تحليل تغييرات ماهانه ارتفاع لايه تروپوپاز بر روي ايران

Analysis of Monthly Changes in Tropopause Height Layer on Iran

تروپوپاز لايه انتقالي از وردسپهر به پوش سپهر است. اين لايه تعيين‌كننده حد بالايي و ضخامت وردسپهر است. در پژوهش حاضر از داده‌هاي ژرفاسنج مادون قرمز اتمسفري (AIRS) سنجنده موديس آكوا ماهواره (EOS) استفاده شد. اين محصول به شكل پارامترهاي ژيوفيزيكي است و در شبكه‌اي به ابعاد 1×1 درجه قوسي توزيع شده است. اين داده‌ها از 180- تا 180 طول جغرافيايي و 90 تا 90 عرض جغرافيايي موجودند كه از سامانه تطبيقي پردازش موديس (MODAPS) دريافت شدند. پس از بارگيري تصاوير مربوط به سال‌هاي 2003 تا 2015 ميلادي، داده‌ها وارد نرم‌افزار MATLAB شد و مقادير ارتفاعي تروپوپاز براي ماتريسي به ابعاد 12×155 براي هر سال محاسبه شد (155 معرف مقادير شبكه‌هاي محاط در مرز ايران و دوازده ماه‌هاي سال‌اند). نتايج حاصل از پردازش‌هاي تصوير وارد محيط نرم‌افزار ArcGis10.2 شد و نقشه‌هاي هر ماه با استفاده از روش كريجينگ به واسطه كمترين مقدار خطا تهيه گرديد. نتايج نشان داد در ماه فوريه بيشترين اختلاف ارتفاع بين جنوب و شمال كشور رخ مي‌دهد. تقريباً در همه پهنه كشور منحني هم‌ارتفاع موازي و مداري‌اند. در ماه‌هاي گرم سال ارتفاع تروپوپاز در جنوب شرق كاهش مي‌يابد و بالاترين ارتفاع تروپوپاز در مركز كشور رخ مي‌دهد.

Introduction Tropopause is the transitional layer of the troposphere to stratosphere. This layer determines the upper limit of the troposphere and somehow expresses the spatial and temporal variations in the thickness of the layers and the layer indicated his thermodynamic variability. The layer that Short and long-term atmospheric phenomena occur in it. On other words, this layer determines the thickness and upper limit of the troposphere layer. Iran in terms of Geographical location is on the north side of the Hadley cells in the general circulation. That’s why when handling the extremely cells have modified the climate of this country. Thatʹs why the country is in the range of atmospheric systems important effects such as (Arabian subtropical high pressure, Siberian high pressure, Azores high pressure, Mediterranean cyclones and Sudan low).also, this country is located in neighborhood of vast deserts of the Arabian Peninsula and Siberia. Existence of two great ranges of Alborz and Zagros Mountain in north and west of Iran and the Dasht-e Kavir and Dasht-e Lut in Central and South East is also remarkably influence at the entry and transit systems and mechanisms of precipitation systems. The all of these factors, caused that troposphere of Iran .was strongly and the tropopause variability and its effects to be observed on tropopause. As regards, the tropopause height chowders is reaction of annual and seasonal variability that happened in troposphere. If these changes can be estimated that the annual seasonal trends or changes in the troposphere layer has been and can be changed and the results of its possible to estimate and predict. For this purpose maps of the height of the tropopause layer altitude on the slope of Iran in the period 2015-2003 is examined in each of the months of the year. Materials and method In this study, data from the Atmospheric Infrared depth (ATMOSPHERIC INFRARED SOUNDER) Moderate-resolution imaging spectroradio meter(MODIS), Aqua, Earth Observing System (EOS) the product(AIRS+AMSU) V006 (AIRX3STD) at GES DISC used. This product series of MODIS data in the form of geophysical parameters in the network have been distributed, 1 × 1 ° arc. The data from -180 to 180 longitude and latitude -90 and 90 are available from bases http://modaps.nascom.nasa.gov are available. After loading the images from 2003 to 2015, data compiled MATLAB software, and using the World Meteorological Organization Tropopause height values for the matrix of size 12 × 155 was calculated for each year (155 networks were introduced and 12 months of the year are inscribed on the Iranian border). The results of image processing software environment was ArcGis10.2 and maps of each month using the least amount of errors were prepared by Kryjng. The next step is to draw longitudinal profile of the height of the tropopause in 3D Analyst software plugin named slice of the North West (to a maximum height of the tropopause) to the South East of the country (as a minimum altitude of the tropopause) drawn and corresponding graphs for each of the months of the year were drawn. Results and discussion The results of this research show that in spring equinox the highest altitude of tropopause layer on Iran belongs to the southeast of it. In this mouth the altitude of tropopause layer in southeast of Iran is 16475 meters and lowest elevation with 11008meters belongs to northwest of Iran. So that, the highest altitudinal gradient between southeast and north of Iran was happened and this gradient was reach to 5600meters, which is as thick as the middle troposphere. From May onward the area of southern elevation layer is wider and this condition continue until the end of October. On the other word, in a large part of the southern half of country, tropopause height variabilities is very little and minor.in contrast, in the months of December, January, February, march, April and may(cold months)this condition is observed in northwest of Iran. Whit the spread of cold waves from northern latitudes due to southward expansion of the polar vortex, northern part of Iran in terms of temperature was more homogeneous and tropopause height veracities from south to north latitudes is function of latitude, from this reason , the ishight have eastern and western extension. However, almost in all months isohight has northeast – southwest tendency .due to north- south extension of Zagros Mountains, tropopause isohights in westward slops of Zagros Mountains tilt toward southwestern. The highest tropopause isohight gradient in south of Iran was happened in January, February and April. While, The highest tropopause isohight gradient in the centurial of Iran in March, May and November and in northern part of Iran was happened in June, July, August, September and October. Basically, tropopause height changes in the south of Iran is very low and in any of the months is not higher than 520 meters. The highest variation in tropopause height in southern part of Iran was happened in February and lowest in July. While, monthly in tropopause elevation in northern part of Iran was very extreme. So that, in some months this change has come over 3000 meters. The highest change was happened in June (3490 m) and the lowest occurred in August. In north belt of Iran, tropopause height from March gradually increases and continued for 5 months, and in July reaches the highest elevations. The highest tropopause height difference between south and north of Iran takes place in February. In this month tropopause height difference was more than 6000 meters. Northward expansion of warm air from vast pester in centurial of country during the warm months and accumulation in southern slops of Alborz Mountains caused that isoheight layer in this part of Iran between north east and northwest is cutoff. Conclusion The height of the tropopause layer of Iran has seasonal fluctuations, yet the intensity of the incoming topography and activity of the system. But the impact of the tropopause height changes more pronounced in the input system from the effects of topography. Although in July reaches its peak height of the tropopause. But fluctuations in tropopause height between the south and north of the country is minimal. In the other months of the year maximum height of the tropopause in the south and north of the country is minimal. While the height of the tropopause in the month of August in the center of the country. In the other months of the year maximum height of the tropopause in the South East are the lowest in the North West. During the cold period in the northern slope of the layer to its minimum. And vice versa during the warm southern slope of the tropopause layer is minimized. This phenomenon has spread south polar vortex in the Siberian high pressure and cold period of year as well as the expansion of the subtropical high pressure north of Saudi Arabia during periods of warm harmonious. The study also showed that during the months of monsoon activity in the South East of it is reduced but not very much of the tropopause layer.