A Possible Linkage between Dust Frequency and the Siberian High in March over Northeast Asia

Spring dust frequency in northeast Asia has been investigated using various approaches to understand the mechanisms of dust emission and transport. However, little attention has been paid to the linkage between dust activity and the Siberian High (SH), particularly when the SH pressure system is highly variable. In this study, we characterize the possible physical mechanisms of dust emission and transport associated with the Siberian High Intensity (SHI) and Siberian High Position Index (SHPI) in March using 18 years of ground-based observations and reanalysis data. We found that when the SHI was strong and the SH’s center was farther east (“Strong–East period”), surface and atmospheric temperatures were cooler than when the SHI was weak and the SH’s center was farther west (“Weak-West period”), due to anomalous anticyclonic pressure and strong easterlies. As a result, a reduction in the meridional temperature gradient in the lower atmosphere suppressed dust emission and transport, due to stagnant atmospheric conditions. This anomalous anticyclonic pressure in the Strong-East case seems to reduce the development of extratropical cyclones (ETC) in northeast Asia, leading to a less effective dust transport. A case study with composite analysis also showed a similar physical mechanism: stagnant air accompanying weakened westerlies in the Strong-East period suppressed dust transport to South Korea. Our findings reveal that the intensity and position of the SH can be utilized to identify spring transboundary air pollutants in northeast Asia.

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Empirical atmospheric thresholds for debris flows and flash floods in the southern French Alps

Natural Hazards and Earth System Science ◽

10.5194/nhess-14-1517-2014 ◽

2014 ◽

Vol 14 (6) ◽

pp. 1517-1530 ◽

Cited By ~ 15

Author(s):

T. Turkington ◽

J. Ettema ◽

C. J. van Westen ◽

K. Breinl

Keyword(s):

Debris Flows ◽

Warning System ◽

Flash Floods ◽

Rain Gauge ◽

Reanalysis Data ◽

Specific Humidity ◽

Atmospheric Conditions ◽

Convective Rainfall ◽

French Alps ◽

Mountainous Regions

Abstract. Debris flows and flash floods are often preceded by intense, convective rainfall. The establishment of reliable rainfall thresholds is an important component for quantitative hazard and risk assessment, and for the development of an early warning system. Traditional empirical thresholds based on peak intensity, duration and antecedent rainfall can be difficult to verify due to the localized character of the rainfall and the absence of weather radar or sufficiently dense rain gauge networks in mountainous regions. However, convective rainfall can be strongly linked to regional atmospheric patterns and profiles. There is potential to employ this in empirical threshold analysis. This work develops a methodology to determine robust thresholds for flash floods and debris flows utilizing regional atmospheric conditions derived from ECMWF ERA-Interim reanalysis data, comparing the results with rain-gauge-derived thresholds. The method includes selecting the appropriate atmospheric indicators, categorizing the potential thresholds, determining and testing the thresholds. The method is tested in the Ubaye Valley in the southern French Alps (548 km2), which is known to have localized convection triggered debris flows and flash floods. This paper shows that instability of the atmosphere and specific humidity at 700 hPa are the most important atmospheric indicators for debris flows and flash floods in the study area. Furthermore, this paper demonstrates that atmospheric reanalysis data are an important asset, and could replace rainfall measurements in empirical exceedance thresholds for debris flows and flash floods.

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Atmospheric conditions of thunderstorms in the European part of the Arctic derived from sounding and reanalysis data

Atmospheric Research ◽

10.1016/j.atmosres.2014.11.001 ◽

2015 ◽

Vol 154 ◽

pp. 60-72 ◽

Cited By ~ 6

Author(s):

Bartosz Czernecki ◽

Mateusz Taszarek ◽

Leszek Kolendowicz ◽

Katarzyna Szyga-Pluta

Keyword(s):

Reanalysis Data ◽

European Part ◽

The Arctic ◽

Atmospheric Conditions

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North African dust transport toward the western Mediterranean basin: Atmospheric controls on dust source activation and transport pathways during June–July 2013

10.5194/acp-2016-497 ◽

2016 ◽

Author(s):

Kerstin Schepanski ◽

Marc Mallet ◽

Bernd Heinold ◽

Max Ulrich

Keyword(s):

