台北盆地小氣候之研究

劉衍淮

Abstract

　　In the campus of the National Taiwan Normal University thermometers for measuring temperatures in the ground were placed and observations at noon time on two days with fine weather in May 1972 will be discussed here. The average temperature on the ground was 36°C, and at 100 cm depth it was 22.9°C. The vertical temperature gradient of the first 10 cm layer was very steep and equaled 1 degree per centimeter. From this gradient we can obtain a heat flow of 5 cal. per square cm per hour downward in the ground. The curve of the temperature change with the depth in the ground resembled in a rather small scale that of the water in the free ocean of the middle latitude which professor A. Defant defined as troposphere of the ocean, and the lower layer as the stratosphere, because the temperature gradient was much smaller. According to the measurement made in Weather Bureau in Taipei on two days in July 1970 and 1971, with fine weather, temperature on the ground was only 3.4 degree C higher than that at a 100 cm depth. The average vertical temperature greadient in the ground in July was much smaller than that we measured in May.
　　According to observations in the two years 1970 and 1971, the mean temperature on the ground surface in July was 15.8 degree C higher than that in January. In the ground, the temperature increased with the depth in January and decreased with the depth in July. At a depth about 370 cm, the temperature in both month January and July were the same, 23.6 degree C. Below 370 cm it was warmer in January than in July, and at 500 cm depth the temperature in January was 1.1 degree C higher than that in July.
　　In two fine weather afternoons in June 1972, three groops of our students were sent by cars to make observations at 20 localities along three routs in the region of Taipei Basil. After that charts of distributions of air temperature, ground (surface) temperature and relative humidity of the air were drawn. The patterns of the same meteorological element in charts on different days were not indentical. The cause of that was the wind conditions in these two afternoons were different. Winds from different directions brought in different airmasses and caused changes of the windward and lee sides in Taipei area. Winds with different velocity stimulated different turbulence of the air. Topography, watercourses, nature of the ground, plants, and settlement with high buildings all are influential factors to the local climate or microclimate of Taipei Basin. However, in the charts of the approximately synchroneous odservations the urban effects on climate in Taipei area were distinctly to be noticed. In the downtown of Taipei it was warmer and dryer than most parts of the outskirts of the city.