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Julia H. Keller

Abstract

A tropical cyclone (TC) undergoing extratropical transition (ET) may support the amplification of a Rossby wave train in the downstream midlatitudes. Within the context of downstream baroclinic development, the TC acts as an additional source of eddy kinetic energy ( ). Previous studies concluded that the impact depends, in particular, on the phasing between the TC and the midlatitude flow and the continuation of the generation during ET. These studies did not quantify the impact of ET on the within a downstream Rossby wave train.

The present study uses ensemble sensitivity analysis to examine the sensitivity of downstream Rossby wave train amplification to the budget of the transitioning TC and of the upstream midlatitude features for Typhoon Choi-Wan (2009) and Hurricane Hanna (2008) in ECMWF ensemble forecasts. The amplification of the downstream wave train is measured using the amplitude of its associated maxima. The sensitivity of the maximum’s intensity at a particular forecast time to the budget terms of the TC and the upstream midlatitudes at earlier forecast times is determined. The results show that increasing the budget terms within Choi-Wan (Hanna) by one standard deviation can result in an up to 36% (23%) more intense downstream maximum. This is favored by the phasing between Choi-Wan and the midlatitude trough, and the reintensification of Hanna, respectively. By contrast, weaker contributions to downstream Rossby wave amplification arise from budget terms associated with flow features in the upstream midlatitudes.

Full access
Julia H. Keller
,
Sarah C. Jones
, and
Patrick A. Harr

Abstract

The extratropical transition (ET) of Hurricane Hanna (2008) and Typhoon Choi-Wan (2009) caused a variety of forecast scenarios in the European Centre for Medium-Range Weather Forecasts (ECMWF) Ensemble Prediction System (EPS). The dominant development scenarios are extracted for two ensemble forecasts initialized prior to the ET of those tropical storms, using an EOF and fuzzy clustering analysis. The role of the transitioning tropical cyclone and its impact on the midlatitude flow in the distinct forecast scenarios is examined by conducting an analysis of the eddy kinetic energy budget in the framework of downstream baroclinic development. This budget highlights sources and sinks of eddy kinetic energy emanating from the transitioning tropical cyclone or adjacent upstream midlatitude flow features. By comparing the budget for several forecast scenarios for the ET of each of the two tropical cyclones, the role of the transitioning storms on the development in downstream regions is investigated. Distinct features during the interaction between the tropical cyclone and the midlatitude flow turned out to be important. In the case of Hurricane Hanna, the duration of baroclinic conversion from eddy available potential into eddy kinetic energy was important for the amplification of the midlatitude wave pattern and the subsequent reintensification of Hanna as an extratropical cyclone. In the case of Typhoon Choi-Wan, the phasing between the storm and the midlatitude flow was one of the most critical factors for the future development.

Full access
Lisa-Ann Quandt
,
Julia H. Keller
,
Olivia Martius
, and
Sarah C. Jones

Abstract

The Euro–Russian atmospheric blocking pattern in the summer of 2010 was related to high-impact weather, including a mega–heat wave in Russia. A set of scenarios for the synoptic evolution during the onset, mature stage, and decay of the block are extracted from the THORPEX Interactive Grand Global Ensemble multimodel ensemble forecast. These scenarios represent the key features of the forecast variability of the block and of the resulting surface impacts. Two heat indices and a fire index are computed to highlight the forecast variability in societal impacts. The study is a proof of concept, showing how information about surface impacts can be derived from available operational ensemble forecasts in an effective manner, and pointing to possible difficulties in this approach. Comparing the forecast for the heat wave’s impact on large spatial domains, and on a near-gridpoint scale, identifies challenges forecasters may face when predicting the development of a heat wave.

Although the block’s onset was highly predictable, the increase in temperature and the extension of the heat-affected area differed between the scenarios. During the mature stage of the block, the variability of its western flank had a considerable influence on the precipitation and heat distribution. Since the blocking was maintained after the analyzed decay in two of three scenarios, the predictability of the decay was low in this forecast. The heat wave ended independently from the block’s decay, as the surface temperature and the impact indices decreased in all scenarios.

