Title Seasonal Differences in Air-Snow Chemical Relationships at Summit,
Greenland
 Collaborators Cliff Davidson (CMU), Jack Dibb (UNH), Mary Albert (Cold Regions Research and Engineering Laboratory), Roger Bales (Univ. of Arizona), Donald Blake (UC-Irvine), Jonathan Kahl (Univ. of Wisconsin)
 Keywords Greenland, ice cores, atmospheric chemistry, snow, meteorology
 Abstract

As this proposal is being submitted, representatives of several of the research teams involved are en route to Summit, Greenland where they
will set up equipment and experiments for the first winter-over sampling program at this site. ("Relationships between air and Snow Chemistry in Winter at Summit, Greenland", cooperative research by UNH, U Az, CRREL, CMU, UW Milwaukee and UC Irvine.) At the end of June, four
winter-over staff will be left at Summit to collect atmospheric and snow samples for chemical analyses, make detailed observations of local meteorological and micrometeorological conditions, document the interaction between snowfall events and subsequent reworking of surface
snow by wind and sublimation that determine the relationship between
depth in the accumulating snow pack and the passage of time, and document the evolution of the microphysical characteristics of snow
grains and layers of snow that control the exchange of energy and material between the snow pack and overlying air. These experiments share the primary objective of quantifying air-snow exchange processes in order to allow more quantitative reconstruction of climate states and the composition of the atmosphere at past times from the extraordinary glaciochemical records recently recovered at Summit by the Greenland ice Sheet Project 2 and the Greenland Icecore Program deep drilling efforts.

The 1997-1998 winter-over campaign also represents a logistical
"experiment", in that new modular structures have been deployed at
Summit, the crew size is considerably smaller than those that used to
man Dye 2 and Dye 3 (DEW line radar stations in south Greenland) or
typically overwinter at South Pole, and especially due to the opportunity to conduct resupply flights throughout the winter. We are confident that this first season will prove that a year-round scientific presence at Summit can be maintained with a high degree of safety and comfort for the winter-over staff, and at a reasonable logistic cost. Given that year-round experimental investigations can safely and economically be conducted at Summit, we are proposing that field measurements of the exchange process that play a key role in atmospheric chemistry and ice core interpretation be conducted for two more years at Summit.

In recognition of the "experimental" nature of the 1997-1998 deployment, sampling and analytical plans were designed with the idea of making key measurements with proven, robust techniques. We wanted to be sure that the winter-over staff would have time to work out any bugs in the new infrastructure and implement improvements in operations, so science duties were designed to take up on the order of 6-8 hours/day. In the future, upkeep of camp should require less time, so more ambitious sampling protocols will be feasible. We intend to continue making all of the basic measurements begun in the 1997-1998 season, in order to gain some impression of inter-annual variability in both the meteorological and chemical conditions at Summit, but we are also proposing to deploy more complicated samplers and instruments. These will allow measurements of additional species and parameters, at the expense of requiring more attention from the site personnel and a higher likelihood of partial failure of some experiments in the harsh winter conditions. The realization that some equipment may require significant modification to function throughout the year provides additional motivation to propose a two year campaign, with the first winter providing invaluable experience and insight into problems that cannot be simulated in a cold-room environment.