Remote Sensing based evapotranspiration estimate
Evapotranspiration (ET) is an important flux that links water, carbon, and energy exchange in many ecosystems, but is considered the most uncertain component in water budget. We developed a robust and efficient way to estimate ET by integrating the AmeriFlux eddy covariance measurements and satellite-derived observations of net radiation and leaf area index. Spatial analysis of these high resolution ET estimates provided evidence for a shift from water-limited to energy-limited ET with increasing precipitation. The ET product can be used to quantify and understand the climatic and vegetation controls on water balance.
Jin, Y., J.T. Randerson, and M. L. Goulden (2011), Continental-scale net radiation and evapotranspiration estimated using MODIS satellite observations, Remote Sensing of Environment, 115(9), 2302-2319, doi: 10.1016/j.rse.2011.04.031. [PDF]
Anderson, R.G., Y. Jin, and M. L. Goulden (2012), Assessing regional evapotranspiration and water balance across a Mediterranean montane climate gradient, Agricultural and Forest Meteorology, 166-167, 10-22, doi:10.1016/j.agrformet.2012.07.004. [PDF]
We developed an algorithm to estimate the annual cumulative absorbed photosynthetically active radiation (APAR), as a proxy for plant production (Jin et al., 2013). APAR was calculated as the product of photosynthetically active radiation (PAR) and the fraction of PAR absorbed by plant canopies (fPAR) that we derived from MODIS and AVHRR vegetation index. The annually integrated APAR derived from remote sensing was well correlated with contemporaneous in-situ Gross Primary Production (GPP) observations based on eddy covariance measurements over desert shrubland, open shrubland, closed shrubland, grassland, savanna, evergreen needleleaf forest, and mixed forest.
Related publication: Jin, Y. and M. L. Goulden (2013), Ecological consequences of precipitation variation: separating short- vs. long-term effects using satellite data, Global Ecology and Biogeography, doi: 10.1111/geb.12135. [PDF]
Burned area detection
We developed algorithms to detect burned area using multi-spectral and multi-temporal satellite observations. Various metrics were also used to quantify burn severity in the boreal region. We are exploring the use of air-borne observations for fire behavior analysis to support disaster reponse efforts.
Roy, D.P., Y. Jin, P. E. Lewis, and C. O. Justice (2005), Prototyping a global algorithm for systematic fire-affected area mapping using MODIS time series data, Remote Sensing of Environment, 97(2), 137-162, doi:10.1016/j.rse.2005.04.007. [PDF]
Jin, Y., J. T. Randerson, S. J. Goetz, P. S. A. Beck, M. M. Loranty, and M. L. Goulden (2012), The influence of burn severity on post-fire vegetation recovery and albedo change during early succession in North American boreal forests, Journal of Geophysical Research-Biogeosciences, 117, G01036, doi:10.1029/2011JG001886. [PDF]