README:  SW Monitor Experimental Drought Indices

In addition to maps of model variables such as soil moisture, swe and runoff, 
the SW Monitor will be used to stage experimental derived analyses targeting 
drought characterization and prediction.  Currently, these include:

 -  the Standardized Precipitation Index (SPI) of McKee et al. (1993), for 
    ten accumulation periods, calculated on the 1/2 degree VIC model grid and 
    based on a rolling monthly climatology of precipitation that nominally 
    spans 1955-2005. 

 - a Standardized Runoff Index (SRI), described in Shukla and Wood (2008; 
   document linked to web page), based on the the same rolling climatology 
   approach, and analogous to the SPI but using runoff instead of precipitation 
   as input. 

Both of these sets of indices will update daily after the primary SW Monitor 
maps are generated.  

Feedback welcome!  (A. Wood:  email aww /at/ u.washington.edu)

References:

McKee, T. B., N. J. Doesken, and J. Kleist (1993), The relationship of drought 
  frequency and duration to timescales, paper presented at 8th Conference on 
  Applied Climatology, Am. Meteorol. Soc., Anaheim, Calif.

Shukla, S., and A.W. Wood (2008), Use of a standardized runoff index for 
  characterizing hydrologic drought, Geophys. Res. Lett., 35, L02405, doi:10.1029/2007GL032487.

This research is supported by a grant from the NOAA Transition of Research 
  Applications to Climate Services (TRACS). 

-A. Wood, 20080107