scholarly journals Impacts of Meteorological Uncertainties on the Haze Formation in Beijing-Tianjin-Hebei (BTH) during Wintertime: A case study

2017 ◽  
Author(s):  
Naifang Bei ◽  
Jiarui Wu ◽  
Tian Feng ◽  
Junji Cao ◽  
Rujin Huang ◽  
...  
Keyword(s):  
Fine Particles ◽  
Initial Conditions ◽  
Control Strategies ◽  
Temporal Variations ◽  
Ensemble Mean ◽  
Haze Episode ◽  
Haze Formation ◽  
Region Scale ◽  
The Impact

Abstract. In the present study, a persistent heavy haze episode from 13 to 20 January 2014 in Beijing-Tianjin-Hebei (BTH) is simulated using the WRF-CHEM model through ensemble simulations to investigate impacts of meteorological initial uncertainties on the haze formation. Model results have shown that uncertainties in meteorological initial conditions substantially influence the aerosol constituent simulations at an observation site in Beijing, and the ratio of the ensemble spread to ensemble mean (RESM) exceeds 50 %. The ensemble mean generally preforms well in reproducing the fine particles (PM2.5) temporal variations and spatial distributions against measurements in BTH. The initial meteorological uncertainties do not alter the PM2.5 distribution pattern in BTH principally or dominate the haze formation and development, but remarkably affect the simulated PM2.5 level, and the RESM of PM2.5 concentrations can be up to 30 % at the region scale. In addition, the rather large RESM in PM2.5 simulations at the city scale also causes difficulties in implementation of the control strategies. Therefore, our results suggest that the ensemble simulation is imperative to avoid the impact of the initial meteorological uncertainties on the haze prediction.

scholarly journals Impacts of meteorological uncertainties on the haze formation in Beijing–Tianjin–Hebei (BTH) during wintertime: a case study

2017 ◽  
Vol 17 (23) ◽  
pp. 14579-14591 ◽  
Author(s):  
Naifang Bei ◽  
Jiarui Wu ◽  
Miriam Elser ◽  
Tian Feng ◽  
Junji Cao ◽  
...  
Keyword(s):  
Fine Particles ◽  
Control Strategies ◽  
Regional Scale ◽  
Temporal Variations ◽  
Ensemble Mean ◽  
Haze Episode ◽  
Haze Formation ◽  
The Impact ◽  
The City

Abstract. In the present study, a persistent heavy haze episode from 13 to 20 January 2014 in Beijing–Tianjin–Hebei (BTH) is simulated using the WRF-CHEM model through ensemble simulations to investigate impacts of meteorological uncertainties on the haze formation. Model results show that uncertainties in meteorological conditions substantially influence the aerosol constituent simulations at an observation site in Beijing, and the ratio of the ensemble spread to the ensemble mean (RESM) exceeds 50 %. The ensemble mean generally preforms well in reproducing the fine particles' (PM2.5) temporal variations and spatial distributions against measurements in BTH. The meteorological uncertainties do not alter the PM2.5 distribution pattern in BTH principally or dominate the haze formation and development, but remarkably affect the simulated PM2.5 level, and the RESM for the simulated PM2.5 concentrations can be up to 30 % at the regional scale. In addition, the rather large RESM in PM2.5 simulations at the city scale also causes difficulties in evaluation of the control strategies. Therefore, our results suggest that the ensemble simulation is imperative to take into account the impact of the meteorological uncertainties on the haze prediction.

scholarly journals Does afforestation deteriorate haze pollution in Beijing–Tianjin–Hebei (BTH), China?

