Study on the cooling effects of urban parks on surrounding environments using Landsat TM data: a case study in Guangzhou,southern China

The temperature cooling effects of ten urban parks on surrounding environments in Guangzhou, southern China, are analysed and quantified using Landsat Thematic Mapper data. The results show that there is a temperature rise (about 1.74°C) between green spaces of parks and bare-ground areas of the surroundings. For those parks whose green area percentage is more than 69% and length:width ratio is close to 1, the average temperature differences between boundaries and surrounding sites of parks have linear relationships with the green areas of parks (R ² > 0.82). Moreover, the nonlinear relationship between the average cooling distance of parks and green areas can be simulated very well using a logarithmic curve (R ² > 0.93). When the green areas of parks are smaller than 10 566 m², parks will have no temperature cooling effects on their surrounding environments. When the green areas of parks reach 740 000 m², the increase of temperature cooling distance is less than 1 m per 10 000 m² increase of the green area. The most appropriate size of green areas of urban parks should fall between 10 566 and 740 000 m². For those parks with water areas larger than 128 889 m², the temperature cooling effects are usually more remarkable. When the length:width ratios of the green areas of urban parks are more than or equal to 2, their temperature cooling distances are always larger than those with length:width ratios equal to 1 given similar green area. Parks with larger green areas (37 163 m²) or larger water areas (>128 889 m²) will have more significant temperature cooling effects in June than in October.