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Christopher C. Walker
and
Gudrun Magnusdottir

Abstract

The nonlinear behavior of planetary waves excited by midlatitude topography is considered in an atmospheric GCM. The GCM is run at standard resolution (T42) and includes all of the complexity normally associated with a GCM. Only two simplifications are made to the model. First, it is run in perpetual January mode, so that the solar radiation takes the diurnally varying value associated with 15 January. Second, the lower boundary is simplified so that it is entirely ocean with zonally symmetric SSTs. Planetary waves are excited by Gaussian-shaped topography centered at 45°N, 90°W. As in earlier studies, the excited wave train propagates toward low latitudes where, for sufficiently large forcing amplitude (i.e., height of topography), the wave will break. Several different experiments are run with different mountain heights. Each experiment is run for a total of 4015 days.

The response of the model depends on the height of the mountain. For the small-amplitude mountain (500 m), the wave is dissipated at low latitudes near its critical latitude. For large-amplitude mountains (2000, 3000, and 4000 m), wave breaking and nonlinear reflection out of the wave breaking region is observed. The spatial character of the reflected wave train is similar to that detected in earlier studies with more idealized models.

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Tapio Schneider
and
Christopher C. Walker

Abstract

In simulations of a wide range of circulations with an idealized general circulation model, clear scaling laws of dry atmospheric macroturbulence emerge that are consistent with nonlinear eddy–eddy interactions being weak. The simulations span several decades of eddy energies and include Earth-like circulations and circulations with multiple jets and belts of surface westerlies in each hemisphere. In the simulations, the eddy available potential energy and the barotropic and baroclinic eddy kinetic energy scale linearly with each other, with the ratio of the baroclinic eddy kinetic energy to the barotropic eddy kinetic energy and eddy available potential energy decreasing with increasing planetary radius and rotation rate. Mean values of the meridional eddy flux of surface potential temperature and of the vertically integrated convergence of the meridional eddy flux of zonal momentum generally scale with functions of the eddy energies and the energy-containing eddy length scale, with a few exceptions in simulations with statically near-neutral or neutral extratropical thermal stratifications. Eddy energies scale with the mean available potential energy and with a function of the supercriticality, a measure of the near-surface slope of isentropes. Strongly baroclinic circulations form an extended regime in which eddy energies scale linearly with the mean available potential energy. Mean values of the eddy flux of surface potential temperature and of the vertically integrated eddy momentum flux convergence scale similarly with the mean available potential energy and other mean fields.

The scaling laws for the dependence of eddy fields on mean fields exhibit a regime transition between a regime in which the extratropical thermal stratification and tropopause height are controlled by radiation and convection and a regime in which baroclinic entropy fluxes modify the extratropical thermal stratification and tropopause height. At the regime transition, for example, the dependence of the eddy flux of surface potential temperature and the dependence of the vertically integrated eddy momentum flux convergence on mean fields changes—a result with implications for climate stability and for the general circulation of an atmosphere, including its tropical Hadley circulation.

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Christopher C. Walker
and
Gudrun Magnusdottir

Abstract

The nonlinear behavior of quasi-stationary planetary waves excited by midlatitude orographic forcing is considered in a three-dimensional primitive equation model that includes a representation of the Hadley circulation. The Hadley circulation is forced by Newtonian cooling to a zonally symmetric reference temperature and vertical diffusion on the zonally symmetric component of the flow. To quantify the effect of the Hadley circulation on wave propagation, breaking, and nonlinear reflection, an initial state with no meridional flow, but with the same zonal flow as the Hadley state, is also considered. In order to allow the propagation of large-scale waves over extended periods, Rayleigh friction is applied at low levels to delay the onset of baroclinic instability.

As in the absence of a Hadley circulation, the waves in the Hadley state propagate toward low latitudes where the background flow is weak and the waves are therefore likely to break. Potential vorticity fields on isentropic surfaces are used to diagnose wave breaking. Nonlinear pseudomomentum conservation relations are used to quantify the absorption–reflection behavior of the wave breaking region. In the presence of a Hadley circulation representative of winter conditions, the nonlinear reflection requires more forcing to get established, but a reflected wave train is still present in the numerical simulations, both for a longitudinally symmetric forcing and for the more realistic case of an isolated forcing. The effect of the thermal damping on the waves is more severe in the current three-dimensional simulations than in the shallow water case considered in an earlier study. Both the directly forced wave train and the reflected wave train are quite barotropic in character; however, in the shallow water case one is essentially assuming an infinite vertical scale.