2018 ◽  
Author(s):  
Xin Long ◽  
Naifang Bei ◽  
Jiarui Wu ◽  
Xia Li ◽  
Tian Feng ◽  
...  
Keyword(s):  
Forest Cover ◽  
Fine Particles ◽  
Control Strategies ◽  
Surface Wind ◽  
Forecast Model ◽  
Surface Wind Speed ◽  
Satellite Measurements ◽  
Haze Pollution ◽  
The Impact

Abstract. Although aggressive emission control strategies have been implemented recently in the Beijing–Tianjin–Hebei area (BTH), China, pervasive and persistent haze still frequently engulfs the region during wintertime. Afforestation in BTH, primarily concentrated in the Taihang and Yanshan Mountains, has constituted one of the controversial factors exacerbating the haze pollution due to its slowdown of the surface wind speed. We report here an increasing trend of forest cover in BTH during 2001–2013 based on long-term satellite measurements and the impact of the afforestation on the fine particles (PM2.5) level. Simulations using the Weather Research and Forecast model with chemistry reveal that the afforestation in BTH since 2001 generally deteriorates the haze pollution in BTH to some degree, enhancing PM2.5 concentrations by up to 6 % on average. Complete afforestation or deforestation in the Taihang and Yanshan Mountains would increase or decrease the PM2.5 level within 15 % in BTH. Our model results also suggest that implementing a large ventilation corridor system would not be effective or beneficial to mitigate the haze pollution in Beijing.

Temporal variations of atmospheric ammonia (NH3) derived from over a decade of IASI satellite measurements

2021 ◽  
Author(s):  
Martin Van Damme ◽  
Lieven Clarisse ◽  
Bruno Franco ◽  
Mark A Sutton ◽  
Jan Willem Erisman ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
The Netherlands ◽  
Temporal Variation ◽  
Temporal Variations ◽  
Meteorological Conditions ◽  
Satellite Measurements ◽  
Atmospheric Sounding ◽  
National Trends ◽  
The Impact

<p>The Infrared Atmospheric Sounding Interferometer (IASI) mission consists of a suite of three infrared sounders providing today over 13 years of consistent global measurements (from end of 2007 up to now). In this work we use the recently developed version 3 of the IASI NH<sub>3</sub> dataset to derive global, regional and national trends from 2008 to 2018. Reported national trends are analysed in the light of changing anthropogenic and pyrogenic NH<sub>3</sub> emissions, meteorological conditions and the impact of sulphur and nitrogen oxides emissions. A case study is dedicated to the Netherlands. Temporal variation on shorter timescales will also be investigated.</p>

scholarly journals Assessing the role of inter-facility patient transfer in the spread of carbapenemase-producing Enterobacteriaceae: the case of France between 2012 and 2015

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Narimane Nekkab ◽  
Pascal Crépey ◽  
Pascal Astagneau ◽  
Lulla Opatowski ◽  
Laura Temime
Keyword(s):  
Control Strategies ◽  
Patient Transfer ◽  
Spatial Distance ◽  
Patient Transfers ◽  
Healthcare Facilities ◽  
Healthcare Settings ◽  
The Impact ◽  
Local Transmission

Abstract The spread of carbapenemase-producing Enterobacteriaceae (CPE) in healthcare settings is a major public health threat that has been associated with cross-border and local patient transfers between healthcare facilities. Since the impact of transfers on spread may vary, our study aimed to assess the contribution of a patient transfer network on CPE incidence and spread at a countrywide level, with a case study of France from 2012 to 2015. Our results suggest a transition in 2013 from a CPE epidemic sustained by internationally imported episodes to an epidemic sustained by local transmission events through patient transfers. Incident episodes tend to occur within close spatial distance of their potential infector. We also observe an increasing frequency of multiple spreading events, originating from a limited number of regional hubs. Consequently, coordinated prevention and infection control strategies should focus on transfers of carriers of CPE to reduce regional and inter-regional transmission.

scholarly journals The Potential of Reflective Journals in Studying Complexity 'In Action'

2005 ◽  
Vol 2 (1) ◽  
Author(s):  
Renata Phelps
Keyword(s):  
Action Research ◽  
Initial Conditions ◽  
Real Life ◽  
External Control ◽  
Learning And Teaching ◽  
Reflective Journals ◽  
Information And Communication ◽  
Learning And Change ◽  
The Impact

