Changing Temperature Inversion Characteristics in the U.S. Southwest and Relationships to Large-Scale Atmospheric Circulation

2011 ◽  
Vol 50 (6) ◽  
pp. 1307-1323 ◽  
Author(s):  
Adriana Bailey ◽  
Thomas N. Chase ◽  
John J. Cassano ◽  
David Noone
Keyword(s):  
Air Quality ◽  
Large Scale ◽  
Salt Lake ◽  
American Southwest ◽  
Radiosonde Data ◽  
Climatic Data ◽  
Large Scale Circulation ◽  
Near Surface ◽  
Inversion Frequency ◽  
Global Telecommunication System

AbstractContinental temperature inversions significantly influence air quality, yet little is known about their variability in frequency and intensity with time or sensitivity to dynamical changes with climate. Inversion statistics for six upper-air stations in the American Southwest are derived for the period 1994–2008 from radiosonde data reported by the Global Telecommunication System (GTS) and National Climatic Data Center (NCDC), which use different significant level standards. GTS data indicate that low-level elevated inversions have increased in frequency at four of six sites, consistent with enhanced regional stagnation projected by models. NCDC data, in contrast, show remarkable declines in weak, near-surface inversions through 2001, indicating local surface conditions may counteract atmospheric dynamics in regulating inversion activity and air quality. To further test the sensitivity of inversion activity to climate, associations between wintertime inversion frequency and large-scale circulation are quantified using the self-organizing map technique. Twenty-four representative circulation patterns are derived from North American Regional Reanalysis (NARR) 500-hPa geopotential height fields, and these patterns are correlated with inversion frequency at each site. Inversion activity in Salt Lake City, Utah, and Albuquerque and Santa Teresa, New Mexico, is found to correspond well with large-scale anticyclonic ridging; however, sensitivities to large-scale circulation in Denver, Colorado, and Flagstaff and Tucson, Arizona, are weak. Denver stands out in exhibiting a higher percentage of near-surface inversions in winter than the other southwestern sites. These findings indicate that dynamical changes with climate will not uniformly influence inversions and hence urban air quality conditions in the American Southwest.

Regional Downscaling for Air Quality Assessment

2007 ◽  
Vol 88 (8) ◽  
pp. 1215-1228 ◽  
Author(s):  
William I. Gustafson ◽  
L. Ruby Leung
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Quality Assessment ◽  
Large Scale ◽  
Dynamical Downscaling ◽  
Circulation Model ◽  
The United States ◽  
Climate Simulation ◽  
Large Scale Circulation ◽  
Air Quality Assessment

Assessing future changes in air quality using downscaled climate scenarios is a relatively new application of the dynamical downscaling technique. This article compares and evaluates two downscaled simulations for the United States made using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model with the goal of understanding how errors in the downscaled climate simulations may introduce uncertainty in air quality assessment. The two downscaled simulations were driven by boundary conditions from the NCEP–NCAR global reanalysis and a global climate simulation generated by the Goddard Institute for Space Studies global circulation model, respectively. Comparisons of the model runs are made against the boundary layer and circulation characteristics of the North American Regional Reanalysis, and also against observed precipitation. The relative dependence of different simulated quantities on regional forcing, model parameterizations, and large-scale circulation provides a framework to understand similarities and differences between model simulations. Results show significant improvements in the downscaled diurnal wind patterns, in response to the complex orography, that are important for air quality assessment. Evaluation of downscaled boundary layer depth and winds, precipitation, and large-scale circulation shows larger biases related to model physics and biases in the GCM large-scale conditions. Based on the comparisons, recommendations are made to improve the utility of downscaled scenarios for air quality assessment.

Linking air stagnation in Europe with the large-scale atmospheric circulation

2021 ◽  
Author(s):  
Jacob Maddison ◽  
Marta Abalos ◽  
David Barriopedro ◽  
Ricardo Garcia Herrera ◽  
José Manuel Garrido Pérez ◽  
...  
Keyword(s):  
Air Quality ◽  
Health Risks ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Climate Models ◽  
Large Scale Circulation ◽  
Rossby Wave Breaking ◽  
The North ◽  
Weak Winds