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Christopher C. Walker
and
Tapio Schneider

Abstract

An idealized GCM is used to investigate how the strength and meridional extent of the Hadley circulation depend on the planet radius, rotation rate, and thermal driving. Over wide parameter ranges, the strength and meridional extent of the Hadley circulation display clear scaling relations with regime transitions, which are not predicted by existing theories of axisymmetric Hadley circulations. For example, the scaling of the strength as a function of the radiative-equilibrium equator-to-pole temperature contrast exhibits a regime transition corresponding to a regime transition in scaling laws of baroclinic eddy fluxes. The scaling of the strength of the cross-equatorial Hadley cell as a function of the latitude of maximum radiative-equilibrium temperature exhibits a regime transition from a regime in which eddy momentum fluxes strongly influence the strength to a regime in which the influence of eddy momentum fluxes is weak.

Over a wide range of flow parameters, albeit not always, the Hadley circulation strength is directly related to the eddy momentum flux divergence at the latitude of the streamfunction extremum. Simulations with hemispherically symmetric thermal driving span circulations with local Rossby numbers in the horizontal upper branch of the Hadley circulation between 0.1 and 0.8, indicating that neither nonlinear nearly inviscid theories, valid for Ro → 1, nor linear theories, valid for Ro → 0, of axisymmetric Hadley circulations can be expected to be generally adequate. Nonlinear theories of axisymmetric Hadley circulations may account for aspects of the circulation when the maximum radiative-equilibrium temperature is displaced sufficiently far away from the equator, which results in cross-equatorial Hadley cells with nearly angular momentum-conserving upper branches.

The dependence of the Hadley circulation on eddy fluxes, which are themselves dependent on extratropical circulation characteristics such as meridional temperature gradients, suggests that tropical circulations depend on the extratropical climate.

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Tapio Schneider
and
Christopher C. Walker

Abstract

It is generally held that atmospheric macroturbulence can be strongly nonlinear. Yet weakly nonlinear models successfully account for scales and structures of baroclinic eddies in Earth's atmosphere. Here a theory and simulations with an idealized GCM are presented that suggest weakly nonlinear models are so successful because atmospheric macroturbulence organizes itself into critical states of weak nonlinear eddy–eddy interactions. By modifying the thermal structure of the extratropical atmosphere such that its supercriticality remains limited, macroturbulence inhibits nonlinear eddy–eddy interactions and the concomitant inverse energy cascade from the length scales of baroclinic instability to larger scales. For small meridional surface temperature gradients, the extratropical thermal stratification and tropopause height are set by radiation and convection, and the supercriticality is less than one; for sufficiently large meridional surface temperature gradients, the extratropical thermal stratification and tropopause height are modified by baroclinic eddies such that the supercriticality does not significantly exceed one. In either case, the scale of the energy-containing eddies is similar to the scale of the linearly most unstable baroclinic waves, and eddy kinetic and available potential energies are equipartitioned. The theory and simulations point to fundamental constraints on the thermal structures and global circulations of the atmospheres of Earth and other planets, for example, by providing limits on the tropopause height and estimates for eddy scales, eddy energies, and jet separation scales.

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Matthew E. Peters
,
Zhiming Kuang
, and
Christopher C. Walker

Abstract

An analysis of atmospheric energy transport in 22 years (1980–2001) of the 40-yr ECMWF Re-Analysis (ERA-40) is presented. In the analyzed budgets, there is a large cancellation between divergences of dry static and latent energy such that the total energy divergence is positive over all tropical oceanic regions except for the east Pacific cold tongue, consistent with previous studies. The west Pacific and Indian Oceans are characterized by a balance between diabatic sources and mean advective energy export, with a small eddy contribution. However, in the central and eastern Pacific convergence zone, total energy convergence by the mean circulation is balanced by submonthly eddies, with a small diabatic source. Decomposing the mean advective tendency into terms due to horizontal and vertical advection shows that the spatial variation in the mean advection is due largely to variations in vertical advection; these variations are further attributed to variations in the vertical profile of the vertical velocity. The eddy energy export, due almost exclusively to eddy moisture export, does not exhibit any significant seasonal variation.

The relationship between the eddies and the mean circulation is examined. Large-scale moisture diffusion is correlated with eddy moisture export on (500 km)2 spatial scales, implying that eddy activity preferentially dries narrow convergence zones over wide ones. Eddy moisture export is further linked to the depth of mean convection in large-scale convergence zones with larger eddy export associated with shallower circulations. This suggests a mechanism that could contribute to the observed variation in mean divergence profiles across the northern tropical Pacific whereby sea surface temperature gradients set the width of convergence zones and eddy activity modulates the tropospheric relative humidity and divergence profile. The importance of variations in the vertical profile of the vertical velocity and eddies in closing the energy budget implies that simple models of the mean tropical circulation should include these effects.

