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Beit Jann, Israel

Levitin Y.,Israel Meteorological Service
NATO Science for Peace and Security Series C: Environmental Security | Year: 2013

The new version of WRF Modeling System (ver. 3.3) is run on nested domains of resolution 27, 9, 3 and 1 km. The three innermost domains with resolution of 1 km overlap three very different topographical areas with the biggest Israeli cities Jerusalem, Tel-Aviv and Haifa. Namely, Jerusalem is located on the southern spur of the Judean Mountains with the elevation of 700-800 m. The Great Tel Aviv urban area includes Tel Aviv itself and several satellite towns. The urban area lies about 20 km along the Mediterranean shoreline at coastal plain and extends about 10 km inland. Haifa is situated on the slopes of the Carmel range, stretching from the Mediterranean shoreline towards the southeast. The object of study is the high resolution pattern of wind and temperature fields, vertical turbulent structure within and over the urban canopy and the urban heat island (UHI) effect. The simulated by the WRF-ARW model wind field and atmospheric turbulent structure are the base for air pollutants transport and diffusion within urban canopy and outside the city. A coupled WRF-Chem modeling system is applied to analyze the temporal and spatial dynamics of pollutant concentration fields, first of all nitrogen oxides from traffic exhausts. The general goal of the study is to develop an easy-to-use tool for urban air quality forecast, based on the operative short-term weather forecast. © Springer Science+Business Media Dordrecht 2014. Source

Shilo E.,Israel Meteorological Service | Ziv B.,Open University of Israel | Shamir E.,Hydrologic Research Center | Rimmer A.,Israel Oceanographic And Limnological Research
Journal of Hydrology | Year: 2015

The relationships between the evaporation from a medium size (168.7km2) Lake Kinneret (Northern Israel), and its governing synoptic factors are well demonstrated during the summer of 2010. During July-August the daily temperature of the air and water surface were 2-4°C higher, the daily wind over the lake was 80% weaker, and the evaporation from the lake was 5% lower than the long-term July-August mean. In this study, we explore the impact of the regional and local synoptic-scale atmospheric conditions on the evaporation from the lake during exceptionally hot days in the mid-summer months (July-August). The factors that were found to be correlated with the lake evaporation are the temperatures at 850hPa (negative) and 500hPa (positive), the sea level pressure difference between Northern Egypt and Armenia (positive), and the height of the marine inversion (positive). Synoptic analysis indicates that two conditions are responsible for the reduction of the Mediterranean Sea Breeze (MSB) during exceptionally hot days, and consequently to the reduction of evaporation from the lake. First, the weakening of the permanent synoptic Etesian winds, which otherwise supports the inland penetration of the MSB; and second, the descent of the marine inversion to a height below the topographic ridge of the Galilee Mountains upwind of the study area, which blocks the Marine Sea Breeze from reaching Lake Kinneret. © 2015 Elsevier B.V. Source

Saaroni H.,Tel Aviv University | Ziv B.,Open University of Israel | Osetinsky I.,Israel Meteorological Service | Alpert P.,Tel Aviv University
Quarterly Journal of the Royal Meteorological Society | Year: 2010

This study examines the ability of the interannual variability in the occurrence of synoptictypes, intensity of large-scale circulation sand global temperature to explain that of the 850hPa temperature in Israel for the summer and the winter.The synoptic factor was represented by 19 types defined by Alpert et al. (2004b). For the summer the deep and the weak Persian Trough explained 35% of the interannual temperature variance. For the winter, the lows to the east and to the north explained 44% of the interannual temperature variance. Two additional factors were incorporated: large-scalecirculations, the North Atlantic Oscillation for the summer and the Arctic Oscillation for the winter; and global radiative forcing, represented by the global temperature. Both of them were found to be significant, and the variance explained by all of them is 56% for the summer and 64% for the winter. In the summer the variation is dominated by warm and cool types whereas in the winter the cold systems dominate The individual contribution of each factor to the long-term temperature trend was estimated. While the global radiative forcing contribution was positive and large in both seasons, the synoptic contribution was positive, four times larger in the summer. The large-scale contribution was negative, three times larger in the winter. The considerable warmingin the summer results from a rapidincrease in the occurrence of the weak Persian Trough, which is a warm type. The study approach may be useful for predicting future temperature regimes, based on predicted synoptic features in climatic models. Copyright © 2010 Royal Meteorological Society. Source

Ganor E.,Tel Aviv University | Stupp A.,Tel Aviv University | Osetinsky I.,Israel Meteorological Service | Alpert P.,Tel Aviv University
Journal of Geophysical Research: Atmospheres | Year: 2010

The goal of this research is to identify meteorological characteristics distinguishing dust storm days from no-dust days. During this pioneering research, the vertical profiles of temperature, wind components, and humidity for days with dust and with no dust were compared and analyzed in order to identify features accompanying dusty conditions. Three data sets, all for the 49 year period of 1958-2006, were used. The first was the daily dust observations at Tel Aviv, Israel. The second was the eastern Mediterranean daily surface synoptic classification. The third was the vertical data over the eastern Mediterranean grid point closest to Tel Aviv at 32.5°N, 35°E. The two latter data sets were based on the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis. The meteorological parameters were averaged over the 49 year period by season, pressure level, synoptic-type, and dust and no-dust days. Prominent differences between dust and no-dust days were found for relative humidity and wind components during fall, winter, and spring at 700, 600, and 500 hPa levels. Relative humidity was found to be higher during dust episodes. This result, linking dust and humidity, looks promising for future research on connection between desert dust, ice nuclei, and precipitation. The governing eastern Mediterranean synoptic systems are low-pressure systems. For these systems, vertical velocity (Omega) values are negative. It was found that absolute Omega values were higher on dust days than on days with no dust. Southerly and westerly components of wind were found to have higher values during dust days. It was found that for most synoptic systems, temperature below the 700 hPa level was equal or higher during dust days. Thus, during dust days the lower troposphere is unstable. Copyright 2010 by the American Geophysical Union. Source

Ganor E.,Tel Aviv University | Osetinsky I.,Israel Meteorological Service | Stupp A.,Tel Aviv University | Alpert P.,Tel Aviv University
Journal of Geophysical Research: Atmospheres | Year: 2010

Dust observations in Israel were carried out since 1958. During 1958-2006, 966 dust days were observed. The dust days have been analyzed through their association with the regional eastern Mediterranean synoptic types, as classified by the Tel Aviv University method. Among the synoptic types, the most contributing were winter lows (with 368 days), Red Sea Troughs (214 days), and highs (211 dust days). Association of dust with highs is a new result, not found in the literature to date. Out of the total occurrences of Sharav lows, 36% are associated with dust, out of total winter lows 13%, with a winter low south to Cyprus having a 30% probability to produce a dust day, and of Red Sea Trough days 6% were associated with dust. Annual occurrence of dust days follows the changes in the occurrence of the regional synoptic systems: the number of dust days associated with Red Sea Troughs has increased by 2.3 d/10 yr, and with highs by 0.9 d/10 yr. The total incidence of dust days has increased with an average rate of 2.7 days per decade. This increasing trend in dust storm occurrence fits with previous results for the eastern Mediterranean and south Europe. Since dust storms are a regional phenomenon and reach south, central, and western Europe, this increase has implications for the entire Mediterranean and European regions. The results show potential for statistical forecasting of dust 1 day in advance. Such forecasts are important for public health warnings and for air transportation. Copyright 2010 by the American Geophysical Union. Source

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