واکاوی پراکنش زمانی-مکانی آلاینده co در دوران همه‌گیری covid-19 (مطالعه موردی: استان خوزستان، اصفهان، تهران)

برای جلوگیری از گسترش همه‎گیری بیماری covid19، محدودیت‎هایی همانند «قرنطینه» در سطح جهان اعمال شده است که این امر منجر به تغییرات قابل‌توجهی در محیط‎زیست، به‎خصوص هوا گردیده است. هدف از این پژوهش، واکاوی توزیع زمانی مکانی آلاینده (co) و تاثیر محدودیت‎های ناشی از کرونا بر آن است. بدین منظور داده‎های co از ماهواره merra2 با گام‌های زمانی ماهانه و مکانی 625/0x 5/0 درجه با پوشش زمانی 20202015 استخراج شد و سپس توزیع داده‎ها به کمک نرم‎افزار arcgis تحلیل شد. در این تحقیق به‎منظور سنجش تاثیر اعمال محدودیت‎های کرونایی روی سطح آلاینده co داده‎های مربوط به دوره اعمال محدودیت‎های کرونایی (ژوئیه 2020) با ماه‎های مشابه مربوطه در دوره پایه (ژوئیه 2019-2015) مقایسه شد، سپس تاثیر کنترلی سامانه‎های همدید و عوامل جوی بر توزیع و پراکندگی این آلاینده در استان‎هایی که بیشینه این آلاینده را در ایران داشتند، بررسی شد. نتایج نشان داد میانگین ماهانه این آلاینده نه‌تنها در استان‎هایی که آنومالی بیشینه co را داشتند کاهش داشت، بلکه بر فراز کل جوّ ایران نیز این کاهش دیده شد. نتایج حاصل از عوامل همدیدی ارتفاع ژئو پتانسیل و حرکت قائم هوا در تراز 500 هکتوپاسکال نشان داد که در هر دو دوره شرایط همدید بر فراز اتمسفر استان‎های تهران، اصفهان و خوزستان یکسان بود، لذا عوامل همدید مورد بررسی در این کاهش نقش نداشته است. با بررسی تعطیلی کارخانه و وضعیت متوسط تردد وسایل نقلیه در برخی از راه‎های پرتردد این استان‎ها کاهش در حمل‌ونقل نیز دیده شد، لذا کاهش سطح co در دوره اعمال محدودیت‎های کرونایی را می‎توان پیامد مثبت covid19 بر کیفیت هوا دانست.

Analyzing Temporal-Spatial Distribution of CO Pollutants during COVID-19 Epidemic (Case Study: Khuzestan Province, Isfahan, Tehran)

