Articles | Volume 11, issue 10
31 May 2011
31 May 2011
On the behaviour of the tropopause folding events over the Tibetan Plateau
X. L. Chen et al.
Related subject area
Subject: Dynamics | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)Turbulent and boundary layer characteristics during VOCALS-RExA foehn-induced haze front in Beijing: observations and implicationsAirborne measurements and large-eddy simulations of small-scale gravity waves at the tropopause inversion layer over ScandinaviaObservational analysis of the daily cycle of the planetary boundary layer in the central Amazon during a non-El Niño year and El Niño year (GoAmazon project 2014/5)Planetary boundary layer evolution over the Amazon rainforest in episodes of deep moist convection at the Amazon Tall Tower ObservatoryDominant patterns of summer ozone pollution in eastern China and associated atmospheric circulationsWhat controls the formation of nocturnal low-level stratus clouds over southern West Africa during the monsoon season?Recent trends in climate variability at the local scale using 40 years of observations: the case of the Paris region of FranceNocturnal boundary layer turbulence regimes analysis during the BLLAST campaignLow-level stratiform clouds and dynamical features observed within the southern West African monsoonResidual layer ozone, mixing, and the nocturnal jet in California's San Joaquin ValleyFrom weak to intense downslope winds: origin, interaction with boundary-layer turbulence and impact on CO2 variabilityOn the fine vertical structure of the low troposphere over the coastal margins of East AntarcticaSpatial and temporal variability of turbulence dissipation rate in complex terrainCharacterizing wind gusts in complex terrainLong-term trends of instability and associated parameters over the Indian region obtained using a radiosonde networkImplication of tropical lower stratospheric cooling in recent trends in tropical circulation and deep convective activityThe observed diurnal cycle of low-level stratus clouds over southern West Africa: a case studyNocturnal low-level clouds in the atmospheric boundary layer over southern West Africa: an observation-based analysis of conditions and processesCharacteristics and evolution of diurnal foehn events in the Dead Sea valleyHigh tropospheric ozone in Lhasa within the Asian summer monsoon anticyclone in 2013: influence of convective transport and stratospheric intrusionsAnthropogenic and natural drivers of a strong winter urban heat island in a typical Arctic cityA comparison of plume rise algorithms to stack plume measurements in the Athabasca oil sandsUpscaling surface energy fluxes over the North Slope of Alaska using airborne eddy-covariance measurements and environmental response functionsClimatological study of the Boundary-layer air Stagnation Index for China and its relationship with air pollutionSelf-organized classification of boundary layer meteorology and associated characteristics of air quality in BeijingThe strengthening relationship between Eurasian snow cover and December haze days in central North China after the mid-1990sObservational analyses of dramatic developments of a severe air pollution event in the Beijing areaThe meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South PoleMountain waves modulate the water vapor distribution in the UTLSRetrieving characteristics of inertia gravity wave parameters with least uncertainties using the hodograph methodIn situ temperature measurements in the upper troposphere and lowermost stratosphere from 2 decades of IAGOS long-term routine observationA meteorological and chemical overview of the DACCIWA field campaign in West Africa in June–July 2016Investigation of the mixing layer height derived from ceilometer measurements in the Kathmandu Valley and implications for local air qualityAir stagnation in China (1985–2014): climatological mean features and trendsModes of vertical thermodynamic and wind variability over the Maritime ContinentDiurnal variability of the atmospheric boundary layer height over a tropical station in the Indian monsoon regionThe open-ocean sensible heat flux and its significance for Arctic boundary layer mixing during early fallControlled meteorological (CMET) free balloon profiling of the Arctic atmospheric boundary layer around Spitsbergen compared to ERA-Interim and Arctic System ReanalysesBoundary layer evolution over the central Himalayas from radio wind profiler and model simulationsEstimation of the advection effects induced by surface heterogeneities in the surface energy budgetTurbulence kinetic energy budget during the afternoon transition – Part 1: Observed surface TKE budget and boundary layer description for 10 intensive observation period daysHow stratospheric are deep stratospheric intrusions? LUAMI 2008Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment?A study of local turbulence and anisotropy during the afternoon and evening transition with an unmanned aerial system and mesoscale simulationVertical wind retrieved by airborne lidar and analysis of island induced gravity waves in combination with numerical models and in situ particle measurementsObservations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisationObservational evidence of temperature trends at two levels in the surface layerCold Smoke: smoke-induced density currents cause unexpected smoke transport near large wildfiresMotion-correlated flow distortion and wave-induced biases in air–sea flux measurements from ships
Dillon S. Dodson and Jennifer D. Small Griswold
Atmos. Chem. Phys., 21, 1937–1961,Short summary
The results here reinforce findings from previous in situ studies of the marine boundary layer. It is found that turbulence is maximized in the middle of the stratocumulus layer from latent heating effects. Precipitation acts to increase turbulence in the sub-cloud layer, while acting to stabilize the entire boundary layer after the evaporation of precipitation in the sub-cloud has stopped. A negative correlation is present between the boundary layer height and turbulence.
