@article { author = {Meshkatee, Amir-Hussain and fotros, shima and Kamali, Gholamali and Sedaghatkerdar, Abdollah}, title = {The effect of NAO and MJO on Tehran metropolitan air pollution}, journal = {Journal of Meteorology and Atmospheric Science}, volume = {2}, number = {2}, pages = {93-113}, year = {2019}, publisher = {Iran Meteorology Society (IMS)}, issn = {2645-7261}, eissn = {2645-727X}, doi = {}, abstract = {The most important factors controlling the distribution of pollutants emitted from different sources and in different season are atmospheric circulations.This study dedicated to the investigation of the impact of two North Atlantic and Maden-Julian Oscillations (NAO and MJO) on Tehran air pollution during the period of 1984-2013. To show those oscillations relationship with the latter said event their correlations with the event were studied. As part of the correlation study the impact of time lag in the relation between those oscillations and the city air pollution was studied, too. Then meteorological fields and their anomalies that were considered effective on the formation of acute periods of air pollution, as well as the significant features and characteristics of atmospheric circulation at different levels were determined by using bootstrap and wavelet statistical methods. Afterwards, correlations between those identified anomalies and characteristics with different phases of the NAO and MJO oscillation was investigated. Accordingly, it was found that the accumulation of pollutants from local sources into the city atmosphere was mainly affected by the positive phase of NAO, which caused the warm and humid westerly air flows departed from the middle east and positive MJO phase especially the fourth phase and departure of convective cell to the eastern part of Indian ocean, during the cold and hot seasons. It was also found that the city atmosphere contamination with pollutants from regional sources mainly take place in both positive and negative phases of NAO. However it was more pronounced with shifts from positive to negative phase of NAO. The negative phases of MJO were also found effective in the formation of such circumstances especially the first phase and when the convective cell was at its closest distance from the deserts of the western and south western neighboring countries. Collectively, it may be stated that warm season contamination of Tehran’s atmosphere from local or regional sources is associated with weak MJO and negative phases of the oscillation (Phases 1, 2, 7 and 8), while contamination occurring during cold seasons is associated with MJO positive phases (phases 3, 4, 5 and 6).}, keywords = {"Air pollution","Bootstrap"," wavelet","NAO"," MJO"}, title_fa = {اثر NAO و MJO بر آلودگی هوای کلانشهر تهران}, abstract_fa = {اثر دور پیوندی دو نوسان اطلس شمالی (NAO) و مَدِن-جولیَن (MJO) بر آلودگی هوای کلان شهر تهران طی دوره آماری 2013-1984 بررسی شد جهت تبیین این ارتباط ابتدا با محاسبه ی بیشینه هم بستگی، تاخیر زمانی تاثیر این نوسانات بر آلودگی هوای تهران محاسبه شد. با استفاده از روش های آماری بوت استرپ و تبدیل موجک، بی هنجاریهای پارامترهای هواشناختی مؤثر بر شکل گیری دوره‌های حاد آلودگی هوا و همچنین خصایص و ویژگی های برجسته در الگوهای مذکور در سطوح مختلف جوّی مشخص گردید. سپس ارتباط مابین ناهنجاریهای موثر بر آلودگی هوا باشرایط مساعد جهت وقوع فازهای مختلف دو نوسانNAO وMJO بررسی شد.با توجه به یافته ها و الگوهای به دست آمده دریافتیم که تجمع آلاینده ها با منشا محلی در فصول سرد و گرم سال با فاز مثبت NAO و دور شدن جریانات گرم و مرطوب غربی از خاورمیانه و همچنین فاز مثبت MJO به خصوص فاز چهارم و عزیمت سلول همرفتی به سوی شرق اقیانوس هند، که شرایط را جهت نزول و تجمع آلاینده های محلی فراهم می نماید، همراه بوده است. از سوی دیگر فرونشست آلاینده ها با منشا فرامحلی غالبا با سهمی یکسان از فازهای مثبت و منفی NAO روی داده‌اند. البته در اکثر نمونه های مورد بررسی تغییر فاز از مثبت به منفی مساعدترین شرایط برای این فرونشینی را فراهم نموده است. همچنین فاز منفیMJO به خصوص فاز اول آن و قرارگرفتن سلول همرفتی در نزدیکترین فاصله نسبت به مناطق بیابانی کشورهای همسایه ی غربی و جنوبغربی ایران در وقوع این شرایط مؤثر بوده است.}, keywords_fa = {گردش جو,نوسان اطلس شمالی,نوسان مدن-جولین,بوت استرپ,تبدیل موجک}, url = {https://www.ims-jmas.net/article_126689.html}, eprint = {https://www.ims-jmas.net/article_126689_2dff250a56a21fb133ee509d27884241.pdf} }