Opposite long-term trends in aerosols between low and high altitudes: a testimony to the aerosol–PBL feedback

Abstract. Interactions between absorbing aerosols and the planetary boundary layer (PBL) play an important role in affecting air pollution near the surface. In this study, a unique feature of the aerosol–PBL interaction is identified that has important implications in monitoring and combating air pollution. Opposite trends in aerosol loading between the lower and upper PBL are shown on a wide range of timescales and data acquired by various platforms: from a short-term field experiment to decadal satellite observations and multidecadal ground observations in China. A novel method is proposed to obtain the vertical profiles of aerosol loading from passive sensors by virtue of varying elevations. The analyses of visibility, aerosol optical depth, and extinction with different temporal scales exhibit the similar trend, i.e., increasing in the lower atmosphere but decreasing in the upper atmosphere. Integration of the reversal aerosol trend below and above the PBL resulted in a much less change in the column-integrated quantities. The surface cooling effect, together with the change in the heating rate induced by the absorbing aerosol, unevenly modifies the atmospheric temperature profile, causing a more stable atmosphere inside the PBL but a destabilized atmosphere above the PBL. Such a change in the atmospheric stability favors the accumulation of pollutants near the surface and the vertical diffusion of aerosol particles in the upper atmosphere, both of which are consistent with the observed reversal aerosol trends. These findings have multiple implications in understanding and combating air pollution, especially in many developing countries with high emissions of light-absorbing aerosols.

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Opposite Long-term Trends in Aerosols between Lower and Higher Altitudes: A Testimony to the Aerosol-PBL Feedback

10.5194/acp-2017-2 ◽

2017 ◽

Author(s):

Zipeng Dong ◽

Zhanqing Li ◽

Xing Yu ◽

Maureen Cribb ◽

Xingmin Li ◽

...

Keyword(s):

Air Pollution ◽

Atmospheric Temperature ◽

Lower Atmosphere ◽

Aerosol Loading ◽

Wide Range ◽

Atmospheric Temperature Profile ◽

Long Term Trends ◽

Novel Method ◽

Absorbing Aerosols ◽

The Stability

Abstract. Interactions between absorbing aerosols and the planetary boundary layer (PBL) play an important role in enhancing air pollution near the surface. In this study, a unique feature of the interaction is found that has important implications in monitoring and combating air pollution. Opposite trends in aerosol loading between the lower and upper PBL are found on a wide range of time scales and from different types of data acquired by various platforms: from a short-term field experiment to decadal satellite observations, and multi-decadal ground observations in China. A novel method is proposed to obtain the vertical profiles of aerosol loading from passive sensors by virtue of varying elevations. Trend analyses of three particulate variables having different temporal scales, namely, visibility, aerosol optical depth, and extinction, all exhibit the same trend: increasing at the lower atmosphere, but decreasing in the upper. Column-integrated quantities are much less variable. The reversal trend is consistent with the strong vertical gradients in the aerosol-induced atmospheric heating rate that unevenly modifies the atmospheric temperature profile and alters the stability differently. These findings have multiple implications in understanding and combating air pollution, especially in many developing countries producing large amounts of black and brown carbon aerosols.

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Atmospheric implications of the lack of H 3 + detection at Neptune

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2020.0100 ◽

2020 ◽

Vol 378 (2187) ◽

pp. 20200100 ◽

Cited By ~ 2

Author(s):

L. Moore ◽

J. I. Moses ◽

H. Melin ◽

T. S. Stallard ◽

J. O’Donoghue

Keyword(s):

Giant Planet ◽

Atmospheric Temperature ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Observational Constraints ◽

