The Vaira Ranch is a grazed annual grassland, near Ione, CA. This was one of the first AmeriFlux sites that we established, in 2000.   The ecosystem experiences a Mediterranean type climate with cool wet winters and hot dry, rainless summers.  Temperatures range between 0 and 40 C. Annual rainfall is on the order of 550 mm/y with 30% variability.

This site has been used to test many in situ and proximal remote sensing indices, like Normalized Vegetation Difference Index, with home made LED sensor, and greenness indices with phenocams.

Ryu, Y., et al. (2010). "Testing the performance of a novel spectral reflectance sensor, built with light emitting diodes (LEDs), to monitor ecosystem metabolism, structure and function." Agricultural and Forest Meteorology 150(12): 1597–1606. https://doi.org/10.1016/j.agrformet.2010.08.009

The vegetation is green after the first rains in the autumn and is dormant during the late spring and summer.

https://ameriflux.lbl.gov/sites/siteinfo/US-Var