Ju Li, Zhaobin Sun, Donald H. Lenschow, Mingyu Zhou, Youjun Dou, Zhigang Cheng, Yaoting Wang, and Qingchun Li
Atmos. Chem. Phys., 20, 15793–15809,Short summary
We analyzed a haze front event involving warm–dry downslope flow in December 2015 in Beijing, China. The haze front was formed by the collision between a clean warm–dry air mass flowing from a nearby mountainous region and a polluted cold–wet air mass over an urban area. We found that the polluted air advanced toward the clean air, resulting in a severe air pollution event. Our study highlights the need to further investigate the warm–dry downslope and its impacts on air pollution.
Sonja Gisinger, Johannes Wagner, and Benjamin Witschas
Atmos. Chem. Phys., 20, 10091–10109,Short summary
Gravity waves are an important coupling mechanism in the atmosphere. Measurements by two research aircraft during a mountain wave event over Scandinavia in 2016 revealed changes of the horizontal scales in the vertical velocity field and of momentum fluxes in the vicinity of the tropopause inversion. Idealized simulations revealed the presence of interfacial waves. They are found downstream of the mountain peaks, meaning that they horizontally transport momentum/energy away from their source.
Rayonil G. Carneiro and Gilberto Fisch
Atmos. Chem. Phys., 20, 5547–5558,Short summary
The objective of this study was to conduct observational evaluations of the daily cycle of the height of the planetary boundary layer from data that were measured and/or estimated using instruments such as a radiosonde, sodar, ceilometer, wind profiler, lidar and microwave radiometer installed in the central Amazon during 2014 (considered a typical year) and 2015 during which an intense El Niño–Southern Oscillation (ENSO) event predominated during the GoAmazon experiment.
Maurício I. Oliveira, Otávio C. Acevedo, Matthias Sörgel, Ernani L. Nascimento, Antonio O. Manzi, Pablo E. S. Oliveira, Daiane V. Brondani, Anywhere Tsokankunku, and Meinrat O. Andreae
Atmos. Chem. Phys., 20, 15–27,Short summary
In this study, data collected during four deep convection events at the 80 m tower from the Amazon Tall Tower Observatory are analyzed. It provides a unique view on how such events affect the local boundary layer and how it recovers after their passage. Quantities analyzed include mean wind speed, virtual potential temperature, turbulent kinetic energy, sensible, and latent heat fluxes. A conceptual model for boundary layer structure along the passage of deep convection events is proposed.
Zhicong Yin, Bufan Cao, and Huijun Wang
Atmos. Chem. Phys., 19, 13933–13943,Short summary
Ozone occurs both in the stratosphere and at ground level. Surface ozone is a man-made air pollutant and has harmful effects on people and the environment. Two dominant patterns of summer ozone pollution were determined. The most dominant pattern in 2017 and 2018 was different from that in previous years. The findings of this study help us to understand the features of surface ozone pollution in eastern China and their relationships with large-scale atmospheric circulations.
Karmen Babić, Norbert Kalthoff, Bianca Adler, Julian F. Quinting, Fabienne Lohou, Cheikh Dione, and Marie Lothon
Atmos. Chem. Phys., 19, 13489–13506,Short summary
This study investigates differences in atmospheric conditions between nights with and without low-level stratus clouds (LLCs) over southern West Africa. We use high-quality observations collected during 2016 summer monsoon season and the ERA5 reanalysis data set. Our results show that the formation of LLCs depends on the interplay between the onset time and strength of the nocturnal low-level jet, horizontal cold-air advection, and the overall moisture level in the whole region.
