Wednesday, 14 January 2004: 1:30 PM
A climatology of large-scale North Pacific cyclones and their predictability
Large scale cyclone events in the North Pacific are instances of persistent
cyclonic flow regimes that occur primarily during the cold season.
These events are characterized by the formation of anomalously intense
large-scale surface cyclones and extended and more equatorially displaced
polar and subtropical jets. At maturity, during the winter season,these
cyclones share characteristics of the positive phase of the Pacific-North
American teleconnection pattern. As a consequence of their impact on
North American weather, understanding the the development of these events
as well as the characteristics of the larger-scale flow the arise
following their development, will contribute to an understanding of the
flow-dependent predictability associated with these events.
In this study, we present the results of a 25 year climatology of these
events. In particular, we describe the distribution of these events
over the N. Pacific (sorted by duration), the variation of events with
respect to phases of ENSO, and the differences in composite evolution for
cold and warm season events.
Additionally, using the adjoints of both research and operational NWP models,
we study the sensitivity of growth of these cyclones to upstream initial
conditions. Further, once these cyclones are established, we focus on
the predictability of downstream flow over North America by identifying
differences in the singular vector amplification factors for event and