Synergistic Use of Remote Sensing and Modeling for Tracing Dust Storms in the Mediterranean

This study focuses on the detection of the dust source region and monitoring of the transport of the dust plume from its primary outflow to final deposition. The application area is the Sahara desert and the eastern Mediterranean, where two dust events occurred during the period 4–6 February 2009, an unusual event for a winter period. The Aqua-MODIS and OMI observations clearly define the spatial distribution of the dust plumes, while the CALIPSO observations of total attenuated backscatter (TAB) at 532 nm, depolarization ratio (DR), and attenuated color ratio (1064/532 nm) on 5 February 2009 provide a clear view and vertical structure of the dust-laden layer. The dust source region is defined to be near the Chad-Niger-Libyan borders, using satellite observations and model (DREAM) output. This dust plume is vertically extended up to 2.5 km and is observed as a mass plume of dust from surface level to that altitude, where the vertical variation of TAB (0.002 to 0.2) and DR (0.2–0.5) implies dust-laden layer with non-spherical particles. CALIPSO profiles show that after the dust plume reached at its highest level, the dust particles start to be deposited over the Mediterranean and the initial dust plume was strongly attenuated, while features of dust were limited below about 1–1.5 km for latitudes northern of ~36° (Greek territory).

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Change of the Asian dust source region deduced from the relationship between anthropogenic radionuclides in surface soil and precipitation in Mongolia

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-2843-2011 ◽

2011 ◽

Vol 11 (1) ◽

pp. 2843-2871

Author(s):

Y. Igarashi ◽

H. Fujiwara ◽

D. Jugder

Keyword(s):

Surface Soil ◽

Source Region ◽

Asian Dust ◽

Soil Samples ◽

Dust Storms ◽

Anthropogenic Radionuclides ◽

Dust Source ◽

Atmospheric Depositions ◽

Specific Activities ◽

Dust Source Region

Abstract. The Asian dust source region may be expanding primarily as a result of recent climate change, especially during the 2000s. This change was investigated by examining anthropogenic radionuclides contained in surface soil samples from Mongolia. Surface soil was globally labeled by radioactive fallout from nuclear testing during the late 1950s and early 1960s. There are no current direct sources for anthropogenic radionuclides in the air, so the radionuclides in the atmosphere are mainly carried by dust from wind-blown surface soil, that is, aeolian dust. Asian dust carries 90Sr, 137Cs, and other anthropogenic radionuclides; the heaviest deposition occurs in spring and has been recorded in Japan since the early 1990s. The composition of anthropogenic radionuclides in atmospheric depositions would be affected by a change in the dust source. Previous studies of atmospheric depositions at long-term monitoring sites (e.g. in Tsukuba, Japan) have detected changes in the 137Cs/90Sr ratio and in the specific activity of the radionuclides. These changes in the composition of observed atmospheric depositions should be a reflection for a change in the climatic conditions of the dust source region. To investigate this dust source change, a field survey for radionuclides (90Sr and 137Cs) in surface soil samples was conducted in September 2007 in the eastern and southern regions of Mongolia, where dust storms have occurred more frequently since 2000. It was found that specific activities of both radionuclides as well as the 137Cs/90Sr ratio in the surface soil correlated well with annual average precipitation in the Mongolian desert-steppe zone. The higher specific activities and the higher 137Cs/90Sr ratio were found in the grassland region with the greater precipitation. This finding suggests that the increased specific activities and the activity ratio detected in the atmospheric depositions in Japan during years of the frequent Asian dust transport event since 2000 should be a sign of grassland degradation.

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Change of the Asian dust source region deduced from the composition of anthropogenic radionuclides in surface soil in Mongolia

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-7069-2011 ◽

2011 ◽

Vol 11 (14) ◽

pp. 7069-7080 ◽

Cited By ~ 26

Author(s):

Y. Igarashi ◽

H. Fujiwara ◽

D. Jugder

Keyword(s):

Surface Soil ◽

Source Region ◽

Asian Dust ◽

Soil Samples ◽

Dust Storms ◽

Anthropogenic Radionuclides ◽

Dust Source ◽

Atmospheric Depositions ◽

Specific Activities ◽

Dust Source Region

Abstract. Recent climate change, especially during the 2000s, may be the primary reason for the expansion of the Asian dust source region. The change in the dust source region was investigated by examining anthropogenic radionuclides contained in surface soil samples from Mongolia. Surface soil was globally labeled by radioactive fallout from nuclear testing during the late 1950s and early 1960s, but there are no current direct sources for anthropogenic radionuclides in the air (before the Fukushima nuclear power plant accident in 2011). Radionuclides in the atmosphere are therefore carried mainly by wind-blown dust from surface soil, that is, aeolian dust. Asian dust carries traces of 90Sr, 137Cs, and other anthropogenic radionuclides; the heaviest deposition occurs in spring and has been recorded in Japan since the early 1990s. The composition of anthropogenic radionuclides in atmospheric depositions would be affected by a change in the dust source. Previous studies of atmospheric deposition at long-term monitoring sites (e.g. in Tsukuba, Japan) have detected changes in the 137Cs/90Sr ratio and in the specific activity of the radionuclides. These changes in the composition of observed atmospheric depositions are supposed to reflect changes in the climatic conditions of the dust source region. To investigate this dust source change, we conducted a field survey of radionuclides (90Sr and 137Cs) in surface soil samples in September 2007 in the eastern and southern regions of Mongolia, where dust storms have occurred more frequently since 2000. The specific activities of both radionuclides as well as the 137Cs/90Sr ratio in the surface soil were well correlated with annual average precipitation in the Mongolian desert-steppe zone. Higher specific activities and a higher 137Cs/90Sr ratio were found in grassland regions that experienced greater precipitation. These findings suggest that the increased specific activities and the activity ratio detected in atmospheric depositions in Japan during years with frequent Asian dust transport events in the 2000s are a sign of grassland degradation.

