**NEW**: AICI Special Issue of Atmospheric Chemistry & Physics
Link to articles summarizing outcomes of AICI Task
To order hard-copies of the AICI ACP Special Issue, go here and specify you want to order a hard copy of the AICI Special Issue of ACP.

Eric Wolff
email: ewwo@bas.ac.uk
British Antarctic Survey
High Cross, Madingley Road
Cambridge CB3 0ET, UK

Paul Shepson
email: pshepson@purdue.edu
Department of Chemistry
Purdue University
560 Oval Drive
West Lafayette, Indiana 47907-2084
USA

AICI web page
http://www.purdue.edu/aici

It is now recognised that changes in one compart-ment of the Earth System can strongly affect the state of other compartments. Feedbacks can amplify or mitigate trends. As the Earth and its climate change, particularly in response to phenomena such as greenhouse gas increases, and stratospheric ozone depletion, it becomes increasingly important to understand the interactions between different parts of the system. This has been the basis for the new structure of IGBP, which studies the three main compartments (land, ocean, and atmosphere) and the exchanges and interactions between them. The cryosphere – ice, snow and permafrost – occurs in all three of these compartments. It forms a large proportion of the surface separating the land and ocean from the atmosphere: a seasonal maximum of 40% of land is covered by snow or ice, while several percent of the ocean is sea-ice covered (Figure 1). The physical processes that involve ice are now being studied by the World Climate Research Pro-gram project CliC (Climate and Cryosphere). Until recently, it was generally assumed that the main bio-geochemical role of ice was that it restricted exchanges between the more active ocean and land surfaces and the atmosphere. However, studies in recent years have revealed evidence that important chemical exchanges also occur between ice and the atmosphere, and it makes sense to study these processes and their consequences generically. AICI aims to do this, forming a bridge between scientists working on ice-covered surfaces in both polar regions and in the mid-latitudes, atmospheric scientists interested in processes occurring on ice particles, laboratory scientists studying the properties of ice, and modellers who need to parameterise processes that involve ice.

This project has been jointly endorsed by IGAC and SOLAS (Surface Ocean Lower Atmosphere Study) – both of which are IGBP Core Projects – but it is also relevant to ILEAPS (Integrated Land Ecosystem-Atmosphere Process Study) and to PAGES (Past Global Changes), as well as to WCRP-CliC.

Until recently, the snow and ice covered regions of the world received little interest from the atmospheric chemistry community. However, a number of field programmes, principally in the Arctic and Antarctic have revealed many unexpected and interesting phenomena, and opened up the possibility that the chemistry of the ice may control aspects of boundary layer chemistry over large regions of the world, rather than the other way round. In addition, for some species the exchanges between snow and the atmos-phere, as well as post-depositional ice processes, have a decisive impact on the signal that is retrieved from ice cores: our best hope of reconstructing atmospheric chemistry from the pre-instrumental period.

Below we outline, as examples, two of the issues that have become apparent in recent years, as a pre-amble to setting questions that will be attacked within the lifespan of the AICI Task.

Example 1 – tropospheric ozone depletion

The discovery of ozone depletion events within the polar marine boundary layer [Bottenheim et al., 1986; Oltmans and Komhyr, 1986] came as a surprise. Since the initial finding, we have learnt much about the phenomenon, but we are still far from being able to predict the spatial or temporal distribution of the depletion, or to model the effects. The surprising magnitude of the effect points to weaknesses in our understanding of tropospheric ozone chemistry. This must be remedied, given its central role with respect to the atmosphere’s oxidizing capacity, and its significant contribution to radiative forcing.

