IEM :: RWIS Data Download

RWIS Atmospheric / Surface Data Download

The IEM archives RWIS information for the network in Iowa based on a direct feed from the DOT. We also archive other states based on an archive provided by the MADIS project. Data for Iowa dates back to 1995, whereas archive availability for other states varies based on their participation within MADIS.

Backend Documentation

Network Selection

1. Select Station(s)

Data Request Configuration

2. Select Start/End Time

Times are in timezone you select in step 5 below.

	Year	Month	Day	Hour
Start:
End:

3. Select Variables

The label value within parenthesis is the output column name.

See below for discussion on "Pavement Sensor Condition"

4. How to view?

5. Timezone of Timestamps

This controls the timezone used for presenting the timestamps in the downloaded file.

6. Data Delimitation

How shall the output values be separated?

7. Include Lat / Lons?

8. Submit Form

Pavement Sensor Condition Explanation

The following applies to most of the Iowa RWIS sensors and is passed along by the Iowa RWIS Coordinator.

The data is taken from the Vaisala FP2000. These readings can be lumped into four general categories: wet, dry, snow/ice, error. The sensor gives quite a few more, especially in the snow/ice realm but functionally it is difficult to distinguish clear differences between them.

From the glossary:

Status	Description
Snow/Ice Warning	Continuous film of ice and water mixture at or below freezing (32°F / 0°C) with insufficient chemical to keep the mixture from freezing. This status can only be reported at Vaisala ESP and SP sites when precipitation occurs.
Ice Warning	Continuous film of ice and water mixture at or below freezing (32°F / 0°C) with insufficient chemical to keep the mixture from freezing. This status can only be reported at NTCIP sites.
Snow Warning	This status can be reported at NTCIP sites, but will not be reported by Vaisala NTCIP sites.
Wet Below Freezing	Moisture on pavement sensor with a surface temperature below freezing (32°F / 0°C). This status will only be reported at Vaisala SCAN Detector sites.
Ice Watch	Thin or spotty film of moisture at or below freezing (32°F / 0°C). This status can only be reported at NTCIP sites when precipitation is not occurring.
Snow/IceWatch	Thin or spotty film of moisture at or below freezing (32°F / 0°C). This status can only be reported at Vaisala ESP and SP sites when precipitation is not occurring.
Snow Watch	This status can be reported at NTCIP sites, but is not detected at Vaisala NTCIP sites.
Frost	Moisture on pavement at or below freezing (32°F / 0°C) with a pavement temperature at or below the dew point temperature. This status can only be reported by Vaisala ESP, SP, and NTCIP sites when precipitation is not occurring.
Chemical Wet	Continuous film of water and ice mixture at or below freezing (32°F or 0°C) with enough chemical to keep the mixture from freezing. This status can only be reported by Vaisala ESP, SP, and NTCIP sites when precipitation occurs.
Wet	Continuous film of moisture on the pavement sensor with a surface temperature above freezing (32°F or 0°C). This status can be reported by Vaisala ESP, SP, SCAN Detector, and NTCIP sites when precipitation has occurred.
Damp	Thin or spotty film of moisture above freezing (32°F or 0°C). This status can only be reported by Vaisala ESP, and SP sites when precipitation is not occurring.
Trace Moisture	Thin or spotty film of moisture above freezing (32°F or 0°C). Surface moisture occurred without precipitation being detected. This status will only be reported at NTCIP sites when precipitation is not occurring.
Absorption at Dew Point, Absorption, & Dew	These statuses can be reported at NTCIP sites, but are not currently detected at Vaisala NTCIP sites.
Dry	Absence of moisture on the surface sensor. This status can be reported by Vaisala ESP, SP, SCAN Dectector, and NTCIP sites.
Other	Other is the standard NTCIP ESS surface condition code to handle conditions not explicitly included in this table. This status will only be reported NTCIP by sensors installed at NTCIP ESS sites.
No Report	The surface sensor is not operating properly and requires maintenance. This status will only be reported by Vaisala ESP and SP sites.
Error	The surface sensor is not operating properly and requires maintenance. This status will only be reported by NTCIP sites.

Publications Citing IEM Data (View All)

These are the most recent 10 publications that have cited the usage of data from this page. This list is not exhaustive, so please let us know if you have a publication that should be added.

Biswas, S. and T. Kwon. 2020, Developing Statewide Optimal RWIS Density Guidelines Using Space-Time Semivariogram Models. Journal of Sensors. https://doi.org/10.1155/2020/1208692
Genc, D., J. Ashlock, et al. 2020, Analysis of In Situ Soil Thermal and Hydraulic Data from a Subgrade Sensor Network under a Granular Roadway. Geo-Congress 2020: Modeling, Geomaterials, and Site Characterization (GSP 317) https://doi.org/10.1061/9780784482803.016
Biswas, S., M. Wu, et al. 2019, Use of Topography, Weather Zones, and Semivariogram Parameters to Optimize Road Weather Information System Station Density across Large Spatial Scales. Journal of the Transportation Research Board. Volume 2673, Issue 12 https://doi.org/10.1177/0361198119846467