Atmospheric Conditions ◽

Atmospheric Escape ◽

Upper Limits ◽

Voyager 2 ◽

The Impact

H 3 + has been detected at all of the solar system giant planets aside from Neptune. Current observational upper limits imply that there is far less H 3 + emission at Neptune than rudimentary modelling would suggest. Here, we explore via modelling a range of atmospheric conditions in order to find some that could be consistent with observational constraints. In particular, we consider that the upper atmosphere might be much cooler than it was during the 1989 Voyager 2 encounter, and we examine the impact of an enhanced influx of external material that could act to reduce H 3 + density. Resulting ionosphere models that are consistent with existing H 3 + observational constraints have an exospheric temperature of 450 K or less, 300 K lower than the Voyager 2 value. Alternatively, if a topside CO influx of 2 × 10 8 cm −2 s −1 is imposed, the upper atmospheric temperature can be higher, up to 550 K. The potential cooling of Neptune’s atmosphere is relevant for poorly understood giant planet thermospheric energetics, and would also impact aerobreaking manoeuvers for any future spacecraft. Such a large CO influx, if present, could imply Triton is a very active moon with prominent atmospheric escape, and/or that Neptune’s rings significantly modify its upper atmosphere, and the introduction of so much exogenic material would complicate interpretation of the origin of species observed in Neptune’s lower atmosphere. This article is part a discussion meeting issue ‘Future exploration of ice giant systems’.

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Direct measurements of the effect of biomass burning over the Amazon on the atmospheric temperature profile

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-12007-2009 ◽

2009 ◽

Vol 9 (3) ◽

pp. 12007-12025 ◽

Cited By ~ 2

Author(s):

A. Davidi ◽

I. Koren ◽

L. Remer

Keyword(s):

Temperature Profile ◽

Amazon Basin ◽

Atmospheric Stability ◽

Radiation Energy ◽

Atmospheric Temperature ◽

Lower Atmosphere ◽

Cloud Formation ◽

Aerosol Layer ◽

Cloud Properties ◽

Atmospheric Temperature Profile

Abstract. Aerosols suspended in the atmosphere interact with the solar radiation and thus change the radiation energy fluxes in the atmospheric column. In particular, absorbing aerosols can stabilize the lower atmosphere by warming the aerosol layer; while cooling both: the layers beneath and the surface. Changes in atmospheric stability can affect cloud formation and cloud properties. In this paper we measure changes in the atmospheric temperature profile as a function of the smoke loading and the cloudiness over the Amazon basin, during the dry seasons (August and September) of 2005–2007. We show that as the aerosol optical depth (AOD) increases from 0.02 to a value of ~0.6, there is a decrease of ~4.3°C at 1000 hPa, and an increase of ~1.6°C at 850 hPa. The warming of the aerosol layer at 850 hPa is likely due to aerosol absorption when the particles are exposed to direct illumination by the sun. The large values of cooling in the lower layers are explained by a combination of aerosol extinction of the solar flux in the layers aloft and by an aerosol-induced increase of cloud cover and further shading of the lower atmosphere. We estimate that the increase in cloud fraction due to aerosol contributes about half of the observed cooling in the lower layers.

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Microwave temperature and pressure measurements with the Odin satellite: I. Observational method

Canadian Journal of Physics ◽

10.1139/p01-158 ◽

2002 ◽

Vol 80 (4) ◽

pp. 443-454 ◽

Cited By ~ 6

Author(s):

J R Pardo ◽

M Ridal ◽

D Murtagh ◽

J Cernicharo

Keyword(s):

Radiative Transfer ◽

Outer Space ◽

Atmospheric Temperature ◽

Upper Atmosphere ◽

Operational Mode ◽

Altitude Range ◽

Molecular Lines ◽

Temperature And Pressure ◽

Radiative Transfer Modeling ◽

Temperature Vertical Profile

The Odin satellite is equipped with millimetre and sub-millimetre receivers for observations of several molecular lines in the middle and upper atmosphere of our planet (~25100 km, the particular altitude range depending on the species) for studies in dynamics, chemistry, and energy transfer in these regions. The same receivers are also used to observe molecules in outer space, this being the astrophysical share of the project. Among the atmospheric lines that can be observed, we find two corresponding to molecular oxygen (118.75 GHz and 487.25 GHz). These lines can be used for retrievals of the atmospheric temperature vertical profile. In this paper, we describe the radiative-transfer modeling for O2 in the middle and upper atmosphere that we will use as a basis for the retrieval algorithms. Two different observation modes have been planned for Odin, the three-channel operational mode and a high-resolution mode. The first one will determine the temperature and pressure on an operational basis using the oxygen line at 118.75 GHz, while the latter can be used for measurements of both O2 lines, during a small fraction of the total available time for aeronomy, aimed at checking the particular details of the radiative transfer near O2 lines at very high altitudes (>70 km). The Odin temperature measurements are expected to cover the altitude range ~3090 km. PACS Nos.: 07.57Mj, 94.10Dy, 95.75Rs

