Profiler assessment and ongoing profiler observation quality monitoring using the Rapid Update Cycle

The Observation Assessment Section of the Earth System Research Laboratory / Global Systems Division's (GSD) Assimilation and Modeling Branch has performed successful observation quality monitoring (OQM) studies in the past for aircraft and surface observations. In these studies, differences between observations and 1-h RUC forecasts have been accumulated over periods from 1 hour to more than a year to detect systematic observational errors not detectable at single observation times. We are now developing a system to apply this kind of monitoring to profiler data.

Monitoring by using profiler-RUC differences generated during individual RUC analyses has already been useful for the NOAA Profiler Network. This method provided key information in the detection of a wind direction error at Syracuse, NY, and other problems with NPN wind or RASS virtual temperature observations, usually within hours of when the problem began.

But an ongoing observation-RUC difference database has not yet been applied to profiler observations. In applications featuring other data sources (most notably aircraft), use of RUC 1-h forecasts as background has been very effective. RUC 1-h forecasts are quite accurate, and give physically consistent filtering (and even removal) of any observational quality problem that eluded detection by the QC procedures in the RUC analysis. Thus, the physical/dynamical consistency in the RUC model provides critical independence (for QC) in its 1-h forecasts from the observations at the previous analysis time.

The current ongoing observation-RUC monitoring has resulted in:

• The generation of daily aircraft reject lists which are now used in the GSD experimental versions of the RUC.

• The generation of mesonet “use lists”, calculated from multiweek statistics that indicate mesonet stations that do not have significant siting problems for wind observations. These lists are now being used in the operational RUC at NCEP and also in the operational RTMA analysis, also at NCEP.

At the conference we will go into more detail about the design and implementation of the profiler observation – RUC 1-h forecast monitoring system and present initial results for the National Profiler Network and for Cooperative Agency Profilers.