Tropospheric ozone depletion occurs in both the Arctic (Figure 2), sub-Arctic and the Antarctic [Wessel et al., 1998]. In the Arctic marine boundary layer in springtime, depletion occurs from the surface up to ~1.5km [Bottenheim et al., 2002b], and occurs over periods of days to weeks, with concentrations as low as 50 ppt at times. The depletion events are associated with halogens, with Br/BrO appearing to play an especially important role [e.g. Barrie et al., 1988; Foster et al., 2001]. Satellite observations of BrO, showing particularly high concentrations over sea ice zones in springtime [Wagner et al., 2001], have reinforced current ideas about the general nature of the reactions leading to depletion, and suggested that sea ice is implicated. Recently it has been suggested that concentrated brines on new sea ice and in frost flowers [Rankin et al., 2002] might be the source of the halogens. This would explain why a similar phenomenon is seen over salt lakes [Stutz et al., 2002] and the Dead Sea [Matveev et al., 2001] where very salty deposits are also available. Brines and frost flowers may also be responsible for a significant part of sea salt aerosol concentrations over the polar regions [Rankin et al., 2002]. Among the chemical effects of the ozone depletion is a perturbation to the biogeochemistry of mercury, leading to enhanced atmospheric removal and deposition to Arctic ecosystems [Lindberg et al., 2002; Schroeder et al., 1998]; this process has also been reported from the Antarctic [Ebinghaus et al., 2002]. Finally, it is also noteworthy that ozone depletion occurs in cirrus clouds; it is conceivable that these chemistries could be related [Roumeau et al., 2000].

This work gives a picture of a phenomenon for which we have a skeleton understanding, but as yet no answers to some important questions. We do not yet understand why depletion occurs in the spring but not in the autumn; we have no confirmation that frost flowers are involved; we have not explored the likely effects on atmospheric boundary layer chemistry in full; we cannot completely identify the precursors to halogen atoms; and we have not established whether the phenomenon is involved in significant climate feedbacks.

Example 2 – snow photochemistry

Until recently, no consideration was given to the concept that the snowpack could itself be affected by photochemistry. However, a series of field [e.g. Honrath et al., 1999; Jones et al., 2000] and laboratory [e.g. Cotter et al., 2003; Dubowski et al., 2001; Honrath et al., 2000] experiments have established beyond doubt that NOx, as the first example, is produced photochemically from snow, with nitrate as the main precursor. In retrospect, this is not surprising – light penetrates at least the top few cm of snowpack, and many hydrophilic UV-absorbing chemicals are present in concentrations that are high relative to those in the atmosphere [Wolff et al., 2002].

Comparisons with model results have shown that emissions out of the snowpack can overwhelmingly control the chemistry of the sunlit Summer boundary layer over snow, particularly in cases where there is little mixing due to a surface inversion. For example, NO was present at South Pole in concentrations over 200 pptv during December 1998 [Davis et al., 2001], when model calculations excluding a snow source would have suggested 1-5 pptv. Very high OH concentrations [Mauldin et al., 2001] were also ob-served, and the NOx rich environment may have been responsible for this, in turn influencing the entire range of chemistry. The full implications have not yet been explored, but ozone production over a large part of the Antarctic plateau is one probable consequence [Crawford et al., 2001].

Many other chemicals seem to be produced photo-chemically from the snowpack – there is evidence so far for at least aldehydes such as HCHO [Sumner and Shepson, 1999; Sumner et al., 2002], CO [Haan et al., 2001], C₂H₂ [Bottenheim et al., 2002a] and HONO [Zhou et al., 2001]. In addition, there is extensive physical exchange of important species such as HCHO and H₂O₂ [Hutterli et al., 2001; Hutterli et al., 1999]. Until now, only the existence of the phe-nomenon, and some tentative flux estimates [e.g. Be-ine et al., 2002; Honrath et al., 2002; Jones et al., 2001] are available. Much work is needed, in the laboratory and the field, to understand the factors controlling the release of each chemical. Only then will it be possible, through modelling studies, to as-sess whether the processes have any large-scale importance. However, it is already clear that such snowpack chemistry will significantly affect both ice phase and boundary layer concentrations for photo-labile species. With our current state of knowledge, we assume that similar emission processes are occurring over mid-latitude and seasonal snowcovers, so that there is the potential for significant alteration of the boundary layer chemistry over substantial parts of the globe, including urban areas.

