The solar cycle is believed to have an important effect on the stratosphere with some degree of modulation by the quasi-biennial oscillation (QBO). To examine the likely effects of solar cycle and their modulation by QBO, in this study, the JRA-55 reanalysis data with a spatial resolution of 1.25 degrees in both the zonal and meridional directions were used for the period of 1958 to 2017 (60 years in total). Also, the solar flux at a wavelength of 10.7 cm, called , was extracted from the LISIRD website data for the study period. The monthly average temperature, geopotential height and potential vorticity (PV) at 30 hPa level as well as the solar flux were determined for the 60-year duration of the study.    The months of the study period were classified into easterly and westerly phases of QBO called EQBO and WQBO, respectively. A similar classificaltion was used for the set of years in which solar activity was greater (lower) than normal, called HS (LS) for high (low) solar. Using the FUB website data, the correlations of temperature, geopotential height and PV at 30 hPa with in the Northern Hemisphere summer (July), early winter (November and December) and late winter (January, February and March) were calculated for the whole set of data and the two subsets obtained for the two phases of QBO. Besides, the changes in temperature and geopotential height between HS and LS phases were investigated.     The main results of this research in terms of solar and QBO phases are as follows. For the temperature and geopotential height at 30 hPa level, the correlations with solar cycle in July are stronger in the subtropics, and larger and spatially wider for the set of EQBO than both the set of all years and the set of WQBO. The correlation ​​of PV with is generally small in July, exhibiting no clear pattern during QBO phases. In early and late winter, for the temperature, geopotential height and PV of 30 hPa, the correlations with are small for the set of all years and the set of WQBO, but attain a relatively large value for the set of EQBO with maximum values found in the tropical regions of both hemispheres. The corresponding correlation pattern for PV is distributed over many regions of both hemispheres with stronger values for the set of EQBO than the set of WQBO. Also, while the temperature and geopotential height difference between HS and LS for the set of WQBO reach their peak in the Southern Hemisphere, there is a spatially wider correlation pattern for the set of EQBO in the tropical regions of both hemispheres. Results also point to a possible impact of solar cycle on the Brewer–Dobson meridional circulation, a topic which needs a separate study.

Ozone trends in the Upper Troposphere and Lower Stratosphere over the Indian region are investigated using three satellite data sets namely Halogen Occultation Experiment (1993-2005), Stratospheric Aerosol and Gas Experiment (1993-2005) II, and Aura Microwave Limb Sounder (MLS, 2005-2011). Estimated ozone trends using multi-variate regression analysis are compared with trends at two Indian ozonesonde stations (Delhi, 28oN, 77oE and Pune, 18oN, 73oE), and a 3-D Chemical Transport Model (CTM, SLIMCAT) for the 1993-2005 time period. Overall, all the observational data sets and model simulations indicate significant increasing trend in the upper troposphere (0-2.5%/year). In the lower stratosphere, estimated trends are slightly positive up to 30 mb and are negative between 30 and 10 mb. Increasing trends in the upper troposphere is probably due to increasing trends in the tropospheric ozone precursor gases (e.g. CO, NO x, NMHCs). Here, we argue that these contrasting ozone-trend profiles might be partially responsible for insignificant long-term trends in the tropical total column ozone. On seasonal scale, positive trends are observed during all the seasons in the upper troposphere while structure of trend profile varies in lower stratosphere. Seasonal variations of ozone trends and its linkages with stratospheric intrusions and increasing trends in lightning flashes in the troposphere are also discussed.

