Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...

Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model [presentation]

Black carbon in soot is an efficient absorbing agent of solar irradiation that is preferentially emitted in the tropics and can form atmospheric brown clouds in mixture with other aerosols. These factors combine to make black carbon emissions the second most important contribution to anthropogenic climate warming, after carbon dioxide emissions.

Global and regional climate changes due to black carbon

There is a direct influence of global warming on precipitation. Increased heating leads to greater evaporation and thus surface drying, thereby increasing the intensity and duration of drought. However, the water holding capacity of air increases by about 7% per 1°C warming, which leads to increased water vapor in the atmosphere. Hence, storms, whether individual thunderstorms, extratropical rain or snow storms, or tropical cyclones, supplied with increased moisture, produce more intense precipitation events. Such events are observed to be widely occurring, even where total precipitation is decreasing: 'it never rains but it pours!' This increases the risk of flooding. The atmo- spheric and surface energy budget plays a critical role in the hydrological cycle, and also in the slower rate of change that occurs in total precipitation than total column water vapor. With modest changes in winds, patterns of precipitation do not change much, but result in dry areas becoming drier (generally throughout the subtropics) and wet areas becoming wetter, especially in the mid- to high latitudes: the 'rich get richer and the poor get poorer'. This pattern is simulated by climate mod- els and is projected to continue into the future. Because, with warming, more precipitation occurs as rain instead of snow and snow melts earlier, there is increased runoff and risk of flooding in early spring, but increased risk of drought in summer, especially over continental areas. However, with more precipitation per unit of upward motion in the atmosphere, i.e. 'more bang for the buck', atmo- spheric circulation weakens, causing monsoons to falter. In the tropics and subtropics, precipitation patterns are dominated by shifts as sea surface temperatures change, with El Nino a good example. The volcanic eruption of Mount Pinatubo in 1991 led to an unprecedented drop in land precipitation and runoff, and to widespread drought, as precipitation shifted from land to oceans and evaporation faltered, providing lessons for possible geoengineering. Most models simulate precipitation that occurs prematurely and too often, and with insufficient intensity, resulting in recycling that is too large and a lifetime of moisture in the atmosphere that is too short, which affects runoff and soil moisture.

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Changes in precipitation with climate change

Climate change projections for the Mediterranean region

Anthropogenic aerosols are intricately linked to the climate system and to the hydrologic cycle. The net effect of aerosols is to cool the climate system by reflecting sunlight. Depending on their composition, aerosols can also absorb sunlight in the atmosphere, further cooling the surface but warming the atmosphere in the process. These effects of aerosols on the temperature profile, along with the role of aerosols as cloud condensation nuclei, impact the hydrologic cycle, through changes in cloud cover, cloud properties and precipitation. Unravelling these feedbacks is particularly difficult because aerosols take a multitude of shapes and forms, ranging from desert dust to urban pollution, and because aerosol concentrations vary strongly over time and space. To accurately study aerosol distribution and composition therefore requires continuous observations from satellites, networks of ground-based instruments and dedicated field experiments. Increases in aerosol concentration and changes in their composition, driven by industrialization and an expanding population, may adversely affect the Earth's climate and water supply.

