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Chapter 3. Climatic Data
3.1 Introduction to Climatic Data
The climatic data include the data necessary to characterize the environment in which the pavement has existed since its construction and throughout the monitoring period. The climatic data elements include:
- Weather Station Identification/Location.
- Average Monthly Temperature.
- Average Maximum Daily Temperature by Month.
- Average Minimum Daily Temperature by Month.
- Average Monthly Maximum Relative Humidity.
- Average Monthly Minimum Relative Humidity.
- Average Monthly Precipitation.
- Average Monthly Percent Sunshine.
- Average Monthly Windspeed.
- Average Annual Number of Days of Precipitation.
- Latitude.
- Longitude.
- Freezing Index.
- Average Number of Annual Freeze-Thaw Cycles.
- Average Annual Number of Days with Temperature Below Freezing.
- Average Annual Number of Days with Temperature Above 32 °C.
- Elevation above Sea Level.
LTPP climatic data have been developed from data obtained from the National Climatic Data Center (NCDC) and the Canadian Climatic Center (CCC). For each GPS test section and SPS project, up to five nearby weather stations were identified. Daily measurements for the selected data items were obtained for each of the identified weather stations. The data for these weather stations were used to estimate site specific climatic stations referred to as virtual weather data. The daily values are summarized to monthly and annual statistics including the mean, standard deviation, minimum, and maximum.
3.2 References Used for Climatic Data
The general reference for the collection and accumulation of climatic data is provided by:
- Data Collection Guide for Long-Term Pavement Performance Studies, Operational Guide No. SHRP-LTPP-OG-001, SHRP, National Research Council, Washington, DC, January 1988, chapter 5.
This chapter provides a brief overview of the efforts involved in obtaining climatic data for LTPP GPS test sections. It was updated as referenced below:
- Data Collection Guide for Long-Term Pavement Performance Studies, Operational Guide No. SHRP-LTPP-OG-001, SHRP, National Research Council, Washington, DC, October 1993, chapter 5.
A separate set of documents was prepared in 1993 to describe data obtained from the National Oceanic and Atmospheric Association (NOAA). It also provides details describing how the data obtained were accumulated and stored in the LTPP database. These data were available in a standard release of LTPP data until 1999. The first document is specific to GPS test sections, and the second is specific to SPS projects. The SPS document dated January 1993 was revised and re-released in May 1993.
- Development of the LTPP Climatic Database, SHRP Report SHRP-P-621, SHRP, National Research Council, Washington, DC, January 1993.
- Climate Data Collection for SPS Test Sites, FHWA, Pavement Performance Division, McLean, VA, January 1993.
- Climate Data Collection for SPS Test Sites, FHWA, Pavement Performance Division, McLean, VA, May 1993.
Environmental data from each test section were replaced with a revised and more complete set of data in 1999. The following document describes how these data were accumulated into the set of statistics that were subsequently stored in the LTPP database.
- LTPP Climatic Data Revision and Expansion, Draft Report, FHWA, Pavement Performance Division, McLean, VA, July 1999.
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