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A Unique Case-Study of Near-Circular Saharan Dust Transport over the Atlantic Ocean

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Atmospheric and Climate Sciences 2014年第2期4卷 164-170页

作者： Joseph Barkan pinhas alpert Department of Geophysics Planetary and Atmospheric Sciences Tel-Aviv University Israel

An occurrence of transportation of Saharan dust from equatorial West African and back to Europe and Africa around theAtlantic Oceanwas synoptically analyzed. The entire circle around the Atlantic took twelve days. The direction and speed of the dust cloud was governed by the position, the strength and the movement of the Center of Activity (COA) of the Azores High. This type of trajectory is quite rare. In the year 2009 (the year of the analyzed trajectory) it occurred only 8 times. We assume, that the interesting point in this type of trajectory is the possibility that in its long way, it collects from and deposits in, different types of aerosols at the American European and African continents and the Ocean between them.

关键词： Dust Azores High Transportation

Dust as a Potential Tracer for the Flow over Topography

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International Journal of Geosciences 2015年第1期6卷 42-50页

作者： pinhas alpert Joseph Barkan Department of Geosciences Tel-Aviv University Tel-Aviv Israel

The distribution of mineral dust around topographical obstacles is examined, employing the dimensionless Froude number that describes different flow regimes in a fluid. Flow around a peak with a near-circular shape in a dusty environment like the Sahara and the Sahel was examined in order to investigate the distribution of the dust around the obstacle. The Total Ozone Mapping Spectrometer Aerosol Index (TOMS-AI) daily Aerosol Index, the u and v wind components and the temperature, were used for the period 1979-1992,?i.e. 14 years. It is found by the AI data that the shape of the dust distribution around the circular peak is in good agreement with the shape of the peak itself. Additionally good correlation exists between the vertical distribution of the dust above the peak and the Froude Number in its vicinity. This method allows for the first time the investigation of the flow above and around topographical obstacles in different flow conditions in the open space employing dust as the flow tracer.

关键词： Dust Sahara Froude Number TOMS Topographic Flow

AOD Trends over Megacities Based on Space Monitoring Using MODIS and MISR

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American Journal of Climate Change 2012年第3期1卷 117-131页

作者： pinhas alpert Olga Shvainshtein Pavel Kishcha Department of Geophysical Atmospheric and Planetary Sciences Tel Aviv University Tel-Aviv Israel

Space monitoring of aerosol optical depth (AOD) trends over megacities can serve as a potential space indicator of global anthropogenic air-pollution changes. Three space aerosol sensors, MODIS-Terra, MODIS-Aqua and MISR, were used in order to study recent decadal trends of AOD over megacities around the world. Space monitoring of AOD trends has the advantage of global coverage and applies the same approach to detecting AOD trends over different sites. In spite of instrumental and time differences among the three sensors investigated, their global pictures of AOD trends over the 189 largest cities in the world are quite similar. The increasing AOD trends over the largest cities in the Indian subcontinent, the Middle East, and North China can be clearly seen. By contrast, megacities in Europe, the north-east of US, and South-East Asia show mainly declining AOD trends. In the cases where all three sensors show similar signs of AOD trends, the results can be considered as reliable. This is supported by the observed trends in surface solar radiation, obtained by using network pyranometer measurements in North and South China, India, and Europe. In the cases where the three sensors show differing signs of AOD trends (e.g. South America), additional research is required in order to verify the obtained AOD trends.