Radiation input from the Sun is the source of energy for the Earth’s climate system (Hartmann, 1994). Most of the solar radiation absorbed at the surface, the rest is absorbed by the atmosphere. The global temperature profile of the atmosphere reflects a balance between the radiative, convective, and dynamical heating/cooling of the surface-atmosphere system. Understanding of the climate change in recent decades is important for the prediction of the future climate. Observed modifications in the vertical temperature structure of the atmosphere have been proposed as a primary indicator of climate change (Marshal, 2002). Radiosonde data are the primary source for monitoring changes in upper-air parameters. The second source is satellite-derived data from the microwave-sounding unit (MSU). Third source of ‘‘observed’’ upper-air data are the reanalysis projects as NCEP/NCAR and ECMWF. In this study, we attempt to estimate trends in the Irans surface and upper atmosphere temperature as an index of climate change on the basis of ECMWF data, which offer substantially higher vertical resolution than radiosounds and the microwave sounding unit (MSU), thus allowing a more accurate identification of the upper atmosphere and possible multiple upper atmosphere levels. In addition, the tempo-spatial resolution of applied data is higher than other data sources.The monthly surface and upper atmospheric air temperature data of Iran during 1/1979 to 4/2014 extracted from European Centre for Medium-Range Weather Forecasts (ECMWF). The spatial resolution 0.125 degree has been applied. Based on selected spatial resolution, 9965 pixels located on the Iran political boundry. The variation of spatial mean air temperature over Iran from surface to 10 hPa was analyzied. The radiosonds recorded air temperature from 11 upper stations over Iran compared to the ECMWF data to evaluate accuracy of applied data. Two non parametric tests of Mann-Kendal and Sen,s estimatotor used to decide about significancy of trend and slope of trend respectively.The results of this study show that using ECMWF data to evaluate varation of surface and upper atmospheric air temperature is useful. The tempo-spatial resolution of applied data is very high in horizontal and vertical. This implies that the ECMWF data do a reasonable job of capturing the variability of upper atmospheric temperature and are more adequate rather than Microwave Sounding Unit (MSU) and radiosounds data. The results also show that trend of surface and upper atmospheric air tempertre is significant at 95% confidence level. The observed trend near the earth surface and low and high troposphere is positive while is negative in the stratosphere. Althoght the trend of Iran’s middle troposphere layer temperature is not significant statistically at the 95% but fitting regression line on the standardized air temperature time series show that trend is positive. The slope rate of Iran’s surface temperature is 0.65oC per decades and is higher that other levels. The observed warming rate in the lower troposphere is higher than upper troposphere. The spatial distribution of the trend slope near the surface show that the highest warimimg observed between 34 to 37 latitudes. In the southern parts of Alborz and eastern parts of Zagros, the slope rate of surface temperature rate is 1.3 to 1.6 degrees C per decade.The obsereved increased tropospheric temperature and cooling of stratosphere is in good agreement with previous studies findings. The temperature change near the surface and lower troposphere is high in the semi northern parts of the country. The rate of upper troposphere temperature is not significant in the semi northern parts. The increase of upper troposphere temperature in the southern parts results in change tropopouse height. The depletion of ozone in the stratosphere (upper atmosphere) maybe contributing to the cooling of the stratosphere layer. The increased man made pollutants, green house gases and ozone in troposphere is also contributing to the warming of the troposphere. In temporal view from 1998, a positive anomay in temperature is observed near the surface and lower troposphere. The highest warming occurred in 2010 and 2001. According to other researchers finding warming of troposphere results in the displacement of Hadley cells and subtropical jet streams towards north and changes in tropical circulation patterns.

ABSTRACT This paper analyses the characteristics of the tropical tropopause, mid-latitude, and polar tropopause based on the sounding temperature data at Mehrabad and Shiraz airport stations in January and July in the statistical period of 2000-2022. The results showed that the observed frequency of the tropical tropopause in Iran in January (41 and 59 present in Mehrabad and Shiraz, respectively) is less than in July January (95 and 94 present in Mehrabad and Shiraz, respectively), and the frequency of the observed tropical tropopause in July is more than that of the mid-latitudes. The reason for this difference can be found in the increased thermal energy of the atmosphere in the warm seasons. In July, due to the development of thermal low pressure over Iran, the thermal energy, the air temperature, and the thickness of the atmosphere increased. As a result, the tropopause elevates and approaches the level of the tropical tropopause. It was also found that the tropical and mid-latitude tropopauses have a higher height in the warm month and are placed in lower pressure levels. For this reason, the temperature of these two tropopauses in the warm month is lower than the corresponding value in the cold month. Based on the results, the average height and temperature in tropical tropopause levels were estimated between 16.5 to 17.4 kilometers and -65 to -78 degree Celsius, respectively, in different regions of Iran. Also, these parameters for mid-latitude tropopause level were estimated from 11.5 to 12.8 kilometers and -52 to -59 degree Celsius, respectively Extended Abstract Introduction The tropopause is usually defined as the transition region separating the stably stratified and turbulent troposphere. These two atmospheric regions differ in numerous dynamic and chemical constituents. Depending on season and latitude, the tropopause is typically found at around 18 km in the tropics and around 8 km at high latitudes. Tropopause is defined based on up to three different definitions. The conventional tropopause is the thermal