To prevent the spread of COVID19 epidemics, restrictions such as &quarantine& have been imposed worldwide led to significant changes in the environment, especially the air. The purpose of this study is to investigate the temporalspatial distribution of pollutants (CO) and the effect of corona constraints on it. For this purpose, CO data was extracted from MERRA2 satellite with monthly and spatial time steps of 0.5 x 0.625 with time coverage of 201520. Then, the data distribution was analyzed by ArcGIS software. In this study, in order to measure the effect of applying corona restrictions on the level of CO pollutants, the data related to the period of applying corona restrictions (July 2020) were compared with the corresponding months in the base period (July 20152019), then the control effect of synoptic systems and atmospheric factors for the distribution and dispersion of this pollutant were studied in the provinces that had maximum of this pollutant in Iran. The results showed that the monthly average of this pollutant decreased not only in the provinces that had the maximum CO anomaly, but also over the whole atmosphere of Iran. The results of synoptic factors of geopotential height and vertical air movement at the level of 500 hPa showed that in both periods, synoptic conditions were the same above the atmosphere of Tehran, Isfahan and Khuzestan provinces, so the studied synoptic factors have no role in this decrease. Examining the factory closure and the average condition of vehicle traffic in some of the busiest roads of these provinces, a decrease in transportation was also observed. The decrease in CO during periods of economic restrictions can be seen as a positive message of COVID19 for air quality.Extended Abstract1IntroductionThe first case of acute respiratory syndrome was appeared in Wuhan, the capital of Hubei Province and China’s sixth most populous city (December, 2017), and later spread rapidly in China and other countries. Due to the spread of this disease in more than 110 countries, on February 1st, 2017, a public health emergency was declared internationally. It was on February 13th, 2017, the disease was named COVID19 or SARSCoV2. On March 23 of the same year, the World Health Organization changed the prevalence of the disease from epidemic to pandemic. In Iran, the first cases of COVID19 were officially confirmed on February 20th, 2017.  In Iran, cases of this disease were first observed in Qom and 15 days later, were reported from other 31 provinces of Iran. As the number of patients increased, preventive measures to control the COVID19 pandemic were taken by the Iranian government and the &Stay Home& campaign was launched.2Materials and MethodsIn this paper, longterm spacetime methods obtained from the MERRA2 model satellite were applied in order to measure the air quality of Iran. The model ModernEra Retrospective Analysis for Research and Applications (Version 2), known as the MERRA2 model, is one of the most reliable models for various researchers of climatology, the environment, etc. that helps make the best use of satellite observations. In this study, the average July data obtained from the average daily variable of carbon monoxide have been used for the entire geographical region of Iran (N90E180S90W180) with emphasis on Tehran, Isfahan and Khuzestan provinces. NAEP / NCAR data were also used to investigate the effect of synoptic conditions on the quantity and quality of pollutants.3 Results and DiscussionCovid19 epidemic not only affects health and the economy, but also has consequences on various aspects of life such as air quality. In order to evaluate these effects on air quality, the amount of CO above the Iranian atmosphere was monitored by satellite monitoring at the base period (July 2015 to 2019) showing a decrease in the period of corona constraints (July 2020). This decrease was also seen in the provinces with the highest anomalies of this pollutant. Considering that the annual production of carbon monoxide is about 260 million tons and 60% of it enters the atmosphere due to human activities, especially incomplete fossil fuels and 40% due to natural processes and more than 70% of carbon monoxide emissions are producing in the air during transport operations and the movement of vehicles. Therefore, it is obvious that the average concentration of this pollutant in the atmosphere will fluctuate by reducing human activities and transportation through applying corona restrictions. In urban areas, fluctuations in monoxide gas, in addition to being dependent on transportation and factory activities, are also affected by synoptic conditions. The study of the synoptic conditions of both periods indicates the dominance of the subtropical high pressure stack and the dynamic behavior of the resulting stack over the mentioned provinces in both periods. The study of omega and rainfall in both periods also showed the establishment of the same synoptic conditions. Therefore, this reduction is independent from the studied synoptic conditions and is related to the restrictions imposed by the Iranian government, which has led to a reduction in traffic and industrial activities, a reduction in the emission of pollutants from vehicles, and so on. 4 ConclusionA review of data on July CO emissions showed that the average monthly CO emissions in the Iranian atmosphere decreased during the application of the corona restrictions. This decrease in July 2020 that coincided with the corona wave and the intensification of corona restrictions was about ppbv5. Due to the role of industry and fixed resources, transportation and homebusiness activities in CO emissions, CO concentrations have decreased significantly in Khuzestan, Tehran and Isfahan provinces following the application of corona restrictions. In order to investigate the control effect of synoptic systems and atmospheric and transport factors on the distribution and dispersion of this pollutant in the provinces that had the highest pollutant, omega maps and geopotential height of 500 hPa were examined determining precipitation factor. The studied atmospheric factors had fixed conditions in both periods and were not involved in this decrease. Therefore, it is obvious that the restrictions imposed by the Iranian government have played a role in this reduction. Because of the imposed restrictions, the average daily traffic of vehicles including passenger cars, vans and small trucks and minibuses, ordinary and threeaxle trucks, buses, trailers and trucks; in some hightraffic axes, it decreased in all three provinces during July 2020 compared to 20152019. Therefore, the decrease in CO level along with the application of corona constraints can be considered as a result of the positive effect of COVID19 on air quality.