Comparison and Homogeneity Analysis of the New and Old Station Observation Data in Gansu Province

Abstract

Accurate and continuous meteorological observation data are necessary in researches of weather forecast and climate prediction， also homogeneity long-series data are necessary in climate change researches.In order to make knowledge of the continuity of the observation data at new and old stations and investigate the potential impact on the long-term data from the change of site location， two indexes of the difference and the standard deviation （SD） of the difference were calculated based on 1a comparative observation records from 15 relocated meteorological sites in Gansu Province to investigate the impact of station relocation on the observation of meteorological elements.The SNHT method was used to test the homogenization of the old and new observations from 2 sites， Zhangye station and Ningxian station， as well as the impact of station relocation on long-series data.The first one has the longest distance change between old and new locations， and the second one has the biggest altitude change.According to the results from the difference and the SD of the difference， the air temperature at new stations is lower than the old ones， and the wind speed is higher at the new sites， and the relative humidity at new stations is generally higher than the old sites.Also， the impact from station relocation on the mean air temperature and the minimum temperature is greater than that on the maximum temperature.those sites with the biggest difference in the mean air temperature and the minimum temperature among all the 15 sites got the relatively longest migrating distance and greatest altitude change.The relationship between two indexes， the absolute difference and the standard deviation of the difference， and the distance and altitude difference of the sites relocated indicated that there is bigger influence from the altitude change on the maximum temperature and average wind speed.while the migration distance produced a bigger influence on the average temperature， minimum temperature and relative humidity.According to the homogeneity test results from selected stations， the big straight-line distance （altitude） change during the relocation will have an impact on the homogeneity of the temperature data.But whether there existed a threshold for this impact or there are some other which will enforce this impact needed to be further researched.It is expected that the possible impact from station relocation on the observations could be paid attention when scientific researchers and business personnel use the meteorological data.

Keywords

• gansu province
• station relocation
• observation data
• comparison
• homogeneity analysis