Fangfang Yao is working with Ben Livneh and Balaji Rajagopalan to improve the understanding of recent global changes in surface water storage. Surface water provides easily accessible water resources for human beings. Spatial and temporal variations of surface water storage not only affect local water supply, but also have implications for the hydrological cycle. Despite its importance, changes in open surface water (especially lakes and reservoirs) are not simulated by existing land surface models due to the challenges of modeling human impacts including damming and water withdrawal. Partially owing to this, land surface models have large uncertainties in estimating both seasonality and long-term trends of terrestrial water storage (TWS; the summation of surface water, soil moisture, groundwater, snow and ice). In this context, Fangfang proposes to investigate global surface water storage dynamics and the impacts on the hydrological cycle using a combination of satellite observations and land surface models. He aims to answer two science questions: i) how global open-surface water has contributed to the recent sea level change, and ii) how an improved observation of open-surface water changes can further benefit the modeling of other terrestrial water components (such as soil moisture and groundwater). These questions are essential to the understanding of terrestrial water cycle and the closure of global sea level budget.