Iowa Environmental Mesonet

Iowa State University Department of Agronomy

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• Quality Control

The most requested feature of the IEM is to provide updated daily climodat reports. The reason this was not being done previously was that the underlying data takes a couple of months to make the round trip from the observer to the National Climatic Data Center and to the State Climatologist for processing. Additionally, this data was processed on a monthly basis.

To help fill in the gap between when the most recent quality controlled data is available and your current data needs, I have written a system to produce estimates of the daily observations. Of course, this system is not perfect, but it is a starting point for future improvement. Some notes on the estimating routines for various variables:

High and Low Temperature

These values are derived from the automated airport sensors with a strong weighting towards the quality controlled ASOS daily summary reports. These values are analyzed on a simple grid and then sampled back to produce the point estimate. Previous experience with this technique has shown it to sufficiently well.

Precipitation

The IEM computed daily totals from the National Weather Service stage4 precipitation product are used. A simple grid point sampling provides the estimated observation. This routine will take a bit more fine tuning due to deficiencies with the stage4 product, but it is a start.

Snowfall and Snow Depth

These values are problematic even when the 'observations' exist. In general, I am taking the NWS COOP reports made each morning and assigning them to the previous day. A gridded analysis process is done here as well. These values will be very suspect, but it is about the best that can be done. These data are not currently used in the climodat reports.

So in general, feedback is very much encouraged. These estimates are not being used in the climatologies, nor the daily record products. Once the QC'd data arrives, they will be blown out of the database. I may produce a report in the monthly news article with some summary statistics to see how 'good' these first guess estimates are.

As with everything we do, this data is not official nor provided with warranty. You should seek official sources for high end needs.