As educators embrace theories of complexity to inform their teaching and research practice, theoretically relevant methods will be required to appropriately conduct and study complexity-based approaches to education. Action research has been identified as offering significant potential for studying complexity, acting as a form of ‘real life modeling’ for learning and teaching. In this paper it is argued that reflection, a key aspect of action research, can be a productive method for both studying and working with complexity in educational contexts. Reflective journals, more specifically, provide scope not only for gathering research data but also for promoting learning and change. As a teaching approach, reflective journals can reduce the impact of external control while providing opportunities to promote and document instability and disequilibrium. Reflective journals allow for documentation of emergence and bifurcation and embrace participants’ involvement in interpretation of data in inherently non-linear ways. Reflective journals assist to build up an holistic picture of the interplay between individuals’ histories and their current and emergent ‘state’, thus providing insight into ‘sensitivity to initial conditions’. This paper illustrates these theoretical ideas through a case study derived from a course in information and communication technology (ICT) for practicing teachers.

scholarly journals Comparison of Ensemble Kalman Filter–Based Forecasts to Traditional Ensemble and Deterministic Forecasts for a Case Study of Banded Snow

2012 ◽  
Vol 27 (1) ◽  
pp. 85-105 ◽  
Author(s):  
Astrid Suarez ◽  
Heather Dawn Reeves ◽  
Dustan Wheatley ◽  
Michael Coniglio
Keyword(s):  
Kalman Filter ◽  
Flow Pattern ◽  
Ensemble Kalman Filter ◽  
Initial Conditions ◽  
Closed Surface ◽  
Flow Patterns ◽  
Precipitation Forecast ◽  
Ensemble Mean ◽  
Correct Location

Abstract The ensemble Kalman filter (EnKF) technique is compared to other modeling approaches for a case study of banded snow. The forecasts include a 12- and 3-km grid-spaced deterministic forecast (D12 and D3), a 12-km 30-member ensemble (E12), and a 12-km 30-member ensemble with EnKF-based four-dimensional data assimilation (EKF12). In D12 and D3, flow patterns are not ideal for banded snow, but they have similar precipitation accumulations in the correct location. The increased resolution did not improve the quantitative precipitation forecast. The E12 ensemble mean has a flow pattern favorable for banding and precipitation in the approximate correct location, although the magnitudes and probabilities of relevant features are quite low. Six members produced good forecasts of the flow patterns and the precipitation structure. The EKF12 ensemble mean has an ideal flow pattern for banded snow and the mean produces banded precipitation, but relevant features are about 100 km too far north. The EKF12 has a much lower spread than does E12, a consequence of their different initial conditions. Comparison of the initial ensemble means shows that EKF12 has a closed surface low and a region of high low- to midlevel humidity that are not present in E12. These features act in concert to produce a stronger ensemble-mean cyclonic system with heavier precipitation at the time of banding.

scholarly journals A Case Study of Downstream Baroclinic Development over the North Pacific Ocean. Part I: Dynamical Impacts

2006 ◽  
Vol 134 (5) ◽  
pp. 1534-1548 ◽  
Author(s):  
Richard E. Danielson ◽  
John R. Gyakum ◽  
David N. Straub
Keyword(s):  
North Pacific ◽  
Initial Conditions ◽  
North Pacific Ocean ◽  
The North ◽  
Potential Vorticity Inversion ◽  
Surface Cyclone ◽  
Upper Level ◽  
The Impact ◽  
The North Pacific

Abstract The impact of eddy energy growth and radiation from a western North Pacific cyclone on the intensity of an eastern North Pacific cyclone a few days later is examined. Associated with the western cyclone is an upstream ridge and trough couplet, initially over Siberia on 8 March 1977. The amplitude of this couplet is perturbed in 5-day numerical simulations of the two marine cyclones. Balanced initial conditions are created by potential vorticity inversion. The magnitude of the upper-level couplet governs much of the subsequent growth of eddy energy in the western cyclone as well as the propagation of eddy energy between the two cyclones. This culminates in measurable changes in the maximum intensity of the eastern surface cyclone. The broader question of the sensitivity of this cyclone to upstream perturbations is also briefly addressed.

scholarly journals Uncertainties in SOA simulations due to meteorological uncertainties in Mexico City during MILAGRO-2006 field campaign

2012 ◽  
Vol 12 (7) ◽  
pp. 16293-16326
Author(s):  
N. Bei ◽  
G. Li ◽  
L. T. Molina
Keyword(s):  
Wind Speed ◽  
Mexico City ◽  
Initial Conditions ◽  
Early Morning ◽  
Temporal Variations ◽  
Basis Set ◽  
Peak Time ◽  
Field Campaign ◽  
Ensemble Simulations ◽  
Ensemble Mean

