Search for: All records

We estimate the effect of model deficiencies in the Global Forecast System that lead to systematic forecast errors, as a first step toward correcting them online (i.e., within the model) as in Danforth & Kalnay (2008a, 2008b). Since the analysis increments represent the corrections that new observations make on the 6 h forecast in the analysis cycle, we estimate the model bias corrections from the time average of the analysis increments divided by 6 h, assuming that initial model errors grow linearly and first ignoring the impact of observation bias. During 2012–2016, seasonal means of the 6 h model bias are generally robust despite changes in model resolution and data assimilation systems, and their broad continental scales explain their insensitivity to model resolution. The daily bias dominates the submonthly analysis increments and consists primarily of diurnal and semidiurnal components, also requiring a low dimensional correction. Analysis increments in 2015 and 2016 are reduced over oceans, which we attribute to improvements in the specification of the sea surface temperatures. These results provide support for future efforts to make online correction of the mean, seasonal, and diurnal and semidiurnal model biases of Global Forecast System to reduce both systematic and random errors, as suggested by Danforth & Kalnay (2008a, 2008b). It also raises the possibility that analysis increments could be used to provide guidance in testing new physical parameterizations. 

The report summarizes the NCRTF workshop, which consisted of a series of presentations and vigorous discussion of NCRTF activities, related developments in the NOAA National Centers for Environmental Prediction (NCEP) and other U.S. weather and climate forecasting centers, and related international efforts. The workshop goals were to 1) highlight advances in these areas across NOAA and at other Federal agencies, international agencies, and universities; 2) identify gaps; 3) improve coordination of future activities to meet the requirements of the diverse array of users of reanalyses; and 4) to strengthen NOAA’s and partner organizations’ development and utilization of new reanalysis and related data sets.