Internal Variability

Contrasting recent and future changes  in the Intertropical Convergence Zone
January 28, 2021

Under global warming, the ITCZ is projected to shift towards the equator, leading to squeeze in the annual-mean tropical ascent and far-reaching impacts on global circulation. Zhou and coauthors researched the observed and projected ITCZ changes based on a variety of observation and reanalysis datasets and ensemble projections of climate models, and found that the observed ITCZ changes are largely opposite to the projected future changes.

The fraction of 1- to 96-day variability in 250-hPa geopotential height anomalies that is associated with the MJO, according to cross-spectral analysis
October 5, 2020

Research by Toms et al. estimates how much impact the QBO has on the global teleconnection signature of the MJO. The authors use a spectral decomposition approach to quantify the relationships between the MJO and upper-tropospheric geopotential separately for each season of the year and for westerly and easterly QBO phases. Similar to previous studies, the results suggest that the MJO is related to upper-tropospheric geopotential anomalies across the globe. The novel contribution of the results lies in the analysis of the impacts of the QBO.

Estimates of interannual variability from new and published coral records from the northern Line Islands
February 13, 2020

A recent study uses large ensembles of an idealized general circulation model to demonstrate how episodic surface warming in the Arctic can lead to delayed responses in the stratosphere that persist for about two months, even in the absence of stationary waves.

The Observational Large Ensemble (Obs-LE) can be used to assess the relative roles of internal variability and anthropogenic influence on 50-year trends in (a-b) temperature and (c-d) precipitation over land.
August 29, 2018

Researchers have developed a complementary approach to creating ensembles for seasonal-average temperature and precipitation over land that can also be used to study internal variability.

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