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Message: upcoming changes in the RUC

Posted by Stan Benjamin on 1 Dec 99, 11:46 MT

There are 2 sets of upcoming changes in the RUC likely within the next few weeks.

The first is a fix for a problem with the RUC soil moisture. When the IBM version of the RUC started 2 weeks ago, a combination of conditions has allowed an exaggeration in the amount of canopy water, leading to too moist soil over much of the US. When the code fix is made for this problem, the soil moisture/temp fields will also be restarted from the FSL backup RUC fields. The effect of this problem includes too high dewpoints, too low sfc temps in the daytime, and too little mixing of winds from aloft in the daytime. At the same time as this change, 3 sfc stations with consistent problems will be flagged from getting into the RUC (KLBL - Liberal, KS - high dewpoint, KLXL - Little Falls, MN - bad wind direction, MMMV - Monclova, MX (Coahuila state) - intermittently high T/Td - mentioned by a user in the RUC forum in July). The automatic QC flagging of these stations has been working some but not all of the time.

The second set of changes is an addition of 8 new diagnostic variables (previously discussed in some forum postings) - visibility, cloud base, cloud top (stable), sfc wind gust speed, PBL height, convective cloud top, equilibrium level, and pressure of max theta-e parcel. Most of these variables can be viewed on the RUC/MAPS web page ( http://maps.fsl.noaa.gov) using the index on the left for products from either "Backup RUC" or "40km MAPS para" (a version with experimental GOES cloud-top assimilation). There are explanations of the derivation of these variables at http://maps.fsl.noaa.gov/vartxt.cgi. In addition to the new variables, there will be a fix for the 3h sfc pressure change, which has not been working correctly with the IBM RUC version.

The new variables are quite interesting -- take a look. As always, comments and questions are welcome, either directly to this forum or email to one of us developers. Also, further postings will be made when the actual time of the changes becomes known.

Stan Benjamin


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