Local Parks Help Cool Down Urban Climate, German Researchers Find
Temperatures are half a degree lower in a park than in the adjacent heavily built-up neighbourhood.
Grotelüschen, Frank. (2013). Local Parks Help Cool Down Urban Climate, German Researchers Find. Hamburg, Germany: Deutsche Welle.
The Hamburg Urban Soil Climate Observatory (HUSCO) project measures the influence of soil and vegetation on the urban climate. For the project, experts installed measuring facilities in the city to find out how much soil cools the surrounding climate and how various types of soil have different effects. One station was set up in a bog with a high groundwater level, and another in a dry area with a low groundwater level.
In both cases, the researchers built mini weather stations that measure the temperature, wind velocity and humidity. They also dug pits and installed soil sensors right under the surface as well as at a depth of 1.6 meters. The sensors collected data over three years.
See http://meetingorganizer.copernicus.org/EMS2010/EMS2010-520.pdf for a further description of the HUSCO project.
The evidence shows that sites dry out to varying degrees during periods with less precipitation. Moist soil is replenished by groundwater, so it tends to dry out less quickly during dry periods than soil with low groundwater levels. Researchers also found that moist soil cools down the surrounding air, considerably more so than dry ground. It is important that cities have open, unsealed land. Parks are important at controlling local climate conditions and are best located on sites with moist soil, where the cooling-down effect functions even better.
"That means city parks have a huge significance for the local climate," project manager Annette Eschenbach says.