Lidar Measuremnt on Dust Transport from the Saharan Desert to the Iran Plateau

Optical properties of long-range Saharan dust particles transported to the Iran Plateau have been investigated. The results were derived from the measurements of a dual-wavelength Depolarized backscatter/Raman lidar and a Cimel CE318-2 sunphotometer. Observations were performed in Zanjan, Northwest Iran. The backward trajectory analysis show that the lofted dust plumes come from the Saharan desert and travel along Mediterranean Sea and Turkey toward Iran. The lidar ratio within the lofted dust layer has been found with mean values of 50 sr at 532 nm. For the depolarization ratio, mean values of 25% have been found.

3-D crustal structure of the Iran plateau using phase velocity ambient noise tomography

SUMMARY More accurate crustal structure models will help us to better understand the tectonic convergence between Arabian and Eurasian plates in the Iran plateau. In this study, the crustal and uppermost mantle velocity structure of the Iran plateau is investigated using ambient noise tomography. Three years of continuous data are correlated to retrieve Rayleigh wave empirical Green's functions, and phase velocity dispersion curves are extracted using the spectral method. High-resolution Rayleigh wave phase velocity maps are presented at periods of 8–60 s. The tomographic maps show a clear consistency with geological structures such as sedimentary basins and seismotectonic zones, especially at short periods. A quasi-3-D shear wave velocity model is determined from the surface down to 100 km beneath the Iran plateau. A transect of the shear wave velocity model has been considered along with a profile extending across the southern Zagros, the Sanandaj-Sirjan Zone (SSZ), the Urumieh-Dokhtar Magmatic Arc (UDMA) and Central Iran and Kopeh-Dagh (KD). Obvious crustal thinning and thickening are observable along the transect of the shear wave velocity model beneath Central Iran and the SSZ, respectively. The observed shear wave velocities beneath the Iran plateau, specifically Central Iran, support the slab break-off idea in which low density asthenospheric materials drive towards the upper layers, replacing materials in the subcrustal lithosphere.

Calipso recordings and monitoring dust storms over the open seas in south of the iran plateau

Open seas in the south of the Iran plateau are under the influence of heavy dust storms which are originating either from the Tigris and Euphrates basin, the Arabian Peninsula or Hamoun lake. We have used the recordings of the CALIPSO satellite to investigate the seasonal variations as well as the origins of the dust storms over the region. CALIPSO data set shows dust activities are frequent during May to September in the interested region and the Hamoun lake has considerable impacts on it.

Evaluation of Relation between Rainfall and El Nino Phenomena in Iran

In this study El Nino effects on rainfall in Iran is evaluated. Annual rainfall data of the selected rain gauging stations for the years when El Nino phenomenon has taken place (1973-2012), have been picked up. Next, annual rainfall of the years with and without El Nino phenomenon were compared and then analyzed (correlation is significant at the 0.01 level). Finally, percentage-frequency of the rainfalls influenced by warm Enso condition was obtained. Regarding that El Nino has different affect on rainfall under different regions of the world, the results approved that El Nino, increases rainfall across Iran plateau as annual rainfall is increased from south to north. While less increasing of rainfall is seen for coastal area. Results showed that El Nino causes increasing of annual rainfall in Iran.