U31C-0500
The First IPY Russia-US expedition in the Siberian Arctic seas: March-April 2007.
One of the key question of polar biogeochemistry is how the flux of carbon and nutrients would be altered by the long-range, inter-annual, and intra-seasonal variability in the atmosphere-land-shelf system in the Arctic. In order to address this question, the present conditions and the processes that govern the near-shore processes in the East Siberian Arctic need to be investigated using field studies with modern techniques and collection of historical data which are quite limited especially in winter. Most wide and shallow continental shelve in the Arctic Ocean and even in the whole World Ocean is the East-Siberian Shelf (ESS). We already established a joint US- Russia long-term study of complex summertime biogeochemical studies in the atmosphere-land-shelf system in the ESS: since 2003 we have accomplished Five joint Russia-USA summertime expeditions with focus in the nearshore zone of the south-eastern part of the Laptev Sea and adjacent part of the East-Siberian Sea which is the area most impacted by ongoing changes. However, this area is still remained largely understudied and provides an excellent natural laboratory to make progress on an improved understanding of the interactions across atmosphere-land-ocean system and their impacts on freshwater dynamics and biogeochemistry. To answer some of these questions (seasonal variability in methane and carbon dioxide release, offshore export of terrestrial organic carbon, sedimentation) the First IPY Russia-US expedition was conducted over the Laptev Sea shelf. A tractor sledge caravan started from Tiksi, Russia on March 30th. April 1st-April 15th was spent in the south- eastern part of the Laptev Sea eastward of the Lena River delta where 53 complex oceanographic stations (CTD/water/sediment sampling) were done through 2m fast ice along the ~1,700km route. Methane measurements, gas extraction, pH and filtering samples were also processed in a mobile laboratory. Extremely high concentrations of methane (up to 5 micromole which is two orders of magnitude higher compared to summer concentrations) were measured. Comparing the data already obtained in the same area using the same techniques during summertime we studied robust inter-seasonal variability of major physical and hydro- chemical environmental parameters.
U31C-0501
Impacts of large-scale oscillations on northern high-latitude terrestrial net primary production
We derived annual time series of vegetation net primary production (NPP) and growing season dynamics for the pan-Arctic basin and Alaska from 1983-2005. We used the MOD17A2/A3 production efficiency model driven by satellite based monthly leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) from NOAA AVHRR Pathfinder and NASA EOS MODIS records, with gridded daily surface meteorology developed from a regional correction of the NCEP/NCAR reanalysis and NASA Solar Radiation Budget daily shortwave solar radiation inputs to compute NPP on a grid cell by cell basis across the domain. Analyses of regional climate oscillations and satellite derived NPP and growing season dynamics for the pan-Arctic region indicate that the oscillations influence NPP by regulating seasonal patterns of low temperature and moisture constraints to photosynthesis. Early-spring (Feb-Apr) patterns of the Arctic Oscillation (AO) are proportional to growing season onset (r=-0.653; P=0.001), while growing season patterns of the Pacific Decadal Oscillation (PDO) are proportional to the supply of plant-available moisture for NPP (r=-0.471; P=0.023). Relatively strong, negative PDO phases from 1988-1991 and 1998-2002 coincided with prolonged regional droughts indicated by a standardized moisture stress index. These severe droughts resulted in widespread reductions in NPP, especially for relatively drought prone boreal ecosystems. The influence of AO and PDO patterns on northern high-latitude vegetation productivity appears to be decreasing and increasing, respectively, as low temperature constraints to plant growth relax and NPP becomes increasingly limited by available water supply under a warming climate. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.
U31C-0502
Will the Magnetic North Pole wind up in Siberia?
The magnetic dip-poles have been the topic of various historical and recent research activity. In addition, their location, and especially their motion, has attracted a large amount of public interest. This interest has been increased during the last few months thanks to the International Polar Year (IPY). The North dip-pole is presently located in the Canadian arctic, moving in a northwest direction, while the South dip-pole is located off the coast of Antarctica, south of Australia. A few important questions will be addressed, as: How fast do the poles move? What causes different motions in the North and South dip-poles? Where will the dip-poles be during the coming years?
U31C-0503
Ozone in the Boundary Layer air over the Arctic Ocean: Measurements During the TARA Expedition.
