HR: 14:20h
AN: A43B-04 [Abstracts]
TI: Pros and Cons of 1-tiered versus 2-tiered Seasonal Forecast Systems
AU: * DeWitt, D G
EM: daved@iri.columbia.edu
AF: International Research Institute for Climate Prediction (IRI), Lamont-Doherty Earth Observatory
61 Route 9W, Palisades, NY 10964 United States
AU: Goddard, L
EM: goddard@iri.columbia.edu
AF: International Research Institute for Climate Prediction (IRI), Lamont-Doherty Earth Observatory
61 Route 9W, Palisades, NY 10964 United States
AU: Li, S
EM: shuhua@iri.columbia.edu
AF: International Research Institute for Climate Prediction (IRI), Lamont-Doherty Earth Observatory
61 Route 9W, Palisades, NY 10964 United States
AB:
All reasonable seasonal forecast systems have advantages and disadvantages.Some advantages/disadvantages may be theoretical;
others may be practical. A clear understanding of where the limitations of a particular forecast system lie is helpful in
making the most of the tool(s) in hand. In this presentation we examine the good, the bad and the ugly in both 1-tiered
forecast systems (i.e. coupled ocean-atmosphere general circulation models or CGCMs) and 2-tiered forecast systems (i.e.
atmospheric general circulation models or AGCMs). AGCMs are potentially hindered by unphysical air-sea fluxes in the
mid-latitudes and warm pool regions, where the observations suggest that the atmosphere forces changes in the ocean, rather
than the other way around. In CGCMs the ocean and atmosphere evolve harmoniously, but that is no guarantee that their air-sea fluxes are correct.And indeed, CGCMs have problems with climate drift and large-scale systematic biases because of
difficulties in getting the proper air-sea fluxes. To what extent these physical limitations limit skill in seasonal climate prediction will be presented. Suggestions will be offered for how one might capitalize on the strengths of both types of
dynamical forecast systems, while minimizing the weaknesses, in constructing a seasonal climate forecast.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly