Visualization of the mass transport carried by particle trajectories
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.

Box-plots for the future phase changes (units: days) in the precipitation annual cycle
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.

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
The Quasi-Biennial Oscillation modulates teleconnections of the Madden-Julian Oscillation

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.

Array locations and simple schematic of water mass overturning transports
First-ever daily time series of the strength of the abyssal MOC cell in the South Atlantic

Kersalé, Meinen, and coauthors investigate the MOC flows at the southern end of the South Atlantic Ocean to evaluate the variability of the oceanic circulation across 34.5°S in the South Atlantic at all depths and at a daily frequency. This research highlights the first-ever daily quantification of the time-varying strength of the abyssal cell at 34.5°S, for which prior studies had only produced once-a-decade "snapshot" ship section estimates.

Composites of NOAA Climate Prediction Center precipitation in mm day-1 broken down by MJO phase for active MJO days for the November 2015 - April 2016 El Niño event.
US precipitation modulated by MJO-ENSO teleconnection interference

Subseasonal to seasonal climate forecasts in the US depends heavily on atmospheric and oceanic conditions in the tropical Indian and Pacific Ocean regions. While ENSO dominates seasonal predictability, the primary source of global predictability on subseasonal timescales is the MJO. To understand how ENSO and MJO interact, the authors isolated both MJO and ENSO signals and found that depending on the simultaneous location of the MJO convection and the background state of ENSO, the two signals can either enhance or mask each other.

Saildrone: Adaptively sampling the marine environment
Saildrone: Adaptively sampling the marine environment

To improve atmospheric and oceanographic monitoring, a new type of autonomous marine vehicle, the Saildrone, has been developed and deployed in over 40 cruises from which data are publicly available. Coupled with data from other sources such as satellites, Saildrone measurements could be useful for future algorithm and numerical model improvements, particularly at the fine spatial scale and in complex and previously data-sparse ocean regions.

Welcome to the US Climate Variability and Predictability Program

Sea Level Hotspots from Florida to Maine: Drivers, Impacts, and Adaptation Workshop Report

Sea Level Hotspots from Florida to Maine Workshop Report Cover

The US CLIVAR Workshop "Sea Level Hotspots from Florida to Maine: Drivers, Impacts, and Adaptation" took place in Norfolk, Virginia from April 23-25, 2019 with the main goal of bringing together the scientific community, decision makers, coastal stakeholders, and practitioners to share state-of-the-art knowledge about sea level changes along the US East Coast. This newly released workshop report provides a summary of the workshop as well as key recommendations.

Best Practice Strategies for Process Studies Designed to Improve Climate Modeling

Best Practice Strategies for Process Studies Designed to Improve Climate Modeling

We are pleased to highlight the recently published BAMS Article on “Best Practice Strategies for Process Studies Designed to Improve Climate Modeling,” authored by Janet Sprintall, Victoria Coles, Kevin Reed, Amy Butler, Greg Foltz, Hyodae Seo, and Steve Penny – current and prior members of the US CLIVAR Process Study and Model Improvement Panel – who compiled and distilled a set of practical strategies and lessons learned to help guide planning and implementation of future process studies within the climate science community.

Tropical Pacific Observing Needs Workshop

Tropical Pacific Observing Needs Workshop

Save the date for the Tropical Pacific Observing Needs Workshop, May 24-26, 2021. This workshop will gather community input on the types of Tropical Pacific ocean and atmosphere observations needed to advance understanding of poorly observed subgrid-scale processes and how such observations could be leveraged to improve satellite retrievals, data assimilation, and parameterized processes in climate, forecast, and biogeochemical models.

Arctic Circulation Workshop Blog

Arctic Circulation Workshop

In preparation for the Workshop on Observing, Modeling, and Understanding the Circulation of the Arctic Ocean and Sub-Arctic Seas, the organizing committee initiated an online topical community discussion to share perspectives in advance of the workshop.

CLIVAR-relevant sessions at 2020 AGU Fall Meeting

AGU Fall Meeting

The 2020 AGU Fall Meeting will be held from December 7-11 virtually (mostly), in San Francisco (possibly), and in other regional hubs (if it is safe). In preparation for the meeting, we have compiled a list of sessions and town halls that are relevant to the community and organized by our Panels, Working Groups, and community members. The list of sessions is not intended to be exhaustive but to help digest the collection of the hundreds of sessions and events.