Arieh Bitan

Spatial distribution and microscale characteristics of the urban heat island in Tel-Aviv, Israel

Abstract A significant urban heat island (UHI) was identified in Tel-Aviv on a stable winter day. The UHI detection was performed using air temperatures at both the roof and the street levels (using fixed-station and car-traverse measurements) and at the surface level (using an airborne thermal video radiometer [TVR]). Whereas the complex microscale characteristics of the UHI studied by the TVR at the surface level showed variations of up to 10°C, at the street level, air temperature variations of 3–5°C were identified between the city center and the surrounding areas. It was found that during the nighttime, the warm Mediterranean Sea has a moderating effect on the roof-level temperatures, whereas, at the street level, the urban heat island is more pronounced. The combined method of monitoring the UHI from different levels and on different scales for the first time enabled a spatial assessment of the city’s UHI and its diverse thermal coverage characteristics. The thermal differences of neighborhoods, urban activity and urban components were compared. It was demonstrated that the city cover plays an important role in the thermal activity of Tel-Aviv. A similar UHI spatial pattern was obtained using isotherm maps, generated from the air temperatures at street level, and thermal images, generated by the TVR at the surface level. It was concluded that there are differences in the magnitude of the UHI at different levels of the canopy layer and at different times, but the UHI pattern has similar trends.

Long-term changes in annual rainfall patterns in Southern Israel

SummaryWithin the study region in southern Israel, the annual average rainfall during the period 1961–1990 increased by up to ~ 30%, with only minor changes in the control stations representing the central and northern parts of the country. The retreat of aridity is made even more pronounced by an appreciable decrease in the coefficient of variation (CV) in nearly all of the 30 rain stations within the study region. The geographical area where maximum CV reductions were found correlates well with the area where intensive land-use variations took place with the initial operation of the National Water Carrier in 1964. A global climate change in the sea surface temperatures starting in the early 1960s may have had an effect to increase seasonal rainfall. Current research is aimed at resolving this issue.

Long-term change in October rainfall patterns in southern Israel

SummaryA comprehensive study of long-term changes in October rainfall patterns in southern Israel, a semi-arid fringe zone between the Mediterranean coastal plain and the Negev Desert, was carried out. It was earlier postulated that the observed positive trend in October rainfall amounts may result from land-use changes in the area following the installation of the National Water Carrier (NWC) in the early 1960s. The purpose of the present study is to delineate the anticipated local effects, as well as their spatial extent, in order to investigate the possibility of climatic change over a larger synoptic scale.In the study region, a total number of 51 rainfall stations with long-term records up to 55 years, were analyzed, along with six control stations in other parts of the country. All stations were analyzed for trends in early seasonal rainfall, spatial variability during the two reference periods before and after the 60s, and for the ratio between rain per day (RPD) and number of rain days (NRD) during the two periods.The results of the analyses point to a well defined localized climatic change in October rainfall patterns within the study area, that is traceable to intensive and extensive land-use changes following the installation of the NWC.

The high climatic quality city of the future

Abstract In the future most of the worlds population will live in urban areas and there also most economic activities will be concentrated. This will lead to enormous environmental and climatological problems, unless urban planners and architects develop a new urban planning strategy and building design methods, which will enable the continuation of the growth of urban areas and also enable its population to live and work in a good climatic environment. To achieve this goal this article presents a new comprehensive climatological and environmental urban planning concept. This concept includes the new term of “climate quality”, which is no less important in the urban space than is air quality. The combination of using alternative energy sources together with integrating climatological factors in all urban planning levels will lead to an expected improved climatic and environmental quality of the urban area.

The methodology of applied climatology in planning and building

Abstract In recent years there has been an increasing awareness and trend to integrate climatological elements in planning and building. The awareness of planners, architects and decision-makers of environmental problems and of the need to improve the quality of living necessitates the integration of climatological factors in planning and building. In this article a methodology is represented which enables the planner and architect, in a systematic way, to integrate the different climatological elements in all levels of planning, from regional planning through settlement planning to the design of buildings. The methodology, which is also represented by a flowchart, is divided into five stages, each one consisting of several subdivisions.

Lake Kinneret (Sea of Galilee) and its exceptional wind system

From 1973–1976, research was performed around the Sea of Galilee, aimed at examining the wind regime in the area and whether the area develops a land-sea breeze despite its particular topographical location.The main conclusions were:(1)During the summer mornings a lake breeze develops, blowing towards the shores of the lake. It ceases at the peak of its development when a westerly wind, originating in the development of a breeze along the Israeli Mediterranean coast, plunges towards the lake.(2)Late at night, a wind flow develops from the land towards the lake, which combines with the katabatic winds that blow along the steep slopes surrounding the Kinneret.(3)The stations at the upper level, at a height of 400–500 m above the Kinneret, are not affected by the lake breeze during the day or by the land breeze at night.(4)In winter, the Kinneret lake breeze is almost as developed as in summer, because the westerly winds, originating in the Mediterranean sea breeze which hardly develops in this season, do not plunge into the Kinneret.

The Jordan Valley project — A case study in climate and regional planning

Abstract Between the years 1970 and 1980 topoclimatological research was performed in the Central Jordan Valley. The aims of this project were to study the climate of one of the hardest climatic regions in Israel, which was to be developed as a new settlement area. The climatological data should be a useful tool for the planners of this new region, as the difficult climate is one of the most important factors ruling and influencing its development. During the ten-year period, more than 15 climatological stations were established, each yielding observations for at least 4 years. It was found that the central Jordan Valley could be divided into 3 climatological subregions: 1. (1) the eastern slopes of the Judean and Samarian mountains; 2. (2) the central Jordan Valley; 3. (3) the northern Dead Sea. The main factors influencing the climate are the great height differences and local topography, the descending winds from the Judean and Samarian hills, and the development of a local lake breeze from the Dead Sea. After calculating the discomfort values and after taking into consideration the heating degree days and the strong winds, the preferred settlement sub-region was found to be the eastern slopes of the Judean and Samarian hills, which is the highest place, although the area suffers from strong wind problems. The second preferred area is along the northern coast of the Dead Sea, and lastly, the central Jordan Valley. Among other aspects dealt with by the research program were the relation between the climate and agriculture of the region, and the impact of climate on the detailed planning of the different settlements.

Climatic Variations In The Moisture and Instability Patterns Of The Atmospheric Boundary Layer On The East Mediterranean Coastal Plain Of Israel

A long-term record (1964–1995) of radiosonde data observed atthe Bet-Dagan aerological station of the Israel Meteorological Service was analyzed to detect possible temporal trends in moisture content and instability of the atmospheric boundary layer. Bet-Dagan issituated in the central part of the south-east Mediterranean coastal plain. During this period surface characteristics in this region have changed drastically due to changes in land use, i.e., urbanization, development of irrigated agriculture and afforestation. The analysis of the radiosonde data reveals a clearly defined, statistically significant, increasing trend in the moisture content, mainly during summer. The stability of the surface layer, characterized by the bulk Richardson Number, shows adecreasing trend since the early 1960s. Relationships between these trends, land-use modifications and possible influence of large-scale influence are discussed.