<div>Air stagnation refers to a period when a stable air mass becomes settled over a region and remains quasi-stationary for an extended amount of time. Weak winds in the lower- to mid-troposphere and the absence of precipitation during air stagnation prohibit the ventilation and washout of particles so pollutants can accumulate near the surface. This allows for such pollutants to reach levels harmful to humans, and poses severe health risks. Understanding the development of stagnant conditions is therefore crucial for studying poor air quality and its societal impact. </div><p><br>Here, the linear relationship between European air stagnation and the large-scale circulation is explored across all seasons and during the 1979--2018 period. Dynamical based indices identifying atmospheric blocking, Rossby wave breaking, subtropical ridges, and the North Atlantic eddy-driven and subtropical jets are used to describe the large-scale circulation as predictors in a statistical model of air stagnation variability. It is found that the large-scale circulation can explain approximately 60% of the variance in monthly air stagnation in five distinct regions within Europe. The variance explained by the model does not vary strongly across regions and seasons. However, the dynamical indices most related to air stagnation do depend on region and season. The blocking and Rossby wave breaking predictors tend to be the most important for describing air stagnation variability in northern regions whereas ridges and the subtropical jet are more important to the south. The demonstrated correspondence between air stagnation and the large-scale circulation can be used to assess the representation of air stagnation in climate models, which is key for understanding how air quality and its associated health risks may change in the future.</p>

The influence of the large-scale circulation on the thermodynamic profiles in the trades from a Lagrangian perspective

2020 ◽  
Author(s):  
Leonie Villiger ◽  
Franziska Aemisegger ◽  
Maxi Boettcher ◽  
Heini Wernli
Keyword(s):  
Large Scale ◽  
Surface Wind ◽  
Cloud Amount ◽  
Phase Changes ◽  
Stable Water Isotopes ◽  
Geophysical Research ◽  
Large Scale Circulation ◽  
Near Surface ◽  
Diabatic Processes ◽  
The Impact

<p>In the tropical winter trades of the North Atlantic in the vicinity of Barbados four different mesoscale organisation patterns of clouds – sugar, gravel, flower, fish - are observed regularly. Each pattern is associated with a distinct cloud amount and radiative footprint. Therefore, the relative occurrence frequency of these patterns affects the global radiative budget. As shown by a recent study (Bony et al. 2019, Geophysical Research Letter), the occurrence of the four patterns is controlled by the near-surface wind speed and the strength of lower tropospheric instability. It is however not yet clear, whether these cloud patterns occur preferably in specific larger-scale flow configurations. These can be associated for example with upper-level wave breaking in the extratropics and different positions and strengths of low-level subtropical anticyclones.</p><p>Lower tropospheric air parcels at different altitudes in the trades are expected to have different transport histories associated with distinct diabatic processes such as radiative effects, phase changes within and below clouds and turbulent mixing. The diabatic processes encountered during transport modulate the thermodynamic properties of the air parcels and therefore influence the vertical thermodynamic structure of the atmosphere in the trades.</p><p>In this study, the impact of large-scale air mass advection on the thermodynamic profiles over Barbados is analysed for each of the four mesoscale organisation patterns observed during EUREC4A. The airmass transport history is characterised for different homogenous atmospheric layers. These layers are identified based on vertical pseudo-soundings above the Barbados Cloud Observatory (BCO) using ECMWF analysis data for cases where profiles agree well with independent observations from balloon soundings. The large-scale circulation within the 10 days prior to the sounding is considered for computing the trajectories of the air masses arriving in these layers. Backward trajectories are calculated with three-dimensional analysis wind fields. Thereby, the thermodynamic history and large-scale circulation configuration associated with the four cloud organisation patterns is described from a Lagrangian perspective. In addition, composites of the sea level pressure field provide information whether the four patterns co-occur with systematically differing positions and/or intensities of subtropical anticyclones. In future work, stable water isotopes will be used as observational tracers to find supportive evidence of the characterised transport history.</p>

scholarly journals Classification of summertime synoptic patterns in Beijing and their associations with boundary layer structure affecting aerosol pollution

2017 ◽  
Vol 17 (4) ◽  
pp. 3097-3110 ◽  
Author(s):  
Yucong Miao ◽  
Jianping Guo ◽  
Shuhua Liu ◽  
Huan Liu ◽  
Zhanqing Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
Layer Structure ◽  
Inversion Layer ◽  
Near Surface ◽  
Synoptic Patterns ◽  
Synoptic Conditions ◽  
Aerosol Pollution ◽  
Fine Resolution