one which is usually characterized by an abrupt change in temperature lapse rate. Its definition is based on the fact that the stratosphere is much more stably stratified than the troposphere. The thermal tropopause is defined as the lowest level above 500hPa at which the lapse rate decreases to 2 K/km or less, provided that also the average lapse rate between this level and all higher levels within 2 km does not exceed 2 K/km. The dynamical tropopause is defined in terms of sharp changes in the potential vorticity, which measures the stratification and wind shears in air masses. The original concept of the dynamical tropopause is based on the isentropic gradient of potential vorticity. It is typically determined in a thin layer with absolute potential vorticity values within 1 and 4 potential vorticity units. The chemical tropopause is another type defined based on the vertical concentrations of trace gases such as ozone and water vapor. In this paper, the tropical, mid-latitudes, and the polar tropopause are defined based on latitude and geographical characteristics. The characteristics of the different tropopauses are analyzed regarding the temperature profiles from radiosonde data of the Mehrabad and Shiraz airport stations in January and July on the statistical period of 2000-2022.   Materials and methods The radiosonde data are obtained from the Integrated Global Radiosonde Archive of the NOAA National Climatic Data Center. The temperature data in January and July 2000-2022 are taken from the two radiosonde stations in the central and southern regions of Iran, including Mehrabad (51.31°E, 35.56°N) and the Shiraz airport stations (52.60°E, 29.53°N). The individual sounding profiles are exerted to determine the location and analyze the lowest tropopause and, if present, the second or the third tropopause based on the definition of the Commission for Aerology of World Meteorological Organization.  In former studies, the data of the 200-hPa pressure surface were often used to measure the mid-latitude tropopause and that of the 100-hPa for the tropical tropopause. However, sounding measurements confirm that a constant pressure surface is a flawed assumption for detecting tropopauses. In this study, the lower tropical tropopause, the mid-latitude tropopause, and the polar tropopause levels data are used (based on the mean pressure of thermal tropopause) in the 0-30°N, 30-60°N, 60-90°N regions to analysis their characteristics.     Results and discussion Comparing the frequency of tropopauses detected in Mehrabad and Shiraz airport stations shows that the frequency of days with two tropopauses detected over Mehrabad airport is lower than in Shiraz station in January. However, the number of days with three and four tropopauses at Mehrabad airport is more meanwhile the not detected tropopause, i.e. the break-down ones is more frequent in Mehrabad station. The days with one tropopause are more frequent in Mehrabad airport in January, but the number of days with two tropopauses is the same. The significantly elevated tropopause of the subtropical region in the warm season is the reason for the detected differences in which the radiosonde may not pass over the tropopause levels. Comparing the frequency of tropical and mid-latitude tropopause shows that at Mehrabad airport (Shiraz station) in January, the number of detected mid-latitude tropopauses is more (less) than that of tropical ones. This difference is related to the combined geographical-latitudinal characteristics of the two stations. The tropical tropopause in July is the most frequent in both stations. 5 up to 6 percent of them are due to subsidence inversion.   Investigations also showed that the average temperature of the tropical tropopause in Shiraz station is lower than Mehrabad airport in January. Mid-latitudinal tropopause temperature is almost the same in both stations, but the mean polar tropopause temperature in January over Mehrabad airport station is lower than in Shiraz station. The analysis of the January precipitation variability of these stations (in the 2000-2022 statistical period) shows that Shiraz is much greater than that of Mehrabad airport, so the average precipitation in this month in Mehrabad airport is 34 mm and in Shiraz station is 70 mm. It seems that in January, the release of latent heat caused by the condensation process in the upper parts of the troposphere and the frequency of the turbulent pressure systems over the Shiraz station was more than that of the Mehrabad airport, which caused the higher polar tropopause temperature in Shiraz station than the Mehrabad airport.   Conclusion This paper analyses the characteristics of the tropical tropopause, mid-latitude, and polar tropopause based on the sounding temperature data at Mehrabad and Shiraz airport stations in January and July in the statistical period of 2000-2022. The results showed that the observed frequency of the tropical tropopause in Iran in January is less than in July, and the frequency of the observed tropical tropopause in July is more than that of the mid-latitudes. The reason for this difference can be found in the increased thermal energy of the atmosphere in the warm seasons. In July, due to the development of thermal low pressure over Iran, the thermal energy, the air temperature, and the thickness of the atmosphere increased. As a result, the tropopause elevates and approaches the level of the tropical tropopause. It was also found that the tropical and mid-latitude tropopauses have a higher height in the warm month and are placed in lower pressure levels. For this reason, the temperature of these two tropopauses in the warm month is lower than the corresponding value in the cold month. Based on the results, the average height, pressure, temperature, and potential temperature in tropical tropopause levels were estimated between 16.5 to 17.4 kilometers, 92 to 96hPa, -65 to -78 degree Celsius, and 386 to 411 Kelvin, respectively, in different regions of Iran. Also, these parameters for mid-latitude tropopause level were estimated from 11.5 to 12.8 kilometers, 200 to 213hPa, -52 to -59 degree Celsius, and 335 to 386 Kelvin, respectively.   Funding There is no funding support.   Authors’ Contribution All of the authors approved thecontent of the manuscript and agreed on all aspects of the work.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments We are grateful to all the scientific consultants of this paper.

