Tropical and Boreal Forest – Atmosphere Interactions: A Review

Paulo Artaxo; Hans-Christen Hansson; Meinrat O. Andreae; Jaana Bäck; Eliane Gomes Alves; Henrique M. J. Barbosa; Frida Bender; Efstratios Bourtsoukidis; Samara Carbone; Jinshu Chi; Stefano Decesari; Viviane R. Després; Florian Ditas; Ekaterina Ezhova; Sandro Fuzzi; Niles J. Hasselquist; Jost Heintzenberg; Bruna A. Holanda; Alex Guenther; Hannele Hakola; Liine Heikkinen; Veli-Matti Kerminen; Jenni Kontkanen; Radovan Krejci; Markku Kulmala; Jost V. Lavric; Gerrit de Leeuw; Katrianne Lehtipalo; Luiz Augusto T. Machado; Gordon McFiggans; arco Aurelio M. Franco; Bruno Backes Meller; Fernando G. Morais; Claudia Mohr; William Morgan; Mats B. Nilsson; Matthias Peichl; Tuukka Petäjä; Maria Praß; Christopher Pöhlker; Mira L. Pöhlker; Ulrich Pöschl; Celso Von Randow; Ilona Riipinen; Janne Rinne; Luciana V. Rizzo; Daniel Rosenfeld; Maria A. F. Silva Dias; Larisa Sogacheva; Philip Stier; Erik Swietlicki; Matthias Sörgel; Peter Tunved; Aki Virkkula; Jian Wang; Bettina Weber; Ana Maria Yáñez-Serrano; Paul Zieger; Eugene Mikhailov; James N. Smith; Jürgen Kesselmeier
2022 | TELLUS B | 74 (24-163)

This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observatory in Central Amazonia, the Zotino Tall Tower Observatory in Siberia, and the Station to Measure Ecosystem-Atmosphere Relations at Hyytiäla in Finland. The review is complemented by short-term observations from networks and large experiments.

The review discusses atmospheric chemistry observations, aerosol formation and processing, physiochemical aerosol, and cloud condensation nuclei properties and finds surprising similarities and important differences in the two ecosystems. The aerosol concentrations and chemistry are similar, particularly concerning the main chemical components, both dominated by an organic fraction, while the boreal ecosystem has generally higher concentrations of inorganics, due to higher influence of long-range transported air pollution. The emissions of biogenic volatile organic compounds are dominated by isoprene and monoterpene in the tropical and boreal regions, respectively, being the main precursors of the organic aerosol fraction.

Observations and modeling studies show that climate change and deforestation affect the ecosystems such that the carbon and hydrological cycles in Amazonia are changing to carbon neutrality and affect precipitation downwind. In Africa, the tropical forests are so far maintaining their carbon sink.

It is urgent to better understand the interaction between these major ecosystems, the atmosphere, and climate, which calls for more observation sites, providing long-term data on water, carbon, and other biogeochemical cycles. This is essential in finding a sustainable balance between forest preservation and reforestation versus a potential increase in food production and biofuels, which are critical in maintaining ecosystem services and global climate stability. Reducing global warming and deforestation is vital for tropical forests.

Atmospheric composition in the European Arctic and 30 years of the Zeppelin Observatory, Ny-Ålesund

Platt, S. M.; Hov, Ø.; Berg, T.; Breivik, K.; Eckhardt, S.; Eleftheriadis, K.; Evangeliou, N.; Fiebig, M.; Fisher, R.; Hansen, G.; Hansson, H.-C.; Heintzenberg, J.; Hermansen, O.; Heslin-Rees, D.; Holmén, K.; Hudson, S.; Kallenborn, R.; Krejci, R.: Krognes, T.; Larssen, S.; Lowry, D.; Lund Myhre, C.; Lunder, C.; Nisbet, E.; Nizzetto, P. B.; Park, K.-T.; Pedersen, C. A.; Aspmo Pfaffhuber, K.; Röckmann, T.; Schmidbauer, N.; Solberg, S.; Stohl, A.; Ström, J.; Svendby, T.; Tunved, P.; Tørnkvist, K.; van der Veen, C.; Vratolis, S.; Yoon, Y. J.; Yttri, K. E.; Zieger, P.; Aas, W.; Tørseth, K.
2022 | Atmos. Chem. Phys. | 22 (3321-3369)

