Spatial distribution of two widespread precipitation events that occurred on 8 May 1995 and 13 September 1961 and geometric illustration of the extent of an SHPE on the ground
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.

Uncertainty for drifter GMSL and GMSL trend estimates
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.

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.

Welcome to the US Climate Variability and Predictability Program

Welcome new Scientific Steering Committee members

Gudrun Magnusdottir, Chair of the US CLIVAR Scientific Steering Committee

The Scientific Steering Committee (SSC) directs the scientific and implementation planning of US CLIVAR, setting the program goals, implementation strategies, and research challenges to be pursued. We welcome the 2021 SSC: Gudrun Magnusdottir (Chair, UC-Irvine), Gokhan Danabasoglu (NCAR), Chidong Zhang (NOAA PMEL), Charlotte DeMott (CSU), Shane Elipot (U. Miami), Michelle Gierach (Caltech/NASA JPL), John Nielsen-Gammon (Texas A&M), Patrick Taylor (NASA Langley), and Haiyan Teng (PNNL).

2021 Call for new US CLIVAR Panel members

2021 Call for new US CLIVAR Panel members

The US CLIVAR Scientific Steering Committee seeks qualified individuals to serve on its three subsidiary panels. Panel members formulate science goals and implementation strategies, catalyze and coordinate activities, and work with agencies and international partners to advance the progress of the climate research community. Applications are due January 15, 2021.

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.