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Federal Highway Administration Research and Technology
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Publication Number: FHWA-RD-03-092
Date: May 2006
Verification of LTPP Virtual Weather Stations Phase I Report: Accuracy and Reliability of Virtual Weather Stations
The following recommendations are given for future work:
- The VWS concept can be used to provide reasonable climatic
estimates at any site.
- In developing the climatic estimates, the elevation differences
of the nearby weather stations should be limited to 250 m. The
temperature could be corrected for the elevation difference using
an algorithm similar to what was developed in this study.
- A simple average (no weight) or inverse distance weight
(1/R) should be used for developing the VWS estimates. The
inverse distance square rule (1/R2) and the
estimates based on the closest weather stations should be avoided
as much as possible.
- The VWS concept provides reasonable estimates regardless of the
- The most accurate characterization of the year-to-year
variation of the climatic data should be made. This variation
should be considered when estimating climatic data for an average
year at a project site.
- Because of the year-to-year variation of the climatic data, the
estimated yearly climatic parameter for a typical year should be
made with reliability.
- The within-site variation of the measured climatic data should
be further investigated.
- SMP data anomalies discovered during this study should be
- The quality and quantity of the windspeed and humidity data in
the LTPP database should be improved.
- It is highly recommended that the procedures developed in this
study be used to develop a user-friendly climatic database for the
LTPP program. Such a database can provide daily, monthly, yearly,
and multiyear climatic estimates for existing and new sections, and
will be updated easily.