scholarly journals Numerical modeling of Asian dust emission and transport with adjoint inversion using LIDAR network observations

2007 ◽  
Vol 7 (6) ◽  
pp. 15955-15987 ◽  
Author(s):  
K. Yumimoto ◽  
I. Uno ◽  
N. Sugimoto ◽  
A. Shimizu ◽  
Z. Liu ◽  
...  
Keyword(s):  
Dust Emission ◽  
Gobi Desert ◽  
Vertical Profiles ◽  
Dust Event ◽  
Dust Layer ◽  
Dust Emissions ◽  
Extinction Coefficients ◽  
Dust Extinction ◽  
Source Regions ◽  
Coarse Mode

Abstract. A four-dimensional variational (4D-Var) data assimilation system for a regional dust model (RAMS/CFORS-4DVAR; RC4) is applied to a heavy dust event which occurred between 20 March and 4 April 2007 over eastern Asia. The vertical profiles of the dust extinction coefficients derived from NIES LIDAR observation network are directly assimilated. We conduct two experiments to evaluate impacts of selections of observation sites: Experiment A uses five Japanese observation sites located only downwind of dust source regions; the other Experiment B uses these sites together with two other sites near source regions (China and Korea). Validations using various observation data (e.g., PM10 concentration, MODIS AOT, OMI Aerosol Index, and the dust extinction coefficient derived by space-based LIDAR NASA/CALIPSO) are demonstrated. The modeled dust extinction coefficients are improved considerably through the assimilation. Assimilation results of Experiment A are consistent with those of Experiment B, indicating that observations of Experiment A can capture the dust event correctly and include sufficient information for dust emission inversion. Time series of dust AOT calculated by modeled and LIDAR dust extinction coefficients show good agreement. At Seoul, Matsue, and Toyama, assimilation reduces the root mean square errors of dust AOT by 31–32%. Vertical profiles of the dust layer observed by CALIPSO are also compared with assimilation results. The dense dust layer was trapped between θ=280–300 K and elevated higher toward the north; the model reproduces those characteristics well. The modeled dust AOT along the orbit paths agrees well with the CALIPSO dust AOT, OMI AI, and the coarse mode AOT retrieved from MODIS; especially the modeled dust AOT and the MODIS coarse mode AOT are consistent quantitatively. Assimilation results increase dust emissions over the Gobi Desert and Mongolia considerably; especially between 29 and 30 March, emission flux is increased by about 2–3 times. The heavy dust event is caused by the heavy dust uplift flux over the Gobi Desert and Mongolia during those days. We obtain the total optimized dust emissions of 57.9 Tg (Experiment A; 57.8% larger than before assimilation) and 56.3 Tg (Experiment B; 53.4% larger).

scholarly journals Adjoint inversion modeling of Asian dust emission using lidar observations

2008 ◽  
Vol 8 (11) ◽  
pp. 2869-2884 ◽  
Author(s):  
K. Yumimoto ◽  
I. Uno ◽  
N. Sugimoto ◽  
A. Shimizu ◽  
Z. Liu ◽  
...  
Keyword(s):  
Dust Emission ◽  
Series Data ◽  
Gobi Desert ◽  
Vertical Profiles ◽  
Dust Event ◽  
Dust Layer ◽  
Dust Emissions ◽  
Extinction Coefficients ◽  
Dust Extinction ◽  
Source Regions

Abstract. A four-dimensional variational (4D-Var) data assimilation system for a regional dust model (RAMS/CFORS-4DVAR; RC4) is applied to an adjoint inversion of a heavy dust event over eastern Asia during 20 March–4 April 2007. The vertical profiles of the dust extinction coefficients derived from NIES Lidar network are directly assimilated, with validation using observation data. Two experiments assess impacts of observation site selection: Experiment A uses five Japanese observation sites located downwind of dust source regions; Experiment B uses these and two other sites near source regions. Assimilation improves the modeled dust extinction coefficients. Experiment A and Experiment B assimilation results are mutually consistent, indicating that observations of Experiment A distributed over Japan can provide comprehensive information related to dust emission inversion. Time series data of dust AOT calculated using modeled and Lidar dust extinction coefficients improve the model results. At Seoul, Matsue, and Toyama, assimilation reduces the root mean square differences of dust AOT by 35–40%. However, at Beijing and Tsukuba, the RMS differences degrade because of fewer observations during the heavy dust event. Vertical profiles of the dust layer observed by CALIPSO are compared with assimilation results. The dense dust layer was trapped at potential temperatures (θ) of 280–300 K and was higher toward the north; the model reproduces those characteristics well. Latitudinal distributions of modeled dust AOT along the CALIPSO orbit paths agree well with those of CALIPSO dust AOT, OMI AI, and MODIS coarse-mode AOT, capturing the latitude at which AOTs and AI have high values. Assimilation results show increased dust emissions over the Gobi Desert and Mongolia; especially for 29–30 March, emission flux is about 10 times greater. Strong dust uplift fluxes over the Gobi Desert and Mongolia cause the heavy dust event. Total optimized dust emissions are 57.9 Tg (Experiment A; 57.8% larger than before assimilation) and 56.3 Tg (Experiment B; 53.4% larger).