Justine Ringard, Marjolaine Chiriaco, Sophie Bastin, and Florence Habets
Atmos. Chem. Phys., 19, 13129–13155,Short summary
This study characterizes the changes observed at Paris urban scale and attempts to identify the surface–atmosphere feedbacks likely to explain the trends observed as a function of the different configurations of large-scale dynamics. This article is interested in several atmospheric parameters and their possible retroactions. Finally, to study urban environments, the analysis at the local scale is essential because it is very poorly represented in the model.
Jesús Yus-Díez, Mireia Udina, Maria Rosa Soler, Marie Lothon, Erik Nilsson, Joan Bech, and Jielun Sun
Atmos. Chem. Phys., 19, 9495–9514,Short summary
This study helps improve the understanding of the turbulence description and the interactions occurring in the lower part of the boundary layer. It is carried out at an orographically influenced site close to the Pyrenees to explore the hockey-stick transition (HOST) theory. HOST is seen to be strongly dependent on both the meteorological conditions and the orographic features. Examples of intermittent turbulence events that lead to transitions between the turbulence regimes are also identified.
Cheikh Dione, Fabienne Lohou, Marie Lothon, Bianca Adler, Karmen Babić, Norbert Kalthoff, Xabier Pedruzo-Bagazgoitia, Yannick Bezombes, and Omar Gabella
Atmos. Chem. Phys., 19, 8979–8997,Short summary
Low atmospheric dynamics and low-level cloud (LLC) macrophysical properties are analyzed using in situ and remote sensing data collected from 20 June to 30 July at Savè, Benin, during the DACCIWA field campaign in 2016. We find that the low-level jet (LLJ), LLCs, monsoon flow, and maritime inflow reveal a day-to-day variability. LLCs form at the same level as the jet core height. The cloud base height is stationary at night and remains below the jet. The cloud top height is found above the jet.
Dani J. Caputi, Ian Faloona, Justin Trousdell, Jeanelle Smoot, Nicholas Falk, and Stephen Conley
Atmos. Chem. Phys., 19, 4721–4740,Short summary
This paper covers the importance of understanding ozone pollution in California’s southern San Joaquin Valley from the perspective of meteorological conditions that occur overnight. Our main finding is that stronger winds aloft allow ozone to be depleted overnight, leading to less ozone the following day. This finding has the potential to greatly improve ozone forecasts in the San Joaquin Valley. This study is primarily conducted with aircraft observations.
Jon Ander Arrillaga, Carlos Yagüe, Carlos Román-Cascón, Mariano Sastre, Maria Antonia Jiménez, Gregorio Maqueda, and Jordi Vilà-Guerau de Arellano
Atmos. Chem. Phys., 19, 4615–4635,Short summary
Thermally driven downslope winds develop in mountainous areas under a weak large-scale forcing and clear skies. In this work, we find that their onset time and intensity are closely connected with both the large-scale wind and soil moisture. We also show how the distinct downslope intensities shape the turbulent and thermal features of the nocturnal atmosphere. The analysis concludes that the downslope–turbulence interaction and the horizontal transport explain the important CO2 variability.
Étienne Vignon, Olivier Traullé, and Alexis Berne
Atmos. Chem. Phys., 19, 4659–4683,Short summary
The future sea-level rise will depend on how much the Antarctic ice sheet gain – via precipitation – or loose mass. The simulation of precipitation by numerical models used for projections depends on the representation of the atmospheric circulation over and around Antarctica. Using daily measurements from balloon soundings at nine Antarctic stations, this study characterizes the structure of the atmosphere over the Antarctic coast and its representation in atmospheric simulations.
Nicola Bodini, Julie K. Lundquist, Raghavendra Krishnamurthy, Mikhail Pekour, Larry K. Berg, and Aditya Choukulkar
Atmos. Chem. Phys., 19, 4367–4382,Short summary
To improve the parameterization of the turbulence dissipation rate (ε) in numerical weather prediction models, we have assessed its temporal and spatial variability at various scales in the Columbia River Gorge during the WFIP2 field experiment. The turbulence dissipation rate shows large spatial variability, even at the microscale, with larger values in sites located downwind of complex orographic structures or in wind farm wakes. Distinct diurnal and seasonal cycles in ε have also been found.