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Sulfuric acid vapor and sulfur dioxide in the atmosphere of Venus as observed by the Venus Express Radio Science Experiment VeRa

10.5194/epsc2021-196 ◽

2021 ◽

Author(s):

Janusz Oschlisniok ◽

Bernd Häusler ◽

Martin Pätzold ◽

Silvia Tellmann ◽

Michael Bird

Keyword(s):

Sulfuric Acid ◽

Transport Model ◽

Lower Atmosphere ◽

Local Times ◽

Acid Vapor ◽

Radio Science ◽

X Band ◽

Wide Range ◽

Venus Express ◽

Atmosphere Of Venus

The main cloud deck within Venus' atmosphere, which covers the entire planet between approx. 50 and 70 km altitude, is believed to consist mostly of liquid sulfuric acid. The temperature below the main clouds is high enough to evaporate the H2SO4 droplets into gaseous sulfuric acid forming a haze layer which extends to altitudes as deep as 35 km. Gaseous sulfuric acid in Venus&#8217; lower atmosphere is responsible for a strong absorption of radio waves as seen in Mariner, Pioneer Venus, Magellan and Venera radio science observations. Radio wave absorption measurements can be used to derive the amount of H2SO4 in Venus&#8217; atmosphere. The radio science experiment VeRa onboard Venus Express probed the atmosphere of Venus between 2006 and 2014 with radio signals at 13 cm (S-band) and 3.6 cm (X-band) wavelengths. The orbit of the Venus Express spacecraft allowed to sound the atmosphere over a wide range of latitudes and local times providing a global picture of the sulfuric acid vapor distribution. We present the global H2SO4(g) distribution derived from the X-band radio signal attenuation for the time of the entire Venus Express mission. The observation is compared with results obtained from a 2-D transport model. The VeRa observations were additionally used to estimate the abundance of SO2 near the cloud bottom. The global distribution of SO2 at these altitudes is presented and compared with results obtained from other experiments. Eight years of VEX observation allow to study the long-term evolution of H2SO4 and SO2. The latter is presented for the northern polar region.

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Global upper-atmospheric heating at Jupiter by the recirculation of auroral energy

10.5194/epsc2021-808 ◽

2021 ◽

Author(s):

James O'Donoghue ◽

Luke Moore ◽

Tanapat Bhakyapaibul ◽

Henrik Melin ◽

Tom Stallard ◽

...

Keyword(s):

Heat Source ◽

Acoustic Waves ◽

Temperature Gradients ◽

Upper Atmosphere ◽

Global Temperature ◽

Lower Atmosphere ◽

Polar Regions ◽

High Resolution Data ◽

Coriolis Forces ◽

Global Circulation Models

Jupiter's upper atmosphere is significantly hotter than expected based on the amount of solar heating it receives. This temperature discrepency is known as the 'energy crisis' due to it's nearly 50-year duration and the fact it also occurs at Saturn, Uranus and Neptune. At Jupiter, magnetosphere-ionosphere coupling gives rise to intense auroral emissions and enormous energy deposition in the magnetic polar regions, so it was presumed long ago that redistribution of this energy could heat the rest of the planet. However, most global circulation models have difficulty redistributing auroral energy globally due to the strong Coriolis forces and ion drag on this rapidly rotating planet. Consequently, other possible heat sources have continued to be studied, such as heating by gravity and acoustic waves emanating from the lower atmosphere. Each global heating mechanism would imprint a unique signature on global temperature gradients, thus revealing the dominant heat source, but these gradients have not been determined due a lack of planet-wide, high-resolution data. The last global map of Jovian upper-atmospheric temperatures was produced using ground-based data taken in 1993, in which the region between 45o latitude (north & south) and the poles was represented by just 2 pixels. As a result, those maps did not (or could not) show a clear temperature gradient, and furthermore, they even showed regions of hot atmosphere near the equator, supporting the idea of an equatorial heat source, e.g. gravity and/or acoustic wave heating. Therefore observationally and from a modeling perspective, a concensus has not been reached to date. Here we report new infrared spectroscopy of Jupiter's major upper-atmospheric ion H3+, with a spatial resolution of 2o longitude and latitude extending from pole to equator, capable of tracing the global temperature gradients. We find that temperatures decrease steadily from the auroral polar regions to the equator. Further, during a period of enhanced activity possibly driven by a solar wind compression, a high-temperature planetary-scale structure was observed which may be propagating from the aurora. These observations indicate that Jupiter's upper atmosphere is predominantly heated via the redistribution of auroral energy, and therefore that Coriolis forces and ion drag are observably overcome.