It is now well established that after sunrise in polar regions, the atmospheric boundary layer experiences episodes where dramatic loss of ozone can be observed. Virtually all measurements in this respect have been made at coastal observatories on land, but there is strong evidence to surmise that such episodes originate over the frozen ocean. Satellite measurements (GOME, SCIAMACHY, OMI) invariably indicate large areas over the ocean with increased concentrations of BrO which can be interpreted as a smoking gun for ozone depletion processes, but no systematic in-situ measurements of ozone do exist to corroborate the satellite data. The TARA expedition (www.taraexpeditions.org) (IPY project # 238) has enabled us for the first time to make long term ozone measurements in the surface air over the Arctic Ocean, and we report here the first results. As expected ozone was found to be stable at approx. 35 ± 5 nmol~mol-1 during the winter, but shortly after local sunrise in mid March, large depletions of ozone were observed which lasted until well into June. A particularly long episode (> 15 days) of virtually no ozone (mole fraction below or near 1 nmol~mol-1) was experienced during late April. 10-day back trajectories were calculated in an attempt to obtain more insight into the potential origin of the depletion episodes. To place the TARA ozone data into context we will compare the data with land based and satellite observations in 2007 when they become available, as well as the limited record of previous observations made from ice islands. Taking all evidence together it is plausible to speculate that large areas over the Arctic Ocean are devoid of ozone in the atmospheric boundary layer in the first months after polar sunrise, and that if anything, this will increase in the coming years. We speculate what the implications might be. This work is a contribution to IPY project #038 (OASIS, Ocean Atmosphere Sea-Ice and Snow interactions in polar regions), sponsored by the Canadian Federal Government Program for the IPY (project OASIS-CANADA).
U31C-0504
Assessment of the ECCO2 Coupled Ocean and Sea Ice Solution in the Arctic
One of the primary objectives of the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project is to realistically estimate the Arctic ocean circulation and sea ice distribution during the ocean satellite era (1978-present). The ECCO2 solution is obtained by fitting a high-resolution (18-km horizontal grid spacing) global-ocean and sea-ice configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) to the available ocean and sea ice data. Here, we compare results of a series of MITgcm sensitivity experiments to satellite and in-situ measurements of(a) sea ice thickness and concentration, (b) sea ice and freshwater fluxes, and (c) ocean temperature/salinity and circulation. An assessment of the model's ability to produce and maintain important water masses such as the warm Atlantic water and cold halocline will be presented. Additional comparison with Arctic Ocean Model Intercomparison Project (AOMIP) will be used to address model deficiency and near-future improvements. This work is a first step toward obtaining an optimized solution for the Arctic ocean and sea ice through data-model residual minimization.
U31C-0505
International Arctic Systems for Observing the Atmosphere (IASOA): 2007 Observatory Upgrades in Canada, Greenland, Russia and the United States
International Arctic Systems for Observing the Atmosphere (IASOA) is a dynamic organization developed to enhance Arctic atmospheric research by fostering collaborations among researchers during the International Polar Year (IPY) and beyond. The member stations are Abisko, Sweden; Alert and Eureka, Canada; Barrow, USA; Cherskii and Tiksi Russia; Ny-Ålesund, Norway; Pallas and Sodankylä, Finland; and Summit, Greenland. All of these observatories operate year-round, with at least minimal staffing in the winter months, are intensive and permanent. Presently, measurement and building upgrades are occurring at the Tiksi, Eureka, Summit and Barrow observatories. A new weather station building has been completed in Tiksi and is currently available for installation of instruments. A second Clean Air Facility (CAF) that will be suitable for aerosol, chemistry, pollutant, greenhouse gases, fluxes and radiation measurements is expected to be completed in the spring of 2008. Real- time continuous measurement instruments for the measurement of ozone and black carbon, and flasks for carbon cycle gas measurements for the new Tiksi station are awaiting shipping from Boulder, CO. At the Eureka site many instruments including a flux tower, several CIMELs for the Aeronet Network, and a Baseline Surface Radiation Network (BSRN) station were installed in the summer of 2007. With IPY funding the level of technical support at the site has been increased to provide more reliable data collection and transmission. The Summit, Greenland observatory has recently released a strategic plan highlighting climate sensitive year- round observations, innovative research platforms and operational plans to increase renewable energy to maintain the pristine platform. Summit also has a new multi-channel GC/MS for continuous measurement of trace halocarbon and CFC gas concentrations. All NOAA instruments have been moved from the Science trench to a new atmospheric watch observatory building. NOAA is now manning the site for the 9-month winter season of the year. The Barrow observatory has two new systems for aerosol size and chemistry composition, as well as new POPs measurements. The meteorology measurement and data system has been completely upgraded. Current IASOA activities include the development of a web site (www.iasoa.org) that will serve as the "go-to" site for atmospheric Arctic researchers to obtain information about the member observatories. Information posted for each station includes a general overview of the observatory, a listing of available measurements and principle investigators, links to data bases, and station contacts. These pages will help Arctic researchers find the data they need to complete their research. The development of these observatory web pages, plus an "observatories- at-a-glance" page, has allowed us to identify gaps in atmospheric measurements in the Arctic.