scholarly journals Quantification of iron-rich volcanogenic dust emissions and deposition over the ocean from Icelandic dust sources

2014 ◽  
Vol 11 (23) ◽  
pp. 6623-6632 ◽  
Author(s):  
O. Arnalds ◽  
H. Olafsson ◽  
P. Dagsson-Waldhauserova
Keyword(s):  
Large Scale ◽  
Dust Emission ◽  
Dust Storms ◽  
Dust Event ◽  
Dust Deposition ◽  
Dust Emissions ◽  
Dust Sources ◽  
Basaltic Composition ◽  
Limiting Nutrient ◽  
Dust Events

Abstract. Iceland has extremely active dust sources that result in large-scale emissions and deposition on land and at sea. The dust has a volcanogenic origin of basaltic composition with about 10% Fe content. We used two independent methods to quantify dust emission from Iceland and dust deposition at sea. Firstly, the aerial extent (map) of deposition on land was extended to ocean areas around Iceland. Secondly, surveys of the number of dust events over the past decades and calculations of emissions and sea deposition for the dust storms were made. The results show that total emissions range from 30.5 (dust-event-based calculation) to 40.1 million t yr−1 (map calculation), which places Iceland among the most active dust sources on Earth. Ocean deposition ranges between 5.5 (dust event calculations) and 13.8 million tons (map calculation). Calculated iron deposition from Icelandic dust ranges between 0.567 and 1.4 million tons, which are distributed over wide areas (>370 000 km2) and consist of fine reactive volcanic materials. The paper provides the first quantitative estimate of total dust emissions and oceanic deposition from Iceland. Iron is a limiting nutrient for primary production in the oceans around Iceland, and the dust is likely to affect Fe levels in Icelandic ocean waters.

scholarly journals Sensitivity of the WRF-Chem (V3.6.1) model to different dust emission parametrisation: assessment in the broader Mediterranean region

2017 ◽  
Vol 10 (8) ◽  
pp. 2925-2945 ◽  
Author(s):  
Emmanouil Flaounas ◽  
Vassiliki Kotroni ◽  
Konstantinos Lagouvardos ◽  
Martina Klose ◽  
Cyrille Flamant ◽  
...  
Keyword(s):  
North Africa ◽  
Eastern Mediterranean ◽  
Dust Emission ◽  
Model Performance ◽  
Dust Particles ◽  
Dust Transport ◽  
Dust Emissions ◽  
Extinction Coefficients ◽  
Airborne Measurements ◽  
Model Aerosol

Abstract. In this study we aim to assess the WRF-Chem model capacity to reproduce dust transport over the eastern Mediterranean. For this reason, we compare the model aerosol optical depth (AOD) outputs to observations, focusing on three key regions: North Africa, the Arabian Peninsula and the eastern Mediterranean. Three sets of four simulations have been performed for the 6-month period of spring and summer 2011. Each simulation set uses a different dust emission parametrisation and for each parametrisation, the dust emissions are multiplied with various coefficients in order to tune the model performance. Our assessment approach is performed across different spatial and temporal scales using AOD observations from satellites and ground-based stations, as well as from airborne measurements of aerosol extinction coefficients over the Sahara. Assessment over the entire domain and simulation period shows that the model presents temporal and spatial variability similar to observed AODs, regardless of the applied dust emission parametrisation. On the other hand, when focusing on specific regions, the model skill varies significantly. Tuning the model performance by applying a coefficient to dust emissions may reduce the model AOD bias over a region, but may increase it in other regions. In particular, the model was shown to realistically reproduce the major dust transport events over the eastern Mediterranean, but failed to capture the regional background AOD. Further comparison of the model simulations to airborne measurements of vertical profiles of extinction coefficients over North Africa suggests that the model realistically reproduces the total atmospheric column AOD. Finally, we discuss the model results in two sensitivity tests, where we included finer dust particles (less than 1 µm) and changed accordingly the dust bins' mass fraction.