Abstract. The purpose of the present study is to investigate the uncertainties in simulating secondary organic aerosol (SOA) in Mexico City metropolitan area (MCMA) due to meteorological initial uncertainties using the WRF-CHEM model through ensemble simulations. The simulated periods (24 and 29 March 2006) represent two typical meteorological episodes ("Convection-South" and "Convection-North", respectively) in the Mexico City basin during the MILAGRO-2006 field campaign. The organic aerosols are simulated using a non-traditional SOA model including the volatility basis-set modeling method and the contributions from glyoxal and methylglyoxal. Model results demonstrate that uncertainties in meteorological initial conditions have significant impacts on SOA simulations, including the peak time concentrations, the horizontal distributions, and the temporal variations. The ensemble spread of the simulated peak SOA at T0 can reach up to 4.0 &microg m−3 during the daytime, which is around 35% of the ensemble mean. Both the basin wide wind speed and the convergence area affect the magnitude and the location of the simulated SOA concentrations inside the Mexico City basin. The wind speed, especially during the previous midnight and the following early morning, influences the magnitude of the peak SOA concentration through ventilation. The surface horizontal convergence zone generally determines the area with high SOA concentrations. The magnitude of the ensemble spreads may vary with different meteorological episodes but has same significance compared to the ensemble mean.

scholarly journals Mesoscale modeling study of the interactions between aerosols and PBL meteorology during a haze episode in China Jing-Jin-Ji and its near surrounding region – Part 2: Aerosols' radiative feedback effects

2014 ◽  
Vol 14 (20) ◽  
pp. 28269-28298 ◽  
Author(s):  
H. Wang ◽  
G. Y. Shi ◽  
X. Y. Zhang ◽  
S. L. Gong ◽  
S. C. Tan ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Radiative Forcing ◽  
Subtropical High ◽  
Shanxi Province ◽  
Radiative Feedback ◽  
Atmospheric Stratification ◽  
Haze Pollution ◽  
Haze Episode ◽  
Haze Formation ◽  
The Impact

Abstract. Two model experiments, namely a control (CTL) experiment without aerosol-radiation feedbacks and a RAD experiment with online aerosol-radiation interactions, were designed to study the radiative feedback on regional radiation budgets, PBL meteorology and haze formation due to aerosols during haze episodes over China Jing-Jin-Ji and its near surroundings (3JNS Region, for Beijing, Tianjin, Hebei Province, East Shanxi Province, West Shandong Province and North Henan Province) with a two-way atmospheric chemical transport model. The impact of aerosols on solar radiation reaching Earth's surface, outgoing longwave emission at the top of the atmosphere, air temperature, PBL turbulence diffusion, PBL height, wind speeds, air pressure pattern and PM2.5 has been studied focusing on a haze episode during the period from 7 to 11 July 2008. The results show that the mean solar radiation flux that reaches the ground decreases about 15% in China 3JNS Region and by 20 to 25% in the region with the highest AOD during the haze episode. The fact that aerosol cools the PBL atmosphere but warms the atmosphere above it leads to a more stable atmospheric stratification over the region, which causes a decrease in about 52% of turbulence diffusion and a decrease in about 33% of the PBL height. This consequently forms a positive feedback on the particle concentration within the PBL and the surface as well as the haze formation. On the other hands, aerosol DRF (direct radiative forcing) increases about 9% of PBL wind speed, weakens the subtropical high by about 14 hPa, which aids the collapse of haze pollution, resulting in a negative feedback to the haze episode. The synthetic impacts from the two opposite feedbacks result in about a 14% increase in surface PM2.5. However, the persistence time of both high PM2.5 and haze pollution is not effected by the aerosol DRF. On the contrary over offshore China, aerosols heat the PBL atmosphere and cause unstable atmospheric stratification, but the impact and its feedback on the PBLH, turbulence diffusion and wind is weak except its evident impacts on the subtropical high.

Sign in / Sign up

Export Citation Format

Share Document