A MODELING AND OBSERVATIONAL STUDY OF THE RELATIONSHIP BETWEEN SEA-SURFACE TEMPERATURE IN THE NORTHWEST ATLANTIC AND THE ATMOSPHERIC GENERAL-CIRCULATION

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Palmer, T, Zhaobo, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Northwest Atlantic
• Online Access: https://doi.org/10.1256/smsqj.47002; https://ora.ox.ac.uk/objects/uuid:db36de7c-4bb8-4492-8c3b-84370b858230

Results from 4 pairs of 50-day wintertime integrations of the Meteorological Office's 5-level general circulation model, with warm and cold sea surface temperature (s.s.t.) anomalies of about 3K in the NW Atlantic, are described. Difference fields between the warm and cold integrations are statistically significant at the 1% level with positive geopotential height over the central N Atlantic, and weaker negative height over Europe. The storm track over the Atlantic is displaced from its normal position. Results from 4 further pairs of integrations with halved s.s.t. anomalies are also described. The response is approximately linear, with systematic differences in 500mb geopotential height over the Atlantic, parts of which are just significant at the 10% level with half the full s.s.t. anomaly. Overall, however, the model's response is weaker than could be obtained with tropical s.s.t. anomalies of the same magnitude. Results from the model integrations are compared with results from an observational study of the relationship between wintertime s.s.t. in the NW Atlantic, and mean sea level pressure and 500mb height. Two independent 30yr periods were chosen for study, thus minimizing the influence of long-term trends in s.s.t. Over the Atlantic and Europe the model results compared well with the observations. With s.s.t. data lagging the atmosphere by one month, the observational study appears to show that the s.s.t. anomalies are initially forced by perturbations in the atmospheric circulation. -from Authors