scholarly journals Assessing atmospheric dust modelling performance of WRF-Chem over the semi-arid and arid regions around the Mediterranean

2016 ◽  
Author(s):  
Emmanouil Flaounas ◽  
Vassiliki Kotroni ◽  
Konstantinos Lagouvardos ◽  
Martina Klose ◽  
Cyrille Flamant ◽  
...  
Keyword(s):  
North Africa ◽  
Eastern Mediterranean ◽  
Dust Emission ◽  
Model Performance ◽  
Model Assessment ◽  
Atmospheric Dust ◽  
Dust Transport ◽  
Dust Emissions ◽  
Extinction Coefficients ◽  
Airborne Measurements

Abstract. In this study we aim at optimizing the WRF-Chem model performance for the purpose of operational forecasting of dust transport over the eastern Mediterranean. For this reason, we compare the model output to observations in order to assess its capacity to realistically reproduce the aerosol optical depth (AOD), focusing on three key regions: North Africa, the Arabian Peninsula and the eastern Mediterranean. Three sets of four simulations each have been performed for the six-month period of spring and summer 2011. Each simulation set uses a different dust emission parametrisation and for each parametrisation, the dust emissions are multiplied with various coefficients in order to tune the model performance. Our approach is based on the model assessment across spatial and temporal scales by comparing its outputs to AOD observations from satellites and ground-based stations, as well as airborne measurements of aerosol extinction coefficients over the Sahara. Tuning the model performance by applying a coefficient to dust emissions may reduce the model AOD bias over a region, but may increase it in other regions. Concerning dust transport over the eastern Mediterranean, the model was shown to realistically reproduce the major transport events, however failing to capture the regional background AOD. Model assessment over the entire domain and simulation period shows that the model presents temporal and spatial variability similar to observed AODs, regardless of the applied dust emission parametrisation. However, when focusing on specific regions, the model’s skill may vary significantly. Further comparison of the model simulations to airborne measurements of the vertical profiles of extinction coefficients over North Africa suggests that the model may realistically reproduce the total atmospheric column AOD. Finally, we show that the inclusion of a finer dust mode (less than 1 μm) in the model presents the advantage of relaxing unrealistically large atmospheric dust loads and yet reproducing realistic AOD values.

scholarly journals Wind-Blown Dust Modeling Using a Backward-Lagrangian Particle Dispersion Model

2017 ◽  
Vol 56 (10) ◽  
pp. 2845-2867 ◽  
Author(s):  
Derek V. Mallia ◽  
Adam Kochanski ◽  
Dien Wu ◽  
Chris Pennell ◽  
Whitney Oswald ◽  
...  
Keyword(s):  
Dispersion Model ◽  
Meteorological Data ◽  
Dust Emission ◽  
Particle Dispersion ◽  
Emission Model ◽  
Dust Event ◽  
Lagrangian Particle ◽  
Modeling Framework ◽  
Source Regions ◽  
Dust Modeling

AbstractPresented here is a new dust modeling framework that uses a backward-Lagrangian particle dispersion model coupled with a dust emission model, both driven by meteorological data from the Weather Research and Forecasting (WRF) Model. This new modeling framework was tested for the spring of 2010 at multiple sites across northern Utah. Initial model results for March–April 2010 showed that the model was able to replicate the 27–28 April 2010 dust event; however, it was unable to reproduce a significant wind-blown dust event on 30 March 2010. During this event, the model significantly underestimated PM2.5 concentrations (4.7 vs 38.7 μg m−3) along the Wasatch Front. The backward-Lagrangian approach presented here allowed for the easy identification of dust source regions with misrepresented land cover and soil types, which required an update to WRF. In addition, changes were also applied to the dust emission model to better account for dust emitted from dry lake basins. These updates significantly improved dust model simulations, with the modeled PM2.5 comparing much more favorably to observations (average of 30.3 μg m−3). In addition, these updates also improved the timing of the frontal passage within WRF. The dust model was also applied in a forecasting setting, with the model able to replicate the magnitude of a large dust event, albeit with a 2-h lag. These results suggest that the dust modeling framework presented here has potential to replicate past dust events, identify source regions of dust, and be used for short-term forecasting applications.

scholarly journals Sensitivity of the WRF-Chem (V3.6.1) model to different dust emission parametrisation: Assessment in the broader Mediterranean region