Abstract. Meteorological conditions within the planetary boundary layer (PBL) are closely governed by large-scale synoptic patterns and play important roles in air quality by directly and indirectly affecting the emission, transport, formation, and deposition of air pollutants. Partly due to the lack of long-term fine-resolution observations of the PBL, the relationships between synoptic patterns, PBL structure, and aerosol pollution in Beijing have not been well understood. This study applied the obliquely rotated principal component analysis in T-mode to classify the summertime synoptic conditions over Beijing using the National Centers for Environmental Prediction reanalysis from 2011 to 2014, and investigated their relationships with PBL structure and aerosol pollution by combining numerical simulations, measurements of surface meteorological variables, fine-resolution soundings, the concentration of particles with diameters less than or equal to 2.5 µm, total cloud cover (CLD), and reanalysis data. Among the seven identified synoptic patterns, three types accounted for 67 % of the total number of cases studied and were associated with heavy aerosol pollution events. These particular synoptic patterns were characterized by high-pressure systems located to the east or southeast of Beijing at the 925 hPa level, which blocked the air flow seaward, and southerly PBL winds that brought in polluted air from the southern industrial zone. The horizontal transport of pollutants induced by the synoptic forcings may be the most important factor affecting the air quality of Beijing in summer. In the vertical dimension, these three synoptic patterns featured a relatively low boundary layer height (BLH) in the afternoon, accompanied by high CLD and southerly cold advection from the seas within the PBL. The high CLD reduced the solar radiation reaching the surface, and suppressed the thermal turbulence, leading to lower BLH. Besides, the numerical sensitive experiments show that cold advection induced by the large-scale synoptic forcing may have cooled the PBL, leading to an increase in near-surface stability and a decrease in the BLH in the afternoon. Moreover, when warm advection appeared simultaneously above the top level of the PBL, the thermal inversion layer capping the PBL may have been strengthened, resulting in the further suppression of PBL and thus the deterioration of aerosol pollution levels. This study has important implications for understanding the crucial roles that meteorological factors (at both synoptic and local scales) play in modulating and forecasting aerosol pollution in Beijing and its surrounding area.

scholarly journals Long-term surface energy balance of the western Greenland ice sheet and the role of large-scale circulation variability

2020 ◽  
Author(s):  
Baojuan Huai ◽  
Michiel R. van den Broeke ◽  
Carleen H. Reijmer
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climate Variables ◽  
Large Scale Circulation ◽  
Near Surface ◽  
Surface Climate

Abstract. We present the surface energy balance (SEB) of the west Greenland ice sheet (GrIS), using an energy balance model forced with hourly observations from nine automatic weather stations (AWS) along two transects: the K-transect with seven AWS in the southwest and the T-transect with two AWS in the northwest. Modeled and observed surface temperatures for non-melting conditions agree well, with RMSEs of 1.1–1.6 K, while reasonable agreement is found between modeled and observed 10-day cumulative ice melt. Absorbed shortwave radiation (Snet) is the main energy source for melting (M), followed by the sensible heat flux (Qh). The multi-year average seasonal cycle of SEB components show that Snet and M peak in July at all AWS. The turbulent fluxes of sensible (Qh) and latent heat (Ql) decrease significantly with elevation, and the latter becomes negative at higher elevations, partly offsetting Qh. Average June, July, August (JJA) albedo values are  0.7 for the higher stations. The near-surface climate variables and surface energy fluxes from reanalysis products ERA-interim, ERA5 and the regional climate model RACMO2.3 were compared to the AWS values. The newer ERA5 product only significantly improves on ERA-interim for albedo. The regional model RACMO2.3, which has higher resolution (5.5 km) and a dedicated snow/ice module, unsurprisingly outperforms the re-analyses for (near-) surface climate variables, but the reanalyses are indispensable to detect dependencies of west Greenland climate and melt on large-scale circulation variability. We correlate ERA5 with the AWS data to show a significant positive correlation of western GrIS summer surface temperature and melt with the Greenland Blocking Index (GBI), and weaker and opposite correlations with the North Atlantic Oscillation (NAO). This analysis may further help to explain melting patterns in the western GrIS from the perspective of circulation anomalies.

scholarly journals Integrated impacts of synoptic forcing and aerosol radiative effect on boundary layer and pollution in the Beijing-Tianjin-Hebei region, China

2019 ◽  
Author(s):  
Yucong Miao ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
Shuhua Liu
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Large Scale ◽  
Radiative Effect ◽  
Synoptic Pattern ◽  
Rapid Urbanization ◽  
Near Surface ◽  
Thermal Inversion ◽  
Mountainous Regions ◽  
Aerosol Radiative

