NDVI Maps of the San Joaquin Valley Region, March 2022 and March 2023
This graphic shows the Landsat Surface Reflectance (SR) Normalized Difference Index (NDVI) maps of the San Joaquin Valley region of California on March 10, 2022 and March 13, 2023. The 2020 map shows the impact on local vegetation after several years of drought. An extremely wet spring in 2023 lead to an early green-up in the valley.
NDVI values range from +1.0 to -1.0. Areas of barren rock, sand, or snow usually show very low NDVI values (for example, 0.1 or less). Sparse vegetation such as shrubs and grasslands or senescing crops may result in moderate NDVI values (approximately 0.2 to 0.5). High NDVI values (approximately 0.6 to 0.9) correspond to dense vegetation such as that found in temperate and tropical forests or crops at their peak growth stage.
NDVI values can be averaged over time to establish "normal" growing conditions in a region for a given time of year. Further analysis can then characterize the health of vegetation in that place relative to the norm. When analyzed through time, NDVI can reveal where vegetation is thriving and where it is under stress, as well as changes in vegetation due to human activities such as deforestation, natural disturbances such as wild fires, or changes in plants' phenological stage.
Learn more about Landsat SR derived NDVI at https://www.usgs.gov/landsat-missions/landsat-normalized-difference-vegetation-index. Landsat spectral indices are produced on-demand, at no cost to users, using the USGS Earth Resources Observation and Science (EROS) Center Science Processing Architecture (ESPA) On Demand Interface. Processing services such as reprojection and spatial sub-setting can also be requested when ordering spectral indices.