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Seasonal and IMF B y effect on the polar cap convection orientation
Author(s) -
Jayachandran P. T.,
MacDougall J. W.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900114
Subject(s) - convection , clockwise , orientation (vector space) , geology , rotation (mathematics) , polar , polar cap , climatology , convection cell , atmospheric sciences , flow (mathematics) , curvature , geodesy , meteorology , geophysics , physics , combined forced and natural convection , geometry , mechanics , natural convection , mathematics , ionosphere , astronomy
Seasonal and IMF B y effect on the polar cap convection orientation is studied using the Canadian Advanced Digital Ionosondes (CADI) situated at Eureka (CGM lat. 88.67°N) and Resolute Bay (CGM lat. 83.55°N), two polar cap stations. In this study, we determined the daily convection orientation (MLT towards which the convection is directed) for each day of 1995. The orientation shows clear seasonal variation, being latest in winter and earliest in summer (strong northward IMF conditions are excluded from the study). The convection pattern is rotated clockwise by ∼ 4hrs from winter to summer. This includes rotation due to the curvature of the flow, ∼2 hours during summer months. The convection pattern also shows an IMF B y dependence. The orientation is earlier by about 2 ½ hours when IMF B y is positive relative to when it is negative. The observed seasonal changes in the convection orientation can be broadly explained by the changes in the ratio of the Region 1 and Region 2 field aligned currents.