NOCTURNAL HEAT ISLAND OF SMALL TOWN, ITS MANIFESTATION AND MECHANISM
NOCTURNAL HEAT ISLAND OF SMALL TOWN, ITS MANIFESTATION AND MECHANISM
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小镇夜间热岛现象及其表现与机制
DOI：
10.4157/grj.54.1
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
H. Ohyama
中科院分区：
文献类型：
--
作者：
H. Tamiya;H. Ohyama
人们对城市热岛问题进行了大量的理论和观测研究。其中一些人打算获取有关小城镇（Tamiya，1968等）和大型购物中心周围热岛的信息。预计这些针对小城镇等的研究结果可以适用于大城市热岛的解释。从这些研究来看，小城镇的热岛被认为是在晴朗、平静的夜晚和强烈的地表逆温条件下形成的。然而，大多数研究都是基于一些观察。本文的目的是根据1978年7月至1979年2月在日落后约5小时内用热敏电阻温度计进行的汽车观测的40个实例，阐明小镇热岛形成的气象条件，并研究其现象的机制。观察 筑波学术新城选取了三个小镇进行观察。它们是大曾町、竹园和并木，1978 年人口分别为 1, 800、2, 000 和 3, 500。大曾町是一个小型乡村聚落，在筑波学术新城建设之前就已经存在，主要由一两层木屋组成。后两座是为新城官员建造的，由多层混凝土砌块建筑组成。这三座位于海拔25-30米的平坦高地上。 1. 东大通大道附近（图1）。观测点及路线如图1所示。小镇外的观测点大多为田野、绿地和空地。观察从点 15 开始，并在经过 1-7-Ohzone-12-25Takezono-28-32-Namiki-34-35 的同一点结束。每次观察大约需要 30 分钟。因此，没有应用时间校正。温度观测日期列于表1。在城镇以外的点进行了重复观测。由于遍历过程中车道和时间的不同，两个观测值必然不同。然而，在实践中，对他们进行歧视是很困难的。图2给出了两个值之间的差异平均值及其标准差，这表明所有点的平均值都小于0.4°C，并且没有发现系统差异。表示周围空气状况的气象数据是从筑波大学环境研究中心（ERC）获取的（图1）。表1还给出了用于分析的元素值。 热岛的一些特征 图3显示了明显热岛的情况（1978年10月16日）。当晚，在晴弱风（1. 2 m/s，NW）条件下，底层28.5m层逆温达到6.0℃。相反，在热岛不明显的情况下（1978年10月29日，图4），天空被云覆盖，白天记录到20毫米的降水量。尽管风力微弱（1.0 m/s），同一底层逆温强度仅为0.9°C。每次观测都会计算每个点与路线平均温度的温度偏差。 40 个观测值的平均值也用标准差表示（图 5）。路线的北部较冷。最冷的是点 6。Ohzone、Takezono 和 Namiki 的平均值分别为 1°C（北侧）-0.5°C（南侧）、1°C 和 0.5°C。为了进一步检查，热岛强度在这里被定义为小镇内部点的平均温度与外部指定点的平均温度之间的差异（对于Ohzone，点3-6和14-19；对于Takezono，点14-19和29-31；对于Namiki，点29-31、34和35）。
A large number of investigations have been theoretically and observationally given on the problems of urban heat island. Some of them have intended to obtain the informations about the heat island of small towns (Tamiya, 1968 etc.) and that around a large shopping center. It is expected that the results from these studies 'on small towns or the like could be applicable to the explanation of the heat island of large cities. Judging from these studies, the heat island of small towns is thought to be formed under the condition of clear calm night with strong surface inversion. Most of the studies were, however, based on a few observations. The aim of this paper is to clarify meteorological conditions by which the heat island of small town is formed, based on forty examples of observations at about five hours after sunset by automobile with thermistor thermometer carried out from July 1978 to February 1979. Then the mechanism of the phenomenonn is examined. Observations Three small towns are selected for the observation in. Tsukuba Academic New Town. They are Ohzone, Takezono and Namiki with population of 1, 800, 2, 000 and 3, 500, respectively, in 1978. Ohzone is a small rural settlement which has been existed before the construction of Tsukuba Academic New Town, and consists of mostly one or two storied wooden houses. The latter two have been constructed for officials of the New Town and consist of multi-storied concrete block buildings. These three are located on a flat upland with a heigh of 25-30m a, s. 1. near the Higashi-Oodori Boulevard (Fig. 1). Observation points and the route are shown in Fig. 1. Most of the points outside the small towns are surrounded by field, green zone and vacancy. Observations were started from the point 15 and ended at the same point running through 1-7-Ohzone-12-25Takezono-28-32-Namiki-34-35. It took about 30 minutes to finish each observation. Therefore, time correction was not applied. The date of the temperature observations are given on Table 1. Duplicate observations were carried out at the points outside the towns. Two observed values must differ because of the difference of the lane and time during the traverses. Discrimination among them is, however, difficult in practice. Means of the differences between two values and their standard deviations are given in Fig. 2, which shows that the mean values at all the points are smaller than 0.4°C, and that no systematic differences are identified. Meteorological data representing the surrounding air conditions are acquired from the Environmental Research Center (ERC) of the University of Tsukuba (Fig. 1). The values of elements used for analysis are also given on Table 1. Some features of the heat island A case of distinct heat island is shown in Fig. 3 (Oct. 16. 1978). In this night, under the condition of clear and weak wind (1. 2 m/s, NW) the inversion reached 6.0°C in the bottom 28.5m layer. On the contrary, in case of indistinct heat island (Oct. 29. 1978, Fig. 4) the sky was covered with cloud and the precipitation of 20mm was recorded during the day. In spite of weak wind (1.0 m/s) inversion intensity was only 0.9°C in the same bottom layer. Temperature deviation at each point from the mean temperature of the route is calculated for every observations. The average values of 40 observations are also indicated with standard deviations (Fig. 5). Northern part of the route is colder. The coldest is the point 6. Mean values of Ohzone, Takezono and Namiki are 1°C (Northern side) -0.5°C (Southern side), 1°C and 0.5°C, respectively. For the further examinations, heat island intensity is defined here as the difference between mean temperature of the points inside the small town and that of specified points outside (for Ohzone, points 3-6 and 14-19; for Takezono, points 14-19 and 29-31; for Namiki, points 29-31, 34 and 35).