We detect the downward planetary wave reflection from the stratosphere back to the troposphere in the Northern hemisphere extended winter season (November-March), using ECMWF (ERA-Interim) reanalysis data (1979-2014). In the previous studies, the wave activity is defined as departure from a long-term time mean. However, we demonstrate some of the shortcomings of the above-mentioned definition. For instance, negative values of the heat flux at the lower stratosphere does not necessarily show the downward wave propagation, but a lower upward wave propagation. Perlwitz-Harnik index of reflection is used to categorize the stratospheric wind regimes into the two distinct states: reflective and non-reflective. Negative and positive values of this index indicate a reflective and non-reflective (either absorptive or propagative) stratospheric states, respectively. Our results show that the negative values of this index during early winter (November-December) suggests that the downward wave coupling is less likely to happen in early winter and most of the direct downward wave coupling occurs during mid-winter and early spring (January-March), which is in agreement with previous studies. Furthermore, 10 stratospheric winter states (out of 34) are reflective, while the remaining states (24 winters) are non-reflective winters. Winters whose their stratosphere experiences a major Sudden Stratospheric Warming (SSW) event is identified to detect the absorptive states of the stratosphere. Our analysis suggests that only in the %33 of the winters with reflective stratosphere a SSW can occur. In the %62 and %38 of the winters with nonreflective stratosphere, a SSW event can occur or Rossby waves can propagate upward freely to the upper stratosphere, respectively. Analysis of the heat flux at the lower stratosphere (50 hPa) using two different definitions (wave as a deviation from the time mean and as a deviation from the zonal mean) provides some useful information. If the waves are defined as a deviation from the zonal mean (V T ), during the reflective years, this quantity is negative (indicating a downward reflection of wave activity from the stratosphere to the troposphere). Similarly, during non-reflective years, this quantity has positive values (suggesting either upward wave propagation or absorption by the mean flow). While the above-mentioned definition is in harmony with our expectation, the definition of the wave as a deviation from the long-term time mean (V*T* ) results in an oscillation curve around zero line, without any useful information either about the upward wave propagation or a downward wave reflection. In order to understand the role of mean flow in influencing the upward wave propagation, we calculate the Rossby wave refractive index (or vertical wavenumber alternatively). Our analysis show some of the problematic features (for instance, a very noisy structure) of this index in understanding the differences of reflective and non-reflective stratospheric states. This is most probably due to the overlapping of very large or very small values of the refractive index which cancel each other and results in a noisy structure. To overcome this problem, we use a modified diagnostic tool (compared to the refractive index), probability of favorable propagation condition for Rossby waves. This index has some clear advantages over the traditional refractive index. Analysis of this index shows that during the non-reflective stratospheric states, Rossby waves are more likely to propagate upward (with higher values of the probability), in comparison to the reflective stratospheric regimes which is a superior demonstration of the influences of the basic mean flow on the upward wave propagation over the traditional refractive index.

