Are long-term changes in mixed layer depth influencing North Pacific marine heatwaves?
A new study by Amaya and co-authors in the Special “Explaining Extremes of 2019 from a Climate Perspective” Issue of BAMS now reveals that the record thin ocean mixed layer depth (MLD) that drove a Blob 2.0 in the northeast Pacific Ocean was exacerbated by a multi-decadal shoaling of the mean MLDs in this region since 1980.
Contrasting recent and future changes in the Intertropical Convergence Zone
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.
Understanding the spatial structure of simultaneous heavy precipitation events over the conterminous United States
Najibi, Devineni, and co-authors present a new idea defined as simultaneous heavy precipitation events (SHPEs) to quantify extreme regional precipitation considering the spatial structure of extreme events. Quantifying the characteristics of SHPEs and modeling their footprints can improve the projections of flood risk and understanding of damages to interconnected infrastructure systems.
Can we measure global mean sea level with an array of drifting buoys?
In a recently published Geophysical Research Letters paper, Elipot demonstrates how a new ocean observing system for measuring local and global sea level changes could piggy-back on the existing array of freely drifting buoys. Development and implementation of such sea level measurements could ultimately provide an independent and resilient observational system to infer natural and anthropogenic sea level changes, augmenting the ongoing tide gauge and satellites records.
Routes of the upper limb of the Atlantic Meridional Overturning Circulation
In a recent article published in Geophysical Research Letters, researchers investigate the origins of the upper limb of the AMOC at 6°S, from different sections in the global ocean, by determining Lagrangian trajectories and tracing particles backward in time for 2,011 years. One of the key results is that all the routes follow the outer edges of the supergyre of the Southern Hemisphere and converge into the Agulhas region.
Why is the seasonal delay of tropical rainfall only evident over land?
A recent study by Song et al. discovered contrasting phase changes of the precipitation annual cycle between land and ocean under global warming, with land delay and ocean advance by examining simulations from 37 CMIP5 models and five large ensembles. They found that the seasonal delay of lands is mainly attributable to the increased effective heat capacity, while there exists a competing mechanism against the impact of increased capacity for the ocean precipitation.
