Cooperative Institute for Research in Environmental Sciences

Cryospheric and Polar Processes Seminar

Wednesday September 19 2018 @ 11:00 am
to 12:00 pm

September

19

Wed

2018

11:00 am - 12:00 pm

Availability

Open to Public

Audience
  • CIRES employees
  • CU Boulder employees
  • General Public
  • NOAA employees
  • Science collaborators
  • Host
    NSIDC

    Modelling the Annual Cycle of Antarctic Sea ice Extent by Marilyn Raphael, UCLA Department of Geography

    Satellite-observed, total Antarctic sea ice extent (SIE) experiences a distinct annual cycle, peaking
    in September and troughing in March on average. The amplitude and phase of the annual cycle
    also varies regionally. What forces the observed annual cycle and its variations is not completely
    understood. The annual cycle may be calculated by simply taking the average SIE for each day of
    the year. However, while simple and transparent, this method produces a value that is subject to
    substantial variation since it is based on fewer than 40 numbers, one for each year of observed
    data. It also disguises the fact that the annual cycle might be slowly changing phase and that the
    amplitude as well as shape of the daily extent might vary. Here, we present a model that allows the
    mathematical and stochastic representation of the proximate forces that lead to the observed
    annual cycle of sea ice extent. These mathematical and stochastic methods allow amplitude and
    phase dilation and contraction. Thus, the annual cycle is not constrained to be a fixed cyclical
    pattern rather, it is a pattern that allows both temporal dilation and contraction as well as amplitude
    modulation. We use this model in an ensemble interpolation to reconstruct missing daily data in
    the early part of the satellite- observed sea ice data set. Results are presented and discussed.