The ozone layer as a protective shield life on biosphere has very oscillations from view point of quantity and volume. The ozone gases in both troposphere and stratosphere layers have been affecting on human life by two ways. The ozone in stratospheric that its name is surface ozone is an extremely poisonous gases and has destructive affect on lung and plant tissue. The surface ozone has been measured in measurement pollutant stations as one of seven pollutant gases. The ozone gas in stratospheric layer unlike the surface ozone is very necessary for human and other organism lives. The stratospheric ozone is measured in meteorological stations by name of total ozone (TO). Studies show that amount of ozone in stratospheric layer has been reduced. Variations in ozone layer were effected of changing in solar radiation, volcano eruption cosmic dust, meteoric stones and etc. that those get name as natural parameter of ozone changes. Effect of natural parameter concentration on stratospheric ozone lead to fix ozone content in long term (spanani 2004). The amount of ozone in stratospheric layer particularly in the lower stratospheric has considerable oscillations (increase/decrease) under the affection of atmospheric activities. For example V. C. Roldugin (2000) showed that passing the wave crest in the pressure field ceases the convergence of ozone poor air under the tropopause and divergence of ozone rich air above the tropopause and decreases the ozone content. The passing of a wave through simulate the opposite process and increase the ozone content T. Narayana Rao at all (2003) opining that the climatology of ozone clearly shows a significant seasonal cycle with the ozone maxima changing with height. The monthly variability of ozone as well as its seasonal maximum is found near the tropopause. Variation in tropopause height is due mainly to the passage of tropospheric weather systems and is responsible for the large monthly variability of ozone near the tropopause. In the lower stratosphere, inter annual variations are at a maximum in winter and spring, and are the result of variations in wave driven stratospheric circulation, which peaks in winter. Regarding this matter that total ozone have been affected from atmospheric parameter in lower stratosphere or upper troposphere, we decide to study the role of pattern circulation on ozone variations in Isfahan.

A sudden stratospheric warming (SSW) represent large scale perturbations of the polar winter stratosphere, which substantively influence the temperature and circulation of the middle atmosphere and also the contents of atmospheric species. SSW occurs mostly in middle and late winter and almost exclusively in the Northern Hemisphere. During an event, the polar stratospheric temperature increases by several tens of degree Celsius within a few days and eventually becomes warmer than that of the mid latitudes, reversing the climatological temperature gradient. At the same time, the prevailing westerly wind speed decreases rapidly and becomes easterly. The tropopause is a transition layer between the troposphere and the stratosphere. The occasional exchange of air, water vapor, trace gases, and energy between the troposphere and the stratosphere occurs in this layer. Based on some concepts,two different tropopause in the name of thermal tropopause and dynamical tropopause are defined. The conventional definition is the thermal tropopause which is detected based on the mark disruption of the vertical temperature lapse rate. The thermal tropopause definition is based on the fact that the stratosphere is more stably stratified than the troposphere. The thermal tropopause is defined as the lowest level at which the lapse rate decreases to 2 K/km or less, provided that also the average lapse rate between this level and all higher levels within 2 km does not exceed 2 K/km. The original concept of the dynamical tropopause was based on the isentropic gradient of potential vorticity. The dynamical tropopause is typically determined in a thin layer with absolute PV values within 1 pvu and 4 pvu. The vertical temperature stratification of the atmosphere plays a basic role in atmospheric motions. In this paper, the Brunt–Väisälä frequency (N2) value is used to detect the change of stratospheric static stability. In this work the NCEP/NCAR reanalysis daily data including temperature at different pressure levels (1000hPa-10hPa), the tropopuse temperature and pressure from 1th of January 1961 to 31th of December 2020 in northern hemisphere are used. The study region covers 0° to 357. 5° geographical longitudes and 0°N to 90°N geographical latitudes. The northern hemisphere is divide into three 30° none overlapping latitudinal band width called as the tropical bands (0°N-27. 5°N), the middle latitude bands (30°N-57. 5°N) and polar bands (60°N-90°N) regions. First of all the potential temperature and Brunt-Väisälä frequency (N2) at different pressure levels are calculated,then the average zonal mean temperatures at 10hPa, the tropopause temperatures, the tropopuse pressures and the values of N2 in three former introduced regions are obtained. To represent the tropopuse's height variations during the sudden stratospheric warming, the daily anomaly of these parameters in the regions are calculated and analyzed. The daily average mean zonal tropopause temperatures and pressure changes in the three meridian divided regions during eighteen major and one minor sudden stratospheric warming (SSW) events are analyzed in this study. The results show that all 19 SSW events in the statistical period of 1979-1920 are associated with positive anomaly of the zonal mean temperature and pressure of tropopuse along with increase of the tropopuse temperature and lowering its height which causes downward development of the stratosphere and thinning the depth of the troposphere. In addition, the tropopuse height reduction in the polar band region is greater than in the middle latitude band. It was also shown that, the static stability (positive anomaly) increment in the stratosphere started before the SSW and decreases during SSW (negative). These changes are greater in the polar cap band with respect to the middle latitudes band. This result reveals that the static stability structure in the lower stratosphere and upper troposphere in the polar cap are more affected by SSW with respect to other regions.