Abstract. Rapid urbanization and industrialization have led to deterioration of air quality in the Beijing-Tianjin-Hebei (BTH) region with high loadings of PM2.5. The heavy aerosol pollutions frequently occur in winter, closely in relation to the meteorological conditions. To unravel the complicated impacts of large-scale atmospheric forcing and the local-scale planetary boundary layer (PBL) characteristics on the pollution there, this study combined long-term observational data analyses, synoptic pattern classification, and meteorology-chemistry coupled simulations. During the winter of 2017 and 2018, Beijing, Langfang, Tianjin, and Tangshan often simultaneously experienced heavy PM2.5 pollution, accompanying with strong thermal inversion aloft. These concurrences of pollution in different cities were primarily regulated by the large-scale atmospheric processes. Using the principal component analysis with the geopotential height fields at the 850-hPa level during winter, the typical polluted synoptic pattern in BTH was identified. The pattern was featured by westerly winds from upstream mountainous regions. By inducing warm advections from the west, the thermal inversion aloft in the BTH could be enhanced, leading to shallow daytime PBLs and high near-surface PM2.5 concentrations. In addition, the aerosol may also modulate the PBL structure through its radiative effect, which was examined using numerical simulations. The aerosol radiative effect can significantly lower the boundary layer height in the afternoon through cooling the surface layer and heating the upper part of PBL. Thus, more aerosols could be accumulated in the lower portion of PBL, bringing about heavy pollution in the BTH. This study has revealed the important roles played by the meteorology-aerosol interaction on the air quality.

scholarly journals Long-term surface energy balance of the western Greenland Ice Sheet and the role of large-scale circulation variability

2020 ◽  
Vol 14 (11) ◽  
pp. 4181-4199
Author(s):  
Baojuan Huai ◽  
Michiel R. van den Broeke ◽  
Carleen H. Reijmer
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climate Variables ◽  
Large Scale Circulation ◽  
Near Surface ◽  
Surface Climate

Abstract. We present the surface energy balance (SEB) of the western Greenland Ice Sheet (GrIS) using an energy balance model forced with hourly observations from nine automatic weather stations (AWSs) along two transects: the Kangerlussuaq (K) transect with seven AWSs in the southwest and the Thule (T) transect with two AWSs in the northwest. Modeled and observed surface temperatures for non-melting conditions agree well with RMSEs of 1.1–1.6 K, while reasonable agreement is found between modeled and observed 10 d cumulative ice melt. Absorbed shortwave radiation (Snet) is the main energy source for melting (M), followed by the sensible heat flux (Qh). The multiyear average seasonal cycle of SEB components shows that Snet and M peak in July at all AWSs. The turbulent fluxes of sensible (Qh) and latent heat (Ql) decrease significantly with elevation, and the latter becomes negative at higher elevations, partly offsetting Qh. Average June, July and August (JJA) albedo values are <0.6 for stations below 1000 m a.s.l. and >0.7 for the higher stations. The near-surface climate variables and surface energy fluxes from reanalysis products ERA-Interim, ERA5 and the regional climate model RACMO2.3 were compared to the AWS values. The newer ERA5 product only significantly improves ERA-Interim for albedo. The regional model RACMO2.3, which has higher resolution (5.5 km) and a dedicated snow/ice module, unsurprisingly outperforms the reanalyses for (near-)surface climate variables, but the reanalyses are indispensable in detecting dependencies of west Greenland climate and melt on large-scale circulation variability. We correlate ERA5 with the AWS data to show a significant positive correlation of western GrIS summer surface temperature and melt with the Greenland Blocking Index (GBI) and weaker and opposite correlations with the North Atlantic Oscillation (NAO). This analysis may further help to explain melting patterns on the western GrIS from the perspective of circulation anomalies.

scholarly journals Climatological Large-Scale Circulation Patterns over The Middle Americas Region

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 745
Author(s):  
Carlos A. Ochoa-Moya ◽  
Yoel A. Cala-Pérez ◽  
Yanet Díaz-Esteban ◽  
Christopher L. Castro ◽  
Paulina Ordoñez-Peréz ◽  
...  
Keyword(s):  
Large Scale ◽  
Low Frequency ◽  
North American Monsoon ◽  
Large Scale Circulation ◽  
Western Atlantic ◽  
Near Surface ◽  
Synoptic Classification ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Circulation Patterns