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Future changes in Beijing haze events under different shared socioeconomic pathways

10.5194/egusphere-egu21-5787 ◽

2021 ◽

Author(s):

Liang Guo ◽

Laura Wilcox ◽

Massimo Bollasina ◽

Steven Turnock ◽

Marianne Lund ◽

...

Keyword(s):

Air Pollution ◽

Global Warming ◽

Greenhouse Gases ◽

Weather Patterns ◽

Greenhouse Gases Emissions ◽

Wide Range ◽

The Future ◽

Aerosol Emissions

The occurrence of severe haze events remains a serious problem in Beijing. Previous studies suggested that the frequency of weather patterns conducive to haze may increase with global warming. The new Shared Socioeconomic Pathways (SSPs) cover a wide range of uncertainties in aerosol and greenhouse gases emissions. Global and Chinese aerosol emissions are projected to decrease in most SSPs, while increases in greenhouse gases and global warming will continue for the rest of the century. The future, therefore, remains unclear.We quantified the air pollution over Beijing and associated weather patterns using multiple indices calculated from the SSPsWe show that the occurrence of weather patterns conducive to the formation of haze significantly increases by the end of the century due to increases in greenhouse gases. Aerosol reductions also cause an increase in their occurrence, but reduce the severity of haze, and overall reducing aerosol emissions will be beneficial.

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Qualitative assessment of air pollution in the working area of energy-intensive materials production by nanoscale aerosols with a solid dispersed phase

Russian Journal of Occupational Health and Industrial Ecology ◽

10.31089/1026-9428-2021-61-12-828-832 ◽

2021 ◽

Vol 61 (12) ◽

pp. 828-832

Author(s):

Boris N. Filatov ◽

Natalya I. Latyshevskaya ◽

Natalya V. Krylova ◽

Irina K. Gorkina ◽

Yulya I. Velikorodnaya ◽

...

Keyword(s):

Air Pollution ◽

Mass Concentration ◽

Solid Phase ◽

Qualitative Assessment ◽

Dust Particles ◽

Dispersed Phase ◽

Forced Circulation ◽

Aluminum Powders ◽

Nanoscale Particles ◽

Wide Range

The presence of grinding, mixing, and fractionation of solid components of formulations leads to the formation of aerosols in the air of the working area with a wide range of dispersion of the solid phase - all this characterizes the organization of technological processes for the production of energy-intensive materials. The study aims to give a qualitative assessment of possible air pollution of the working area of energy-intensive materials production by nanoscale aerosols with a solid dispersed phase. The researchers carried out the sampling of the working area air and flushes from solid horizontal surfaces to produce energy-intensive materials. We carried out the sampling by forced circulation of the test air through the absorption devices of Polezhaev. Scientists used Triton TX-114 solution with a mass concentration of 2.0 mg/dm3 as an absorption medium. The researchers performed flushing from surfaces using cloth tampons moistened with Triton TX-114 solution with a mass concentration of 2.0 mg/dm3. We determined the particle sizes in the samples using NanotracULTRA (Microtrac). Scientists found aluminum and nitrocellulose particles with sizes from 36 to 102 nm in the air of the working area and flushes from horizontal surfaces. The study of the fractional composition of RDX and aluminum powders of the ASD-1 brand showed the presence of nanoscale particles in them. Nanoscale dust particles pollute the air of the working area and solid horizontal surfaces at certain stages of the production of energy-intensive materials. There are nanoscale particles in the composition of powders of some standard components of formulations. Flushes from solid horizontal surfaces are an adequate qualitative indicator of the presence of nanoaerosols in the air of the working area.

