عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Reduced rainfall in many parts of the world have prompted scientists to try to manipulate, in different ways, to the nature, causing precipitation from accumulated water in the atmosphere. Atmospheric ionization is a new method for producing precipitation and has attracted much attention. In this regard, in recent years, in some regions of the world, in different ways, the relation between meteorological phenomena, especially tropical cyclones, and ionosphere are studied. Because of importance of water and precipitation, in present paper in order to detect the presence or absence of correlation between ionosphere and the precipitation meteorological phenomena, used three kind of data consist of geomagnetic, ionospheric and meteorological data.
The meteorological and geomagnetic data are measured data but the ionospheric data derived from raw GPS data. For analysis, In the first step, it analyzed the geomagnetic conditions by use of two geomagnetic indices consist of Kp and Dst for an especial period. In the second step, analyzed the data of ionospheric Vertical Total Electron Content (VTEC) and omitted geomagnetic disturbed days from same period. The daily maximums of VTEC, as the differentiating factor of various days, was selected. In the third step, it analyses and compares time series of maximums of ionospheric VTEC from processing of data from two GPS stations, in quiet geomagnetic conditions, with variations of precipitation recorded in two synoptic stations situated in same place of GPS stations, that have considerable difference in precipitation. These stations are Shiraz as the high rainfall station and Esfahan as the low rainfall station that considered in A 41-day period since 1 Jan to 10 February 2011. Also it is compared and analyzed the time series of variations of maximums of VTEC, to mean the difference of maximum of VTEC in any day than maximum of VTEC in days ago, with time series of precipitation in both stations. With these analysis it was observed that there is systematic relationship between variations of maximum of ionospheric VTEC and occurrence of precipitation. So that after occurrence intense fluctuations with special amplitude in maximum of VTEC, occur precipitation peaks. Therefore along with mild changes of maximums of ionospheric VTEC in a period, it observe tropospheric stable conditions and along with intense changes of maximums of ionospheric in the same period, it observed unstable tropospheric conditions and precipitation occurred. Also, the time series of maximums of VTEC in the same period obtained from running the global ionospheric model IRI2012 and compared with the time series of maximums of ionospheric VTEC from processing the raw data of GPS. it seems that the best kind of data for study the troposphere-ionosphere correlation, are ionospheric data from processing the raw data of GPS stations and the ionospheric data from running the ionospheric global models, due to the inability show details, are not suitable for this. It may be because of this, that maximums VTEC from processing raw data of GPS in this paper are point measurements and the maximums of VTEC from global ionospheric model IRI2012 has global scale and simulate large scale variations of ionospheric parameters.