Soil Temperature at Depths and Cooling Potential for the Tropics

摘要

Soil temperature to depths of one and two metres is being measured in Townsville. A tropical and coastal area in the north of Australia, Townsville has a mean annual air temperature of around 24°C. At depth two metres, mean annual soil temperature is about 27°C, a maximum of slightly higher than 29°C in summer and a minimum of over 24°C in winter. Peak soil temperature in summer is approximately 1°C lower for the soil adjacent to a concrete slab of a building, which is partially shaded by a half-metre roof overhang. Compared with other climates, temperature of tropical soil at depths does not fluctuate much around its mean annual temperature. Approximately having the shape of a sine wave, the soil temperature pattern recorded for the year 2000 has an amplitude of fluctuation of 2.5°C. Lower for the soil near the slab. Cooling potential is theoretically assessed, assuming a peak temperature of 26°C is achievable in summer by appropriate soil surface treatments. Calculation results indicate a range of air flowrates from 1 to 2 m/s and pipe diameters from 25 mm to 50 mm are capable of producing an outlet air temperature range within the generally accepted level of human thermal comfort during tropical summer days.