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Extreme heat in India and anthropogenic climate change

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-365-2018 ◽

2018 ◽

Vol 18 (1) ◽

pp. 365-381 ◽

Cited By ~ 28

Author(s):

Geert Jan van Oldenborgh ◽

Sjoukje Philip ◽

Sarah Kew ◽

Michiel van Weele ◽

Peter Uhe ◽

...

Keyword(s):

Air Pollution ◽

Global Warming ◽

Health Effects ◽

Climate Models ◽

Decadal Variability ◽

Heat Waves ◽

Health Impact ◽

Heat Index ◽

Maximum Temperature ◽

Surface Cooling

Abstract. On 19 May 2016 the afternoon temperature reached 51.0 °C in Phalodi in the northwest of India – a new record for the highest observed maximum temperature in India. The previous year, a widely reported very lethal heat wave occurred in the southeast, in Andhra Pradesh and Telangana, killing thousands of people. In both cases it was widely assumed that the probability and severity of heat waves in India are increasing due to global warming, as they do in other parts of the world. However, we do not find positive trends in the highest maximum temperature of the year in most of India since the 1970s (except spurious trends due to missing data). Decadal variability cannot explain this, but both increased air pollution with aerosols blocking sunlight and increased irrigation leading to evaporative cooling have counteracted the effect of greenhouse gases up to now. Current climate models do not represent these processes well and hence cannot be used to attribute heat waves in this area. The health effects of heat are often described better by a combination of temperature and humidity, such as a heat index or wet bulb temperature. Due to the increase in humidity from irrigation and higher sea surface temperatures (SSTs), these indices have increased over the last decades even when extreme temperatures have not. The extreme air pollution also exacerbates the health impacts of heat. From these factors it follows that, from a health impact point of view, the severity of heat waves has increased in India. For the next decades we expect the trend due to global warming to continue but the surface cooling effect of aerosols to diminish as air quality controls are implemented. The expansion of irrigation will likely continue, though at a slower pace, mitigating this trend somewhat. Humidity will probably continue to rise. The combination will result in a strong rise in the temperature of heat waves. The high humidity will make health effects worse, whereas decreased air pollution would decrease the impacts.

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Arctic smoke – aerosol characteristics during a record air pollution event in the European Arctic and its radiative impact

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-2275-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 2275-2324 ◽

Cited By ~ 2

Author(s):

R. Treffeisen ◽

P. Turnved ◽

J. Ström ◽

A. Herber ◽

J. Bareiss ◽

...

Keyword(s):

Air Pollution ◽

Size Distribution ◽

Climate Model ◽

Atmospheric Stability ◽

The Arctic ◽

Aerosol Size Distribution ◽

Geometric Standard Deviation ◽

Transfer Model ◽

Climatic Effects ◽

Pollution Event

Abstract. In early May 2006 a record high air pollution event was observed at Ny-Ålesund, Spitsbergen. An atypical weather pattern established a pathway for the rapid transport of biomass burning aerosols from agricultural fires in Eastern Europe to the Arctic. Atmospheric stability was such that the smoke was constrained to low levels, within 2 km of the surface during the transport. A description of this smoke event in terms of transport and main aerosol characteristics can be found in Stohl et al. (2007). This study puts emphasis on the radiative effect of the smoke. The aerosol size distribution was characterized as having an accumulation mode centered at 165–185 nm and almost 1.6 for geometric standard deviation of the mode. Nucleation and small Aitken mode particles were almost completely suppressed within the smoke plume measured at Ny-Ålesund. Chemical and microphysical aerosol information obtained at Mt. Zeppelin (474 m.a.s.l) was used to derive input parameters for a one-dimensional radiation transfer model to explore the radiative effects of the smoke. The daily mean heating rate calculated on 2 May 2006 for the average size distribution and measured chemical composition reached 0.55 K day−1 at 0.5 km altitude for the assumed external mixture of the aerosols but showing much higher heating rates for an internal mixture (1.7 K day−1). In comparison a case study for March 2000 showed that the local climatic effects due to Arctic haze, using a regional climate model, HIRHAM, amounts to a maximum of 0.3 K day−1 of heating at 2 km altitude (Treffeisen et al., 2005).

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