As far as we know, the phenomena described above occur under natural conditions and have always been present. However, changes in UV radiation, in concentrations of pollutants, in snow cover, and in temperature, could all affect the extent of the processes. For example, the tropospheric ozone production reported at the South Pole [Crawford et al., 2001] seems to have increased over the last 30 years; this could be partly a result of increased NOx production that would be predicted from increased UV radiation reaching the surface (because of stratospheric ozone depletion) [Jones and Wolff, 2003]; indeed we would expect all the photochemical reactions in snow to be enhanced in this way. The chemistry of halogen activation, as well as emission of species such as HONO, may be pH-dependent and thus impacted by acidic deposition from anthropogenic sources.

One of the key expectations of a warming world (under increased greenhouse gas concentrations) is that the cryosphere will shrink. In the near-term, seasonal snow cover and sea ice extent are expected to diminish. This will both reduce the scope for the snow-atmosphere interactions (such as those de-scribed above) to occur, and enhance the interactions of the atmosphere and the increased land and ocean areas. As an example, if the springtime depletion of tropospheric ozone is indeed linked to brine layers on new sea ice, then any change in the production rate of new sea ice will alter the locations and extent of this phenomenon. There are indications that Arctic ozone depletion events, and concomitant deposition of Hg, have increased in recent decades [Lindberg et al., 2002; Tarasick and Bottenheim, 2002]. We would also anticipate a change in the concentration of sea salt aerosol, with further possible direct and indirect climate effects.

Surface uptake by ice is highly temperature dependent, so that climate change can effect the deposition of contaminants (such as persistent organic pol-lutants (POPs)) to the polar regions. Even the nature of the surface of ice is highly temperature dependent, and this may affect the nature of ice surface chemistry [Cho et al., 2002]. Assessments of possible feedbacks such as these are central to understanding the effects of global change.

IGAC has two over-arching science questions, and each has a corresponding question directly relevant to the AICI Task:

• What is the role of atmospheric chemistry in amplifying or damping climate change?
• How will changing amounts of sea ice, snow cover, and atmospheric ice alter atmospheric chemistry and composition and are there important feedbacks to climate?

• Within the Earth System, what effects do changing regional emissions and depositions have on air quality and the chemical composition of the planetary boundary layer?
• What are the present regional emissions and losses over snow, ice and sea ice, and how could they alter with changing climate?

For the sea ice component, these same issues address various SOLAS activities, such as: sea-salt par-ticle formation and transformations; trace gas emis-sions and photochemical feedbacks; and understand-ing halogen release from sea ice.

Obviously the two science questions we have highlighted in bold, as well as the associated IGAC ques-tions, are similarly large, and unlikely to be satisfactorily answered in the suggested ~3-year timeframe for an IGAC Task. We have therefore established a more limited set of goals that we will undertake in the first phase of the AICI Task:

• To document the full range of processes and emitted trace gases that arise at the air-ice interface, and how they depend on environmental conditions.
• To quantify the fluxes of trace gases and aero-sol between atmosphere and ice under a range of field experimental conditions
• To determine the main factors that control the fluxes of trace gases between air and ice, using both field data and carefully designed labora-tory experiments
• To build simple models that include processes in the upper firn and lower atmosphere, to assess the effects of air-ice fluxes
• To make a first assessment of the scale of these processes, and assess the significance for climate or atmospheric chemistry within the global troposphere, the atmospheric boundary layer, or regionally, and in urban environments
• To develop simple parameterisations of the fluxes and processes studied for incorporation into sophisticated global chemical modelsM

Based on the outcome of this first phase of AICI, we envisage a second AICI project in which more quantitative fluxes and parameterisations will be made, and the effects of changing climate and cryosphere will be rigorously assessed, through a combination of regional scale field studies, with as-sociated laboratory and modeling activities.

Addressing the goals outlined above will require a combined programme of field measurements, laboratory measurements, satellite data retrieval, and modelling studies. The field work poses a particular challenge because of the remoteness of the polar sites, so that only through a range of international cooperative activities can sufficient data be obtained. The organisation of Arctic and Antarctic logistics has previously dictated that most studies were led by a single country, with participation from others; we regard the future integration of the different experiments and leveraging of multinational resources to be an important added value that AICI can provide. The following elements will be essential, some of which are already in place, and some of which we will encourage:

• Comprehensive studies in snow/ice covered areas of a range of types, locations, and time periods. Some studies will focus on particular times of year, but year-round studies will also be important so that we can be sure all relevant processes are being observed. Profiling studies, involving aircraft, tethered balloons, and towers, will be needed, as well as ground-based studies. The range of environments should in-clude:
• Clean permanent inland ice sheet locations, where snow photochemistry can most simply be studied (ANTCI at South Pole and Geosummit in Greenland are examples of studies that are already funded and whose value could be enhanced by the addition of AICI activities).
• Coastal marine ice sheet sites, where both snow photochemistry under different climatic and snow conditions, as well as gas phase and aerosol processes associated with new sea ice surfaces, can be studied. The year-round CHABLIS project at Halley Bay (Antarctica), ongoing studies at sites such as Neumayer and Dumont d’Urville (Antarctica), Alert, Barrow and Ny Ålesund (Arctic) are examples of this category. Again additional activities could be added to these existing sites.
• Studies within the sea ice zone, using for example a ship or platform, are ideal for studying processes over sea ice. The pro-posed US SOLAS OASIS study falls into this category.
• Studies over Alpine and seasonal snow-cover environments are necessary to assess how widely applicable the polar findings are and to determine the importance of re-gional scale anthropogenic inputs to the snowpack and the resultant impact of the subsequent photochemical processes.
• Studies in urban snow-impacted environments, which are likely to have much higher concentrations of key ice-surface reactants – e.g. nitrate, organic matter, etc.
• Laboratory experiments to assess the fundamental processes and controlling factors. These are likely to include use of idealised artificial ice experiments, to determine quantum yields and uptake coefficients, diffusion coefficients, reaction rates and equilibrium constants, as well as controlled studies of natural snow to isolate the factors controlling fluxes.
• Use of satellite data to determine the spatial and seasonal distribution of key species and environments. For example, it is expected that far more specific indicators of sea ice type (including algorithms for frost flower extent) will be developed, which can be correlated with the occurrence of BrO or of ozone loss.
• The field studies above will necessarily be limited to fairly local areas, and the satellite data will mainly look at columns and will be less able to assess the extent of phenomena (such as boundary layer ozone depletion) at ground level. To gain a full picture of the spatial extent, it will be necessary to develop autonomous instrument packages that could produce a low resolution year-round record of key species at unattended sites. Such platforms would be a highly appropriate contribution to the planned International Polar Year (IPY; 2007-08). While IPY will not fall into this phase of AICI, the package develop-ment, which could be used by many nations, will.
• Improvements in instrumentation will be needed to make the necessary measurements at the low concentrations, and under the difficult conditions, encountered at some sites
• Simple models of the processes within the upper snowpack and the lower atmosphere will be used to assess: 1) the full range of likely impacts of the fluxes observed, 2) the possible influence on the larger-scale atmosphere, and 3) influences on the material finally preserved in the ice core record. 1-D and 3-D chemical transport models will ultimately need to incorporate these ice-atmosphere interactions

AICI does not include field studies of ice in the upper troposphere (e.g. cirrus), but we recognise that such studies, by others, can benefit from and contribute to advances in the other areas discussed here.

The role of the AICI Task Team is to coordinate international research and education activities along the lines described and to efficiently leverage multi-national research, human, and logistics resources with the assistance of IGAC and SOLAS. The AICI Steering Committee has representation from key participating countries, and critical science areas. The function of the SC is to disseminate information about activities falling within the AICI remit, to coordinate such activities, and to encourage activities that are not currently funded or planned.