Frederick Letson, Rebecca J. Barthelmie, Weifei Hu, and Sara C. Pryor
Atmos. Chem. Phys., 19, 3797–3819,Short summary
Wind gusts are a key driver of aerodynamic loading, and common approximations used to describe wind gust behavior may not be appropriate in complex terrain at heights relevant to wind turbines and other structures. High-resolution observations from sonic anemometers and vertically pointing Doppler lidars collected in the Perdigão experiment are analyzed to provide a foundation for improved wind gust characterization in complex terrain.
Rohit Chakraborty, Madineni Venkat Ratnam, and Shaik Ghouse Basha
Atmos. Chem. Phys., 19, 3687–3705,Short summary
Intense convective phenomena are a common climatic feature in the Indian tropical region which occur during the pre-monsoon to post-monsoon seasons (April–October) and are generally accompanied by intense thunderstorms, lightning, and wind gusts with heavy rainfall. Here we show long-term trends of the parameters related to convection and instability obtained from 27 radiosonde stations across six subdivisions over the Indian region during the period 1980–2016.
Kunihiko Kodera, Nawo Eguchi, Rei Ueyama, Yuhji Kuroda, Chiaki Kobayashi, Beatriz M. Funatsu, and Chantal Claud
Atmos. Chem. Phys., 19, 2655–2669,Short summary
The recent cooling of the equatorial eastern Pacific Ocean occurred in conjunction with enhanced cross-equatorial southerlies associated with a strengthening of the boreal summer Hadley circulation. A combination of land surface warming and reduced static stability in the tropical tropopause layer due to stratospheric cooling is suggested to have caused the increase in the deep ascending branch of the Hadley circulation and related recent decadal change in the tropical troposphere and ocean.
Karmen Babić, Bianca Adler, Norbert Kalthoff, Hendrik Andersen, Cheikh Dione, Fabienne Lohou, Marie Lothon, and Xabier Pedruzo-Bagazgoitia
Atmos. Chem. Phys., 19, 1281–1299,Short summary
The first detailed observational analysis of the complete diurnal cycle of low-level clouds (LLC) and associated atmospheric processes over southern West Africa is performed using the data gathered within the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa) ground-based campaign. We find cooling related to the horizontal advection, which occurs in connection with the inflow of cool maritime air mass and a prominent low-level jet, to have the dominant role in LLC formation.
Bianca Adler, Karmen Babić, Norbert Kalthoff, Fabienne Lohou, Marie Lothon, Cheikh Dione, Xabier Pedruzo-Bagazgoitia, and Hendrik Andersen
Atmos. Chem. Phys., 19, 663–681,Short summary
This study deals with nocturnal stratiform low-level clouds that frequently form in the atmospheric boundary layer over southern West Africa. We use observational data from 11 nights to characterize the clouds and intranight variability of boundary layer conditions as well as to assess the physical processes relevant for cloud formation. We find that cooling is crucial to reach saturation and a large part of the cooling is related to horizontal advection of cool air from the Gulf of Guinea.
Jutta Vüllers, Georg J. Mayr, Ulrich Corsmeier, and Christoph Kottmeier
Atmos. Chem. Phys., 18, 18169–18186,Short summary
This paper investigates frequently occurring foehn at the Dead Sea, which strongly impacts the local climatic conditions, in particular temperature and humidity, as well as evaporation from the Dead Sea, the aerosol load, and visibility. A statistical classification exposes two types of foehn and first-time, high-resolution measurements reveal trigger mechanisms and relevant characteristics, such as wind velocities, affected air layers, and resulting phenomena such as hydraulic jumps and rotors.
Dan Li, Bärbel Vogel, Rolf Müller, Jianchun Bian, Gebhard Günther, Qian Li, Jinqiang Zhang, Zhixuan Bai, Holger Vömel, and Martin Riese
Atmos. Chem. Phys., 18, 17979–17994,Short summary
Balloon-borne measurements performed over Lhasa in August 2013 are investigated using CLaMS trajectory calculations. Here, we focus on high ozone mixing ratios in the free troposphere. Our findings demonstrate that both stratospheric intrusions and convective transport of air pollution play a major role in enhancing middle and upper tropospheric ozone.