In this study, twenty large-scale circulation patterns are identified to generate a synoptic classification of Weather Types (WT) over a region that comprises Mexico, the Intra-Americas Seas, Central America, and northern South America. This classification is performed using Self-Organizing Maps (SOMs) with mean sea-level pressure standardized anomalies from reanalysis. The influence of quasi-permanent pressure centers over the region, such as North Atlantic Subtropical High (NASH) and North Pacific High (NPH) are well captured. Seasonal variability of high-pressure centers for dry (November–April) and wet (May–October) periods over the entire region are also well represented in amplitude and pattern among the WTs. The NASH influence and intensification of the Caribbean low-level jet and the North American monsoon system is well captured. During the dry period, a strong trough wind advects cold air masses from mid-latitudes to the subtropics over the western Atlantic Ocean. High-frequency transitions among WTs tend to cluster around the nearest neighbors in SOM space, while low-frequency transitions occur along columns instead of rows in the SOM matrix. Low-frequency transitions are related to intraseasonal and seasonal scales. The constructed catalog can identify near-surface atmospheric circulation patterns from a unified perspective of synoptic climate variability, and it is in high agreement with previous studies for the region.

scholarly journals Coupled Air Quality and Boundary-Layer Meteorology in Western U.S. Basins during Winter: Design and Rationale for a Comprehensive Study

2021 ◽  
pp. 1-94
Author(s):  
A. Gannet Hallar ◽  
Steven S. Brown ◽  
Erik Crosman ◽  
Kelley C. Barsanti ◽  
Christopher D. Cappa ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Chemistry ◽  
Salt Lake ◽  
Control Strategies ◽  
Research Area ◽  
Future Research ◽  
Surface Boundary ◽  
Mixing Processes ◽  
Near Surface

AbstractWintertime episodes of high aerosol concentrations occur frequently in urban and agricultural basins and valleys worldwide. These episodes often arise following development of persistent cold-air pools (PCAPs) that limit mixing and modify chemistry. While field campaigns targeting either basin meteorology or wintertime pollution chemistry have been conducted, coupling between interconnected chemical and meteorological processes remains an insufficiently studied research area. Gaps in understanding the coupled chemical-meteorological interactions that drive high pollution events make identification of the most effective air-basin specific emission control strategies challenging. To address this, a September 2019 workshop occurred with the goal of planning a future research campaign to investigate air quality in Western U.S. basins. Approximately 120 people participated, representing 50 institutions and 5 countries. Workshop participants outlined the rationale and design for a comprehensive wintertime study that would couple atmospheric chemistry and boundary-layer and complex-terrain meteorology within western U.S. basins. Participants concluded the study should focus on two regions with contrasting aerosol chemistry: three populated valleys within Utah (Salt Lake, Utah, and Cache Valleys) and the San Joaquin Valley in California. This paper describes the scientific rationale for a campaign that will acquire chemical and meteorological datasets using airborne platforms with extensive range, coupled to surface-based measurements focusing on sampling within the near-surface boundary layer, and transport and mixing processes within this layer, with high vertical resolution at a number of representative sites. No prior wintertime basin-focused campaign has provided the breadth of observations necessary to characterize the meteorological-chemical linkages outlined here, nor to validate complex processes within coupled atmosphere-chemistry models.

Air Quality Characteristics and the Meteorological Conditions for the Few Air Polluted Examples during the Spring Festivals

2013 ◽  
Vol 726-731 ◽  
pp. 1260-1264
Author(s):  
Chang Song Gai ◽  
Yu Han ◽  
Fan Hua Min
Keyword(s):  
Air Quality ◽  
Large Scale ◽  
Pollution Source ◽  
Quality Characteristics ◽  
Meteorological Conditions ◽  
Meteorological Observation ◽  
Large Scale Circulation ◽  
Typical Sample ◽  
Spring Festival ◽  
Variation Characteristics

Analysis on the variation characteristics of the air quality in Chongqing during the spring festivals from 2001 to 2013, and the weather-affecting system of the typical sample. The result shows that: Prior to and after the ban-lifting for the firecrackers setting in 2006, significant differences had shown in the API Index from the lunar New Years Eve to Jan.1. After an analysis on the large-scale circulation background during the spring festival of 2006 and 2008 with the meteorological observation data.The result shows that the air pollution during the spring festival is co-resulted from the pollution source of firecrackers setting and the meteorological system that is unsuitable for the pollutant diffusion.

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