Capturing the Stratosphere's Influence on Seasonal and Intraseasonal Predictability in a State-of-the-Art Navy Global Environmental Model (NAVGEM)

• Main Author: Eckermann, Stephen D
• Other Authors: NAVAL RESEARCH LAB WASHINGTON DC
• Format: Text
• Language: English
• Published: 2013
• Subjects: Atmospheric Physics; *STRATOSPHERE; ANOMALIES; MESOSPHERE; SEASONAL VARIATIONS; WEATHER FORECASTING; Arctic; Baldwin; North Atlantic; North Atlantic oscillation
• Online Access: http://www.dtic.mil/docs/citations/ADA597793; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA597793

Recent research has revealed that the stratosphere influences medium- and long-range weather prediction, sometimes strongly (NAS 2010). The North Atlantic Oscillation (NAO) one of the most prominent modes of intraseasonal tropospheric variability extending from the subtropical Atlantic to the Arctic (Hurrell et al. 2003) has been recognized only within the past decade as one regional manifestation of a larger hemispheric phenomenon, known synonymously as the Arctic Oscillation (AO) or Northern Annular Mode (NAM). The NAM extends continuously into the stratosphere and mesosphere, and an analogous deep Southern Annular Mode (SAM) occurs in the southern hemisphere. NAM/SAM anomalies often appear first in the upper stratosphere or mesosphere, then descend gradually over a period of weeks, sometimes reaching the surface where they change weather patterns throughout the polar region (Baldwin and Dunkerton 2001; Coy et al. 2011). Descending stratospheric NAM/SAM anomalies also play a pivotal role in controlling the response of high-latitude weather to the El-Ni o/Southern Oscillation in the tropics (Bell et al. 2009; Ineson and Scaife 2009), while the tropical stratosphere and mesosphere may also impact tropical seasonal prediction through an improved Madden-Julian Oscillation (Weare et al. 2012). These examples, and others like them, point to the important role that the overlying stratosphere-mesosphere system can play in presaging and regulating large-scale global surface weather changes over periods of weeks to months (e.g., Baldwin et al. 2003), prompting recent reports from the World Climate Research Programme (WCRP 2008) and the National Academy of Sciences (NAS 2010) that note (quote) the stratosphere s potential to improve seasonal forecasts is largely untapped.