Results/Conclusions We found that LE, Hs and Fc were significantly different for seasons among six years: (1) effects of years on LE, Hs and Fc were significantly different (P<0.0001), except for Hs in autumn (P=0.0808), Fc in summer (0.0022) and winter (P=0.1917); (2) effects of months on LE, Hs and Fc were significantly different (P<0.0001) , except for Hs in autumn (P=0.0034); (3) effects of the years × months interaction on LE, Hs and Fc were significantly different (P<0.0001), except for Fc in summer (P=0.0839) and Hs in autumn (P= 0.0072). Over the study period, Hs increased gradually, while LE and Fc fluctuated.