Remote sensing of the Earth with satellites is one of the ways scientists monitor important changes throughout the complex climate system, and is especially important for regions far from human settlements such as the vast oceans and polar regions. Researchers at ESR use a wide range of satellite data to study the ocean, ice and atmosphere. These studies range from determining iceberg distributions in the Southern Ocean to monitoring global surface salinity changes.
Many ESR scientists are also members of NASA science teams, where they provide input into how the satellite data are processed, and look for novel applications. The following science teams have ESR members.
Some examples of ESR’s satellite-based studies are given below. See our Oceans and Cryosphere research pages for more information.
The polar regions are remote and difficult to access, especially in the winter months when sea ice, constant darkness and storms complicate ship and aircraft operations. However, they are critical to understanding the long-term changes in earth’s climate. ESR scientists use data from several satellites to track changes in sea surface temperature, sea ice concentration, motion and freeboard, iceberg distributions and motion, and changes in ice shelves around Antarctica.
ICESat-2: Our scientists use NASA’s ICESat-2 laser altimetry satellite for several applications. In polar regions, ICESat-2 provides us with precise measurements of surface heights of the ocean, sea ice, ice shelves and ice sheets. By repeating these measurements a few times per year, height changes of about an inch can be detected, helping us estimate snowfall, melting of the base of ice shelves, and ocean height changes. One application pioneered by ESR scientists is the creation of a database of icebergs around Antarctica. Other satellites can monitor iceberg sizes and locations better than ICESat-2, but ICESat-2 provides precise information on iceberg heights. This can be converted to draft (depth of the iceberg base below the sea surface). Icebergs on the continental shelf around Antarctica are often stationary, indicating that they have run aground in relatively shallow water. These grounded icebergs provide information on water depth (which may not have been measured in other way), and set the scene for changes in sea ice conditions that, in turn, affect coastal ocean circulation and ice shelf bottom melting.
See how ICESat 2 measures Sea ice thickness:
SWOT: ESR researchers are collaborating with the University of Maryland and Colorado School of Mines to explore applications of the Surface Water and Ocean Topography ( SWOT) satellite to polar regions. We want to improve our understanding of processes linking the ocean, sea ice, and glaciers along the Antarctic coast by combining data from SWOT, ICESat-2, and visible and thermal-infrared imagery datasets. We also aim to improve SWOT’s ability to measure sea surface height when sea ice is nearby, and develop open-source cloud-computing capabilities through “CryoCloud”.
Sea surface salinity (SSS) is an essential climate variable and a key indicator of changes in Earth’s water cycle. Monitoring and understanding the distribution of SSS and its variability is crucial for understanding changes in river outflows, rainfall, and evaporation. The nature of climate change, and the ability to predict it, places a particular focus on long and continuous SSS data records from satellite measurements.
As a member of the NASA Ocean Salinity Science Team (OSST), ESR provides validation of satellite derived ocean surface salinity using Argo and other in situ data. The goal of the Salinity Validation Data System (SVDS), is to provide systematic estimation and assessment of satellite sea surface salinity over the global ocean. Evaluation of SSS from NASA satellites Aquarius/SAC-D and SMAP (Soil Moister Active Passive ) has been completed for each dataset version and has helped reduce data biases and errors. Recognizing the importance of satellite SSS data for ocean and climate research and the need for a continuous SSS data record, ESR researchers build such data record from satellite L-band radiometer measurements. This record is known as Sea Surface Salinity Optimum Interpolation analysis or OISSS. The OISSS, an ongoing NASA OSST research project, combines observations from Aquarius/SAC-D, SMAP and SMOS satellite missions into a continuous and consistent, high-quality, long-term SSS data record. Long and continuous observations of SSS are required to help identify climate change, particularly the part caused by human activity, which can be slow and subtle. This is very important as SSS is inherently linked to the global freshwater cycle, a vital component of life on Earth. (learn more)
Watch a short animation demonstrating the SMAP spacecraft
Watch a short animation demonstrating the OISSS dataset
As part of the Ocean Vector Winds Science Team (OVWST), ESR scientists look to understand how winds drive the currents in the upper ocean. The Ocean Surface Current Analyses Real-time (OSCAR) project is an ongoing NASA funded research project at ESR that produces surface currents using ocean physics that rely entirely on satellite remotely sensed data: sea surface height, ocean vector winds, and sea surface temperature. A main research objective of the OSCAR project is to further our understanding of the mechanisms behind the transfer of momentum between the atmosphere and the ocean through the planetary boundary layer and in doing so improve the generation of surface currents by satellite sensed ocean vector winds.
Check out this animation of Surface currents from OSCAR:
In collaboration with Reflective Earth, ESR scientists have developed tools to evaluate and monitor solar radiation management interventions aimed at mitigating the impacts of climate change on urban areas and reservoirs. Our tools use a combination of Sentinel-2 reflectance products and models of climatological insolation to determine the radiative impact of reflective surface paints in urban areas, and reflective covers for reservoirs. These quantitative evaluations will help underpin incentives and rewards for interventions that ethically mitigate the impacts of human-induced climate change.