Data Monitor Glossary

Monitors maintained by the CoastWatch Team

Data Assurance (DA) refers to the availability of data

Field Observations are in-situ environmental data collection which measures geophysical targets at point locations. These types of observations are often used to help calibrate remote-sensing instruments by providing "field truth". 

Radiation from the ocean surface of light in the visible wavelengths gives information about the color of the ocean. This "ocean color" (radiances) can be used to estimate chlorophyll concentration (the pigment in plants and phytoplankton responsible for photosynthesis and the dominant source of color in the open ocean) or the coefficients of light attenuation through the water column and other parameters (generally related to biological processes). In coastal areas, other biological compounds and minerals add complexity to interpretation. Clouds will block remotely sensed OC.

Oceanic currents include the movement and transport of sea water across the world's oceans. They are driven by tides, winds, and differences in water density. 

Oceanic Heat Content (OHC) is the measure of the integrated vertical temperature from the sea surface to the depth of the 26°C isotherm and computed from the altimeter-derived isotherm depths in the upper ocean relative to 20°C

Both thermal and microwave sensors can be used to estimate sea ice.  The thermal method has higher spatial resolution but is impacted by clouds (e.g., VIIRS).  The microwave method is lower spatial resolution but not impacted by clouds (e.g. AMSR-2).

Quality Assurance (QA) refers to the accuracy, precision, or scientific merit of data

Monitors maintained by accredited groups, organizations, or programs who partner with NOAA CoastWatch

Satellite altimeters use active radar to observe the surface height of the ocean which is not smooth or flat. Fluid hills and valleys deviate from a reference (mean geoid) height at the ocean surface. These vertical gradients are of interest for sea level rise, storm predictions, ocean currents, ecosystem ecology and other applications.

Spaceborne Synthetic Aperture Radar (SAR) imagery maps the surface microwave radar reflectivity at resolutions from a sub-meter to 100 m depending on the particular SAR satellite and mode. Since a radar provides its own illumination, imagery is independent of the time of day. At typical radar frequencies, SARs can image through clouds, so SARs are considered "all-weather" instruments.  Several gephysical parameters can be derived from SAR including sea surface wind speed.

The salinity of seawater at the ocean surface can be remotely sensed using microwave frequencies. Currently, this technique is valid for open ocean measurements, while recognizing decreased sensitivity for colder water. Measurements within approximately 50 km of land are biased by land contamination and less accurate. Salinity is a defining parameter for ocean dynamics and can also serve as a proxy for certain biogeochemical processes.

Satellite SST is the longest and most mature application of ocean remote sensing. Passive observations are made with infrared (IR) sensors onboard multiple polar-orbiting and geostationary platforms, and microwave sensors onboard polar platforms. The IR sensors have higher spatial (1-4km) and temporal (10-15min, onboard geostationary satellites) resolution, and superior radiometric performance.

Sea Surface Winds also known as Ocean Surface Vector Winds (OSVW) for some techniques

Winds, both magnitude (speed) and direction over the ocean drive other physical and chemical processes and so are used to model dynamic earth/ocean/atmosphere coupled systems ocean and are used for marine weather forecasting. Different remote sensing techniques may be used for gathering information on ocean surface winds including active radar and passive microwave

Identifying spatially explicit water masses with particular biogeochemical features using a model and satellite-derived measurements

Visible radiances can be combined to form images that look similar to a "photograph" of the earth and ocean from the satellite perspective.