IEM :: Reanalysis Data

IEM Reanalysis (IEMRE)

IEM Reanalysis is an effort to provide a regular dataset of Iowa Environmental Data without many of the problems associated with single site observations. The IEM will continue to provide single site observational data, but for some purposes, this dataset will be easier to work with. No dataset is perfect and this dataset is provided without warranty.

Why do this?
Previously, the IEM has only provided raw observations with limited quality control checks in place. Quality control is hard! Many times, users are simply looking for something "close" and perhaps not as perfect as high quality sensor observations can be. Producing a gridded analysis is one way to produce a dataset from point observations which can be sampled as a means of spatial interpolation.
Isn't this a duplication of effort?
While there are other "reanalysis" type projects out there with data freely available, many times their data does not update in near real-time and does not include many of the datasets the IEM uniquely collects. We may also produce an analysis on sub-hourly timescales.

Data Flow

1. Input Datasets

NCEP Stage IV Precipitation
This is an hourly gridded product with precipitation estimates derived by RADAR and then bias corrected by gauge data. The IEM caches the grib data and makes hourly plots available here.
MRMS Precipitation
Currently, this is only used to populate a daily total in a dedicated netcdf file.
ASOS/AWOS Daily Summaries
NWS Daily Climate Summaries
HRRR/MERRA/NARR Daily Solar Radiation
NWS COOPerative Observations
Manually QC'd Iowa COOP data from Iowa's State Climatologist
NCDC QC'd COOP Data

2. IEM ReAnalysis Gridded Datasets

Daily Maps of Gridded Variables
View a smoothed or gridded plot of IEMRE data
Download the raw NetCDF Files here.

3. Climodat Station Data

The location of the IEM Longterm tracked climate stations are used to sample from the IEMRE grid to produce daily values of high / low temperature, precipitation, snowfall, snow depth, and radiation. For some stations, a direct copy of the corresponding ASOS station data is used.

Climodat Reports
These are pre-generated reports answering many of the commonly asked climatology questions.

Data Availability

Hourly Interval	Daily Interval
2 Meter Air Temperature 10 Meter Wind Speed and Direction Precipitation	High and Low 2 Meter Air Temperature Precipitation

Data Access

Here are some JSON web services you may try.

MultiDay Request
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Form: https://mesonet.agron.iastate.edu/iemre/multiday/{YYYY-MM-DD::date1}/{YYYY-MM-DD::date2}/{LAT}/{LON}/json
Example: https://mesonet.agron.iastate.edu/iemre/multiday/2010-05-01/2010-09-30/42.54/-96.40/json

IEMRE data is stored on the server as netCDF files. You can directly download these files from here.