Method for extracting real-time index of quasi-biweekly oscillation (QBWO) at Eurasian medium-high latitude in summer

Abstract

The invention discloses a method for extracting a real-time index of quasi-biweekly oscillation (QBWO) at Eurasian medium-high latitude in summer, which comprises the following steps of: firstly, performing EEOF analysis on 500hPa potential height fields of 10-30 days of band-pass filtering lagged by -6, -3 and 0 days in medium-high latitude from May to September in summer in 1979-2018 to obtain first four modals; secondly, extracting a 500hPa potential height distance flat field for 10-30 days by adopting a non-filtering method; projecting the 10-30 days of non-filtered 500hPa potential height distance flat fields including -6, -3 and 0 days to the first two EEOF modals to obtain a real-time index of quasi-biweekly oscillation at Eurasian medium-high latitude; and then projecting the 10-30 days of non-filtered 500hPa potential height distance flat fields including -6, -3 and 0 days to a third EEOF modal and a fourth EEOF modal to obtain a second real-time index of quasi-biweekly oscillation at Eurasian medium-high latitude. According to the method, the key area of the medium-high-latitude QBWO and the circulation structure and propagation characteristics thereof are grasped, the relation between the medium-high-latitude QBWO and weather and climate in China and even in the East Asian region is embodied, and the method is applied to real-time monitoring and provides reference for evaluation of the simulation capacity of the mode QBWO.

Description

technical field [0001] The invention relates to an index extraction method, in particular to an extraction method for a real-time index of quasi-biweekly oscillation in summer in mid-high latitudes in Eurasia. Background technique [0002] Quasi-biweekly oscillation (QBWO) is also called Sub-monthly Oscillation by scholars (Yokoi and Satomura, 2006; Wen et al., 2011), which is an important phenomenon whose time scale is smaller than seasonal variation , a large number of studies have shown that QBWO is in monsoon or tropical regions (Lau et al., 1988; Chen and Chen, 1995a; Fukutomi and Yasunari, 1999, Krishnamurti and Bhalme, 1976; Krishnamurti and Ardanuy, 1980), mid-high latitudes (Wu Bingyi et al., 1994; Li Chongyin and Zhou Yaping, 1995), and even globally (Kikuchi and Wang, 2009). [0003] At present, domestic research on QBWO real-time index mainly focuses on the research on signals from middle and low latitudes: Lee et al. (2013) proposed a real-time index for the no...

AI Technical Summary

Problems solved by technology

However, there is currently a lack of research on real-time indices of quasi-bicycle oscillations in middle and high latitudes

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