Full access
Lisa-Ann Quandt
,
Julia H. Keller
,
Olivia Martius
,
Joaquim G. Pinto
, and
Sarah C. Jones

Abstract

In summer 2010, the weather conditions in the Euro-Russian sector were affected by a long-lasting atmospheric block that led to a heat wave in Russia and floods in Pakistan. Following previous studies describing the block’s predictability, the present study aims to investigate uncertainties in the upper-level wave pattern and diabatic processes that were responsible for the block’s forecast variability during its onset, mature, and decay phases. With this aim, an ensemble sensitivity analysis (ESA) is performed for three medium-range THORPEX Interactive Grand Global Ensemble multimodel ensemble forecasts, one associated with each phase of the block’s life cycle. The ESA revealed that the block’s predictability was influenced by forecast uncertainties in the general wave pattern and in the vertically integrated water vapor transport (IVT), used here as a proxy for diabatic processes. These uncertainties are associated with spatial shifts and intensity changes of synoptic waves and IVT during the whole life cycle of the block. During the onset phase, specific features include an Atlantic precursor block and the occurrence of several cyclones. During the mature stage, the blocking ridge itself was highly predictable, while forecast uncertainties in the wave pattern and in IVT primarily were associated with uncertainties in the block’s western flank. During the decay phase, the ESA signals were less intense, but the forecast variability significantly depended on the transformation of the block into a high-over-low pattern. It can be concluded that ESA is suitable to investigate the block’s forecast variability in multimodel ensembles.

Full access
Andrea Schneidereit
,
Dieter H. W. Peters
,
Christian M. Grams
,
Julian F. Quinting
,
Julia H. Keller
,
Gabriel Wolf
,
Franziska Teubler
,
Michael Riemer
, and
Olivia Martius

Abstract

Tropospheric forcing of planetary wavenumber 2 is examined in the prephase of the major stratospheric sudden warming event in January 2009 (MSSW 2009). Because of a huge increase in Eliassen–Palm fluxes induced mainly by wavenumber 2, easterly angular momentum is transported into the Arctic stratosphere, deposited, and then decelerates the polar night jet. In agreement with earlier studies, the results reveal that the strongest eddy heat fluxes, associated with wavenumber 2, occur at 100 hPa during the prephase of MSSW 2009 in ERA-Interim. In addition, moderate conditions of the cold phase of ENSO (La Niña) contribute to the eddy heat flux anomaly. It is shown that enhanced tropospheric wave forcing over Alaska and Scandinavia is caused by tropical processes in two ways. First, in a climatological sense, La Niña contributes to an enhanced anticyclonic flow over both regions. Second, the Madden–Julian oscillation (MJO) has an indirect influence on the Alaskan ridge by enhancing eddy activity over the North Pacific. This is manifested in an increase in cyclone frequency and associated warm conveyor belt outflow, which contribute to the maintenance and amplification of the Alaskan anticyclone. The Scandinavian ridge is maintained by wave trains emanating from the Alaskan ridge propagating eastward, including an enhanced transport of eddy kinetic energy. The MSSW 2009 is an extraordinary case of how a beneficial phasing of La Niña and MJO conditions together with multiscale interactions enhances tropospheric forcing for wavenumber 2–induced zonal mean eddy heat flux in the lower stratosphere.

Full access
Richard Swinbank
,
Masayuki Kyouda
,
Piers Buchanan
,
Lizzie Froude
,
Thomas M. Hamill
,
Tim D. Hewson
,
Julia H. Keller
,
Mio Matsueda
,
John Methven
,
Florian Pappenberger
,
Michael Scheuerer
,
Helen A. Titley
,
Laurence Wilson
, and
Munehiko Yamaguchi

Abstract

The International Grand Global Ensemble (TIGGE) was a major component of The Observing System Research and Predictability Experiment (THORPEX) research program, whose aim is to accelerate improvements in forecasting high-impact weather. By providing ensemble prediction data from leading operational forecast centers, TIGGE has enhanced collaboration between the research and operational meteorological communities and enabled research studies on a wide range of topics.

The paper covers the objective evaluation of the TIGGE data. For a range of forecast parameters, it is shown to be beneficial to combine ensembles from several data providers in a multimodel grand ensemble. Alternative methods to correct systematic errors, including the use of reforecast data, are also discussed.

TIGGE data have been used for a range of research studies on predictability and dynamical processes. Tropical cyclones are the most destructive weather systems in the world and are a focus of multimodel ensemble research. Their extratropical transition also has a major impact on the skill of midlatitude forecasts. We also review how TIGGE has added to our understanding of the dynamics of extratropical cyclones and storm tracks.

Although TIGGE is a research project, it has proved invaluable for the development of products for future operational forecasting. Examples include the forecasting of tropical cyclone tracks, heavy rainfall, strong winds, and flood prediction through coupling hydrological models to ensembles.