Mikhail Varentsov, Pavel Konstantinov, Alexander Baklanov, Igor Esau, Victoria Miles, and Richard Davy
Atmos. Chem. Phys., 18, 17573–17587,Short summary
This study reports on the urban heat island (UHI) in a typical Arctic city in winter. Using in situ observations, remote sensing data and modeling, we show that the urban temperature anomaly reaches up to 11 K with a mean value of 1.9 K. At least 50 % of this anomaly is caused by the UHI effect, driven mostly by heating. The rest is created by natural microclimatic variability over the hilly terrain. This is a strong argument in support of energy efficiency measures in the Arctic cities.
Mark Gordon, Paul A. Makar, Ralf M. Staebler, Junhua Zhang, Ayodeji Akingunola, Wanmin Gong, and Shao-Meng Li
Atmos. Chem. Phys., 18, 14695–14714,Short summary
This work uses aircraft-based measurements of smokestack plumes carried out in northern Alberta in 2013. These measurements are used to test equations used to predict how high in the air smokestack plumes rise. It is important to predict plume rise height accurately as it tells us how far downwind pollutants are carried and what air quality can be expected at the surface. We found that the equations that are typically used significantly underestimate the plume rise at this location.
Andrei Serafimovich, Stefan Metzger, Jörg Hartmann, Katrin Kohnert, Donatella Zona, and Torsten Sachs
Atmos. Chem. Phys., 18, 10007–10023,Short summary
In order to support the evaluation of coupled atmospheric–land-surface models we investigated spatial patterns of energy fluxes in relation to land-surface properties and upscaled airborne flux measurements to high resolution flux maps. A machine learning technique allows us to estimate environmental response functions between spatially and temporally resolved flux observations and corresponding biophysical and meteorological drivers.
Qianqian Huang, Xuhui Cai, Jian Wang, Yu Song, and Tong Zhu
Atmos. Chem. Phys., 18, 7573–7593,Short summary
Air stagnation index is a vital meteorological measure of the atmosphere's ability to dilute air pollutants. We propose a Boundary-layer air Stagnation Index (BSI) based on daily maximal ventilation, real latent instability and precipitation. The BSI is positively correlated with API during 2000–2012, tracks the day-by-day variation of PM2.5 concentration during January 2013 in Beijing well, and successfully represents the improved air quality during November and December in 2017.
Zhiheng Liao, Jiaren Sun, Jialin Yao, Li Liu, Haowen Li, Jian Liu, Jielan Xie, Dui Wu, and Shaojia Fan
Atmos. Chem. Phys., 18, 6771–6783,Short summary
This paper investigates the modulation effect of ABL meteorology on Beijing’s surface air quality based on self-organizing maps. The self-organized ABL types correspond to significantly distinct pollutant loadings and diurnal evolution, particularly in winter. Anomalous stable ABL conditions are estimated to contribute 58.3 %, 46.4 % and 73.3 % of the elevated PM2.5 concentrations in January 2013, December 2015 and December 2016.
Zhicong Yin and Huijun Wang
Atmos. Chem. Phys., 18, 4753–4763,Short summary
In China, the haze pollution in December has become increasingly serious over recent decades. The relationship between the snow cover and the December haze days was analyzed. This relationship significantly strengthened after the mid-1990s, which is attributed to the effective connections between the snow cover and the Eurasian atmospheric circulations.
Ju Li, Jielun Sun, Mingyu Zhou, Zhigang Cheng, Qingchun Li, Xiaoyan Cao, and Jingjiang Zhang
Atmos. Chem. Phys., 18, 3919–3935,Short summary
A rapid increase in the PM2.5 concentration in Beijing, China, on 30 November 2015 was found to be transported from south of Beijing by both turbulent mixing and advection processes. The nighttime relatively clean air was from the downslope flow northwest of Beijing; the rapid increase in the PM2.5 concentration in the morning resulted from the downward convective turbulent transfer of the polluted air that was rapidly advected over the nighttime stable boundary layer.
