Change of pan evaporation in Xinjiang and its periods based on wavelet analysis
QIN Rong;LI Lin-chao;YANG Xian;YANG Hua;YANG Yan-ling;HE Ya-ping;Xinjiang Meteorology Information Center;College of Water Resources and Architecture Engineering,Northwest A&F University;Xinjiang Meteorological Service Center;Hami Meteorological Bureau;
The 20 cm-in-diameter and E601 type evaporation pans have been used in Xinjiang,China,but these two kinds of data sequences so far are incomplete since the start of observation,especially since 2003,the data have not been integrated and corrected,which restricted the use of pan evaporation data and their further analysis. Based on the co-observation data of 20 cm-in-diameter( E_(20)) and E601 pan evaporation( E601),the 57 meteorological stations in Xinjiang were selected and analyzed for the conversion coefficient K between E_(20) and E601 from April to October. Taking the Kashi( in southern Xinjiang) and Tacheng stations( in northern Xinjiang)( both had relatively long data sequences and are representative) as an example,the changes of K at daily and monthly time scales were analyzed,and used later in the estimations of E_(20) values for the period from April 1 to September 30 in the span of14 years( from 2003 to 2016). Therefore,the complete data sequences of daily E_(20) for Kashi and Tacheng over the period from 1961 to 2016 were obtained and could be further used in the spectral characteristics and periodic change analysis using the complex Morlet wavelet function. The results showed as follows:( 1) The conversion coefficient of E_(20) and E601 in Xinjiang region had significant spatial differences from April to October,and K values were larger in the southern Xinjiang than those in northern Xinjiang.( 2) The complete daily E_(20) data series during the period from 1961 to 2016 at Kashi and Tacheng station had typical periodical changes on yearly basis. The monthly E_(20) was the largest in July,and the annual E_(20) had an obvious increase trend. Daily,monthly and annual E_(20) values in Kashi were all larger than those in Tacheng.( 3) The main period and quasi-period of E_(20) ranged within 2-16 years from January to December,and the main period were 7 years for both stations. The quasi-periods at Kashi station were 2 and 4 years,but at Tacheng station they were 3 and 6 years,respectively. This research could provide useful references for the interpolation and further application of pan evaporation in Xinjiang.
【Fund】： 国家重点研发计划(2017YFC0403303);; 国家外专局111计划(B12007)
【CateGory Index】： P426.2
【CateGory Index】： P426.2