HR: 1340h
AN: C23A-0983    [Abstracts]
TI: Analysis of near-zero temperature anomalies in high latitude regions
AU: Lammers, R B
EM: richard.lammers@unh.edu
AF: Water Systems Analysis Group, Morse Hall University of New Hamsphire, Durham, NH 03824 United States
AU: * Proussevitch, A
EM: alex.proussevitch@unh.edu
AF: Water Systems Analysis Group, Morse Hall University of New Hamsphire, Durham, NH 03824 United States
AB: Daily temperatures follow quasi-sinusoidal time-series over annual periods. It is expected that the daily temperature frequencies form bimodal distributions corresponding to the winter and summer temperature modes. Unlike the expectation, analysis of high latitude temperature datasets revealed tri-modal temperature frequencies in many areas. The third mode falls into the near-zero temperature range and it is most likely a buffer resulting from the latent heat of phase transition of water during snow melt. There is no statistically considerable change in the slope on the daily time-series curves around near-zero temperatures. We have analyzed daily climatology modes for individual days during the melt and freeze periods and found bimodal distributions for those days which are unique relative to all other days during the year. In these cases, one of the modes is linked to the zero temperature mark. A statistical algorithm was developed that allows for the identification and quantification of the influence of water phase transition on the daily temperature frequencies that cause these anomalies. Mapping of the sub-zero temperature anomalies over the Pan-Arctic domain showed that they tend to be in non-mountainous regions under continental climate conditions. Milder near-ocean climates and mountainous regions do not show these near-zero anomalies. Southern parts of the pan-Arctic are also affected by the near-zero anomalies in such a way that the warmer winter mode is eroded and skewed toward the anomaly.
DE: 9315 Arctic region
DE: 3309 Climatology (1620)
DE: 1878 Water/energy interactions
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting