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ABSTRACT. Seasonal and interannual variations in surface elevation at the Greenland summit are modeled using a new temperature-dependent formulation of firn densification and are compared with elevations from European Remote-sensing Satellite (ERS-1/-2) radar altimetry. The rate constant and activation energy, usually set as constants in the Arrheniustype relation, are strongly temperature-dependent, based on measurements of crystalgrowth rates. A multiplicative factor in the densification rate accounts for differences between densification and grain-growth rates and is chosen to match the modeled and measured density profiles from 0 to 40 m.The stronger temperature dependence produces a significant seasonal cycle in the densification rate in the upper firn. Much of the densification and consequent surface lowering occur within 3 months in late spring/early summer, followed by a build-up from accumulation. Modeled elevation changes, using automatic weather station measurements of temperature and accumulation and modeled precipitation, agree well with observations. The respective seasonal amplitudes are 18 and 25 cm peak-to-peak with minima in mid-summer. The minimum elevation in 1995 is driven mainly by a temporary accumulation decrease and secondarily by warmer temperatures. Increased compaction driven by a summer warming trend decreases the modeled elevation (1992^99) by 20 cm, but accumulation increases in latter years dominate the overall 4.2 cm a^1 trend.

India is of prime interest due to the large past and ongoing use of pesticidal persistent organic pollutants (POPs). Rapid dissipation of POPs to the atmosphere in the tropical climate of India infers an atmospheric outflow of these chemicals. Yet data on POPs in the atmosphere of India are sparse. Passive air samplers consisting of polyurethane foam disks were therefore deployed concurrently at 18 locations and exposed for 6 weeks from July 30, 2006, to September 26, 2006, along the coastal length of India to screen for POPs in the atmosphere. The sampling sites were selected to form categories of urban, rural, and background (mangrove/wetlands) locations. Derived air concentrations (pg/m3) ranged as fellows: the sum of 28 PCB congeners, 120-1080; DDTs, 16-2950; HCHs, 66-5400; chlordanes, 9-921; endosulfans, 0.45-1120; and the sum of 9 PBDE congeners, 1-181. The highest levels of all the detected POPs (except endosulfan) were observed at the urban sites, indicating the dominant areas of usage and emissions. An urban-rural composition fractionation of PCBs indicates their atmospheric movement. The gamma-HCH levels were more than double those of alpha-HCH, indicating the sporadic use of lindane. DDT concentrations were elevated, at levels comparable to China, but with much higher percentages of p,p'-DDE, reflecting a more 'weathered' feature. Although no dicofol use was recorded in India, the o,p'-/p,p'-DDT ratios were observed to be even higher than in China. Chlordanes showed high trans-/cis-chlordane (TC/CC) ratios, indicative of the current use of technical chlordane and a contribution from heptachlor usage.