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Showing 2 results for Atmospheric Middle Level

Meysam Toulabi Nejad, Dr Zahra Hejazizadeh, Mrs Atefeh Bosak, Mrs Nasrin Bazmi,
Volume 18, Issue 49 (5-2018)
Abstract

The purpose of this study was to investigate the effects of the North Atlantic Oscillation on the middle levels of Atmosphere and precipitation changes in the West of country. To do this, first monthly rainfall data of 17 synoptic stations of the West Country in period of 30 years from 1984 to 2014 of country were collected from Meteorological Organization. As well as North Atlantic Oscillation data and anomalies geopotential height data, sea level pressure and precipitation were received from NOAA. To clarify the relationship between the NAO index phase with precipitation of west of Iran used Pearson correlation coefficient was at least 95%, (P_value = 0.05). Finally, using synoptic maps, spatial relationships among data, were analyzed. The results indicate that between North Atlantic Oscillation changes with middle level height anomalies of the Atmosphere and the amount of precipitation in West of Iran in January, March, April and November there is communication and concurrency.  The results showed that , at a time of sovereignty positive phase of the North Atlantic oscillation , an average of height atmospheric middle level in mid - western Iran 17 meters long - term and less than the average rainfall per month 23.5 mm increased and wetly sovereign. But when phase of governance is negative, high atmospheric middle level anomaly to an average of 20 meters more than normal. As a result, the drought will prevail in the west and precipitation in the region each month will face a reduction of 30 mm. In general, we can say that droughts more severe than wet coincide with the negative phase of the North Atlantic Oscillation is positive phase.

Sayyed Mohamad Hosseini, Abdolhossein Adelzadeh,
Volume 19, Issue 52 (3-2019)
Abstract

In this research, applied synoptic model for determining the average daily temperature and its relationship with the Geopotential Height in middle level (500 HPa). Therefore, two database were used: database of atmospheric circulations, includes the data of geopotential height at 500 HPa and its data were extracted from the NCEP/DOE(US National Oceanic and Atmospheric Administration) in hours 00:00; 03:00; 06:00; 09:00; 12:00; 15:00; 18:00; and 21:00 in Zulu and other, database of environmental (surface) events. Contain of average daily temperature in the Mashhad, Torbat-Heydarieh and Sabzevar stations in Khorasan Razavi Province. The maximum and minimum of these stations in the time interval from 01/01/1987 to 01/01/2014 equal as 9862 days from the meteorological organization of Iran. Then, was calculated the correlation of the average daily temperature of selected stations with high atmospheric data (500 HPa level) with the northern hemisphere in Surfer Software. The result shown, four regions in the northern hemisphere which had high correlations with selected stations. The correlation results suggest that the United States has 25 pixels, Northern China 25 pixels, Africa 45 pixels and Japan with 65 pixels. Then, weighted average of pixels in heights by multiple regression equation station. The results of diagnostic models indicate that, per geopotential height increase in the profile, the average daily temperatures of selected stations in the Sabzevar 1.4, Torbat-Heydarieh 1.3 and Mashhad 1.3 degrees Celsius will increase.
 



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