Plant Production Change - Estimated difference in plant production from NASA satellite data (in grams of carbon per square meter) between any selected drought month and the same month during the baseline year (2010). Negative values indicate declining plant production, with resulting loss of forage and fiber products.
Soil Water Storage Change - Estimated difference in soil water storage (in centimeters water) between any selected drought month and the same month during the baseline year (2010). Negative values indicate soil drying rates and monthly recharge deficits.
Potential Evapotranspiration (PET) - Rate (in centimeters water per month) calculated by the method of Thornthwaite, C. W. and Mather, J. R., 1955, The water balance. Publications in Climatology, Volume VIII, 86 pp.
Climate Moisture Index (CMI) - Drought indicator based on rainfall and PET that ranges from -1 to +1, with negative values for relatively dry months/years, and positive values for relatively wet months/years (see Willmott, C.J. and Feddema, J.J., 1992, Professional Geographer, 44, 84-88.)