基于MOD16蒸散量的海南岛干旱特征分析

Analysis of drought characteristics in Hainan Island based on MOD16 evapotranspiration data

以MOD16月蒸散产品数据为基础,探讨了海南岛蒸散量的时空变化规律,并结合降水资料分析了典型区域的干旱特点。研究结果如下:(1)海南岛多年平均蒸散量为1 020 mm,年际变化不大,年内具有明显的季节变化;(2)空间分布呈中间山区高四周低的趋势,蒸散量旱季和雨季的差异中部山区并不明显,差异大致从北向南,从东向西逐渐显著;(3)海口、东方、三亚和琼海这4个典型区域MOD16蒸散量均小于参考作物蒸散量,且两者之间的差值随时空变异较大;(4)通过衡量降水对需水量的满足程度发现海南冬、春季(12月份到第二年4月)全岛普遍干旱,东方、三亚地区旱情最重,冬季三亚地区降水的保障能力弱于东方,琼海地区干旱最轻,解除也最早,一般在4月份。

In this paper, based on the MOD16 evapotranspiration （ET） product, the spatiotemporal variation of ET in Hainan Island was discussed, and the characteristics of drought in some representative regions were also analyzed by combining the precipitation data. The results show that average annual evapotranspiration was about 1020mm in Hainan Island during the period of 2000 - 2014, with low interannual variation and high seasonal variation. The difference of evapotranspiration between the dry season and the rainy season in the central mountain area is not ob- vious, the difference is gradually remarkable from north to south, from east to West. In terms of spatial distribu- tion, the ET is higher in the central mountain region of Hainan Island than in the surrounding region. The MOD16 ET is lower than the reference crop evapotranspiration （ET0） in four typical areas ：Haikou, Dongfang, Sanya and Qionghai. Meanwhile, the difference between the MODI6 ET and ETO in these areas shows large spatiotemporal variability. Then, by measuring the effectiveness of rainfall meeting crop water requirements, it is found that drought occurs widely in the whole Hainan island in both winter and spring （December through April） , with the worst drought in Dongfang and Sanya. The effectiveness of precipitation in Sanya is weaker than in Dongfang in winter. The lightest drought occurs in Qionghai where the drought could end in April at the earliest.