بمكت المكرمت رجب 3410 ھ كليت التربيت للبناث جامعت الملك عبد العزيز جدة- المملكت العربيت السعوديت - يوليو 9002 م تاريخ المناقشت) 3410/7/34 ھ(

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1 بمكت المكرمت رجب 40 ھ كليت التربيت للبناث جامعت الملك عبد العزيز جدة- المملكت العربيت السعوديت - يوليو 900 م تاريخ المناقشت) 40/7/4 ھ(

2 Abstract

3 NCEP/ETA 6 4 Summary

4 NCEP/ETA Model TOMS

5 7 978 NCEP/ETA Model

6 NCEP/ETA Model TOMS

9 Indirect circulation

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11 Abstract The present study addressed the phenomenon of dust storms in Makkah al- Mukarramah Administrative Area. The phenomenon, because of its impacts on physical and human aspects, has drawn the attention of researchers in the Kingdom of Saudi Arabia in the last two decades. The data used in the study had been obtained from the Ministry of Water and Electricity, and from the General Presidency of Meteorology and Environment conservation, in Saudi Arabia during the period The study used several statistical methods which are common in climate and Meteorological studies. A number of results are reached in the present studies: Winter and Spring witness the most frequent dust storms dvring the year. In these seasons the area is subjected to the prevalence of the Sudan thermal low that accompanied with warm, humid, winds blowing from the south borne with dust storms along the eastern coast of the Red Sea, the western edge of the study area. The thermal low line is characterized by vertical movement that helps to raise up dust and sand to the upper atmosphere over the area. The compared results of the numerical model (NCEP/ETA) on dust storms with the obtained data from the Toms Sensor proved to be successful. In this connection, forecast of dust distribution in the atmosphere is made for two out of the total three cases. The researcher hopes that the current study provided a clear idea about the usefulness of several models and satellite images in forecasting dust storms expected in Saudi Arabia. The study concludes with an appeal to establish new monitoring stations for further control and monitoring of the phenomenon of the dust storms, as well as the establishment of monitoring stations to forecast the suspension of the dust and its concentration in the air. The study recommends to empower the early warning capabilities, in favor of population who are exposed to the dangers of storms, and even by establishing a center for prediction of the recurrence of the dust storm phenomenon. The study recommends also that the concerned authorities adopt and encourage researches in the fields of climate and meteorology aiming to identify the precise characteristics of the patterns and trends of dust and sandstorms; and to intensify training of manpower in those fields. Finally, the study recommends the improvement of the methods to protect roads, farms and other human activities in the areas exposed to dust storms.

12 Summary This research has dealt with studying the characteristics of dust and Sand storms in Makkah Al-Mukarramah region, There is no doubt that this phenomenon, in the last two decades, has received considerable attention because of its effects on both physical and human aspects. The data of the study was derived from the Ministry of Water and Electricity and from the General Presidency of Meteorology and Environmental protection in Saudi Arabia during the period Several statistical methods which are common in climate and meteorological studies were used. the study included five chapters: Chapter Ι : concerned with definition of the study problem, questions, importance, hypotheses and objectives of the study, also this chapter explained methods and approaches adopted during the study as well as characterizing the limits of the study area from geographical and astronomical perspectives, this chapter also reviewed previous relative studies and some definitions of terms used in the study. Chapter п : bincluded physical factors and their characteristics affecting the study area e.g. geology, topography, water resources, soil and natural vegetation cover. Chapter ш : addressed climatic elements and their characteristics, including solar radiation, temperature, wind, air pressure, and dust storms phenomenon linked to the wind direction and speed, as well as relative humidity, evaporation and rainfall. Chapter IV : reviewed the main climatic and local factors which help dust storms incidence, this chapter also has been studying dust storms distribution pattern frequency as monthly, seasonally, and yearlywise, as well as to compare some climatic stations that have recorded more frequent of dust storms with selected ones from other regions in the Kingdom in order to know their levels, and also the study interested to find relationship of wind storms with wind speed, to explain some severe cases of dust storms. the numerical model NCEP / ETA and satellite images were used in this chapter to clarify the most important negative effects of dust storms on human health and the impact on agriculture and lack of horizontal vision-causing traffic accidents as well as their impact

13 on maritime on the Red Sea and air navigation and also its impact of homes and public roads destruction. The conclusion came in Chapter V carrying the findings of the study as a number of results and recommendations as follows: The most frequently of dust storms are take place in Winter and Spring seasons as a consequent that the area is subject, at that time, to face the Sudan thermal low, which causes active, warm, humid, winds blowing from the south and accompanied with dust storms along the east coast of the Red Sea, which limits the study area from the west. This thermal low is characterized by vertical movement helps to raise up dust and sand in the area to the upper atmosphere. It was clear during testing the numerical model (NCEP/ETA) on dust storms compared with the obtained data from the Toms Sensor, a successful forecast of the dust distribution in the atmosphere two times was obtained out of the total of three cases. The researcher hopes that the current study may provides a clear idea to use numerical models and satellite images for forecasting dust storms expected in Saudi Arabia. The study concludes by calling to establish new monitoring stations for further control and monitoring of the phenomenon of the dust storms, as well as the establishment of monitoring stations to focus the pending soil concentration in the air. The study recommended to empower the early warning capabilities, in favor of population who are exposed to the dangers of storms, and even by establishing a center of prediction recurrence. It also recommended for the concerned authorities to adopt and encourage researches in the fields of climate and meteorology aiming to identify the precise characteristics of patterns and trends of dust and sandstorms; and to intensify training of human crews working in this fields. Finally, the study recommended to improve methods to protect roads, farms and other human activities in the areas exposed to dust the storms.

Dust Storm: An Extreme Climate Event in China

Dust Storm: An Extreme Climate Event in China ZHENG Guoguang China Meteorological Administration Beijing, China, 100081 zgg@cma.gov.cn CONTENTS 1. Climatology of dust storms in China 2. Long-term variation