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An Analysis of Simulated Summer Blocking Episodes
Author(s) -
Kung Ernest C.,
Min Wei,
Susskind Joel,
Park ChungKyu
Publication year - 1992
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711850408
Subject(s) - predictability , blocking (statistics) , northern hemisphere , climatology , environmental science , anomaly (physics) , meteorology , atmospheric sciences , geology , statistics , geography , mathematics , physics , condensed matter physics
Using the high‐resolution 2 × 2.5 degree version of the Goddard Laboratory for Atmospheres general circulation model, experiments were performed for a 46‐day summer period from 1 July to 15 August 1979. During the simulation, sea‐surface‐temperature (s.s.t.) anomalies were updated daily with observed s.s.t.s to provide a realistic surface heating field. A parallel control run used climatology s.s.t.s. in lieu of observed s.s.t.s. Both the s.s.t. updating experiment and control run were able to simulate the persistent blocking patterns in Eurasia and the eastern Pacific during July. However, only the s.s.t. updating experiment was able to generate the realistic blocking episodes in the last 10‐day period during the 46‐day simulation. Forecast skill was examined in terms of 500 mb anomaly correlation and error kinetic energy. When the blocking patterns develop or become reinforced, a high forecast skill is apparent in nearly half of the northern hemisphere including the area of blocking and its downstream region. Unlike the major winter blockings, which may be treated as the manifestation of wave number one and two, the summer blockings are localized, and have a smaller scale than that of winter blockings. However, summer blockings treated in this study are persistent, and possess a considerable predictability.