About the dataset
Soil moisture is estimated by a
one-layer hydrological model (Huang et al., 1996, van den Dool et al., 2003). The model
takes observed precipitation and temperature and calculates soil moisture, evaporation and
runoff. The potential evaporation is estimated from observed temperature.
Model parameters are constant spatially (tuned based on Oklahoma observed runoff data).
Tuning the model to runoff of serveal small river basins in eastern Oklahoma resulted in a maximum holding
capacity of 760mm of water. Along with a common porosity of 0.47 this implies a soil column of 1.6 meter.
Please be aware of the problems caused by using
real time station data in calculating soil moisture for the current month: Daily station
preciptation tends to be heavier compared to climate division data.
Please be aware that when using Grads to plot
station data, we implicitly use Cressman analysis. It may create some unrealistic values,
especially in areas with big gradients or in the boundary area.