Assessment and Implications of NCEP Stage IV Quantitative Precipitation Estimates for Product Intercomparisons

Abstract

The National Centers for Environmental Prediction (NCEP) stage IV quantitative precipitation estimates (QPEs) are used in many studies for intercomparisons including those for satellite QPEs. An overview of the National Weather Service precipitation processing system is provided here so as to set the stage IV product in context and to provide users with some knowledge as to how it is developed. Then, an assessment of the stage IV product over the period 2002–12 is provided. The assessment shows that the stage IV product can be useful for conditional comparisons of moderate-to-heavy rainfall for select seasons and locations. When evaluating the product at the daily scale, there are many discontinuities due to the operational processing at the radar site as well as discontinuities due to the merging of data from different River Forecast Centers (RFCs) that use much different processing algorithms for generating their precipitation estimates. An assessment of the daily precipitation estimates is provided based on the cumulative distribution function for all of the daily estimates for each RFC by season. In addition it is found that the hourly estimates at certain RFCs suffer from lack of manual quality control and caution should be used.

Evaluation of precipitation estimates over CONUS derived from satellite, radar, and rain gauge data sets at daily to annual scales (2002–2012)

“…Stage IV displays a negative bias for summer when compared to GHCN-D and PRISM (≈ −19 %) and comparable with the bias observed for winter (−12 %). Differences remain significant despite the fact that Stage IV uses the PRISM/Mountain Mapper algorithm that combines automated rain gauge observations and PRISM monthly precipitation climatology (Hou et al, 2014;Nelson et al, 2015). Conversely, 3B42 presents a very good agreement with GHCN-D (−1.7 %) and PRISM (−2.4 %) and contrasts with the severe underestimation observed on the right side of the distribution during winter (Fig.…”

“…tal scales (Huffman et al, 2001;Sorooshian et al, 2002;Nesbitt and Zipser, 2003;Liu and Zipser, 2008;Nesbitt and Anders, 2009;Sapiano and Arkin, 2009;Prat and Barros, 2010a;Sahany et al, 2010;Kidd et al, 2012;Nelson, 2013a, b, 2014 among others).…”

“…The Stage IV precipitation data are available via http://data.eol.ucar.edu/codiac/dss/id= 21.093. The reader will find a more detailed description of the Stage IV precipitation retrievals from the RFC level and up to the final mosaicked product in Nelson et al (2015). In addition to radar only reflectivity scanning and processing (beam blockage, hot and cold biases, bright-band contamination, anomalous propagation, cone of silence), the final mosaicked estimates present biases that are visible in the long-term averages.…”

Simulating North American mesoscale convective systems with a convection-permitting climate model

“…For the model evaluation, we use the National Centers for Environmental Prediction (NCEP) stage-IV analysis (Fulton et al 1998;Nelson et al 2016) that provides hourly precipitation on a 4-km Contiguous United States (CONUS) grid based on radar and gauge reports. Since stage-IV has quality issues over the western half of the CONUS, over ocean regions, and prior to 2002 [e.g., Nelson et al (2016)] we decided to constrain the analysis to land regions east of the Continental Divide for the period January 2002 to September 2013 (see colored area in Fig.…”

“…Since stage-IV has quality issues over the western half of the CONUS, over ocean regions, and prior to 2002 [e.g., Nelson et al (2016)] we decided to constrain the analysis to land regions east of the Continental Divide for the period January 2002 to September 2013 (see colored area in Fig. 1).…”