A satellite view of aerosols in the climate system

The annual link between the solar insolation, the surface temperature, and the dust load in the atmosphere as estimated by the TOMS Aerosol Index was compared in five major sandy deserts around the globe A high correlation was found between the insolation and the dust in all deserts, while the correlation of dust with temperature was lower The peaks of the insolation and the dust occurred almost simultaneously on the same date in three out of the five deserts ie Sahara, SW North American, Atacama In the other two deserts ie, Australian, Taklimakan, the peak of the dust occurs earlier in the year The temperature peaks occur on a later date in all the deserts Our conclusion is, that in the deserts of the world the radiation is the major cause of the total dust loading Alpert et al 2006 (1) found that the total amount of dust in the atmosphere is highly correlated with the solar insolation over the Saharan desert Moreover, the annual maximum is reached almost on the same day, while the maximum temperature occurs a month later This high match exists in the very great expanse of the Sahara, while in smaller areas (like the three distinct parts of the Sahara that were examined), other variables, like the local topography, the synoptic situation, etc, appear to weaken the link between dust and insolation, thus lowering the correlation The theoretical foundation for this high correlation was discussed in detail in that paper and are summarized in chapter 2 of this paper In this manuscript, we compare the annual link between dust, solar insolation, and the surface temperature in the Sahara and four other major sandy deserts in the world The four other deserts examined are: the sandy part of the Australian desert, the Arizona and Sonora deserts in the Southwestern US and Mexico, the Taklimakan Desert in China, and the Atacama Desert in Chile We show that in all these deserts the role of solar insolation concerning dust loading is very important, even dominant This, in spite of the smaller areas of these deserts when compared with the Sahara, as well as their less favorable environment, such as more rugged topography, and stronger and more erratic synoptic systems One potential application of the present findings may be the direct incorporation of the solar insolation in dust prediction models The strong correlation of radiation and dust load dates in the major deserts around the world can further improve these models Better models for short and long term forecasting of dust events can aid in dealing with

/pdf/the-linkage-between-solar-insolation-and-dust-in-the-major-2awmee9pg7.pdf

The Linkage Between Solar Insolation and Dust in the Major World Deserts

The 7-13 September extreme dust downfall over the East Mediterranean A two ceilometers study

A model was developed for pollutant dispersion from a point source simulating the Hadera (Israel) power plant stack. The model is based on the NCAR mesoscale meteorological MM4 model that provides the wind fields and coefficients of turbulent diffusion. The model was implemented using an implicit numerical scheme with changing directions. A comparison between the model calculations and an analytical solution for the advection-diffusion equation shows good agreement. Relatively low numerical diffusion of the adopted advection scheme was noted. Results for the hilly region of central Israel are presented for a summer case.

The Use of a Meso-Gamma Scale Model for Evaluation of Pollution Concentration over an Industrial Region in Israel (Hadera)

Sea-salt aerosol (SSA) is the dominant contributor to cloud condensation nuclei over ocean areas, where wind speed is significant. Thereby, SSA could affect cloud formation and play an important role in the Earth weather and climate. Rainfall could produce large impact on SSA concentration due to wet removal processes. An analysis of changes in sea-salt aerosol concentration after rainfall is essential for a deeper understanding of the process of SSA loading in the boundary layer. The current experimental study focused on analyzing time variations of SSA mass concentration after rainfall, on the basis of long-term daily SSA measurements during the three-year period 2006–2008, at the tiny Mediterranean island of Lampedusa (Central Mediterranean). To study the effect of rainfall on SSA time variations, we used the superposed epoch method. We applied this approach to differing rainfall events related to different months and atmospheric/sea conditions. Integrated processing was applied to SSA concentration anomalies, in order to filter out random variability. Observational evidence of SSA mass concentration oscillations after rainfall with a maximum on the 2nd day and a minimum on the 4th day was obtained. The knowledge of SSA variations after rainfall is important for validating rainout parameterization in existing sea-salt aerosol and climate models.

https://www.tau.ac.il/~pinhas/papers/2012/Kishcha_et_al_IRSN_Meteorology_2012.pdf

Pinhas Alpert

Papers

The Linkage Between Solar Insolation and Dust in the Major World Deserts

The 7-13 September extreme dust downfall over the East Mediterranean A two ceilometers study

The Use of a Meso-Gamma Scale Model for Evaluation of Pollution Concentration over an Industrial Region in Israel (Hadera)

Sea-Salt Aerosol Mass Concentration Oscillations after Rainfall, Derived from Long-Term Measurements in Lampedusa (Central Mediterranean)

Characteristics of the summer 3-D katabatic flow in a semi-arid zone—The case of the Dead Sea