The Zeppelin Observatory (78.90∘ N, 11.88∘ E) is located on Zeppelin Mountain at 472 m a.s.l. on Spitsbergen, the largest island of the Svalbard archipelago. Established in 1989, the observatory is part of Ny-Ålesund Research Station and an important atmospheric measurement site, one of only a few in the high Arctic, and a part of several European and global monitoring programmes and research infrastructures, notably the European Monitoring and Evaluation Programme (EMEP); the Arctic Monitoring and Assessment Programme (AMAP); the Global Atmosphere Watch (GAW); the Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS); the Advanced Global Atmospheric Gases Experiment (AGAGE) network; and the Integrated Carbon Observation System (ICOS). The observatory is jointly operated by the Norwegian Polar Institute (NPI), Stockholm University, and the Norwegian Institute for Air Research (NILU). Here we detail the establishment of the Zeppelin Observatory including historical measurements of atmospheric composition in the European Arctic leading to its construction. We present a history of the measurements at the observatory and review the current state of the European Arctic atmosphere, including results from trends in greenhouse gases, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), other traces gases, persistent organic pollutants (POPs) and heavy metals, aerosols and Arctic haze, and atmospheric transport phenomena, and provide an outline of future research directions.

Tropical and Boreal Forest Atmosphere Interactions: A Review

Artaxo, P; Hansson, HC; Andreae, MO; Back, J; Alves, EG; Barbosa, HMJ; Bender, F; Bourtsoukidis, E; Carbone, S; Chi, JS; Decesari, S; Despres, VR; Ditas, F; Ezhova, E; Fuzzi, S; Hasselquist, NJ; Heintzenberg, J; Holanda, BA; Guenther, A; Hakola, H; Heikkinen, L; Kerminen, VM; Kontkanen, J; Krejci, R; Kulmala, M; Lavric, JV; de Leeuw, G; Lehtipalo, K; Machado, LAT; McFiggans, G; Franco, MAM; Meller, BB; Morais, FG; Mohr, C; Morgan, W; Nilsson, MB; Peichl, M; Petaja, T; Prass, M; Pohlker, C; Pohlker, ML; Poschl, U; Von Randow, C; Riipinen, I; Rinne, J; Rizzo, LV; Rosenfeld, D; Dias, MAFS; Sogacheva, L; Stier, P; Swietlicki, E; Sorgel, M; Tunved, P; Virkkula, A; Wang, J; Weber, B; Yanez-Serrano, AM; Zieger, P; Mikhailov, E; Smith, JN; Kesselmeier, J
2022 | Tellus Ser. B-Chem. Phys. Meteorol. | 74 (1) (24-163)

The Atmospheric Aerosol over Western Greece-Six Years of Aerosol Observations at the Navarino Environmental Observatory

Hansson, HC; Tunved, P; Krejci, R; Freud, E; Kalivitis, N; Hennig, T; Maneas, G; Gerasopoulos, E
2021 | ATMOSPHERE | 12 (4)
aerosol , atmosphere , background , long-term , mediterranean , particle size
The Eastern Mediterranean is a highly populated area with air quality problems. It is also where climate change is already noticed by higher temperatures and s changing precipitation pattern. The anthropogenic aerosol affects health and changing concentrations and properties of the atmospheric aerosol affect radiation balance and clouds. Continuous long-term observations are essential in assessing the influence of anthropogenic aerosols on climate and health. We present six years of observations from Navarino Environmental Observatory (NEO), a new station located at the south west tip of Peloponnese, Greece. The two sites at NEO, were evaluated to show the influence of the local meteorology and to assess the general background aerosol possible. It was found that the background aerosol was originated from aged European aerosols and was strongly influenced by biomass burning, fossil fuel combustion, and industry. When subsiding into the boundary layer, local sources contributed in the air masses moving south. Mesoscale meteorology determined the diurnal variation of aerosol properties such as mass and number by means of typical sea breeze circulation, giving rise to pronounced morning and evening peaks in pollutant levels. While synoptic scale meteorology, mainly large-scale air mass transport and precipitation, strongly influenced the seasonality of the aerosol properties.

From a polar to a marine environment: has the changing Arctic led to a shift in aerosol light scattering properties?

2020 | Atmos. Chem. Phys. | 20 (13671-13686)

The study of long-term trends in aerosol optical properties is an important task to understand the underlying aerosol processes influencing the change of climate. The Arctic, as the place where climate change manifests most, is an especially sensitive region of the world. Within this work, we use a unique long-term data record of key aerosol optical properties from the Zeppelin Observatory, Svalbard, to ask the question of whether the environmental changes of the last 2 decades in the Arctic are reflected in the observations. We perform a trend analysis of the measured particle light scattering and backscattering coefficients and the derived scattering Ångström exponent and hemispheric backscattering fraction. In contrast to previous studies, the effect of in-cloud scavenging and of potential sampling losses at the site are taken explicitly into account in the trend analysis. The analysis is combined with a back trajectory analysis and satellite-derived sea ice data to support the interpretation of the observed trends. We find that the optical properties of aerosol particles have undergone clear and significant changes in the past 2 decades. The scattering Ångström exponent exhibits statistically significant decreasing of between −4.9 % yr−1 and −6.5 % yr−1 (using wavelengths of λ=450 and 550 nm), while the particle light scattering coefficient exhibits statistically significant increasing trends of between 2.6 % yr−1 and 2.9 % yr−1 (at a wavelength of λ=550 nm). The magnitudes of the trends vary depending on the season. These trends indicate a shift to an aerosol dominated more by coarse-mode particles, most likely the result of increases in the relative amount of sea spray aerosol. We show that changes in air mass circulation patterns, specifically an increase in air masses from the south-west, are responsible for the shift in aerosol optical properties, while the decrease of Arctic sea ice in the last 2 decades only had a marginal influence on the observed trends.

The Roles of the Atmosphere and Ocean in Driving Arctic Warming Due to European Aerosol Reductions

Krishnan, S; Ekman, AML; Hansson, HC; Riipinen, I; Lewinschal, A; Wilcox, LJ; Dallafior, T
2020 | Geophys Res Lett | 47 (7)
Clean air policies can have significant impacts on climate in remote regions. Previous modeling studies have shown that the temperature response to European sulfate aerosol reductions is largest in the Arctic. Here we investigate the atmospheric and ocean roles in driving this enhanced Arctic warming using a set of fully coupled and slab-ocean simulations (specified ocean heat convergence fluxes) with the Norwegian Earth system model (NorESM), under scenarios with high and low European aerosol emissions relative to year 2000. We show that atmospheric processes drive most of the Arctic response. The ocean pathway plays a secondary role inducing small temperature changes mostly in the opposite direction of the atmospheric response. Important modulators of the temperature response patterns are changes in sea ice extent and subsequent turbulent heat flux exchange, suggesting that a proper representation of Arctic sea ice and turbulent changes is key to predicting the Arctic response to midlatitude aerosol forcing. Plain Language Summary Aerosols are liquid or solid particles suspended in air, which may have adverse air quality and health impacts. Sulfate aerosols also have a cooling influence on climate and can mask some of the greenhouse gas-induced global warming. While aerosol emissions are variable in space and time, their impacts are not limited to where they are emitted. In fact, studies using global climate models have shown that changing sulfur dioxide emissions in Europe can have significant impacts on Arctic climate. Here we investigate the roles of changes in atmospheric and ocean heat transport in driving these changes in the Arctic by conducting a series of climate model simulations with specified anthropogenic sulfur dioxide emissions and different ocean heat transport fluxes. We find that changes through the atmosphere play a primary role in affecting the Arctic climate. These changes are modulated by changes in sea ice extent and the energy exchange between ocean and atmosphere in the sub-Arctic. Aerosol-driven changes in ocean heat transport play a smaller, secondary role in the Arctic and tend to reduce the impacts. Our results show that the proper representation of Arctic sea ice is crucial for accurately modeling the Arctic response to changes in midlatitude aerosol forcing.

Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes

Boy, M; Thomson, ES; Navarro, JCA; Arnalds, O; Batchvarova, E; Back, J; Berninger, F; Bilde, M; Brasseur, Z; Dagsson-Waldhauserova, P; Castarede, D; Dalirian, M; de Leeuw, G; Dragosics, M; Duplissy, EM; Duplissy, J; Ekman, AML; Fang, KY; Gallet, JC; Glasius, M; Gryning, SE; Grythe, H; Hansson, HC; Hansson, M; Isaksson, E; Iversen, T; Jonsdottir, I; Kasurinen, V; Kirkevag, A; Korhola, A; Krejci, R; Kristjansson, JE; Lappalainen, HK; Lauri, A; Lepparanta, M; Lihavainen, H; Makkonen, R; Massling, A; Meinander, O; Nilsson, ED; Olafsson, H; Pettersson, JBC; Prisle, NL; Riipinen, I; Roldin, P; Ruppel, M; Salter, M; Sand, M; Seland, O; Seppa, H; Skov, H; Soares, J; Stohl, A; Strom, J; Svensson, J; Swietlicki, E; Tabakova, K; Thorsteinsson, T; Virkkula, A; Weyhenmeyer, GA; Wu, YS; Zieger, P; Kulmala, M
2019 | Atmos. Chem. Phys. | 19 (3) (2015-2061)
aerosol-climate interactions , biogenic volatile emissions , black carbon deposition , boreal forest , cloud droplet activation , earth system model , elemental carbon , eurasian experiment peex , organic compounds , sea-ice conditions

The Nordic Centre of Excellence CRAICC (Cryosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011-2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change-cryosphere interactions that affect Arctic amplification.

Arctic sea ice melt leads to atmospheric new particle formation.