William Neff, Jim Crawford, Marty Buhr, John Nicovich, Gao Chen, and Douglas Davis
Atmos. Chem. Phys., 18, 3755–3778,Short summary
Our study examined the effect of the seasonal cycle in meteorology from November through December and the role of stratospheric ozone depletion in the photochemical production of nitrogen oxide (NO) from nitrate in the snow at the South Pole. We found that ozone depletion which now extends into late November–early December coincides with optimum meteorological conditions (clear skies, a stable shallow boundary layer, and light winds) for high concentrations of NO to accumulate at the surface.
Romy Heller, Christiane Voigt, Stuart Beaton, Andreas Dörnbrack, Andreas Giez, Stefan Kaufmann, Christian Mallaun, Hans Schlager, Johannes Wagner, Kate Young, and Markus Rapp
Atmos. Chem. Phys., 17, 14853–14869,
Gopa Dutta, Palla Vinay Kumar, and Salauddin Mohammad
Atmos. Chem. Phys., 17, 14811–14819,Short summary
Gravity wave stress is crucial for weather prediction purposes. It is found that proper filtering of the data is essential to reduce uncertainties in the popular hodograph method to delineate low-frequency gravity wave parameters. Our research helped in improving the estimates of gravity wave stress by reducing errors.
Florian Berkes, Patrick Neis, Martin G. Schultz, Ulrich Bundke, Susanne Rohs, Herman G. J. Smit, Andreas Wahner, Paul Konopka, Damien Boulanger, Philippe Nédélec, Valerie Thouret, and Andreas Petzold
Atmos. Chem. Phys., 17, 12495–12508,Short summary
This study highlights the importance of independent global measurements with high and long-term accuracy to quantify long-term changes, especially in the UTLS region, and to help identify inconsistencies between different data sets of observations and models. Here we investigated temperature trends over different regions within a climate-sensitive area of the atmosphere and demonstrated the value of the IAGOS temperature observations as an anchor point for the evaluation of reanalyses.
Peter Knippertz, Andreas H. Fink, Adrien Deroubaix, Eleanor Morris, Flore Tocquer, Mat J. Evans, Cyrille Flamant, Marco Gaetani, Christophe Lavaysse, Celine Mari, John H. Marsham, Rémi Meynadier, Abalo Affo-Dogo, Titike Bahaga, Fabien Brosse, Konrad Deetz, Ridha Guebsi, Issaou Latifou, Marlon Maranan, Philip D. Rosenberg, and Andreas Schlueter
Atmos. Chem. Phys., 17, 10893–10918,Short summary
In June–July 2016 DACCIWA (Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa), a large, EU-funded European–African project, organised an international field campaign in densely populated southern West Africa, including measurements from ground sites, research aircraft, weather balloons and urban sites. This paper gives an overview of the atmospheric evolution during this period focusing on meteorological (precipitation, cloudiness, winds) and composition (gases, particles) aspects.
Andrea Mues, Maheswar Rupakheti, Christoph Münkel, Axel Lauer, Heiko Bozem, Peter Hoor, Tim Butler, and Mark G. Lawrence
Atmos. Chem. Phys., 17, 8157–8176,Short summary
Ceilometer measurements taken in the Kathmandu Valley, Nepal, were used to study the temporal and spatial evolution of the mixing layer height in the valley. This provides important information on the vertical structure of the atmosphere and can thus also help to understand the mixing of air pollutants (e.g. black carbon) in the valley. The seasonal and diurnal cycles of the mixing layer were found to be highly dependent on meteorology and mainly anticorrelated to black carbon concentrations.
Qianqian Huang, Xuhui Cai, Yu Song, and Tong Zhu
Atmos. Chem. Phys., 17, 7793–7805,Short summary
Air stagnation is an important meteorological measure of unfavorable air conditions, and previous studies have found that stagnation events are usually related to air pollution episodes. China is currently experiencing heavy air pollution, but to our knowledge, little is known about air stagnation in the country. In this paper, we conducted a comprehensive investigation of air stagnation climatology in China based on sounding and surface observations across the country.
Jennie Bukowski, Derek J. Posselt, Jeffrey S. Reid, and Samuel A. Atwood
Atmos. Chem. Phys., 17, 4611–4626,Short summary
The Maritime Continent (MC) exhibits tremendous meteorological variability. In this study, multiple years of atmospheric soundings over the MC are analyzed to identify key sources of variability in the region's temperature, water vapor, and wind structure. Coherent vertical structures are found among profiles sampled from different geographic locations. The results indicate that the complex meteorology of the region can be described using a few simple structure functions.
