Background:

Koren et al. (1998) used information from seasonal and annual Free Water Surface (FWS) evaporation maps in NOAA Technical Report 33 (Farnsworth et al., 1982) and mean monthly station data from NOAA Technical Report 34 (Farnsworth and Thompson, 1982) to derive parameters for an equation that predicts seasonal variability of mean daily free water surface evaporation. These parameters were used to derive the mean monthly FWS evaporation estimates for DMIP basins. Summing the monthly values yields results consistent with the annual and seasonal maps in NOAA Technical Report 33. Mean monthly FWS evaporation estimates are used as potential evaporation (PE) estimates in the NWS lumped calibrations using the Sacramento model. In the Sacramento model, PE values are adjusted to account for the effects of vegetation to produce PEDemand values; however, the values provided here are unadjusted PE values. 12 mean monthly values are provided here for the DMIP basins. The units are [mm/day].

Data:

OKLAHOMA BASINS

J F M A M J J A S O N D
Elk River nr Tiff City, MO
0.86 1.38 2.24 3.32 4.29 4.90 4.97 4.48 3.57 2.49 1.52 0.93

Illinois River near Watts, OK.
0.81 1.34 2.19 3.28 4.25 4.85 4.91 4.41 3.51 2.42 1.46 0.87

Flint Creek in Kansas, OK
0.84 1.36 2.24 3.36 4.35 4.97 5.04 4.54 3.62 2.50 1.50 0.90

Illinois River at Tahlequah, OK (Values are for total area including subbasins.)
0.84 1.36 2.23 3.34 4.32 4.92 5.00 4.49 3.58 2.48 1.49 0.90

Baron Fork at Eldon, OK
0.87 1.40 2.28 3.38 4.38 5.00 5.07 4.57 3.63 2.53 1.53 0.92

Blue River at Blue, OK
1.68 2.18 2.98 4.03 4.98 5.58 5.67 5.22 4.36 3.31 2.36 1.76

WESTERN BASINS

North Fork of the American River above North Fork Dam
0.7 1.1 2.0 3.2 4.4 5.2 5.5 5.1 4.2 3.0 1.8 1.0

East Fork of the Carson River above Gardnerville
0.6 1.0 1.8 3.0 4.1 4.9 5.1 4.7 3.8 2.7 1.6 0.8

References:

Farnsworth, R.K., and E.S. Thompson (1982) "Mean Monthly, Seasonal, and Annual Pan Evaporation for the United States," NOAA Technical Report NWS 34, Washington, D.C., 82 p.

Farnsworth, R.K., E.S. Thompson, and E.L. Peck (1982). "Evaporation Atlas for the Contiguous 48 United States," NOAA Technical Report NWS 33, Washington, D.C.

Koren, V., J. Schaake, Q. Duan, M. Smith, and S. Cong, Unpublished Report: "PET Upgrades to NWSRFS, Project Plan," unpublished report, August 13, 1998.