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Tapio Schneider
,
Karen L. Smith
,
Paul A. O’Gorman
, and
Christopher C. Walker

Abstract

Based on reanalysis data for the years 1980–2001 from the European Centre for Medium-Range Weather Forecasts (ERA-40 data), a climatology of tropospheric zonal-mean water vapor fields and fluxes in isentropic coordinates is presented. In the extratropical free troposphere, eddy fluxes dominate the meridional flux of specific humidity along isentropes. At all levels, isentropic eddy fluxes transport water vapor from the deep Tropics through the subtropics into the extratropics. Isentropic eddy fluxes of specific humidity diverge near the surface and in the tropical and subtropical free troposphere; they converge in the extratropical free troposphere. Isentropic mean advective fluxes of specific humidity play a secondary role in the meridional water vapor transport in the free troposphere; however, they dominate the meridional flux of specific humidity near the surface, where they transport water vapor equatorward and, in the solstice seasons, across the equator. Cross-isentropic mean advective fluxes of specific humidity are especially important in the Hadley circulation, in whose ascending branches they moisten and in whose descending branches they dry the free troposphere.

Near the minima of zonal-mean relative humidity in the subtropical free troposphere, the divergence of the cross-isentropic mean advective flux of specific humidity in the descending branches of the Hadley circulation is the dominant divergence in the mean specific humidity balance; it is primarily balanced by convergence of cross-isentropic turbulent fluxes that transport water vapor from the surface upward. Although there are significant isentropic eddy fluxes of specific humidity through the region of the subtropical relative humidity minima, their divergence near the minima is generally small compared with the divergence of cross-isentropic mean advective fluxes, implying that moistening by eddy transport from the Tropics into the region of the minima approximately balances drying by eddy transport into the extratropics. That drying by cross-isentropic mean subsidence near the subtropical relative humidity minima is primarily balanced by moistening by upward turbulent fluxes of specific humidity, likely in convective clouds, suggests cloud dynamics may play a central role in controlling the relative humidity of the subtropical free troposphere.