Atmospheric Circulation ◽

Mediterranean Basin ◽

Dust Emission ◽

Western Mediterranean ◽

North African ◽

Atmospheric Dust ◽

Dust Source ◽

Dust Transport ◽

The Mediterranean ◽

Heat Low

Abstract. Dust transported from North African source region toward the Mediterranean basin and Europe is an ubiquitous phenomenon in the Mediterranean region. Winds formed by large-scale pressure gradients foster dust entrainment into the atmosphere over North African dust source regions and advection of dust downwind. The constellation of centers of high and low pressure determines wind speed and direction, and thus the chance for dust emission over Northern Africa and transport toward the Mediterranean. Here, we present characteristics of the atmospheric dust life-cycle determining dust transport toward the Mediterranean basin. Using the atmosphere-dust model COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdelling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model), a complementary analysis of dust source activation, emission fluxes, transport pathways, and deposition rates is provided with focus on the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) special observation period in June and July 2013. Modes of atmospheric circulation, identified from empirical orthogonal function (EOF) analysis of the geopotential height at 850 hPa are used for investigating the characteristics of the atmospheric dust life-cycle regarding the atmospheric circulation over the Mediterranean. Two different phases are identified from the first EOF, which in total are explaining 45 % of the variance. They are characterized by the propagation of the subtropical ridge into the Mediterranean basin, the position of the Saharan heat low and the predominance Iberian heat low and discussed illustrating a dipole pattern for enhanced (reduced) dust emission fluxes, stronger (weaker) meridional dust transport, and consequent increased (decreased) atmospheric dust concentrations and deposition fluxes. In case of a predominant high pressure zone over the western and central Mediterranean (positive phase), a hot spot in dust emission flux is evident over the Grand Erg Occidental and reduced level of atmospheric dust loading occurs over the western Mediterranean basin. The meridional transport in northward direction is reduced due to prevailing northerly winds. In case of a predominant heat low trough linking the Iberian and the Sahara heat low (negative phase), meridional dust transport toward the western Mediterranean is increased due to prevailing southerly winds resulting into an enhanced atmospheric dust loading over the western Mediterranean. Altogether, results form this study illustrate the relevance of knowing dust source location in concert with atmospheric circulation. The study elaborates the question on the variability of dust transport toward the Mediterranean and Europe in dependence on the atmospheric circulation as a driver for dust emission and a determinant for dust transport routes, exemplarily for the two-month period June to July 2013. Ultimately, outcomes from this study contribute to the understanding of the variance in dust transport into a populated region.

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Atmospheric forcing of coastal polynyas in the south-western Weddell Sea

Antarctic Science ◽

10.1017/s0954102014000893 ◽

2015 ◽

Vol 27 (4) ◽

pp. 388-402 ◽

Cited By ~ 13

Author(s):

Verena Haid ◽

Ralph Timmermann ◽

Lars Ebner ◽

Günther Heinemann

Keyword(s):

Sea Ice ◽

Large Scale ◽

Reanalysis Data ◽

Ocean Model ◽

Weddell Sea ◽

Small Scale ◽

Atmospheric Conditions ◽

Atmospheric Forcing ◽

The South ◽

Ice Production

AbstractThe development of coastal polynyas, areas of enhanced heat flux and sea ice production strongly depend on atmospheric conditions. In Antarctica, measurements are scarce and models are essential for the investigation of polynyas. A robust quantification of polynya exchange processes in simulations relies on a realistic representation of atmospheric conditions in the forcing dataset. The sensitivity of simulated coastal polynyas in the south-western Weddell Sea to the atmospheric forcing is investigated with the Finite-Element Sea ice-Ocean Model (FESOM) using daily NCEP/NCAR reanalysis data (NCEP), 6 hourly Global Model Europe (GME) data and two different hourly datasets from the high-resolution Consortium for Small-Scale Modelling (COSMO) model. Results are compared for April to August in 2007–09. The two coarse-scale datasets often produce the extremes of the data range, while the finer-scale forcings yield results closer to the median. The GME experiment features the strongest winds and, therefore, the greatest polynya activity, especially over the eastern continental shelf. This results in higher volume and export of High Salinity Shelf Water than in the NCEP and COSMO runs. The largest discrepancies between simulations occur for 2008, probably due to differing representations of the ENSO pattern at high southern latitudes. The results suggest that the large-scale wind field is of primary importance for polynya development.

