GRACE satellite derived total water storage anomaly (TWSA) from April 2002 to December 2014

The Total Water Storage Anomaly (TWSA) data are derived from the Gravity Recovery and Climate Experiment satellite mission, with temporal and spatial resolutions of monthly and 1 degree respectively. The processed GRACE-derived TWSA data covered the period from April 2002 to December 2014.

Related publication: Zunyi Xie, Alfredo Huete, Natalia Restrepo-Coupe, Xuanlong Ma, Rakhesh Devadas, Graziella Caprarelli, Spatial partitioning and temporal evolution of Australia's total water storage under extreme hydroclimatic impacts, Remote Sensing of Environment, Volume 183, 2016, Pages 43-52, ISSN 0034-4257, http://dx.doi.org/10.1016/j.rse.2016.05.017

Total water storage anomaly data, derived from release-5, level-2 GRACE data, was obtained from NASA's GRACE Tellus wetsite (JPL, 2012) for the Australian continent over the period July 2002 to December 2014. The GRACE TWSA data was pre-processed to remove the
signal from atmosphere and ocean and was retrieved at monthly and 1° resolutions, with units of cm. To minimize the uncertainties associated with data processing, an ensemble average TWSA was calculated using GRACE data processed independently by three research centres, NASA Jet Propulsion Laboratory (JPL), University of Texas Center for Space Research (CSR) and the GeoForschungsZentrum (GFZ) Potsdam. As terrestrial gravity variations in space and time are mainly caused by changes in water storage, TWSA was obtained by subtracting the monthly GRACE data by a historical mean (2004–2009). We chose to use a file of scaling factors obtained from the NCAR's Community Land Model 4.0 (CLM4.0) to correct and restore the GRACE signal loss during low-pass filtering. The uncertainty range in TWSA time series was calculated at a 95% Confidence Interval (CI).

File name example: Au.3Centers.200207.LND.RL05.tif
Au=Australia
3Centers = Original data from three centres download from https://grace.jpl.nasa.gov/data/get-data/monthly-mass-grids-land/
200207 = yyyymm
LND = GRACE land product
RL05 = GRACE land product version 5

总水储量异常（Total Water Storage Anomaly, TWSA）数据源自重力恢复与气候实验（Gravity Recovery and Climate Experiment, GRACE）卫星任务，时间分辨率为月度，空间分辨率为1度。经处理的GRACE衍生TWSA数据覆盖时段为2002年4月至2014年12月。

相关学术文献：谢遵义（Zunyi Xie）、阿尔弗雷多·韦特（Alfredo Huete）、纳塔利娅·雷斯特雷波-库普（Natalia Restrepo-Coupe）、马轩龙（Xuanlong Ma）、拉凯什·德瓦达斯（Rakhesh Devadas）、格拉齐耶拉·卡普拉雷利（Graziella Caprarelli），《极端水文气候影响下澳大利亚总水储量的空间分区与时间演变》，《环境遥感》（Remote Sensing of Environment），第183卷，2016年，第43-52页，ISSN 0034-4257，DOI: 10.1016/j.rse.2016.05.017。

本次所用总水储量异常数据源自GRACE第5版二级数据（release-5, level-2 GRACE data），从美国国家航空航天局（National Aeronautics and Space Administration, NASA）的GRACE Tellus网站（JPL, 2012）获取，覆盖澳大利亚大陆2002年7月至2014年12月的时段。该GRACE TWSA数据已完成预处理，剔除了大气与海洋信号，以月度、1°的分辨率输出，单位为厘米（cm）。为降低数据处理带来的不确定性，研究采用由美国喷气推进实验室（NASA Jet Propulsion Laboratory, JPL）、德克萨斯大学空间研究中心（University of Texas Center for Space Research, CSR）以及波茨坦地学研究中心（GeoForschungsZentrum, GFZ）三家机构独立处理的GRACE数据，通过集合平均得到TWSA数据集。由于地表重力的时空变化主要由水储量变化引起，因此通过将月度GRACE数据减去历史均值（2004-2009年）得到TWSA。本次研究选用美国国家大气研究中心（National Center for Atmospheric Research, NCAR）的通用陆面模型4.0（Community Land Model 4.0, CLM4.0）生成的缩放因子文件，对低通滤波过程中产生的GRACE信号损失进行校正与恢复。TWSA时间序列的不确定性范围通过95%置信区间（Confidence Interval, CI）计算得到。

文件名示例：Au.3Centers.200207.LND.RL05.tif
各字段含义如下：
Au：代表澳大利亚（Australia）；
3Centers：指从https://grace.jpl.nasa.gov/data/get-data/monthly-mass-grids-land/ 下载的三家机构的原始数据；
200207：为年-月格式的时间戳；
LND：代表GRACE陆地产品；
RL05：代表GRACE陆地产品第5版。