Glossary

Glossary

Eddy Covariance A method to calculate fluxes of CO2, water, or other trace gases between a surface and the atmosphere over time. The method relies on knowing the concentration of the gas of interest in a parcel of air, and the speed and direction the parcel travels over time—i.e. the covariance between the concentration of interest and wind speed.
Albedo Surface reflectivity, or the ratio of reflected radiation (light) to incident radiation (light). Albedo values range from 0 (pitch black) to 1 (perfect reflector).
Sensible Heat A measurement of the energy released that results in warmer surface temperatures that we can feel or “sense” (e.g. urban heat islands), but does not represent a phase change.
Latent Heat A measurement representing the amount of energy released through evaporation, transpiration, or evapotranspiration  (i.e. a phase change) that does not lead to an increase in local temperature.
Evapotranspiration A measurement representing the amount of water lost to the atmosphere from both evaporation and plant transpiration over an area per unit time.
Climate Forcing The influence on climate that results from interactions between the land surface and the atmosphere including surface reflectivity (albedo) and greenhouse gas fluxes.
Net Radiation The difference between incoming (downwelling) and outgoing (upwelling) radiation of both short and longwave wavelengths. Net radiation (Rn) is usually positive during the day, and negative at night.
PAR Photosynthetically Active Radiation, or radiation in the photosynthetically active range of the spectrum,  measured as photon flux in the wavelength range from ~400nm to 700nm.