A Precursor of the Monthly-Mean Large-Scale Atmospheric Circulation Anomalies over the North Pacific

Abstract

The North Pacific shows dominant monthly-mean largescale atmospheric circulation anomalies, even after removing the variabilities of the Northern Hemisphere annular mode and the El Niño/Southern Oscillation. This work examines the precursors and their development for these residual anomalous circulations by applying objective reanalysis data to empirical orthogonal function (EOF) analysis. The first EOF mode (EOF1) features a monopole, while a dipole characterizes the second EOF mode (EOF2) over the North Pacific. Transient eddies (TEs) interactively induce the two EOF modes.The precursors of EOF1 and EOF2 are detected in the anomalies of one month earlier; these are the systematic zonal bands detected in surface temperature and baroclinic instability (BI) in the lower troposphere over Eurasia and North America. The BI anomalies further extend into the central North Pacific at different latitudes between EOF1 and EOF2. Coherent zonal bands also appear in the geopotential height anomalies of upper troposphere. Such zonal bands reflect the ovalization of Arctic circumpolar circulation with different continent-ward shifts of the longer axis. The direction of this shift determines which EOF mode develops by the following month through the guided activation of TEs at a designated latitude over the North Pacific.(Citation: Tomita, T., and T. Yamaura, 2017: A precursor of the monthly-mean large-scale atmospheric circulation anomalies over the North Pacific. SOLA, 13, 85−89,

Soft Periodic Convolutional Recurrent Network for Spatiotemporal Climate Forecast

“…Z300 is at the same height as the jet stream, a strong upper-tropospheric wind axis 9-12 km above sea level. The jet stream wind separates the high and low pressure systems representing hot and cold weather, respectively.Atmospheric variation in the upper troposphere is used for weather prediction at the surface because the air circulation can be a precursor to weather prediction [47]. Moreover, an upper troposphere change can cause extreme winter cold [48] over northern Europe and cold air outflows in the Northern Hemisphere [49].…”