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Tim Boyer
,
Ellen Bartow-Gillies
,
A. Abida
,
Melanie Ades
,
Robert Adler
,
Susheel Adusumilli
,
W. Agyakwah
,
Brandon Ahmasuk
,
Laura S. Aldeco
,
Mihai Alexe
,
Eric J. Alfaro
,
Richard P. Allan
,
Adam Allgood
,
Lincoln. M. Alves
,
Jorge A. Amador
,
John Anderson
,
B. Andrade
,
Orlane Anneville
,
Yasuyuki Aono
,
Anthony Arguez
,
Carlo Arosio
,
C. Atkinson
,
John A. Augustine
,
Grinia Avalos
,
Cesar Azorin-Molina
,
Stacia A. Backensto
,
Stephan Bader
,
Julian Baez
,
Rebecca Baiman
,
Thomas J. Ballinger
,
Alison F. Banwell
,
M. Yu Bardin
,
Jonathan Barichivich
,
John E. Barnes
,
Sandra Barreira
,
Rebecca L. Beadling
,
Hylke E. Beck
,
Emily J. Becker
,
E. Bekele
,
Guillem Martín Bellido
,
Nicolas Bellouin
,
Angela Benedetti
,
Rasmus Benestad
,
Christine Berne
,
Logan. T. Berner
,
Germar H. Bernhard
,
Uma S. Bhatt
,
A. E. Bhuiyan
,
Siiri Bigalke
,
Tiago Biló
,
Peter Bissolli
,
W. Bjerke Jarle
,
Kevin Blagrave
,
Eric S. Blake
,
Stephen Blenkinsop
,
Jessica Blunden
,
Oliver Bochníček
,
Olivier Bock
,
Xavier Bodin
,
Michael Bosilovich
,
Olivier Boucher
,
Deniz Bozkurt
,
Brian Brettschneider
,
Francis G. Bringas
,
Francis Bringas
,
Dennis Buechler
,
Stefan A. Buehler
,
Brandon Bukunt
,
Blanca Calderón
,
Suzana J. Camargo
,
Jayaka Campbell
,
Diego Campos
,
Laura Carrea
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Duo Chan
,
Elise Chandler
,
Kai-Lan Chang
,
Hua Chen
,
Lin Chen
,
Lijing Cheng
,
Vincent Y. S. Cheng
,
Leah Chomiak
,
Hanne H. Christiansen
,
John R. Christy
,
Eui-Seok Chung
,
Laura M. Ciasto
,
Leonardo Clarke
,
Kyle R. Clem
,
Scott Clingan
,
Caio A.S. Coelho
,
Judah L. Cohen
,
Melanie Coldewey-Egbers
,
Steve Colwell
,
Owen R. Cooper
,
Richard C. Cornes
,
Kris Correa
,
Felipe Costa
,
Curt Covey
,
Lawrence Coy
,
Jean-François Créatux
,
Lenka Crhova
,
Theresa Crimmins
,
Meghan F. Cronin
,
Thomas Cropper
,
Molly Crotwell
,
Joshua Culpepper
,
Ana P. Cunha
,
Diego Cusicanqui
,
Rajashree T. Datta
,
Sean M. Davis
,
Veerle De Bock
,
Richard A. M. de Jeu
,
Jos De Laat
,
Bertrand Decharme
,
Doug Degenstein
,
Reynald Delaloye
,
Mesut Demircan
,
Chris Derksen
,
Ricardo Deus
,
K. R. Dhurmea
,
Howard J. Diamond
,
S. Dirkse
,
Dmitry Divine
,
Martin T. Dokulil
,
Markus G. Donat
,
Shenfu Dong
,
Wouter A. Dorigo
,
Caroline Drost Jensen
,
Matthew L. Druckenmiller
,
Paula Drumond
,
Marcel du Plessis
,
Hilary A. Dugan
,
Dashkhuu Dulamsuren
,
Devon Dunmire
,
Robert J. H. Dunn
,
Imke Durre
,
Geoff Dutton
,
Gregory Duveiller
,
Mithat Ekici
,
Alesksandra Elias Chereque
,
M. ElKharrim
,
Howard E. Epstein
,
Jhan-Carlo Espinoza
,
Thomas W. Estilow
,
Nicole Estrella
,
Nicolas Fauchereau
,
Robert S. Fausto
,
Richard A. Feely
,
Chris Fenimore
,
David Fereday
,
Xavier Fettweis
,
vitali E. Fioletov
,
Johannes Flemming
,
Chris Fogarty
,
Ryan L. Fogt
,
Bruce C. Forbes
,
Michael J. Foster
,
Bryan A. Franz
,
Natalie M. Freeman
,
Helen A. Fricker
,
Stacey M. Frith
,
Lucien Froidevaux
,
(JJ)
,
Steven Fuhrman
,
Martin Füllekrug
,
Catherine Ganter
,
Meng Gao
,
Alex S. Gardner
,
Judith Garforth
,
Jay Garg
,
Sebastian Gerland
,
Badin Gibbes
,
Sarah T. Gille
,
John Gilson
,
Karin Gleason
,
Nadine Gobron
,
Scott J. Goetz
,
Stanley B. Goldenberg
,
Gustavo Goni
,
Steven Goodman
,
Atsushi Goto
,
Jens-Uwe Grooß
,
Alexander Gruber
,
Guojun Gu
,
Charles “Chip” P. Guard
,
S. Hagos
,
Sebastian Hahn
,
Leopold Haimberger
,
Bradley D. Hall
,
Benjamin D. Hamlington
,
Edward Hanna
,
Inger Hanssen-Bauer
,
Daniel S. Harnos
,
Ian Harris
,
Qiong He
,
Richard R. Heim Jr.
,
Sverker Hellström
,
Deborah L. Hemming
,
Stefan Hendricks
,
J. Hicks
,
Hugo G. Hidalgo
,
Martin Hirschi
,
(Ben)
,
W. Hobbs
,
Robert M. Holmes
,
Robert Holzworth
,
Filip Hrbáček
,
Guojie Hu
,
Zeng-Zhen Hu
,
Boyin Huang
,
Hongjie Huang
,
Dale F. Hurst
,
Iolanda Ialongo
,
Antje Inness
,
Ketil Isaksen
,
Masayoshi Ishii
,
Gerardo Jadra
,
Svetlana Jevrejeva
,
Viju O. John
,
W. Johns
,
Bjørn Johnsen
,
Bryan Johnson
,
Gregory C. Johnson
,
Philip D. Jones
,
Timothy Jones
,
Simon A. Josey
,
G. Jumaux
,
Robert Junod
,
Andreas Kääb
,
K. Kabidi
,
Johannes W. Kaiser
,
Robb S.A. Kaler
,
Lars Kaleschke
,
Viktor Kaufmann
,
Amin Fazl Kazemi
,
Linda M. Keller
,
Andreas Kellerer-Pirklbauer
,
Mike Kendon
,
John Kennedy
,
Elizabeth C. Kent
,
Kenneth Kerr
,
Valentina Khan
,
Mai Van Khiem
,
Richard Kidd
,
Mi Ju Kim
,
Seong-Joong Kim
,
Zak Kipling
,
Philip J. Klotzbach
,
John A. Knaff
,
Akash Koppa
,
Natalia N. Korshunova
,
Benjamin M. Kraemer
,
Natalya A. Kramarova
,
A. C. Kruger
,
Andries Kruger
,
Arun Kumar
,
Michelle L’Heureux
,
Sofia La Fuente
,
Alo Laas
,
Zachary M. Labe
,
Rick Lader
,
Mónika Lakatos
,
Kaisa Lakkala
,
Hoang Phuc Lam
,
Xin Lan
,
Peter Landschützer
,
Chris W. Landsea
,
Timothy Lang
,
Matthias Lankhorst
,
Kathleen O. Lantz
,
Mark J. Lara
,
Waldo Lavado-Casimiro
,
David A. Lavers
,
Matthew A. Lazzara
,
Thierry Leblanc
,
Tsz-Cheung Lee
,
Eric M. Leibensperger
,
Chris Lennard
,
Eric Leuliette
,
Kinson H. Y. Leung
,
Jan L. Lieser
,
Tanja Likso
,
I-I. Lin
,
Jackie Lindsey
,
Yakun Liu
,
Ricardo Locarnini
,
Norman G. Loeb
,
Bryant D. Loomis
,
Andrew M. Lorrey
,
Diego Loyola
,
Rui Lu
,
Rick Lumpkin
,
Jing-Jia Luo
,
Kari Luojus
,
John M. Lyman
,
Stephen C. Maberly
,
Matthew J. Macander
,
Michael MacFerrin
,
Graeme A. MacGilchrist
,
Michelle L. MacLennan
,
Remi Madelon
,
Andrew D. Magee
,
Florence Magnin
,
Jostein Mamen
,
Ken D. Mankoff
,
Gloria L. Manney
,
Izolda Marcinonienė
,
Jose A. Marengo
,
Mohammadi Marjan
,
Ana E. Martínez
,
Robert A. Massom
,
Shin-Ichiro Matsuzaki
,
Linda May
,
Michael Mayer
,
Matthew R. Mazloff
,
Stephanie A. McAfee
,
C. McBride
,
Matthew F. McCabe
,
James W. McClelland
,
Michael J. McPhaden
,
Tim R. Mcvicar
,
Carl A. Mears
,
Walter N. Meier
,
A. Mekonnen
,
Annette Menzel
,
Christopher J. Merchant
,
Mark A. Merrifield
,
Michael F. Meyer
,
Tristan Meyers
,
David E. Mikolajczyk
,
John B. Miller
,
Diego G. Miralles
,
Noelia Misevicius
,
Alexey Mishonov
,
Gary T. Mitchum
,
Ben I. Moat
,
Leander Moesinger
,
Aurel Moise
,
Jorge Molina-Carpio
,
Ghislaine Monet
,
Stephan A. Montzka
,
Twila A. Moon
,
G. W. K. Moore
,
Natali Mora
,
Johnny Morán
,
Claire Morehen
,
Colin Morice
,
A. E. Mostafa
,
Thomas L. Mote
,
Ivan Mrekaj
,
Lawrence Mudryk
,
Jens Mühle
,
Rolf Müller
,
David Nance
,
Eric R. Nash
,
R. Steven Nerem
,
Paul A. Newman
,
Julien P. Nicolas
,
Juan J. Nieto
,
Jeannette Noetzli
,
Ben Noll
,
Taylor Norton
,
Kelsey E. Nyland
,
John O’Keefe
,
Naomi Ochwat
,
Yoshinori Oikawa
,
Yuka Okunaka
,
Timothy J. Osborn
,
James E. Overland
,
Taejin Park
,
Mark Parrington
,
Julia K. Parrish
,
Richard J. Pasch
,
Reynaldo Pascual Ramírez
,
Cécile Pellet
,
Mauri S. Pelto
,
Melita Perčec Tadić
,
Donald K. Perovich
,
Guðrún Nína Petersen
,
Kyle Petersen
,
Irina Petropavlovskikh
,
Alek Petty
,
Alexandre B. Pezza
,
Luciano P. Pezzi
,
Coda Phillips
,
Gareth K. Phoenix
,
Don Pierson
,
Izidine Pinto
,
Vanda Pires
,
Michael Pitts
,
Stephen Po-Chedley
,
Paolo Pogliotti
,