Dall'Osto, M.; Beddows, DCS.; Tunved, P.; Krejci, R.; Strom, J.; Hansson, HC.; Yoon, YJ.; Park, KT.; Becagli, S.; Udisti, R.; Onasch, T.; O'Dowd, CD.; Simo, R.; Harrison, RM.
2017 | Sci Rep | 10

Future Response of Temperature and Precipitation to Reduced Aerosol Emissions as Compared with Increased Greenhouse Gas Concentrations

Navarro, JCA; Ekman, AML; Pausata, FSR; Lewinschal, A; Varma, V; Seland, O; Gauss, M; Iversen, T; Kirkevag, A; Riipinen, I; Hansson, HC
2017 | J Clim | 30 (3) (939-954)
air quality , circulation , climate response , earth system model , global climate , intertropical convergence zone , late 20th-century , noresm1-m , pollutants , sensitivity

Experiments with a climate model (NorESM1) were performed to isolate the effects of aerosol particles and greenhouse gases on surface temperature and precipitation in simulations of future climate. The simulations show that by 2025-49 a reduction of aerosol emissions from fossil fuels following a maximum technically feasible reduction (MFR) scenario could lead to a global and Arctic warming of 0.26 and 0.84 K, respectively, as compared with a simulation with fixed aerosol emissions at the level of 2005. If fossil fuel emissions of aerosols follow a current legislation emissions (CLE) scenario, the NorESM1 model simulations yield a nonsignificant change in global and Arctic average surface temperature as compared with aerosol emissions fixed at year 2005. The corresponding greenhouse gas effect following the representative concentration pathway 4.5 (RCP4.5) emission scenario leads to a global and Arctic warming of 0.35 and 0.94 K, respectively. The model yields a marked annual average northward shift in the intertropical convergence zone with decreasing aerosol emissions and subsequent warming of the Northern Hemisphere. The shift is most pronounced in the MFR scenario but also visible in the CLE scenario. The modeled temperature response to a change in greenhouse gas concentrations is relatively symmetric between the hemispheres, and there is no marked shift in the annual average position of the intertropical convergence zone. The strong reduction in aerosol emissions in the MFR scenario also leads to a net southward cross-hemispheric energy transport anomaly both in the atmosphere and ocean, and enhanced monsoon circulation in Southeast Asia and East Asia causing an increase in precipitation over a large part of this region.

Amplification of Arctic warming by past air pollution reductions in Europe

Acosta Navarro, J.; Varma, V.; Riipinen, I.; Seland, Ø.; Kirkevåg, A.; Struthers, H.; Iversen, T.; Hansson, H.-C.; Ekman, A. M. L.
2016 | Nat. Geosci. | 9 (277-281)

Multi-seasonal ultrafine aerosol particle number concentration measurements at the Gruvebadet observatory, Ny-lesund, Svalbard Islands

Lupi, A; Busetto, M; Becagli, S; Giardi, F; Lanconelli, C; Mazzola, M; Udisti, R; Hansson, HC; Henning, T; Petkov, B; Strom, J; Krejci, R; Tunved, P; Viola, AP; Vitale, V
2016 | Rend. Lincei.-Sci. Fis. Nat. | 27 (59-71)
aerosol size distribution , alesund , arctic aerosol , arctic air-pollution , arctic haze , boundary layer , cycle , lognormal fitting procedure , size distributions , summer , ultrafine aerosol concentration , winter , zeppelin station
The object of this study was to investigate the different modal behavior of ultrafine aerosol particles collected at the Gruvebadet observatory located in Ny-lesund (Svalbard Islands, 78A degrees 55'N, 11A degrees 56'E). Aerosol particle size distribution was measured in the size range from 10 to 470 nm typically from the beginning of spring to the beginning of fall during four (non-consecutive) years (2010, 2011, 2013 and 2014). The median concentration for the whole period taken into account was 214 particles cm(-3), oscillating between the median maximum in July with a concentration of 257 particles cm(-3) and a median minimum in April with 197 particles cm(-3). The median total number concentration did not present a well-defined seasonal behavior, as shown by contrast looking at the sub/modal number concentration, where distinct trends appeared in the predominant accumulation concentration recorded during April/May and the preponderant concentration of Aitken particles during the summer months. Lastly, the short side-by-side spring 2013 campaign performed at the Zeppelin observatory with a differential mobility particle sizer was characterized by an aerosol concentration mean steady difference between the two instruments of around 14 %, thereby supporting the reliability of the device located at Gruvebadet.

Amplification of Arctic warming by past air pollution reductions in Europe (vol 9, pg 277, 2016)

Navarro, JCA; Varma, V; Riipinen, I; Seland, O; Kirkevag, A; Struthers, H; Iversen, T; Hansson, HC; Ekman, AML
2016 | Nat. Geosci. | 9 (6) (470-470)

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