Feature January 17, 2007 A Tale of Two Sites: Impacts of Relocating In the classic 1859 novel, "A Tale of Two Cities," Charles Dickens spins a moral tale of dramatic contrasts between 18th century
A new comparative study of daily temperature and rainfall records in Los Angeles by NASA and university scientists finds the move -- to a location nearly 6 kilometers (almost 4 miles) closer to the coast and 27 meters (90 feet) lower in elevation -- has produced weather records reflecting conditions that are cooler, drier and less extreme than those at the previous location.
At the annual meeting of the American Meteorological Society in
"The move from downtown
This is hardly the first move of the downtown
The National Weather Service moved the station as part of a nationwide effort to locate all official weather stations on ground-level sites in natural settings. The Department of Water and Power site remained operational, however, allowing the direct comparisons used by Patzert and his colleagues.
The study found that between August 1999 and June 2006, maximum temperatures averaged 1 degree Celsius (1.8 degrees Fahrenheit) higher at the Department of Water and Power site, while the average temperatures at the new site were about a half-degree Celsius (0.9 degrees Fahrenheit) warmer. Minimum temperatures were about the same at both sites. The greatest differences in maximum temperatures occurred in late summer and early fall, with the smallest differences seen in late winter and spring. The Department of Water and Power site was cooler than USC in the spring and summer and warmer in the fall and winter. The authors attribute these seasonal differences to two factors: distance from the ocean and land use.
"In southern
Because of the abundance of trees and grass, the USC station tends to be cooler during the day than the urbanized Department of Water and Power site. At night, the trees can block outgoing radiation, and the moisture in the lawns tends to absorb more heat than the drier, open Department of Water and Power site.
The USC site averaged about 25.4 millimeters (about one inch) less rainfall than the higher and more inland Department of Water and Power location. Again, elevation and distance from the coast are driving factors in the differences. In the
The weather station relocation kept
LaDochy cited the record heat wave of June and July 2006 as an example of how the move has made temperature records less extreme. At the USC station, the all-time record for the highest minimum temperature (overnight low) was set on June 4, with 20 degrees Celsius (68 degrees Fahrenheit). However, that same week, the Department of Water and Power station recorded highest overnight lows three days in a row. Similarly, for the month of July, USC station temperatures broke or tied seven all-time records, while the Department of Water and Power site broke nine.
Since the Department of Water and Power station is still operational, Patzert and his co-authors suggest its records be reinstated as the official
Other study authors include JPL's Dr. Josh Willis and Teni Mardirosian, -end- Media contact: Alan Buis/JPL (818) 354-0474 |