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Northeast Asian Dust Transport: A Case Study of a Dust Storm Event from 28 March to 2 April 2012

Atmosphere ◽

10.3390/atmos10020069 ◽

2019 ◽

Vol 10 (2) ◽

pp. 69 ◽

Cited By ~ 3

Author(s):

Purevsuren Tsedendamba ◽

Jugder Dulam ◽

Kenji Baba ◽

Katsuro Hagiwara ◽

Jun Noda ◽

...

Keyword(s):

Lower Layer ◽

Northeast Asia ◽

Source Area ◽

Northern China ◽

Storm Event ◽

Dust Transport ◽

Lidar Measurements ◽

Dust Storm Event ◽

Northeast Asian ◽

The Vertical Distribution

The distribution and transport of windblown dust that occurred in Northeast Asia from 28 March to 2 April 2012 was investigated. Data of particulate matter less than 10 micrometers (PM10) near the surface and light detection and ranging (LiDAR) measurements from the ground up to 18 km were used in the study. A severe dust event originated over southern Mongolia and northern China on 28 March 2012, and the widespread dust moved from the source area southeastward toward Japan over several days. Windblown dust reached Japan after two days from the originating area. LiDAR measurements of the vertical distribution of the dust were one to two km thick in the lower layer of the atmosphere, and increased with the increasing distance from the source area.

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The Determination of Aerosol Distribution by a No-Blind-Zone Scanning Lidar

Remote Sensing ◽

10.3390/rs12040626 ◽

2020 ◽

Vol 12 (4) ◽

pp. 626 ◽

Cited By ~ 1

Author(s):

Jie Wang ◽

Wenqing Liu ◽

Cheng Liu ◽

Tianshu Zhang ◽

Jianguo Liu ◽

...

Keyword(s):

Mass Movement ◽

Ground Level ◽

Pollution Sources ◽

Lower Atmosphere ◽

In Situ Observation ◽

Atmospheric Conditions ◽

Lidar System ◽

Blind Zone ◽

Aerosol Distribution ◽

Receiver System

A homemade portable no-blind zone laser detection and ranging (lidar) system was designed to map the three-dimensional (3D) distribution of aerosols based on a dual-field-of-view (FOV) receiver system. This innovative lidar prototype has a space resolution of 7.5 m and a time resolution of 30 s. A blind zone of zero meters, and a transition zone of approximately 60 m were realized with careful optical alignments, and were rather meaningful to the lower atmosphere observation. With a scanning platform, the lidar system was used to locate the industrial pollution sources at ground level. The primary parameters of the transmitter, receivers, and detectors are described in this paper. Acquiring a whole return signal of this lidar system represents the key step to the retrieval of aerosol distribution with applying a linear joining method to the two FOV signals. The vertical profiles of aerosols were retrieved by the traditional Fernald method and verified by real-time observations. To effectively and reliably retrieve the horizontal distributions of aerosols, a composition of the Fernald method and the slope method were applied. In this way, a priori assumptions of even atmospheric conditions and the already-known reference point in the lidar equation were avoided. No-blind-zone vertical in-situ observation of aerosol illustrated a detailed evolution from almost 0 m to higher altitudes. No-blind-zone detection provided tiny structures of pollution distribution in lower atmosphere, which is closely related to human health. Horizontal field scanning experiments were also conducted in the Shandong Province. The results showed a high accuracy of aerosol mass movement by this lidar system. An effective quantitative way to locate pollution sources distribution was paved with the portable lidar system after validation by the mass concentration of suspended particulate matter from a ground air quality station.

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The spatial distribution of mineral dust and its shortwave radiative forcing over North Africa: modeling sensitivities to dust emissions and aerosol size treatments

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-8821-2010 ◽

2010 ◽

Vol 10 (18) ◽

pp. 8821-8838 ◽

Cited By ~ 174

Author(s):

C. Zhao ◽

X. Liu ◽

L. R. Leung ◽

B. Johnson ◽

S. A. McFarlane ◽

...

Keyword(s):

North Africa ◽

Radiative Forcing ◽

Mineral Dust ◽

Regional Climate ◽

Dust Emission ◽

Radiative Properties ◽

Lower Atmosphere ◽

Dust Particles ◽

Dust Emissions ◽

Sahel Region

Abstract. A fully coupled meteorology-chemistry-aerosol model (WRF-Chem) is applied to simulate mineral dust and its shortwave (SW) radiative forcing over North Africa. Two dust emission schemes (GOCART and DUSTRAN) and two aerosol models (MADE/SORGAM and MOSAIC) are adopted in simulations to investigate the modeling sensitivities to dust emissions and aerosol size treatments. The modeled size distribution and spatial variability of mineral dust and its radiative properties are evaluated using measurements (ground-based, aircraft, and satellites) during the AMMA SOP0 campaign from 6 January to 3 February of 2006 (the SOP0 period) over North Africa. Two dust emission schemes generally simulate similar spatial distributions and temporal evolutions of dust emissions. Simulations using the GOCART scheme with different initial (emitted) dust size distributions require ~40% difference in total emitted dust mass to produce similar SW radiative forcing of dust over the Sahel region. The modal approach of MADE/SORGAM retains 25% more fine dust particles (radius<1.25 μm) but 8% less coarse dust particles (radius>1.25 μm) than the sectional approach of MOSAIC in simulations using the same size-resolved dust emissions. Consequently, MADE/SORGAM simulates 11% higher AOD, up to 13% lower SW dust heating rate, and 15% larger (more negative) SW dust radiative forcing at the surface than MOSAIC over the Sahel region. In the daytime of the SOP0 period, the model simulations show that the mineral dust heats the lower atmosphere with an average rate of 0.8 ± 0.5 K day−1 over the Niamey vicinity and 0.5 ± 0.2 K day−1 over North Africa and reduces the downwelling SW radiation at the surface by up to 58 W m−2 with an average of 22 W m−2 over North Africa. This highlights the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, the WRF-Chem simulations can generally capture the measured features of mineral dust and its radiative properties over North Africa, suggesting that the model is suitable for more extensive simulations of dust impact on regional climate over North Africa.

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Examination of Errors in Near-Surface Temperature and Wind from WRF Numerical Simulations in Regions of Complex Terrain

Weather and Forecasting ◽

10.1175/waf-d-12-00109.1 ◽

2013 ◽

Vol 28 (3) ◽

pp. 893-914 ◽

Cited By ~ 90

Author(s):

Hailing Zhang ◽

Zhaoxia Pu ◽

Xuebo Zhang

Keyword(s):

Complex Terrain ◽

Forecast Error ◽

Wrf Model ◽

Atmospheric Temperature ◽

Lower Atmosphere ◽

Forecast Errors ◽

Atmospheric Conditions ◽

Near Surface ◽

System A ◽

Synoptic Forcing

Abstract The performance of an advanced research version of the Weather Research and Forecasting Model (WRF) in predicting near-surface atmospheric temperature and wind conditions under various terrain and weather regimes is examined. Verification of 2-m temperature and 10-m wind speed and direction against surface Mesonet observations is conducted. Three individual events under strong synoptic forcings (i.e., a frontal system, a low-level jet, and a persistent inversion) are first evaluated. It is found that the WRF model is able to reproduce these weather phenomena reasonably well. Forecasts of near-surface variables in flat terrain generally agree well with observations, but errors also occur, depending on the predictability of the lower-atmospheric boundary layer. In complex terrain, forecasts not only suffer from the model's inability to reproduce accurate atmospheric conditions in the lower atmosphere but also struggle with representative issues due to mismatches between the model and the actual terrain. In addition, surface forecasts at finer resolutions do not always outperform those at coarser resolutions. Increasing the vertical resolution may not help predict the near-surface variables, although it does improve the forecasts of the structure of mesoscale weather phenomena. A statistical analysis is also performed for 120 forecasts during a 1-month period to further investigate forecast error characteristics in complex terrain. Results illustrate that forecast errors in near-surface variables depend strongly on the diurnal variation in surface conditions, especially when synoptic forcing is weak. Under strong synoptic forcing, the diurnal patterns in the errors break down, while the flow-dependent errors are clearly shown.