Sanjay Kumar Mehta, Madineni Venkat Ratnam, Sukumarapillai V. Sunilkumar, Daggumati Narayana Rao, and Boddapaty V. Krishna Murthy
Atmos. Chem. Phys., 17, 531–549,Short summary
Study of the diurnal variation of the atmospheric boundary layer (ABL) height is important for the knowledge of pollutant dispersion, crucial for all living beings. The most difficult part in the study of the diurnal variation is in identification of the stable boundary layer which occurs ~ 50% of times only and mostly during nighttime winter. Surface temperature and clouds directly affect the diurnal pattern of the ABL. Thus, stronger (weaker) diurnal variation found during pre-monsoon (winter).
Manisha Ganeshan and Dong L. Wu
Atmos. Chem. Phys., 16, 13173–13184,Short summary
The amplified Arctic warming has seen a rapid decline in sea ice with serious implications for global climate. The loss of heat from the ocean to the atmosphere is considered important for the recovery of the diminishing sea ice. Yet there is little observational evidence regarding the efficiency of this process. In our study, we explore and quantify the ability of the open ocean to lose heat through sensible heat fluxes. It is found to depend on the prevailing cloud and wind regime.
Tjarda J. Roberts, Marina Dütsch, Lars R. Hole, and Paul B. Voss
Atmos. Chem. Phys., 16, 12383–12396,Short summary
We present Controlled Meteorological (CMET) balloon flights in the Arctic. CMETs are a novel balloon that can be controlled (by satellite link) to change altitude during the flight and remain in the troposphere up to several days. We performed automated repeated soundings in the Arctic boundary layer during the flight and compared the observations (temperature, humidity, wind) to output from two atmospheric models. CMETs are a valuable tool for probing the lower atmosphere in remote regions.
Narendra Singh, Raman Solanki, Narendra Ojha, Ruud H. H. Janssen, Andrea Pozzer, and Surendra K. Dhaka
Atmos. Chem. Phys., 16, 10559–10572,Short summary
Our study presents measurements and model simulations of boundary layer evolution over a mountain peak in the central Himalayas. The observations were made as a part of the Ganges Valley Aerosol Experiment. The implications of biases in model simulated boundary layer towards simulations of trace species is investigated.
Joan Cuxart, Burkhard Wrenger, Daniel Martínez-Villagrasa, Joachim Reuder, Marius O. Jonassen, Maria A. Jiménez, Marie Lothon, Fabienne Lohou, Oscar Hartogensis, Jens Dünnermann, Laura Conangla, and Anirban Garai
Atmos. Chem. Phys., 16, 9489–9504,Short summary
Estimations of the effect of thermal advection in the surface energy budget are provided. Data from the experimental campaign BLLAST, held in Southern France in summer 2011, are used, including airborne data by drones and surface-based instrumentation. Model data outputs and satellite information are also inspected. Surface heterogeneities of the order of the kilometer or larger seem to have little effect on the budget, whereas hectometer-scale structures may contribute significantly to it.
Erik Nilsson, Fabienne Lohou, Marie Lothon, Eric Pardyjak, Larry Mahrt, and Clara Darbieu
Atmos. Chem. Phys., 16, 8849–8872,Short summary
The evolution of near-surface turbulence kinetic energy (TKE) and its budget in the afternoon transition has been studied based on field measurements. The study shows that TKE transport is an important budget term that needs to be taken into account in modeling of TKE. A non-local parametrization of dissipation using a TKE–length scale model which takes into account of boundary layer depth also gave improved results compared to a local parametrization.
Thomas Trickl, Hannes Vogelmann, Andreas Fix, Andreas Schäfler, Martin Wirth, Bertrand Calpini, Gilbert Levrat, Gonzague Romanens, Arnoud Apituley, Keith M. Wilson, Robert Begbie, Jens Reichardt, Holger Vömel, and Michael Sprenger
Atmos. Chem. Phys., 16, 8791–8815,Short summary
A rather homogeneous deep stratospheric intrusion event was mapped by vertical sounding over central Europe and by model calculations along the transport path. The very low minimum H2O mixing ratios demonstrate almost negligible mixing with tropospheric air during the downward transport. The vertical distributions of O3 and aerosol were transferred from the source region to Europe without major change. A rather shallow outflow from the stratosphere was found.
Thomas M. Freismuth, Blake Rutherford, Mark A. Boothe, and Michael T. Montgomery
Atmos. Chem. Phys., 16, 8511–8519,Short summary
Numerical model analyses are used to investigate the role of dry, environmental air in the failed redevelopment of a tropical cyclone (ex-Gaston, 2010). As early as 12:00 UTC 2 September 2010, a dry layer at and above 600 hPa results in a decrease in the vertical mass flux and vertical, relative vorticity. The intrusion of dry air led to a reduction in vorticity and a compromised pouch at these middle levels. This study supports work looking at the role of dry air in moist convection.
Astrid Lampert, Falk Pätzold, Maria Antonia Jiménez, Lennart Lobitz, Sabrina Martin, Gerald Lohmann, Guylaine Canut, Dominique Legain, Jens Bange, Dani Martínez-Villagrasa, and Joan Cuxart
Atmos. Chem. Phys., 16, 8009–8021,Short summary
For a large field experiment in summer 2011 in southern France (BLLAST campaign), the development of turbulence in the atmosphere was analysed during the afternoon and evening. Besides ground-based remote sensing and in situ observations, turbulence parameters were measured with an unmanned aerial vehicle and analysed by numerical simulation. Turbulence decreased during the afternoon, but increased after sunset due to local wind systems. Turbulent eddies lost symmetry during the transition.
Fernando Chouza, Oliver Reitebuch, Michael Jähn, Stephan Rahm, and Bernadett Weinzierl
Atmos. Chem. Phys., 16, 4675–4692,Short summary
This study presents the analysis of island induced gravity waves observed by an airborne Doppler wind lidar (DWL). First, the instrumental corrections required for the retrieval vertical wind measurements from an airborne DWL are presented. Then, the method is applied to two case studies to determine, in combination with numerical models and in situ measurements, the main characteristics of the observed waves.
A. D. Elvidge, I. A. Renfrew, A. I. Weiss, I. M. Brooks, T. A. Lachlan-Cope, and J. C. King
Atmos. Chem. Phys., 16, 1545–1563,Short summary
Rare aircraft observations of surface momentum flux over the Arctic marginal ice zone provide the best means yet to constrain model representation of MIZ surface roughness. The sensitivity of surface roughness to ice concentration over the Arctic MIZ is presented; these results do not support the values used in many models. However, a leading parameterization scheme (that of Lüpkes et al., 2012) is found to provide a good representation of form drag, after some parameter alterations.
X. Lin, R. A. Pielke Sr., R. Mahmood, C. A. Fiebrich, and R. Aiken
Atmos. Chem. Phys., 16, 827–841,Short summary
We found that the near-surface lapse rate has significantly decreased with a trend of −0.18 ± 0.03 °C (10 m)−1 per decade. We also showed that the 9 m height temperatures increased faster than temperatures at the 1.5 m screen level and/or conditions at the 1.5 m height cooled faster than at the 9 m height.
N. P. Lareau and C. B. Clements
Atmos. Chem. Phys., 15, 11513–11520,Short summary
This paper presents first observations of smoke-induced density currents, which are a boundary-layer flow phenomenon resulting from radiative shading by wild fire smoke. Our analysis uses a mobile Doppler lidar to reveal the anatomy and evolution of one such density current in northern California. The results show that these density currents can flow counter to the ambient wind and spread over long distances (e.g. 25km), causing unexpected smoke impacts.
J. Prytherch, M. J. Yelland, I. M. Brooks, D. J. Tupman, R. W. Pascal, B. I. Moat, and S. J. Norris
Atmos. Chem. Phys., 15, 10619–10629,Short summary
Signals at scales associated with wave and platform motion are often apparent in ship-based turbulent flux measurements, but it has been uncertain whether this is due to measurement error or to wind-wave interactions. We show that the signal has a dependence on horizontal ship velocity and that removing the signal reduces the dependence of the momentum flux on the orientation of the ship to the wind. We conclude that the signal is a bias due to time-varying motion-dependent flow distortion.
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