Some of the field activities necessary for AICI are already funded and planned, which is fortunate given the long lead time of polar field studies, and the need for many of them to run for a year or more. The data from several of these field campaigns should become available throughout the task period. In order to stimulate linking activities between them, as well as further field and modelling studies, we will take ad-vantage of the "Air-ice interactions" session at the September, 2004 IGAC conference in Christchurch, New Zealand and will hold AICI meetings in conjunction with it. We also plan to hold small workshops where the data from the campaigns, laboratory and other work can be discussed, during 2005-6. The task will close with an AICI symposium and a related journal special issue late in 2006, at which future plans, and the need for a further task, will be discussed.

The data obtained as part of the AICI project will be open to public access after each experiment so that they may be widely used by various science communities. The individual campaigns that fall under the AICI umbrella will have requirements (not least from funding agencies) to make their data available on accessible databases. The AICI steering committee will encourage all participants to open their data in a timely manner. A directory of links to the appropriate data will be maintained on the AICI web page.

Many educational institutes will be involved in the AICI Task. The effect of a concerted series of funded campaigns, linked by additional laboratory and modeling studies, will be to create a group of students with a strong interest in this topic, and our workshop and symposium activities will bring them together. The planning for an international polar year campaign will allow other nations, including the many with Antarctic presence, to develop a capacity in this field of work. An AICI web site, linked upwards to the IGAC website, and downwards to individual campaign web sites, will be maintained throughout the period of the task. The coordinators will prepare a summary of the main science issues, suitable for a general audience, for publication on the AICI, IGAC and SOLAS web sites. We will also coordinate wherever appropriate with other IGAC and IGBP efforts to educate the public about the impacts of climate change on environmental systems, and in particular about the role of the cryosphere in the biogeochemistry of the Earth System.

Barrie, L.A., J.W. Bottenheim, R.C. Schnell, P.J. Crutzen, and R.A. Rasmussen, Ozone Destruction and Photochemi-cal-Reactions at Polar Sunrise in the Lower Arctic Atmosphere, Nature, 334, 138-141, 1988.

Beine, H.J., R.E. Honrath, F. Domine, W.R. Simpson, and J.D. Fuentes, NOx during background and ozone depletion periods at Alert: Fluxes above the snow surface, J. Geophys. Res., 107, 4584, doi:10.1029/2002JD002082, 2002.

Bottenheim, J.W., H. Boudries, P.C. Brickell, and E. Atlas, Alkenes in the Arctic boundary layer at Alert, Nunavut, Canada, Atmos. Env., 36, 2585-2594, 2002a.

Bottenheim, J.W., J.D. Fuentes, D.W. Tarasick, and K.G. Anlauf, Ozone in the Arctic lower troposphere during winter and spring 2000 (ALERT2000), Atmos. Env., 36, 2535-2544, 2002b.

Bottenheim, J.W., A.G. Gallant, and K.A. Brice, Measurements of Noy Species and O₃ at 82-Degrees-N Latitude, Geophys. Res. Let., 13, 113-116, 1986.

Cho, H., P.B. Shepson, L.A. Barrie, J.P. Cowin, and R. Zaveri, NMR investigation of the quasi-brine layer in ice/brine mixtures, J. Phys. Chem. B, 106, 11226-11232, 2002.

Cotter, E.S., A.E. Jones, E.W. Wolff, and S.J.-B. Bauguitte, What controls photochemical NO and NO₂ production from Antarctic snow? Laboratory investigation assessing the wave-length and temperature dependence, J. Geophys. Res., 108, 4147, doi:10.1029/2002JD002602, 2003.

Crawford, J.H., D.D. Davis, G. Chen, M. Buhr, S. Oltmans, R. Weller, L. Mauldin, F. Eisele, R. Shetter, B. Lefer, R. Ari-moto, and A. Hogan, Evidence for photochemical production of ozone at the South Pole surface, Geophys. Res. Let., 28, 3641-3644, 2001.

