Urmia Lake dust storms occurrences: investigating the relationships with changes in water zone and land cover in the eastern part using remote sensing and GIS

Urmia Lake is the largest lake in the Middle East which has greatly decreased in recent years. It has had a great impact on the environmental properties of areas around the lake. This study aimed to identify the relationship among dust storms in the eastern part of Urmia Lake and the surrounding vegetation due to the annual and long-term variability of this water zone during the statistical period 1999-2019. Normalized difference water index (NDWI), normalized difference vegetation index (NDVI), Aerosol Optical Depth (AOD), and Dust Storm Index (DSI) were used due to trend and correlation analysis models and T-student analysis. The study results found that, first, the decreasing trend of Urmia Lake, directly and significantly, has led to an increase in dust concentration (AOD) in the lake's eastern part. On the other hand, changes in the water level of Lake Urmia have led to a general decreasing trend in vegetation in the region which led to an increase in the frequency of DSI in the region. The model developed showed that changes in the water zone of Urmia Lake as a very powerful driver leads to an increase in the intensity and frequency of dust storms in the eastern part of the lake and intensifies the dust conditions in the region. The synergistic resultant of these two drivers was maximized in years when both lake area and vegetation were at a minimum at the same time (2011-2016). The estimated scenario of this model is that if the decreasing trend of Urmia Lake intensifies in the study area, more frequent and severe dust storms will occur in the region.

Monitoring atmospheric particulate matters using vertically resolved measurements of a polarization lidar, in-situ recordings and satellite data over Tehran, Iran

The highly polluted atmosphere above Tehran has been investigated by using a polarization lidar operating at 532 nm, in-situ particulate matter suites distributed over the city, and meteorological observations. The measurement campaign is conducted from Nov. 2014 to Jan. 2016. Three typical cases are studied in detail where, the atmosphere is polluted with urban pollution, mixture of urban pollution and dust particles from local sources, and long range transported dust from the Arabian Peninsula. For these cases, vertical profiles of the lidar backscatter coefficient, extinction coefficients, particle depolarization ratio (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\delta _{\text {p}}$$\end{document}δp) and mass concentrations of atmospheric aerosols (separated into dust and non-dust particles) are presented. Using the lidar recordings, variations of the planetary boundary layer height above the city are investigated along the year. During November to February, lidar profiles frequently show polluted boundary layers that are reaching up to 1 km above the ground level. The depolarization ratio (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\delta _{\text {p}}$$\end{document}δp) varies between 0.04 and 0.08 in the polluted boundary layer. During the campaign, for 103 days the urban pollution was dominant, 45 recorded dust events (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.15<\delta _{\text {p}}<0.20$$\end{document}0.15<δp<0.20) were originated from the dry regions in the south of Tehran and 15 dust events (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.20<\delta _{\text {p}}<0.35$$\end{document}0.20<δp<0.35) impacted the city that were originated from the Arabian Desert and Mesopotamia.

Monitoring Atmospheric Aerosols Over the Urmia Lake by CALIPSO and a Ground Based Depolarized Lidar

The Urmia Lake, a hypersaline lake in Northwest Iran is facing a severe drying scenario. We have installed an azimuthal scanning depolarized backscatter lidar in the coast of the lake to monitor the atmospheric aerosols that may originate from the dried lake bed. We also used the CALIPSO recordings to monitor the aerosol optical depth and particulate depolarization ratio just over the lake. Recordings of the lidar and CALIPSO both show that dry salt particles can be found in the atmospheric boundary layer over the lake especially in summer times. Also CALIPSO data in synergy with HYSPLIT model show that the lake is not an intense aerosol source comparing to neighboring sources like the Mesopotamia region but it is under their influence.

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.

Impacts of climate and synoptic fluctuations on dust storm activity over the Middle East

Dust events in the Middle East are becoming more frequent and intense in recent years with impacts on air quality, climate, and public health. In this study, the relationship between dust, as determined from Aerosol Optical Depth (AOD) and meteorological parameters (precipitation, temperature, pressure and wind field) are examined using monthly data from 2000 to 2015 for desert areas in two areas, Iraq-Syria and Saudi Arabia. Bivariate regression analysis between monthly temperature data and AOD reveals a high correlation for Saudi Arabia (R = 0.72) and Iraq-Syria (R = 0.64). Although AOD and precipitation are correlated in February, March and April, the relationship is more pronounced on annual timescales. The opposite is true for the relationship between temperature and AOD, which is evident more clearly on monthly time scales, with the highest temperatures and AOD typically between August and September. Precipitation data suggest that long-term reductions in rainfall promoted lower soil moisture and vegetative cover, leading to more intense dust emissions. Superimposed on the latter effect are more short term variations in temperature exacerbating the influence on the dust storm genesis in hot periods such as the late warm season of the year. Case study analysis of March 2012 and March 2014 shows the impact of synoptic systems on dust emissions and transport in the study region. Dust storm activity was more intense in March 2012 as compared to March 2014 due to enhanced atmospheric turbulence intensifying surface winds.