water vaper show quasi-periodic oscillation. （4） The spatial change trend of water vapor and condensate renewal cycle was very similar to that of water vapor， which decreased from west Gansu to east Gansu. The water vapor recycle period in the west Hexi was over 50 days， and the water vapor recycle period in the east Gansu and south Gansu was about 8 days. The renewal rate of condensate was greater than that of water vapor （the fastest was about 4 h）. （5） The evolution of water vapor in Gansu had a high regional consistency， the interannual variability was small， and the amount of atmospheric cloud water resources was relatively stable， providing feasibility for utilization of atmospheric water resources. Hedong region was sensitive of climate change for water vapor， and Qilian Mountains was relatively stable and rich in water vapor. The characteristics of the interannual and intraannual oscillation evolution was helpful for artificial rain enhancement operation.

Key words: atmospheric water resources, renewal, precipitation distribution, relationship, Gansu