Hydrological Terms
River Basin: An area of land drained by a river and its tributaries.
Terrestrial Water Storage (TWS): The summation of all water on the land surface and below the surface.
Land Water Equivalent (LWE): A concept typically used in hydrology and environmental science to express the equivalent amount of water that would cover the entire land surface. It’s a way to quantify the volume of water required to cover the land to a certain depth, simlar to how the term “rainfall depth” is used to describe the depth of water that falls over an area due to precipitation.
Groundwater: Water present beneath the Earth’s surface that exists in saturated zones.
Aquifer: A body of saturated rock undergound through which water can easily move.
Surface Water: Water that is present on top of land, forming terrestrial waterbodies, such as lakes, rivers or reservoirs.
Snow Water Equivalent (SWE): Describes the amount of liquid water stored in snow pack. For example, if 10 inches of snow falls at 10% density, then there would be 1 inch of SWE.
Root Zone Soil Moisture: Water stored in soil that is available to plants, generally considered to be in the upper 200 centimeters of soil.
Technical Terms
GRACE: Gravity Recovery and Climate Experiment is a collaboration of the U.S. and German space agencies (NASA and DLR) that launched twin satellites on March 17, 2002 that make detailed measurements of Earth’s gravity field changes.
GLDAS: Global Land Data Assimilation System ingests setallite- and ground-based observational data products, using advanced land surface modeling and data assimilation techniques to generate optimal fields of land surface states and fluxes resulting in a massive archibe of modeled and obseved, global, surface meteorological data, parameter maps, and output.
Baseline/Long-Term Mean: The average over a specified time period you are interested in comparing all other points to. For example, if you know there is a drought in the years 2002-2005, you could use this as your baseline mean.
Anomaly: The deviation from a baseline mean. For example, in the above example using drought years as your baseline, an anomaly during one time period would simply be the difference between that time period’s value and the baseline mean.
Mascon: Mass concentration resulting in a local increase in gravitational pull
Shapefile: A widely used geospatial vector data format to store geographic data
Pixel: The smallest individual unit of a digital image
Upsampling: Increasing the resolution or scale of a map by adding more pixels to it.