Relation between total ozone and sub-tropical jet stream

This article investigates the relationship between total ozone and subtropical jet stream (STJ). Total ozone data have been obtained from the total ozone mapping spectrometer (TOMS) instrument on the Nimbus - 7 satellite and have been examined in conjunction with meteorological data in the region 90°- 160°E, 20° -50°N, i.e., the entrance region of the East Asian STJ from October 1982 to September 1983. The STJ marks the boundary between the high tropical tropopause (ca. 1000 hPa) and lower subtropical tropopause (ca. 200 hPa). In winter it has been found that the total ozone contours are almost parallel to the wind direction, and the horizontal gradient in total ozone increases as the wind speed strengthens. The STJ normally marks a steep gradient in total ozone but in spring anomalous patterns are seen sometimes with very small gradients across the jet. A particular study has been conducted of these events, which are associated with a layer of relatively low but still stratospheric potential vorticity (PV) at around 150 hPa (380K) on the poleward side of the jet. This appears to be consistent with a transfer of air from troposphere to stratosphere above the jet core in March and April.

The Effect of Merging Subtropical Jet Stream and Polar Fronts Jet Stream on Heavy Rainfall in Southwest Asia

The purpose of this paper is to show the effect of high troposphere winds and currents on low troposphere events at sea level. For this study, precipitation data from atmospheric stations in South Asia and west of the Zagros Mountains were used. After preparing these data, 500 and 300 hectopascal level maps were used to interpret the weather conditions. Vertical transect flow maps were used to identify the position of the jet stream. The results showed that the merger of the polar front jet stream and the subtropical jet stream provide the conditions for accelerating atmospheric currents and reaching more humidity and stronger ascent conditions to South Asia. Jet streams merger have three major effects on low pressure. If the Jet stream vorticity is the same as the curvature vorticity, the low-pressure centers on the low level will be strengthened, otherwise they will weaken due to the opposite effects. The low pressure under the Jet stream divergence area helps to strengthen it. The difference in wind speed in the jet stream with low pressures, stranger low pressures in the low level.

Climatic analysis of effective jet streams frequency on extreme precipitations in west of Iran

In this study, the frequency of effective jet streams was analyzed in extreme and widespread precipitations in the west of Iran. For this purpose, the daily precipitation of 69 synoptic and climatic stations over 18,624 days (1961–2010) were selected. Then, 119 days of extreme and widespread precipitation in the study area were chosen based on generalized distribution for conducting related reviews and analyses. The frequency of jet streams in the geographical location from 0° to 120°E and −10° to 80°N were reviewed at four levels (250, 300, 400 and 500 hPa). Due to the large volume of information, only the highest and lowest levels (250 and 500 hPa) in relation to the surface were considered. According to the results, the highest frequency of jet stream was observed at 250 hPa. The second quarter of the jet stream core lay over the west of Iran (which is associated with increasing positive vorticity as well as upper-level divergence and lower-level convergence of the atmosphere). In general, the extension of jet stream up to 500 hPa indicated an unstable layer thickness, which can cause extreme and widespread precipitation in the west of Iran. The results of selected days based on cluster analysis and Lund correlation revealed that in rainy days, the wind speed was more than 50 m/s and the subtropical jet stream speed was over 40 m/s, leading to extreme precipitation in the west of Iran.