Journal of Ecology and Rural Environment ›› 2017, Vol. 33 ›› Issue (5): 474-480.doi: 10.11934/j.issn.1673-4831.2017.05.013

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Estimation of Parameters in Daily Total Solar Radiation Model for Lake Songhua Region

QIU Min1, CHEN Ming-yuan2, LUO Lian-cong3, LI Hui-yun3, DAI Shu-jun3   

  1. 1. Department of Ecology, Jinan University, Guangzhou 510632, China;
    2. Hangzhou Environmental Monitoring Center, Hangzhou 310007, China;
    3. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
  • Received:2016-07-26 Online:2017-05-25 Published:2017-05-25

Abstract:

Lack of daily total solar radiation (DTSR) data for the Lake Songhua Region leaves a blank in the research on DTSR models for the region. Consequently, an attempt to estimate parameters in the DTSR model for the region based on hours of sunshine was taken. On the basis of generalization of methods and equations used currently for calculate of DTSR based on hours of sunshine, the 1961-2000 data of DTSR and daily number of sunshine hours recorded at Changchun and Yanji Stations were cited for calculation of parameters, using the generalized pattern search algorithm. The calculated parameters were then validated with the 2001-2012 data of DTSR and number of sunshine hours from the same cities. Verification demonstrates that the DTSR model performed well with fitting values being quite approximate to the observed values. The fitting was 0.93 and 0.94 in Nash-Sutcliffe Efficiency (NSE) coefficient and 22.39 and 19.53 W·m-2 in Root Mean Square Error (RMSE), respectively, at Changchun and Yanji. On such a basis, two empirical parameters, as and bs for DTSR were figured out to be 0.164 34 and 0.591 02, respectively by regression. In view of the geographical location of the Lake Songhua Region, the mean of as and bs could be used as the empirical parameter of calculation of DTSR of the region. Analysis of the DTSR and hours of sunshine in the Lake Songhua Region reveals that DTSR is positively related to hours of sunshine at both multi-year and annual scales, DTSR in the Lake Songhua Region has been on a declining trend in the past 50 years and the change was lower in 1982-2010 than in other years. The index of hours of sunshine followed a similar trend.

Key words: daily total solar radiation, hours of sunshine, model, Lake Songhua

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