Kristin Poinar
,
Lorenzo Polvani
,
Wolfgang Preimesberger
,
Colin Price
,
Merja Pulkkanen
,
Sarah G. Purkey
,
Bo Qiu
,
Kenny Quisbert
,
Willy R. Quispe
,
M. Rajeevan
,
Andrea M. Ramos
,
William J. Randel
,
Mika Rantanen
,
Marilyn N. Raphael
,
James Reagan
,
Cristina Recalde
,
Phillip Reid
,
Samuel Rémy
,
Alejandra J. Reyes Kohler
,
Lucrezia Ricciardulli
,
Andrew D. Richardson
,
Robert Ricker
,
David A. Robinson
,
M. Robjhon
,
Willy Rocha
,
Matthew Rodell
,
Esteban Rodriguez Guisado
,
Nemesio Rodriguez-Fernandez
,
Vladimir E. Romanovsky
,
Josyane Ronchail
,
Matthew Rosencrans
,
Karen H. Rosenlof
,
Benjamin Rösner
,
Henrieke Rösner
,
Alexei Rozanov
,
Jozef Rozkošný
,
Frans Rubek
,
Olga O. Rusanovskaya
,
This Rutishauser
,
C. T. Sabeerali
,
Roberto Salinas
,
Ahira Sánchez-Lugo
,
Michelle L. Santee
,
Marcelo Santini
,
Katsunari Sato
,
Parnchai Sawaengphokhai
,
A. Sayouri
,
Theodore Scambos
,
Verena Schenzinger
,
Semjon Schimanke
,
Robert W. Schlegel
,
Claudia Schmid
,
Martin Schmid
,
Udo Schneider
,
Carl J. Schreck
,
Cristina Schultz
,
Science Systems and Applications Inc.
,
Z. T. Segele
,
Serhat Sensoy
,
Shawn P. Serbin
,
Mark C. Serreze
,
Amsari Mudzakir Setiawan
,
Fumi Sezaki
,
Sapna Sharma
,
Jonathan D. Sharp
,
Gay Sheffield
,
Jia-Rui Shi
,
Lei Shi
,
Alexander I. Shiklomanov
,
Nikolay I. Shiklomanov
,
Svetlana V. Shimaraeva
,
R. Shukla
,
David A. Siegel
,
Eugene A. Silow
,
F. Sima
,
Adrian J. Simmons
,
David A. Smeed
,
Adam Smith
,
Sharon L. Smith
,
Brian J. Soden
,
Viktoria Sofieva
,
Everaldo Souza
,
Tim H. Sparks
,
Jacqueline Spence-Hemmings
,
Robert G. M. Spencer
,
Sandra Spillane
,
O. P. Sreejith
,
A. K. Srivastava
,
Paul W. Stackhouse Jr.
,
Sharon Stammerjohn
,
Ryan Stauffer
,
Wolfgang Steinbrecht
,
Andrea K. Steiner
,
Jose L. Stella
,
Tannecia S. Stephenson
,
Pietro Stradiotti
,
Susan E. Strahan
,
Dmitry A. Streletskiy
,
Divya E. Surendran
,
Anya Suslova
,
Tove Svendby
,
William Sweet
,
Kiyotoshi Takahashi
,
Kazuto Takemura
,
Suzanne E. Tank
,
Michael A. Taylor
,
Marco Tedesco
,
Stephen J. Thackeray
,
W. M. Thiaw
,
Emmanuel Thibert
,
Richard L. Thoman
,
Andrew F. Thompson
,
Philip R. Thompson
,
Xiangshan Tian-Kunze
,
Mary-Louise Timmermans
,
Maxim A. Timofeyev
,
Skie Tobin
,
Hans Tømmervik
,
Kleareti Tourpali
,
Lidia Trescilo
,
Mikhail Tretiakov
,
Blair C. Trewin
,
Joaquin A. Triñanes
,
Adrian Trotman
,
Ryan E. Truchelut
,
Luke D. Trusel
,
Mari R. Tye
,
Ronald van der A
,
Robin van der Schalie
,
Gerard van der Schrier
,
Cedric J. Van Meerbeeck
,
Arnold J.H. van vliet
,
Ahad Vazife
,
Piet Verburg
,
Jean-Paul Vernier
,
Isaac J. Vimont
,
Katrina Virts
,
Sebastián Vivero
,
Denis L. Volkov
,
Holger Vömel
,
Russell S. Vose
,
(Skip)
,
John E. Walsh
,
Bin Wang
,
Hui Wang
,
Muyin Wang
,
Ray H. J. Wang
,
Xinyue Wang
,
Rik Wanninkhof
,
Taran Warnock
,
Mark Weber
,
Melinda Webster
,
Adrian Wehrlé
,
Caihong Wen
,
Toby K. Westberry
,
Matthew J. Widlansky
,
David N. Wiese
,
Jeannette D. Wild
,
Jonathan D. Wille
,
An Willems
,
Kate M. Willett
,
Earle Williams
,
J. Willis
,
Takmeng Wong
,
Kimberly M. Wood
,
Richard Iestyn Woolway
,
Ping-Ping Xie
,
Dedi Yang
,
Xungang Yin
,
Ziqi Yin
,
Zhenzhong Zeng
,
Huai-min Zhang
,
Li Zhang
,
Peiqun Zhang
,
Lin Zhao
,
Xinjia Zhou
,
Zhiwei Zhu
,
Jerry R. Ziemke
,
Markus Ziese
,
Scott Zolkos
,
Ruxandra M. Zotta
,
Cheng-Zhi Zou
,
Jessicca Allen
,
Amy V. Camper
,
Bridgette O. Haley
,
Gregory Hammer
,
S. Elizabeth Love-Brotak
,
Laura Ohlmann
,
Lukas Noguchi
,
Deborah B. Riddle
, and
Sara W. Veasey

Abstract

—J. BLUNDEN, T. BOYER, AND E. BARTOW-GILLIES

Earth’s global climate system is vast, complex, and intricately interrelated. Many areas are influenced by global-scale phenomena, including the “triple dip” La Niña conditions that prevailed in the eastern Pacific Ocean nearly continuously from mid-2020 through all of 2022; by regional phenomena such as the positive winter and summer North Atlantic Oscillation that impacted weather in parts the Northern Hemisphere and the negative Indian Ocean dipole that impacted weather in parts of the Southern Hemisphere; and by more localized systems such as high-pressure heat domes that caused extreme heat in different areas of the world. Underlying all these natural short-term variabilities are long-term climate trends due to continuous increases since the beginning of the Industrial Revolution in the atmospheric concentrations of Earth’s major greenhouse gases.

In 2022, the annual global average carbon dioxide concentration in the atmosphere rose to 417.1±0.1 ppm, which is 50% greater than the pre-industrial level. Global mean tropospheric methane abundance was 165% higher than its pre-industrial level, and nitrous oxide was 24% higher. All three gases set new record-high atmospheric concentration levels in 2022.

Sea-surface temperature patterns in the tropical Pacific characteristic of La Niña and attendant atmospheric patterns tend to mitigate atmospheric heat gain at the global scale, but the annual global surface temperature across land and oceans was still among the six highest in records dating as far back as the mid-1800s. It was the warmest La Niña year on record. Many areas observed record or near-record heat. Europe as a whole observed its second-warmest year on record, with sixteen individual countries observing record warmth at the national scale. Records were shattered across the continent during the summer months as heatwaves plagued the region. On 18 July, 104 stations in France broke their all-time records. One day later, England recorded a temperature of 40°C for the first time ever. China experienced its second-warmest year and warmest summer on record. In the Southern Hemisphere, the average temperature across New Zealand reached a record high for the second year in a row. While Australia’s annual temperature was slightly below the 1991–2020 average, Onslow Airport in Western Australia reached 50.7°C on 13 January, equaling Australia's highest temperature on record.

While fewer in number and locations than record-high temperatures, record cold was also observed during the year. Southern Africa had its coldest August on record, with minimum temperatures as much as 5°C below normal over Angola, western Zambia, and northern Namibia. Cold outbreaks in the first half of December led to many record-low daily minimum temperature records in eastern Australia.

The effects of rising temperatures and extreme heat were apparent across the Northern Hemisphere, where snow-cover extent by June 2022 was the third smallest in the 56-year record, and the seasonal duration of lake ice cover was the fourth shortest since 1980. More frequent and intense heatwaves contributed to the second-greatest average mass balance loss for Alpine glaciers around the world since the start of the record in 1970. Glaciers in the Swiss Alps lost a record 6% of their volume. In South America, the combination of drought and heat left many central Andean glaciers snow free by mid-summer in early 2022; glacial ice has a much lower albedo than snow, leading to accelerated heating of the glacier. Across the global cryosphere, permafrost temperatures continued to reach record highs at many high-latitude and mountain locations.

