2002-2010年长江流域GRACE水储量时空变化特征

利用高斯平滑滤波对2002年4月-2010年12月逐月GRACE卫星的时变重力场数据反演得到长江流域大尺度陆地水储量变化,对其时空变化进行研究,并将结果与全球陆面同化数据(GLDAS)模拟结果进行比较。其结论为:根据GRACE数据反演与GGLDAS模拟得到的水储量结果在大多数区域变化趋势相同,两者具有一致性,相关性达到0.89(P<0.05)。GRACE水储量研究结果表明:①2002-2010年长江流域水储量呈增加趋势,平均增长速率为0.43mm/月,相当于约95.04亿m³/年。长江上游增长速率为0.53mm/月,相当于约67.13亿m³/年;中游增长速率为0.51mm/月,相当于25.73亿m³/年;下游增长速率为0.36mm/月,相当于9.14亿m³/年。近9年长江流域水储量共增加约855.33亿m³。②从多年平均水储量空间分布来看,长江流域冬季月份(12、1、2、3月)水储量处于亏损状态,7-9月水储量处于盈余状态,4-6月下游至上游地区由亏损向盈余状态过渡,而10-11月则从上游至下游地区由盈余向亏损状态过渡。③全流域、上游及中游水储量逐月增长速率最大值出现在9月,分别为1.01cm/a、1.37cm/a、1.05cm/a;而下游地区则出现在7月,增长速率为1.62cm/a。

Temporal and spatial pattern of water storage changes over the Yangtz river basin during 2002-2010 based on GRACE satellite data

The large-scale change of the amount of water storage over the Yangtze River basin is obtained by using monthly gravity field data, derived from GRACE satellite data between April of 2002 and December of 2010 with Gaussian filter. The temporal and spatial variations of water storage over the Yangtze River basin are compared to the data from GLDAS (Global Land Data Assimilation System) model. The results indicate that: (1) The two sets of data, derived from GRACE satellite and GLDAS model, show the same trend of change in the majority of the areas with high level of consistency; the correlation coefficient is 0.89 (P<0.05). (2) The amount of water storage over the Yangtze River Basin from 2002 to 2010 has an increasing trend. The average annual growth rate is 0.43cm/month, equivalent to 95.04×10⁹ m³/a, with an average annual growth rate of 0.53 cm/month (67.13×10⁹ m³/a) in the upstream area, 0.51cm/month (25.73×10⁹ m³/a) in the midstream area, and 0.36 cm/month (9.14×10⁹ m³/a) in the downstream area. The increasing amount of water storage over the Yangtze River Basin during the time period of nearly nine years is estimated to be 855.33×10⁹ m³/a. Judging from the spatial distribution of average annual water storage over the Yangtze River Basin, there is a shortage in January, February, March, and December, and a surplus in July, August, and September, with a clear transition from shortage to surplus in April, May and June from downstream to upstream, and a transition from surplus to shortage in October and November from upstream to downstream. The maximum increase rate of water storage over the whole basin, in the upstream and midstream areas is in September, with 1.01 cm/a, 1.37 cm/a, and 1.05 cm/a, respectively, whereas in the downstream area the maximum increase rate is in July, with 1.62 cm/a.