Nonlinear modulation of ENSO condition on the interannual frequency variation of long-lived cross-equatorial flow events over the Maritime Continent in boreal summer.
Saved in:
| Title: | Nonlinear modulation of ENSO condition on the interannual frequency variation of long-lived cross-equatorial flow events over the Maritime Continent in boreal summer. |
|---|---|
| Authors: | Zhao, Xiaoxuan1 (AUTHOR) zhaoxiaoxuan@mail.iap.ac.cn, Lu, Riyu2,3 (AUTHOR), Sun, Jianqi1,3 (AUTHOR) |
| Source: | Journal of Climate. Jul2026, Vol. 39 Issue 13, p1-11. 11p. |
| Subjects: | El Niño, La Niña |
| Abstract: | This study examines the interannual variability of cross-equatorial flow (CEF) event frequency (herein defined as the total count of event days) over the Maritime Continent during June–September, using reanalysis data from 1979 to 2020. Results show that the frequency of long-lived CEF events exhibits pronounced interannual variation and is closely related to ENSO condition in simultaneous summer. Notably, this relationship is highly nonlinear, with difference in event frequency between El Niño and neutral years (~30 days per year) far exceeding that between La Niña and neutral years (~6 days per year). The relationship between ENSO and long-lived CEF events is established through ENSO's modifications to the seasonal mean CEF, which serves as a background state for the occurrence of CEF events. Although the seasonal mean CEF anomalies under the warm and cold phases of ENSO are opposite and comparable, the effect of the background state on CEF events is fundamentally nonlinear. Specifically, the frequency of long-lived events is not sensitive to the CEF background state when it is lower than 0.51 m s −1 , but becomes highly sensitive when the background state becomes stronger. Additionally, Boreal Summer Intraseasonal Oscillation (BSISO) further modulates the interannual variation of long-lived CEF events: The active phases of BSISO can amplify the nonlinearity of the relationship between CEF events and ENSO, while the suppressed phases tend to narrow it. In contrast to long-lived events, the short-lived events exhibit relatively weak interannual variability, and this variability shows negligible relationship with ENSO. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Climate is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
|
Full text is not displayed to guests.
Login for full access.
|
|
| Abstract: | This study examines the interannual variability of cross-equatorial flow (CEF) event frequency (herein defined as the total count of event days) over the Maritime Continent during June–September, using reanalysis data from 1979 to 2020. Results show that the frequency of long-lived CEF events exhibits pronounced interannual variation and is closely related to ENSO condition in simultaneous summer. Notably, this relationship is highly nonlinear, with difference in event frequency between El Niño and neutral years (~30 days per year) far exceeding that between La Niña and neutral years (~6 days per year). The relationship between ENSO and long-lived CEF events is established through ENSO's modifications to the seasonal mean CEF, which serves as a background state for the occurrence of CEF events. Although the seasonal mean CEF anomalies under the warm and cold phases of ENSO are opposite and comparable, the effect of the background state on CEF events is fundamentally nonlinear. Specifically, the frequency of long-lived events is not sensitive to the CEF background state when it is lower than 0.51 m s −1 , but becomes highly sensitive when the background state becomes stronger. Additionally, Boreal Summer Intraseasonal Oscillation (BSISO) further modulates the interannual variation of long-lived CEF events: The active phases of BSISO can amplify the nonlinearity of the relationship between CEF events and ENSO, while the suppressed phases tend to narrow it. In contrast to long-lived events, the short-lived events exhibit relatively weak interannual variability, and this variability shows negligible relationship with ENSO. [ABSTRACT FROM AUTHOR] |
|---|---|
| ISSN: | 08948755 |
| DOI: | 10.1175/JCLI-D-25-0392.1 |