Finally, the paper considers the legacy of TIGGE. We discuss the priorities and key issues in predictability and ensemble forecasting, including the new opportunities of convective-scale ensembles, links with ensemble data assimilation methods, and extension of the range of useful forecast skill.

Full access
Julia H. Keller
,
Christian M. Grams
,
Michael Riemer
,
Heather M. Archambault
,
Lance Bosart
,
James D. Doyle
,
Jenni L. Evans
,
Thomas J. Galarneau Jr.
,
Kyle Griffin
,
Patrick A. Harr
,
Naoko Kitabatake
,
Ron McTaggart-Cowan
,
Florian Pantillon
,
Julian F. Quinting
,
Carolyn A. Reynolds
,
Elizabeth A. Ritchie
,
Ryan D. Torn
, and
Fuqing Zhang

Abstract

The extratropical transition (ET) of tropical cyclones often has an important impact on the nature and predictability of the midlatitude flow. This review synthesizes the current understanding of the dynamical and physical processes that govern this impact and highlights the relationship of downstream development during ET to high-impact weather, with a focus on downstream regions. It updates a previous review from 2003 and identifies new and emerging challenges and future research needs. First, the mechanisms through which the transitioning cyclone impacts the midlatitude flow in its immediate vicinity are discussed. This “direct impact” manifests in the formation of a jet streak and the amplification of a ridge directly downstream of the cyclone. This initial flow modification triggers or amplifies a midlatitude Rossby wave packet, which disperses the impact of ET into downstream regions (downstream impact) and may contribute to the formation of high-impact weather. Details are provided concerning the impact of ET on forecast uncertainty in downstream regions and on the impact of observations on forecast skill. The sources and characteristics of the following key features and processes that may determine the manifestation of the impact of ET on the midlatitude flow are discussed: the upper-tropospheric divergent outflow, mainly associated with latent heat release in the troposphere below, and the phasing between the transitioning cyclone and the midlatitude wave pattern. Improving the representation of diabatic processes during ET in models and a climatological assessment of the ET’s impact on downstream high-impact weather are examples for future research directions.

Open access
Paolo M. Ruti
,
Oksana Tarasova
,
Julia H. Keller
,
Greg Carmichael
,
Øystein Hov
,
Sarah C. Jones
,
Deon Terblanche
,
Cheryl Anderson-Lefale
,
Ana P. Barros
,
Peter Bauer
,
Véronique Bouchet
,
Guy Brasseur
,
Gilbert Brunet
,
Phil DeCola
,
Victor Dike
,
Mariane Diop Kane
,
Christopher Gan
,
Kevin R. Gurney
,
Steven Hamburg
,
Wilco Hazeleger
,
Michel Jean
,
David Johnston
,
Alastair Lewis
,
Peter Li
,
Xudong Liang
,
Valerio Lucarini
,
Amanda Lynch
,
Elena Manaenkova
,
Nam Jae-Cheol
,
Satoru Ohtake
,
Nadia Pinardi
,
Jan Polcher
,
Elizabeth Ritchie
,
Andi Eka Sakya
,
Celeste Saulo
,
Amith Singhee
,
Ardhasena Sopaheluwakan
,
Andrea Steiner
,
Alan Thorpe
, and
Moeka Yamaji

Abstract

Whether on an urban or planetary scale, covering time scales of a few minutes or a few decades, the societal need for more accurate weather, climate, water, and environmental information has led to a more seamless thinking across disciplines and communities. This challenge, at the intersection of scientific research and society’s need, is among the most important scientific and technological challenges of our time. The “Science Summit on Seamless Research for Weather, Climate, Water, and Environment” organized by the World Meteorological Organization (WMO) in 2017, has brought together researchers from a variety of institutions for a cross-disciplinary exchange of knowledge and ideas relating to seamless Earth system science. The outcomes of the Science Summit, and the interactions it sparked, highlight the benefit of a seamless Earth system science approach. Such an approach has the potential to break down artificial barriers that may exist due to different observing systems, models, time and space scales, and compartments of the Earth system. In this context, the main future challenges for research infrastructures have been identified. A value cycle approach has been proposed to guide innovation in seamless Earth system prediction. The engagement of researchers, users, and stakeholders will be crucial for the successful development of a seamless Earth system science that meets the needs of society.

Free access
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
,
Gerald V. Frost
,
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
,
Shu-peng Ho
,
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. 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
,
Donald A. Walker
,
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