Development of Prototype National Water Model Soil Moisture Products for Drought Monitoring

NOAA’s new National Water Model (NWM) offers fine spatial and temporal analyses and predictions of hydrologic variables of relevance to drought monitoring and forecasts. We present preliminary results exploring the potential for NWM soil moisture nowcasts to inform drought monitoring. Because drought monitoring relies on an accurate representation of climatological soil moisture values to establish anomalies, we begin our analysis focused on comparisons of this climatology in the NWM with climatologies from in situ soil moisture observations and soil moisture climatologies from other gridded datasets currently used to inform the National Drought Monitor, specifically those from the NOAA Climate Prediction Center’s leaky bucket soil moisture model and from North American Land Data Assimilation System (NLDAS).

In this study, we utilize NOAA PSD’s instrumentation network in California’s Russian River watershed (a NIDIS Pilot basin) to establish a simple, information-rich method for displaying an anomaly given soil moisture’s highly non-Gaussian, strongly seasonally varying probability density function. This method is used to illustrate differences in the climatology and anomalies during California’s recent drought across the various soil moisture datasets. Differences in the climatologies and anomalies will be discussed in the context of implications for drought monitoring.