Davis, D., J.B. Nowak, G. Chen, M. Buhr, R. Arimoto, A. Hogan, F. Eisele, L. Mauldin, D. Tanner, R. Shetter, B. Lefer, and P. McMurry, Unexpected high levels of NO observed at South Pole, Geophys. Res. Let., 28, 3625-3628, 2001.

Dubowski, Y., A.J. Colussi, and M.R. Hoffmann, Nitrogen dioxide release in the 302nm band photolysis of spray-frozen aqueous nitrate solutions. Atmospheric implications, J. Phys. Chem. A, 105, 4928-4932, 2001.

Ebinghaus, R., H.H. Kock, C. Temme, J.W. Einax, A.G. Lowe, A. Richter, J.P. Burrows, and W.H. Schroeder, Antarctic springtime depletion of atmospheric mercury, Env. Sci.& Tech., 36, 1238-1244, 2002.

Foster, K.L., R.A. Plastridge, J.W. Bottenheim, P.B. Shepson, B.J. Finlayson-Pitts, and C.W. Spicer, The role of Br-2 and BrCl in surface ozone destruction at polar sunrise, Science, 291, 471-474, 2001.

Haan, D., Y. Zuo, V. Gros, and C.A.M. Brenninkmeijer, Photo-chemical production of carbon monoxide in snow, J. Atmos. Chem., 40, 217-230, 2001.

Honrath, R.E., S. Guo, M.C. Peterson, M.P. Dziobak, J.E. Dibb, and M.A. Arsenault, Photochemical production of gas phase NOx from ice crystal NO₃, J. Geophys. Res., 105I, 24183-24190, 2000.

Honrath, R.E., Y. Lu, M.C. Peterson, J.E. Dibb, M.A. Arsenault, N.J. Cullen, and K. Steffen, Vertical fluxes of NOx, HONO, and HNO₃ above the snowpack at Summit, Greenland, Atmos. Env., 36, 2629-2640, 2002.

Honrath, R.E., M.C. Peterson, S. Guo, J.E. Dibb, P.B. Shepson, and B. Campbell, Evidence of NOx production within or upon ice particles in the Greenland snowpack, Geophys. Res. Let., 26, 695-698, 1999.

Hutterli, M.A., J.R. McConnell, R.W. Stewart, H.W. Jacobi, and R.C. Bales, Impact of temperature- driven cycling of hydro-gen peroxide (H₂O₂) between air and snow on the planetary boundary layer, J. Geophys. Res., 106, 15395-15404, 2001.

Hutterli, M.A., R. Rothlisberger, and R.C. Bales, Atmosphere-to-snow-to-firn transfer studies of HCHO at Summit, Greenland, Geophys. Res. Let., 26, 1691-1694, 1999.

Jones, A.E., R. Weller, P.S. Anderson, H.W. Jacobi, E.W. Wolff, O. Schrems, and H. Miller, Measurements of NOx emissions from the Antarctic snowpack, Geophys. Res. Let., 28, 1499-1502, 2001.

Jones, A.E., R. Weller, E.W. Wolff, and H.W. Jacobi, Speciation and rate of photochemical NO and NO₂ production in Antarctic snow, Geophys. Res. Let., 27, 345-348, 2000.

Jones, A.E., and E.W. Wolff, An analysis of the oxidation potential of the South Pole boundary layer and the influence of stratospheric ozone depletion, J. Geophys. Res., 108 (D18), 4565, doi:10.1029/2003JD003379, 2003.

Lindberg, S.E., S. Brooks, C.J. Lin, K.J. Scott, M.S. Landis, R.K. Stevens, M. Goodsite, and A. Richter, Dynamic oxidation of gaseous mercury in the Arctic troposphere at polar sunrise, Env. Sci. & Tech., 36, 1245-1256, 2002.