2017 ◽  
Author(s):  
Emmanouil Flaounas ◽  
Vassiliki Kotroni ◽  
Konstantinos Lagouvardos ◽  
Martina Klose ◽  
Cyrille Flamant ◽  
...  
Keyword(s):  
North Africa ◽  
Eastern Mediterranean ◽  
Dust Emission ◽  
Model Performance ◽  
Dust Transport ◽  
Dust Emissions ◽  
Extinction Coefficients ◽  
Spatial And Temporal Scales ◽  
Airborne Measurements ◽  
Model Aerosol

Abstract. In this study we aim to assess the WRF-Chem model capacity to reproduce dust transport over the eastern Mediterranean. For this reason, we compare the model aerosol optical depth (AOD) outputs to observations, focusing on three key regions: North Africa, the Arabian Peninsula and the eastern Mediterranean. Three sets of four simulations have been performed for the six-month period of spring and summer 2011. Each simulation set uses a different dust emission parametrisation and for each parametrisation, the dust emissions are multiplied with various coefficients in order to tune the model performance. Our assessment approach is performed across different spatial and temporal scales using AOD observations from satellites and ground-based stations, as well as from airborne measurements of aerosol extinction coefficients over the Sahara. Assessment over the entire domain and simulation period shows that the model presents temporal and spatial variability similar to observed AODs, regardless of the applied dust emission parametrisation. On the other hand, when focusing on specific regions, the model skill varies significantly. Tuning the model performance by applying a coefficient to dust emissions may reduce the model AOD bias over a region, but may increase it in other regions. In particular, the model was shown to realistically reproduce the major dust transport events over the eastern Mediterranean, but failed to capture the regional background AOD. Further comparison of the model simulations to airborne measurements of vertical profiles of extinction coefficients over North Africa suggests that the model realistically reproduces the total atmospheric column AOD. Finally, we discuss the model results in two sensitivity tests, where we included finer dust mode (less than 1 μm) and changed accordingly the dust bins mass fraction.

scholarly journals A Livestock Trampling Function for Potential Emission Rate of Wind-blown Dust in a Mongolian Temperate Grassland

2017 ◽  
Author(s):  
Erdenebayar Munkhtsetseg ◽  
Masato Shinoda ◽  
Masahide Ishizuka ◽  
Masao Mikami ◽  
Reiji Kimura ◽  
...  
Keyword(s):  
Dust Emission ◽  
Background Level ◽  
Temperate Grassland ◽  
Atmospheric Environment ◽  
Test Surface ◽  
Dust Emissions ◽  
Source Regions ◽  
Livestock Density ◽  
Abrupt Changes ◽  
Emission Fluxes

Abstract. Mongolian Grasslands is one of the natural dust source regions and it contributes to anthropogenic dust due to its long tradition of raising livestock. Decades of abrupt changes in a nomadic society necessitate a study on effects of livestock trampling on dust emissions, so that research studies may help maintain sustainable ecosystem and well-conditioned atmospheric environment. For scaling the effect strength of trampling, therefore, we conducted a mini-wind tunnel experiment (by PI-SWERL® device) to measure dust emission fluxes from trampling (at 3 disturbance levels of livestock density, N) and zero trampling (the background level) at test areas in a Mongolian temperate grassland. We found the substantial increase in dust emissions due to the livestock trampling. This positive effect of trampling on dust emissions was persistent throughout all wind friction velocities, u* (varying from 0.44 to 0.82 ms−1). Significantly higher dust loading had occurred after a certain disturbance level has reached by the livestock trampling. Our result suggests that both friction velocity (u*) and disturbance level of livestock density (N) has enormous combinational effect on dust emission from trampling test surface. Furthermore, we successfully developed a livestock trampling function dependant on u* and N. In the livestock trampling function, almost 4 times greater of determinant power for u* than of for N was determined (fL (N, u*) ∼ N1.1u*4). It points that the effect strength of trampling get magnified with an increase in u*, and, therefore dust will emit much as stronger wind prevails at the trampled surfaces. This finding indicates that the effect of trampling can be seen or get into a play in emission when wind is strong. It emphasizes that a better management for livestock allocation coupled with strategies to prevent dust loads is needed, however, there are many uncertainties and assumptions to be improved in this study. The applicability of our result is feasible with a care to other areas beyond the study location.