关键词： Megacities Aerosols Aerosol Optical Depth Space Monitoring

Semi Operational Prediction of the Dead Sea Evaporation—A Synoptic Systems Approach

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Journal of Water Resource and Protection 2015年第13期7卷 1058-1074页

作者： Eyal Ilotoviz Haim Shafir Philipp Gasch pinhas alpert Department of Atmospheric Sciences The Hebrew University of Jerusalem Jerusalem Israel Department of Geosciences Tel Aviv University Tel Aviv Israel Institute of Meteorology and Climate Research Karlsruhe Institute of Technology Karlsruhe Germany

The predictability of pan evaporation and air temperature in the southern part of the Dead-Sea region (Sdom) was investigated according to two approaches, prediction by mesoscale models and with the aid of synoptic classification. First, the predicted temperature, wind speed and relative humidity that directly affect the evaporation are obtained from the WRF mesoscale model predictions. Predictions according to multilinear regression equations and a Penman-Monteith approach were also validated against observations in Sdom. The WRF model predicts the temperature reasonably well. However, the wind speed and relative humidity predictions were found to be very poor. The unique approach in this paper is employing a semi-objective synoptic systems classification according to the global GFS model. Relationships were defined between the 19 Eastern Mediterranean’s (EM) synoptic systems and the Sdom evaporation, temperature, wind speed and relative humidity. A monthly evaluation was performed for each of the systems and the semi-objective prediction was verified by the semi-objective classification. Since some synoptic systems affect the evaporation and temperature similarly, the 19 synoptic systems were grouped into seven clusters, each containing systems with similar evaporation and temperature records. This method has yielded a significant improvement in the daily prediction of evaporation and temperature. Semi-objective definitions for the synoptic systems were performed for the ranges of 12 - 132 hours. The synoptic system approach succeeded in the prediction of the evaporation and temperature changes in Sdom for a few days in advance. The predictability skill for the 12 hour forecast achieved about 80% of success, dropping to 70% at 36 hours. For 60 to 132 hours the prediction stabilized at a skill of 60%.The method presented here is a new attempt to predict meteorological parameters by using a synoptic classification approach in the Dead-Sea area where even high-resolution mesoscale modeling forecasts are not very s

关键词： Synoptic Classification Dead-Sea Evaporation Eastern Mediterranean

Recent Trends and Future Predictions until 2060 of Urban Warming in Four Israeli Cities Employing the RegCM Climate Model

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American Journal of Climate Change 2016年第4期5卷 464-484页

作者： Hofit Itzhak-Ben-Shalom Rana Samuels Oded Potchter pinhas alpert The Porter School of Environmental Studies Tel-Aviv University Tel-Aviv Israel Department of Geosciences Tel-Aviv University Tel-Aviv Israel Department of Geography and the Human Environment Tel-Aviv University and Department of Geography Beit-Berl Academic College Tel-Aviv Israel

During periods of global warming (GW), expected increases in urban temperatures can have adverse impacts on city climate and thermal discomfort due to combined urban and global warming effects. The different climates in four cities in Israel are studied for the purpose of differentiating global vs. urban warming. Trends in urban and nearby rural areas were compared in order to estimate the urbanization effect on the local climate zones. Daily 06:00 and 15:00 Local Time (LT) temperatures for July 1980-2014 were investigated. The linear relationship between the urban warming and population growth observed in present climate data is assumed to continue into the near future. The Regional Climate Model (RegCM) temperature trends into the 21st century are assumed to represent primarily the GW because of the relatively coarse grid interval of 25 km. Hence, this study first differentiates between global and local warming past trends, and then uses this past result to make future projections that consider both factors. A unique feature of this study is the large climatic variety over Israel—a small country that encompasses no less than 5 different K?ppen climatic zones. The urban minus rural temperature (1980-2014) changes, ΔTu-r, show more intense warming in the afternoon in all 4 cities. For instance, in Jerusalem and Eilat, the ΔTu-r has increased by ~1.2°C. Following the RegCM predictions, by 2060 with “No population growth”, this temperature increase is expected to continue, by 1.114°C and 1.119°C, respectively. If, however, these cities grow rapidly, air temperature will increase by 2.937°C - 4.129°C and 2.778°C - 3.939°C, respectively.

关键词： Urban Warming Climatic Change Future Prediction Global Warming Israeli Cities