Actual Evapotranspiration for Australia using CMRSET algorithm

This dataset provides accurate, high-resolution (30 m) / high-frequency (monthly) / continuous (no gaps due to cloud) actual evapotranspiration (AET) for Australia using the CMRSET algorithm. The CMRSET algorithm uses reflective remotely sensed indices to estimate AET from potential evapotranspiration (PET; calculated using daily gridded meteorological data generated by the Bureau of Meteorology). Blending high-resolution / low-frequency AET estimates (e.g., Landsat and Sentinel-2) with low-resolution / high-frequency AET estimates (e.g., MODIS and VIIRS) results in AET data that are high-resolution / high-frequency / continuous (no gaps due to cloud) and accurate. These are all ideal characteristics when calculating the water balance for a wetland, paddock, river reach, irrigation area, landscape or catchment.

Accurate AET information is important for irrigation, food security and environmental management. Like many other parts of the world, water availability in Australia is limited and AET is the largest consumptive component of the water balance. In Australia 70% of available water is used for crop and pasture irrigation and better monitoring will support improved water use efficiency in this sector, with any water savings available as environmental flows. Additionally, ground-water dependent ecosystems (GDE) occupy a small area yet are "biodiversity hotspots", and knowing their water needs allows for enhanced management of these critical areas in the landscape. Having high-resolution, frequent and accurate AET estimates for all of Australia means this AET data source can be used to model the water balance for any catchment / groundwater system in Australia.

Details of the CMRSET algorithm and its independent validation are provided in Guerschman, J.P., McVicar, T.R., Vleeshouwer, J., Van Niel, T.G., Peña-Arancibia, J.L. and Chen, Y. (2022) Estimating actual evapotranspiration at field-to-continent scales by calibrating the CMRSET algorithm with MODIS, VIIRS, Landsat and Sentinel-2 data. Journal of Hydrology. 605, 127318, doi:10.1016/j.jhydrol.2021.127318

We strongly recommend users to use the TERN CMRSET AET V2.2. Details of the TERN CMRSET AET V2.2 data product generation are provided in McVicar, T.R., Vleeshouwer, J., Van Niel, T.G., Guerschman, J.P., Peña-Arancibia, J.L. and Stenson, M.P. (2022) Generating a multi-decade gap-free high-resolution monthly actual evapotranspiration dataset for Australia using Landsat, MODIS and VIIRS data in the Google Earth Engine platform: Development and use cases. Journal of Hydrology (In Preparation).

本数据集基于CMRSET算法，为澳大利亚提供精准、高分辨率（30米）、高频率（月度）且连续无云隙的实际蒸散发（actual evapotranspiration, AET）数据。CMRSET算法借助反射遥感指数，基于潜在蒸散发（potential evapotranspiration, PET）估算AET，其中PET由澳大利亚气象局（Bureau of Meteorology）生成的逐日格点气象数据计算得到。将高分辨率低频次AET估算结果（如Landsat、Sentinel-2）与低分辨率高频次AET估算结果（如MODIS、VIIRS）进行融合，可得到兼具高分辨率、高频率、连续无云隙且精度优异的AET数据。上述特性均为湿地、农牧地块、河段、灌区、景观或流域开展水平衡计算的理想条件。

精准的AET信息对灌溉、粮食安全与环境管理具有重要意义。与全球多数地区类似，澳大利亚的水资源供给有限，而AET是水平衡中占比最高的消耗性组分。澳大利亚70%的可用水资源用于作物与牧场灌溉，优化AET监测可提升该领域的用水效率，节省的水量可转化为生态流量。此外，依赖地下水的生态系统（ground-water dependent ecosystems, GDE）虽占地面积狭小，却是"生物多样性热点区域"，明确其需水量可强化对这类关键景观区域的管理。覆盖全澳大利亚的高分辨率、高频次且精准的AET估算数据，可用于建模澳大利亚任意流域或地下水系统的水平衡。

CMRSET算法的细节与独立验证过程详见文献：Guerschman, J.P., McVicar, T.R., Vleeshouwer, J., Van Niel, T.G., Peña-Arancibia, J.L. 与 Chen, Y. (2022) 《通过MODIS、VIIRS、Landsat及Sentinel-2数据校准CMRSET算法以实现田块至洲际尺度的实际蒸散发估算》，《Journal of Hydrology》，第605卷，127318页，doi:10.1016/j.jhydrol.2021.127318。

我们强烈建议用户使用TERN CMRSET AET V2.2版本。该TERN CMRSET AET V2.2数据产品的生成细节详见文献：McVicar, T.R., Vleeshouwer, J., Van Niel, T.G., Guerschman, J.P., Peña-Arancibia, J.L. 与 Stenson, M.P. (2022) 《在谷歌地球引擎（Google Earth Engine）平台上利用Landsat、MODIS与VIIRS数据生成澳大利亚多十年无隙高分辨率月度实际蒸散发数据集：开发与应用场景》，《Journal of Hydrology》（已拟刊）。