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Convective distribution of dust over the Arabian Peninsula: the impact of model resolution

10.5194/acp-2019-197 ◽

2019 ◽

Cited By ~ 1

Author(s):

Jennie Bukowski ◽

Susan C. van den Heever

Keyword(s):

Arabian Peninsula ◽

Dust Emission ◽

Dust Storms ◽

Radiation Budget ◽

Grid Spacing ◽

Heating Rates ◽

Dust Transport ◽

Order Of Magnitude ◽

The Impact ◽

Cumulus Parameterizations

Abstract. Along the coasts of the Arabian Peninsula, convective dust storms are a considerable source of mineral dust to the atmosphere. Reliable predictions of convective dust events are necessary to determine their effects on air quality, visibility, and the radiation budget. In this study, the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) is used to simulate a 2016 summertime dust event over the Arabian Peninsula and examine the variability in dust fields and associated vertical transport due to the choice of convective parameterization and explicit versus parameterized convection. Simulations are run at 45 km and 15 km grid spacing with multiple cumulus parameterizations, and are compared to a 3 km simulation that permits explicit convective processes. Five separate cumulus parameterizations at 15 km grid spacing were tested to quantify the spread across different parameterizations. Finally, the impact these variations have on radiation, specifically aerosol heating rates is also investigated. On average, in these simulations the explicit case produces higher quantities of dust than the parameterized cases in terms of dust uplift potential, vertical dust concentrations, and vertical dust fluxes. Major drivers of this discrepancy between the simulations stem from the explicit case exhibiting higher surface windspeeds during convective activity, lower dust emission wind threshold velocities due to drier soil, and more frequent, stronger vertical velocities which transport dust aloft and increase the atmospheric lifetime of these particles. For aerosol heating rates in the lowest levels, the shortwave effect prevails in the explicit case with a net cooling effect, whereas a longwave net warming effect is present in the parameterized cases. The spread in dust concentrations across cumulus parameterizations at the same grid resolution (15 km) is an order of magnitude lower than the impact of moving from parameterized to explicit convection. We conclude that tuning dust emissions in coarse resolution simulations can only improve the results to first-order and cannot fully rectify the discrepancies originating from disparities in the representation of convective dust transport.

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Climatic variability of the mean flow and stationary planetary waves in the NCEP/NCAR reanalysis data

Annales Geophysicae ◽

10.5194/angeo-26-1233-2008 ◽

2008 ◽

Vol 26 (5) ◽

pp. 1233-1241 ◽

Cited By ~ 11

Author(s):

A. Yu. Kanukhina ◽

E. V. Suvorova ◽

L. A. Nechaeva ◽

E. K. Skrygina ◽

A. I. Pogoreltsev

Keyword(s):

Lower Stratosphere ◽

Climatic Variability ◽

Reanalysis Data ◽

Planetary Waves ◽

Lower Atmosphere ◽

Wave Number ◽

Mean Flow ◽

The Mean ◽

The 1960S ◽

Environmental Prediction

Abstract. NCEP/NCAR (National Center for Environmental Prediction – National Center for Atmospheric Research) data have been used to estimate the long-term variability of the mean flow, temperature, and Stationary Planetary Waves (SPW) in the troposphere and lower stratosphere. The results obtained show noticeable climatic variabilities in the intensity and position of the tropospheric jets that are caused by temperature changes in the lower atmosphere. As a result, we can expect that this variability of the mean flow will cause the changes in the SPW propagation conditions. The simulation of the SPW with zonal wave number m=1 (SPW1), performed with a linearized model using the mean flow distributions typical for the 1960s and for the beginning of 21st century, supports this assumption and shows that during the last 40 years the amplitude of the SPW1 in the stratosphere and mesosphere increased substantially. The analysis of the SPW amplitudes extracted from the geopotential height and zonal wind NCEP/NCAR data supports the results of simulation and shows that during the last years there exists an increase in the SPW1 activity in the lower stratosphere. These changes in the amplitudes are accompanied by increased interannual variability of the SPW1, as well. Analysis of the SPW2 activity shows that changes in its amplitude have a different sign in the northern winter hemisphere and at low latitudes in the southern summer hemisphere. The value of the SPW2 variability differs latitudinally and can be explained by nonlinear interference of the primary wave propagation from below and from secondary SPW2.

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