Fine-scale rainfall over New Caledonia under climate change
Cyril Dutheil
(1, 2)
,
Christophe E. Menkès
(3)
,
Matthieu Lengaigne
(4, 5)
,
Jérôme Vialard
(4, 1)
,
Alexandre Peltier
(6)
,
Margot Bador
(7)
,
X. Petit
(1)
1
LOCEAN -
Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
2 ENTROPIE [Réunion] - Ecologie marine tropicale dans les Océans Pacifique et Indien
3 ENTROPIE [Nouvelle-Calédonie] - Ecologie marine tropicale des océans Pacifique et Indien
4 VARCLIM - Océan et variabilité du climat
5 UMR MARBEC - MARine Biodiversity Exploitation and Conservation
6 DIRNC - Météo-France Direction Interrégionale de la Nouvelle Calédonie
7 UNSW - University of New South Wales [Sydney]
2 ENTROPIE [Réunion] - Ecologie marine tropicale dans les Océans Pacifique et Indien
3 ENTROPIE [Nouvelle-Calédonie] - Ecologie marine tropicale des océans Pacifique et Indien
4 VARCLIM - Océan et variabilité du climat
5 UMR MARBEC - MARine Biodiversity Exploitation and Conservation
6 DIRNC - Météo-France Direction Interrégionale de la Nouvelle Calédonie
7 UNSW - University of New South Wales [Sydney]
Christophe E. Menkès
- Fonction : Auteur
- PersonId : 936770
Matthieu Lengaigne
- Fonction : Auteur
- PersonId : 181017
- IdHAL : matthieulengaigne
- ORCID : 0000-0002-0044-036X
- IdRef : 080621686
Jérôme Vialard
- Fonction : Auteur
- PersonId : 184288
- IdHAL : jerome-vialard
- ORCID : 0000-0001-6876-3766
- IdRef : 155038257
Margot Bador
- Fonction : Auteur
- PersonId : 1303602
- IdHAL : margot-bador
Résumé
Global climate models projections indicate no clear future rainfall changes over the Southwestern Pacific islands in response to anthropogenic forcing. Yet, these models have low (~ 100–200 km) spatial resolution and suffer from large systematic biases, such as the trademark “double ITCZ”. Here, 4 km-resolution simulations were used with a nested regional atmospheric model, which resolves the New Caledonian mountainous topography. The resulting present-day rainfall amount, spatial structure, seasonal cycle, and extremes compare much better with observations than at 20 km resolution. We applied projected changes from global climate models under the RCP8.5 scenario at the boundaries, following an approach that corrects both their present-day and projected sea surface temperature biases. Unlike climate models, our refined projections reveal an 18% decrease in annual mean rainfall over New Caledonia by 2080–2100, especially on the leeward side of the island (up to 30%) and during the hot season (that accounts for ~ 80% of the rainfall decrease). This drying is robust without bias correction, and much stronger than at ~ 20 km resolution. It is mainly driven by circulation changes. A weather regime classification further demonstrates that ~ 80% of the hot season drying relates to a strong anti-cyclonic and air subsidence anomalies centred on the north of NC, which reduces moisture convergence over the archipelago. The frequency and intensity of extreme precipitation events is also reduced by ~ 20% by 2080–2100. This drastic projected drying would have dramatic impacts on water resources and terrestrial ecosystems, pleading for carefully-planned adaptation policies for New Caledonia.
Domaines
ClimatologieFormat du dépôt | Fichier |
---|---|
Type de dépôt | Article dans une revue |
Titre |
en
Fine-scale rainfall over New Caledonia under climate change
|
Résumé |
en
Global climate models projections indicate no clear future rainfall changes over the Southwestern Pacific islands in response to anthropogenic forcing. Yet, these models have low (~ 100–200 km) spatial resolution and suffer from large systematic biases, such as the trademark “double ITCZ”. Here, 4 km-resolution simulations were used with a nested regional atmospheric model, which resolves the New Caledonian mountainous topography. The resulting present-day rainfall amount, spatial structure, seasonal cycle, and extremes compare much better with observations than at 20 km resolution. We applied projected changes from global climate models under the RCP8.5 scenario at the boundaries, following an approach that corrects both their present-day and projected sea surface temperature biases. Unlike climate models, our refined projections reveal an 18% decrease in annual mean rainfall over New Caledonia by 2080–2100, especially on the leeward side of the island (up to 30%) and during the hot season (that accounts for ~ 80% of the rainfall decrease). This drying is robust without bias correction, and much stronger than at ~ 20 km resolution. It is mainly driven by circulation changes. A weather regime classification further demonstrates that ~ 80% of the hot season drying relates to a strong anti-cyclonic and air subsidence anomalies centred on the north of NC, which reduces moisture convergence over the archipelago. The frequency and intensity of extreme precipitation events is also reduced by ~ 20% by 2080–2100. This drastic projected drying would have dramatic impacts on water resources and terrestrial ecosystems, pleading for carefully-planned adaptation policies for New Caledonia.
|
Auteur(s) |
Cyril Dutheil
1, 2
, Christophe E. Menkès
3
, Matthieu Lengaigne
4, 5
, Jérôme Vialard
4, 1
, Alexandre Peltier
6
, Margot Bador
7
, X. Petit
1
1
LOCEAN -
Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
( 541821 )
- case 100 - 4 place Jussieu - 75252 PARIS CEDEX 05 ; Institut de Recherche pour le Développement - Centre de recherche d'Ile-de-France - 32 avenue Henri Varagnat - 93143 Bondy Cedex
- France
2
ENTROPIE [Réunion] -
Ecologie marine tropicale dans les Océans Pacifique et Indien
( 418794 )
- UNIVERSITE DE LA REUNION
Faculté des Sciences et Technolo
15 Avenue René Casin
BP 92003
97744 ST DENIS CEDEX 9
- France
3
ENTROPIE [Nouvelle-Calédonie] -
Ecologie marine tropicale des océans Pacifique et Indien
( 456389 )
- Centre IRD Nouméa
101 av, Roger Laroque, Anse Vata
BP A5, 98848
Nouméa, Nouvelle-Calédonie
- Nouvelle-Calédonie
4
VARCLIM -
Océan et variabilité du climat
( 541822 )
- France
5
UMR MARBEC -
MARine Biodiversity Exploitation and Conservation
( 422717 )
- Centre de Sète UMR MARBEC SETE - Avenue Jean Monnet - CS30171
34203 SETE CEDEX
- France
6
DIRNC -
Météo-France Direction Interrégionale de la Nouvelle Calédonie
( 548065 )
- 5 rue Vincent Auriol
Faubourg Blanchot
98800 NOUMEA
- Nouvelle-Calédonie
7
UNSW -
University of New South Wales [Sydney]
( 74661 )
- High St
Kensington, Sydney, NSW 2052
- Australie
|
Langue du document |
Anglais
|
Vulgarisation |
Non
|
Comité de lecture |
Oui
|
Audience |
Internationale
|
Nom de la revue |
|
Volume |
56
|
Page/Identifiant |
87–108
|
Date de publication électronique |
2020-10-06
|
Date de publication |
2020-10
|
Domaine(s) |
|
Mots-clés |
en
Climate change, Downscaling, Regional climate models, Precipitation, New Caledonia
|
DOI | 10.1007/s00382-020-05467-0 |
Base Horizon | fdi:010079814 |
UT key WOS | 000575756900001 |
Origine :
Publication financée par une institution
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