Introduction As a dominant oscillation in tropical stratosphere, the Quasi-Biennial Oscillation (QBO) is believed to have significant effect on the extratropical troposphere. This study examines the extratropical effects of QBO from an energy viewpoint.

This paper presents a methodology for conceptual design of long endurance stratospheric airships and establish a baseline of specifications for a conventional configuration stratosphere airship, according to given performance and operational requirements. The methodology is validated by other design concepts, which previously developed for similar missions. The shape optimization of airship was introduced into the design process, and several optimum objectives can be selected including minimum drag, minimum surface area and minimum weight. Also, a multi-objective function was used to take account of various factors which influence airship subsystems- e.g. aerodynamics, structures, energy and weight- to determine the optimal shape of airship. An algorithm for generating the shape is developed and appropriate mathematical models for subsystems are constructed. Simulation results show the optimized shape gives an improvement in the multi-objective function compared with a reference shape. The baseline specifications of stratosphere airships designed for various shapes by this methodology are presented.

Summary:The role of stratospheric circulations in large-scale and intense anomalies over a largepart of Asia including Iran in Winters of 2007–2008 and 2009–2010 was investigated using NCEP/NCAR reanalysis data available four times a day and in daily and monthly averages for 17 pressure levels as well as for isentropic and sigma levels. The spatial resolution of the data set was 2.5×2.5 in the longitudinal and latitudinal directions which provided adequate resolution to study large-scale dynamical processes.Anomalies in the wind and temperature fields induced by the interaction of verticallypropagating planetary waves with a stratospheric mean flow first appear in the winter stratosphere and subsequently with downward propagation, they affect the surface climate. The time series of each meteorological quantity contains a set of variability modes. Using Empirical Orthogonal Functions (EOFs), it is possible to extract and determine the contribution of each variability mode in the time series of a given meteorological quantity. The highest variability is contained in the first mode of variability, also called the leading mode. The vertical and horizontal structures of the resulting spatial patterns illustrate the internal variability of each atmospheric layer, telleconnection patterns as well as the interactions of atmospheric layers. Using EOFs, the stratosphere–roposphere interactions in the two above winters were investigated.Comparing the two winters, it was found that the variance of the leading mode of the 10- hPa gepotential height was larger in Winter 2007–008, indicating a stronger polar vortex than that in Winter 2009-2010. With regard to this situation at various levels, it was shown that the cold winter in the region in Winter 2007–008 coincided with the existence of a strong polar vortex and minor sudden stratospheric warming (SSW). In Winter 2009–010, the reverse is true. That is, the warm winter in the region coincided with the existence of a weak polar vortex, early SSW and the displacement of the dipolar pattern of a temperature anomaly to higher latitudes.As an important tool in understanding the time evolving flows, Eulerian diagnostics were employed to corroborate the results obtained using the statistical method. The results for a temperature anomaly at 850 hPa were consistent with surface observations in which the winters 2007–008 and 2009-2010 were, respectively, cold and warm over the region. The changes in the temperature pattern in these two winters were believed to be related to the effects of a stratospheric circulation in the surface climate. The SSW events were classified according to the definition provided by the World Meteorological Organization. The SSW events were classified and the stratosphere–roposphere interaction was investigated using Eulerian diagnostics. Consistent with the statistical analysis, the time evolution of Eulerian diagnostics illustrates marked differences in the behavior of a polar vortex in the two winters.The results obtained using EOFs and Eulerian diagnostics showed that in Winter 2007–2008 the occurrence of a major or minor sudden stratospheric warming was associated with the displacement of a dipolar pattern of temperature to lower (higher) latitudes and thus a prolonged cold anomaly over Iran. The opposite situation was found to prevail in Winter 2009–010.