Seasonal Statistical Study by Using Limited Area Model in Simulation of the Blocking Phenomena in Atmosphere

The present thesis investigates the simulation of blocking systems by limited area model, Regional Climatic Model, (RegCM3). 6-hour datasets of geopotential height, synoptic charts and NCEP/NECAR reanalyzed at surface and 500 hpa levels through the period (1994 –2005) had been used in the present work. In addition to that the input data required for limited area model (RegCM3) has been used through that period. In winter season, the absolute error varies from 0.4 to 2.2% between the actual and estimated pressure in the first and second low, while varies from 0.5 to 12.4 in first high and second high. While in spring season the absolute error varies from (0.8 to 4.7) % between the actual and estimated pressure in the first and second low, while slightly varies between the first and second high. This due to the not differences in the pressure for actual and estimated values in first and second high is greater than in the first and second low. But in summer season the absolute error varies from (0.2 to 1.6) % between the actual and estimated pressure in the first and second low, while varies from (0.2 to 2.8) % between the first and second high, and in autumn season the absolute error varies from (0.7 to 2.9) % between the actual and estimated pressure in the first and second low, while slightly varies between the first and second high. From the above results and compared between the actual and estimated charts by using RgCM3 horizontal resolution 100km, we can order the different seasonal according to the accuracy: spring, winter, autumn and summer seasons. This means that, the simulation of blocking systems using of limited area model (RegCM3) will clarify the role played by blocking systems in abnormal weather and eliminate the hazards of the sever abnormal weather phenomena which related to blocking systems.