Matveev, V., M. Peleg, D. Rosen, D.S. Tov-Alper, K. Hebestreit, J. Stutz, U. Platt, D. Blake, and M. Luria, Bromine oxide - ozone interaction over the Dead Sea, J. Geophys. Res., 106, 10375-10387, 2001.

Mauldin, R.L., F.L. Eisele, D.J. Tanner, E. Kosciuch, R. Shetter, B. Lefer, S.R. Hall, J.B. Nowak, M. Buhr, G. Chen, P. Wang, and D. Davis, Measurements of OH, H₂SO₄, and MSA at the South Pole during ISCAT, Geophys. Res. Let., 28, 3629-3632, 2001.

Oltmans, S.J., and W.D. Komhyr, Surface ozone distributions and variations from 1973-1984 measurements at the NOAA Geophysical Monitoring for Climate Change baseline observatories, J. Geophys. Res., 91, 5229-5236, 1986.

Rankin, A.M., E.W. Wolff, and S. Martin, Frost flowers - implications for tropospheric chemistry and ice core interpretation, J. Geophys. Res., 107, 4683, doi:10.1029/2002JD002492, 2002.

Roumeau, S., P. Bremaud, E. Riviere, S. Baldy, and J.L. Baray, Tropical cirrus clouds: a possible sink for ozone, Geophys. Res. Let., 27, 2233-2236, 2000.

Schroeder, W.H., K.G. Anlauf, L.A. Barrie, J.Y. Lu, A. Steffen, D.R. Schneeberger, and T. Berg, Arctic springtime depletion of mercury, Nature, 394, 331-332, 1998.

Stutz, J., R. Ackermann, J.D. Fast, and L. Barrie, Atmospheric reactive chlorine and bromine at the Great Salt Lake, Utah, Geophys. Res. Let., 29, art. no.1380, 2002.

Sumner, A.L., and P.B. Shepson, Snowpack production of for-maldehyde and its effect on the Arctic troposphere, Nature, 398, 230-233, 1999.

Sumner, A.L., P.B. Shepson, A.M. Grannas, J.W. Bottenheim, K.G. Anlauf, D. Worthy, W.H. Schroeder, A. Steffen, F. Domine, S. Perrier, and S. Houdier, Atmospheric chemistry of formaldehyde in the Arctic troposphere at Polar Sunrise, and the influence of the snowpack, Atmos. Env., 36, 2553-2562, 2002.

Tarasick, D.W., and J.W. Bottenheim, Surface ozone depletion episodes in the Arctic and Antarctic from historical ozone-sonde records, Atmos. Chem, & Phys., 2, 197-205, 2002.

Wagner, T., C. Leue, M. Wenig, K. Pfeilsticker, and U. Platt, Spatial and temporal distribution of enhanced boundary layer BrO concentrations measured by the GOME instru-ment aboard ERS-2, J. Geophys. Res., 106, 24225-24235, 2001.

Wessel, S., S. Aoki, P. Winkler, R. Weller, A. Herber, H. Gernandt, and O. Schrems, Tropospheric ozone depletion in polar regions - A comparison of observations in the Arctic and Antarctic, Tellus B, 50, 34-50, 1998.

Wolff, E.W., A.E. Jones, T.J. Martin, and T.C. Grenfell, Modelling photochemical NOx production and nitrate loss in the upper snowpack of Antarctica, J. Geophys. Res., 29, 1944, doi:10.1029/2002GL015823, 2002.

Zhou, X.L., H.J. Beine, R.E. Honrath, J.D. Fuentes, W. Simpson, P.B. Shepson, and J.W. Bottenheim, Snowpack photochemical production of HONO: a major source of OH in the Arctic boundary layer in springtime, Geophys. Res. Let., 28, 4087-4090, 2001.

A Core Project of the International Geosphere-Biosphere Programme (IGBP)

In Cooperation with IAMAS Commission on Atmospheric Chemistry and Global Pollution

Web page maintained by the Seattle IGAC office and hosted by NOAA-PMEL. Disclaimer Privacy Policy Accessibility Statement