The anatomy of the long-term mean AMOC at northern high latitudes
The AMOC is a key player in climate. However, directly observed long-term mean AMOC state over the past several decades is not available to serve as a reference for historical and future AMOC change, which makes it difficult to know whether model-simulated AMOC changes are reliable. In a recent study authored by Zhang and Thomas, Robust Diagnostic Calculations conducted in a high-resolution global coupled climate model constrained by observed hydrographic climatology provide a holistic picture of the long-term mean AMOC at northern high latitudes over the past several decades.
How does the Deep Western Boundary Current “leak”?
In a recent study Solodoch et al. researched the dynamics of the leakiness of material from the Deep Western Boundary Current to interior pathways. Through numerical modeling and observational analyses, they discovered that the leakiness is largely concentrated near several hotspots and manifests largely as a steady offshore flow, consistent with inertial separation. This study joins a host of other studies charting and explaining the three dimensional pathways of the AMOC in recent years.
Predicting the duration of El Niño and La Niña events with multiyear lead time
A new study by Wu and co-authors shows that the duration of individual ENSO events during 1954-2015 can be predicted up to two years in advance using a suite of multiyear retrospective forecasts conducted with the Community Earth System Model version 1, a climate model that well simulates the statistical and dynamical features of the temporal evolution of ENSO events.
Record-high Beaufort Sea freshwater content could alter local and global ocean circulations
The Beaufort Sea increased its freshwater content by 40% over the past two decades. How and where this water will flow into the Atlantic Ocean is important for local and global ocean conditions. Zhang and colleagues simulated ocean circulation and tracked the Beaufort Sea freshwater’s spread during a historical release episode from 1983 to 1995.
Models with corrected double-ITCZ projected drier winters for the US Southwest
Climate models generally project wetter winters for the US Southwest under global warming. Dong et al. discovered a strong relationship between a common model bias with future precipitation changes over this region. More specifically, models with excessive double-ITCZ biases tend to exaggerate the future precipitation increase.
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.