In the high northern latitudes, the annual surface-air temperature across the Arctic was the fifth highest in the 123-year record. The seasonal Arctic minimum sea-ice extent, typically reached in September, was the 11th-smallest in the 43-year record; however, the amount of multiyear ice—ice that survives at least one summer melt season—remaining in the Arctic continued to decline. Since 2012, the Arctic has been nearly devoid of ice more than four years old.

In Antarctica, an unusually large amount of snow and ice fell over the continent in 2022 due to several landfalling atmospheric rivers, which contributed to the highest annual surface mass balance, 15% to 16% above the 1991–2020 normal, since the start of two reanalyses records dating to 1980. It was the second-warmest year on record for all five of the long-term staffed weather stations on the Antarctic Peninsula. In East Antarctica, a heatwave event led to a new all-time record-high temperature of −9.4°C—44°C above the March average—on 18 March at Dome C. This was followed by the collapse of the critically unstable Conger Ice Shelf. More than 100 daily low sea-ice extent and sea-ice area records were set in 2022, including two new all-time annual record lows in net sea-ice extent and area in February.

Across the world’s oceans, global mean sea level was record high for the 11th consecutive year, reaching 101.2 mm above the 1993 average when satellite altimetry measurements began, an increase of 3.3±0.7 over 2021. Globally-averaged ocean heat content was also record high in 2022, while the global sea-surface temperature was the sixth highest on record, equal with 2018. Approximately 58% of the ocean surface experienced at least one marine heatwave in 2022. In the Bay of Plenty, New Zealand’s longest continuous marine heatwave was recorded.

A total of 85 named tropical storms were observed during the Northern and Southern Hemisphere storm seasons, close to the 1991–2020 average of 87. There were three Category 5 tropical cyclones across the globe—two in the western North Pacific and one in the North Atlantic. This was the fewest Category 5 storms globally since 2017. Globally, the accumulated cyclone energy was the lowest since reliable records began in 1981. Regardless, some storms caused massive damage. In the North Atlantic, Hurricane Fiona became the most intense and most destructive tropical or post-tropical cyclone in Atlantic Canada’s history, while major Hurricane Ian killed more than 100 people and became the third costliest disaster in the United States, causing damage estimated at $113 billion U.S. dollars. In the South Indian Ocean, Tropical Cyclone Batsirai dropped 2044 mm of rain at Commerson Crater in Réunion. The storm also impacted Madagascar, where 121 fatalities were reported.

As is typical, some areas around the world were notably dry in 2022 and some were notably wet. In August, record high areas of land across the globe (6.2%) were experiencing extreme drought. Overall, 29% of land experienced moderate or worse categories of drought during the year. The largest drought footprint in the contiguous United States since 2012 (63%) was observed in late October. The record-breaking megadrought of central Chile continued in its 13th consecutive year, and 80-year record-low river levels in northern Argentina and Paraguay disrupted fluvial transport. In China, the Yangtze River reached record-low values. Much of equatorial eastern Africa had five consecutive below-normal rainy seasons by the end of 2022, with some areas receiving record-low precipitation totals for the year. This ongoing 2.5-year drought is the most extensive and persistent drought event in decades, and led to crop failure, millions of livestock deaths, water scarcity, and inflated prices for staple food items.

In South Asia, Pakistan received around three times its normal volume of monsoon precipitation in August, with some regions receiving up to eight times their expected monthly totals. Resulting floods affected over 30 million people, caused over 1700 fatalities, led to major crop and property losses, and was recorded as one of the world’s costliest natural disasters of all time. Near Rio de Janeiro, Brazil, Petrópolis received 530 mm in 24 hours on 15 February, about 2.5 times the monthly February average, leading to the worst disaster in the city since 1931 with over 230 fatalities.

On 14–15 January, the Hunga Tonga-Hunga Ha'apai submarine volcano in the South Pacific erupted multiple times. The injection of water into the atmosphere was unprecedented in both magnitude—far exceeding any previous values in the 17-year satellite record—and altitude as it penetrated into the mesosphere. The amount of water injected into the stratosphere is estimated to be 146±5 Terragrams, or ∼10% of the total amount in the stratosphere. It may take several years for the water plume to dissipate, and it is currently unknown whether this eruption will have any long-term climate effect.

Open access