1. introduction one of the most important conditions to have dusty weather beside of unstable weather is existence or non-existence of humidity. unstable weather having enough humidity will produce rain and thunder storm, else if the result will be dust storm. number of particles of dusty storm is depended to wind speed, sec of soil and its dimension. furthermore, vegetation type has importance...

near surface ozone in urban areas can be potentially hazardous for the city dwellers. as a secondary pollutant it can also be an indicator for other air pollutants as nitrogen oxides, nox and phenol acetate nitrate (pan). in this paper time and spatial variations of near surface ozone and the effective meteorological parameters influencing it concentrations, have been investigated for tehran fo...

Hot and wet conditions in the equatorial or low latitude region degrade satellite positioning accuracy noticeably. The degradation is related to the strong tropospheric effect, especially the wet component which is approximately proportional to the content of water vapor in the troposphere and thus makes satellite positioning more challenging in this region. Despite the efforts to achieve bette...

Observations show that large variations in the strength of the stratospheric circulation, appearing first above approximately 50 kilometers, descend to the lowermost stratosphere and are followed by anomalous tropospheric weather regimes. During the 60 days after the onset of these events, average surface pressure maps resemble closely the Arctic Oscillation pattern. These stratospheric events ...

A strong spatio-temporal variation of the wet component in the troposphere leaves us in a peculiar predicament. The residual tropospheric delay will remain in the measurements and therefore affect the estimation of related parameters. In the areas of hot and wet climate conditions, especially in the equatorial or low latitude regions, the strong tropospheric effect on GPS measurements is unques...

in this paper, synoptic patterns associated with maximum precipitation over the khorasan region, between 1985-2000 with the computation of some forcing functions are studied and classified into three types. type a: consists of the anticyclones that move from the scandinavian peninsula and central-europe in an east and south-east direction during cold seasons, with relatively high speed and cold...

introduction air pollution as one of the most important technological risks of contemporary era is mainly resulted from the emergence of large cities and fast growing industries. one of the main objectives of climatic and environmental studies is to survey atmospheric pollutions. tabriz is one of the metropolises where air pollution is a problem in it. of course, what is essential regarding the...

Many large-scale weather forecast models prescribes too much turbulent mixing stably stratified conditions, which causes problems with the depth of nocturnal or high-latitude winter boundary layers, lack of inertially driven low-level wind maxima and inversion-capped low clouds. The link between the turbulent momentum flux and the associated Ekman pumping and therefore the lifetime of synoptics...

in order to identify the pressure patterns causing the cold weather over the northwestern iran, daily lowest temperatures of six stations of the study area during january- march months of the 1986-2003 period were obtained from meteorological organization of islamic republic of iran (irimo) in the quality controlled format. according to the defined threshold, the very cold days were extracted a...

[1] We present concentration distributions of C1-C4 alkyl nitrates observed during the NASA airborne campaigns Pacific Exploratory Mission (PEM) -Tropics A (September– October 1996) and PEM-Tropics B (March–April 1999). The total geographic range for PEM-Tropics A was 45 N–72 S latitude and 153 E–75 W longitude, and for PEMTropics B was 40 N–36 S latitude and 149 E–75 W longitude. The maximum a...