Recent advances in our understanding of dust source emission processes

2013 ◽  
Vol 37 (3) ◽  
pp. 397-421 ◽  
Author(s):  
Robert G. Bryant
Keyword(s):  
Remote Sensing ◽  
Radiative Forcing ◽  
Climate Models ◽  
Dust Emission ◽  
Remote Sensing Data ◽  
Limiting Factors ◽  
Dust Source ◽  
Dust Emissions ◽  
Sensing Data ◽  
Source Regions

The dust cycle can play an important role in the land–atmosphere–ocean system through interaction with biogeochemical cycles and direct and indirect radiative forcing of the atmosphere. One of the limiting factors for existing global models of dust transport, atmospheric processing and deposition is the quality and availability of data to allow evaluation and validation of emission schemes against in situ data from source regions. This review provides a critical overview of recent studies of aeolian processes from within or on dust sources, and focuses on studies dealing with retrieval of dust emission data, quantification of the contribution and variability of dust emissions from specific landforms, and the use of remote sensing data to reconcile dust storm inventories by direct comparison to dust source geomorphology. These case studies highlight significant advances in both field measurement and regional understanding of important components of the dust cycle derived through use of remote sensing data. However, recent research also demonstrates that most source regions exhibit significant spatial and temporal heterogeneity in dust emissions from candidate geomorphologies, which has direct implications for strategies aimed at inclusion of dust emission schemes at a scale relevant to climate models. To accommodate these factors and other significant scaling issues, additional research is needed to increase our quantification of a wider range of dust source types and geomorphological contexts over longer time periods.

scholarly journals Large-Scale Dust Event in East Asia in May 2017: Dust Emission and Transport from Multiple Source Regions

SOLA ◽  
2018 ◽  
Vol 14 (0) ◽  
pp. 33-38 ◽  
Author(s):  
Yuki Minamoto ◽  
Kotaro Nakamura ◽  
Minrui Wang ◽  
Kei Kawai ◽  
Kazuma Ohara ◽  
...  
Keyword(s):  
East Asia ◽  
Large Scale ◽  
Dust Emission ◽  
Multiple Source ◽  
Dust Event ◽  
Source Regions

scholarly journals Radiative Effect and Mixing Processes of a Long-Lasting Dust Event over Athens, Greece, during the COVID-19 Period

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 318
Author(s):  
Panagiotis Kokkalis ◽  
Ourania Soupiona ◽  
Christina-Anna Papanikolaou ◽  
Romanos Foskinis ◽  
Maria Mylonaki ◽  
...  
Keyword(s):  
Atmospheric Pollutants ◽  
Saharan Dust ◽  
Radiative Effect ◽  
Atmospheric Conditions ◽  
Dust Event ◽  
Mixing Processes ◽  
Hysplit Model ◽  
European Continent ◽  
Dust Layer ◽  
Ground Based Lidar

We report on a long-lasting (10 days) Saharan dust event affecting large sections of South-Eastern Europe by using a synergy of lidar, satellite, in-situ observations and model simulations over Athens, Greece. The dust measurements (11–20 May 2020), performed during the confinement period due to the COVID-19 pandemic, revealed interesting features of the aerosol dust properties in the absence of important air pollution sources over the European continent. During the event, moderate aerosol optical depth (AOD) values (0.3–0.4) were observed inside the dust layer by the ground-based lidar measurements (at 532 nm). Vertical profiles of the lidar ratio and the particle linear depolarization ratio (at 355 nm) showed mean layer values of the order of 47 ± 9 sr and 28 ± 5%, respectively, revealing the coarse non-spherical mode of the probed plume. The values reported here are very close to pure dust measurements performed during dedicated campaigns in the African continent. By utilizing Libradtran simulations for two scenarios (one for typical midlatitude atmospheric conditions and one having reduced atmospheric pollutants due to COVID-19 restrictions, both affected by a free tropospheric dust layer), we revealed negligible differences in terms of radiative effect, of the order of +2.6% (SWBOA, cooling behavior) and +1.9% (LWBOA, heating behavior). Moreover, the net heating rate (HR) at the bottom of the atmosphere (BOA) was equal to +0.156 K/d and equal to +2.543 K/d within 1–6 km due to the presence of the dust layer at that height. On the contrary, the reduction in atmospheric pollutants could lead to a negative HR (−0.036 K/d) at the bottom of the atmosphere (BOA) if dust aerosols were absent, while typical atmospheric conditions are estimated to have an almost zero net HR value (+0.006 K/d). The NMMB-BSC forecast model provided the dust mass concentration over Athens, while the air mass advection from the African to the European continent was simulated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model.

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