Journal
JOURNAL OF CLIMATE
Volume 35, Issue 6, Pages 1901-1913Publisher
AMER METEOROLOGICAL SOC
DOI: 10.1175/JCLI-D-21-0531.1
Keywords
Atmosphere; North America; Tropics; Atmosphere-ocean interaction; Convection; Rossby waves; Diabatic heating; Intraseasonal variability; Oscillations
Categories
Funding
- National Natural Science Foundation of China [41925020, 41721004]
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This study investigates the characteristics and climate impacts of the quasi-biweekly oscillation (QBWO) over the western North Pacific (WNP) in boreal winter. The wintertime convection over the WNP is influenced by significant biweekly variability, with a leading mode of northwestward-propagating convection dipole. When the convection-active center of this QBWO is located to the east of the Philippines, it can induce upper-tropospheric divergence and excite a Rossby wave train propagating towards North America, leading to cold anomalies over central North America in the following week.
This study investigates the characteristics and climate impacts of the quasi-biweekly oscillation (QBWO) over the western North Pacific (WNP) in boreal winter based on observational and reanalysis data and numerical experiments with a simplified model. The wintertime convection over the WNP is dominated by significant biweekly variability with a 10-20-day period, which explains about 66% of the intraseasonal variability. Its leading mode on the biweekly time scale is a northwestward-propagating convection dipole over the WNP, which oscillates over a period of about 12 days. When the convection-active center of this QBWO is located to the east of the Philippines, it can generate an anticyclonic vorticity source to the south of Japan via inducing upper-tropospheric divergence and excite a Rossby wave train propagating toward North America along the Pacific rim. The resultant lower-tropospheric circulation facilitates cold advection and leads to cold anomalies over central North America in the following week. This result highlights a cause-effect relationship between the WNP convection and the North American climate on the quasi-biweekly time scale and may provide some prediction potential for the North American climate.
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