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Aerosol Optical Properties Retrieval and Separation of Asian Dust using AERONET Sun/Sky Radiometer Measurement at the Asian Dust Source Region

Korean Journal of Remote Sensing ◽

10.7780/kjrs.2016.32.3.4 ◽

2016 ◽

Vol 32 (3) ◽

pp. 245-251 ◽

Cited By ~ 1

Author(s):

Dongho Shin ◽

Youngmin Noh

Keyword(s):

Optical Properties ◽

Source Region ◽

Asian Dust ◽

Aerosol Optical Properties ◽

Dust Source ◽

Radiometer Measurement ◽

Dust Source Region

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Ground-based measurements of immersion freezing in the eastern Mediterranean

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-5217-2014 ◽

2014 ◽

Vol 14 (10) ◽

pp. 5217-5231 ◽

Cited By ~ 32

Author(s):

K. Ardon-Dryer ◽

Z. Levin

Keyword(s):

Eastern Mediterranean ◽

Aerosol Particles ◽

Eastern Mediterranean Region ◽

Freezing Temperature ◽

Dust Storms ◽

Dust Particles ◽

High Concentration ◽

Back Trajectories ◽

Ice Nuclei ◽

Immersion Freezing

Abstract. Ice nuclei were measured in immersion-freezing mode in the eastern Mediterranean region using the FRIDGE-TAU (FRankfurt Ice-nuclei Deposition freezinG Experiment, the Tel Aviv University version) chamber. Aerosol particles were sampled during dust storms and on clean and polluted days (e.g., Lag BaOmer). The aerosol immersion-freezing potential was analyzed in the laboratory using a drop-freezing method. Droplets from all the samples were found to freeze between −11.8 °C and −28.9 °C. Immersion-freezing nuclei (FN) concentrations range between 0.16 L−1 and 234 L−1, while the activated fraction (AF) ranges between 8.7 × 10−8 and 4.9 × 10−4. The median temperature at which the drops from each filter froze was found to be correlated with the corresponding daily average of PM10, PM2.5 and PM10–PM2.5. A higher correlation value between FN concentrations and PM10–PM2.5 suggests that the larger particles are generally more effective as FN. The measurements were divided into dust storms and "clean" conditions (this is a relative term, because dust particles are always present in the atmosphere is this region) based on the air mass back trajectories and the aerosol mass concentrations (PM10). Droplets containing ambient particles from dust storm days froze at higher temperatures than droplets containing particles from clean days. Statistically significant differences were found between dust storms and clean conditions primarily in terms of the initial temperature at which the first drops froze, the median freezing temperature and the aerosol loading (PM values). FN concentrations and AF values in dust storms were larger by more than a factor of 2 than in the clean conditions. This observation agrees with previous studies showing that some dust particles are almost always present in the atmosphere in this region. Measurements of aerosol particles emitted from wood burning bonfires during a Lag BaOmer holiday showed that although a high concentration of particles was emitted, those particles' effectiveness as FN was relatively poor. The most likely reason for the low FN efficiency is the combination of relatively low fire temperatures and high organic carbon fraction in the aerosols.

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Multi-model simulations of springtime dust storms in East Asia: Implications of an evaluation of four commonly used air quality models (CMAQv5.2.1, CAMxv6.50, CHIMEREv2017r4, and WRF-Chem v3.9.1)

10.5194/gmd-2019-57 ◽

2019 ◽

Cited By ~ 1

Author(s):

Siqi Ma ◽

Xuelei Zhang ◽

Chao Gao ◽

Daniel Q. Tong ◽

Aijun Xiu ◽

...

Keyword(s):

Air Quality ◽

East Asia ◽

Parameter Tuning ◽

Dust Storms ◽

Dust Particles ◽

Dust Event ◽

Local Data ◽

Dust Source ◽

Quality Models ◽

Dust Flux

Abstract. Mineral dust particles play an important role in the Earth system, imposing a variety of effects on air quality, climate, human health, and economy. Accurate forecasts of dust events are highly desirable to provide early-warning and inform decision-making. East Asia is one of the largest dust sources in the world. This study applies and evaluates four widely used regional air quality models to simulate dust storms in East Asia. Three dust schemes in the Weather Research and Forecast with Chemistry (WRF-Chem) (version 3.9.1), two schemes in CHIMERE (version 2017r4) and CMAQ (version 5.2), and one scheme in CAMx (version 6.50), were applied to a dust event during May 4th~6th, 2015 in Northeastern China. Most of these models were able to capture this dust event, except CAMx which has no dust source map covering the study area, hence is excluded from subsequent analysis. Although these models reproduced the spatial pattern of the dust plume, there were large discrepancies between predicted and observed PM10 concentrations in each model. In general, CHIMERE had relatively better performance among all simulations with default configurations. After parameter tuning, WRF-Chem with the AFWA scheme using seasonal dust source map from Ginoux et al. (2012) showed the best performance, followed by WRF-Chem with UOC_Shao2011 scheme, CHIMERE, and CMAQ. This study suggested that the dust source maps should be carefully selected or replaced with a new one constructed with local data. Moreover, further study and measurement on sandblasting efficiency of different soil types and locations should be conducted to improve the accuracy of estimated vertical dust flux in air quality models.

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