Title
Projection of upwelling-favorable winds in the Peruvian upwelling system under the RCP8.5 scenario using a high-resolution regional model
Date Issued
01 July 2021
Access level
open access
Resource Type
journal article
Publisher(s)
Springer Science and Business Media Deutschland GmbH
Abstract
The Peruvian upwelling system (PUS) is the most productive Eastern Boundary Upwelling System (EBUS) of the world ocean. Contrarily to higher latitude EBUSs, there is no consensus yet on the response of upwelling-favorable winds to regional climate change in this region. Global climate models are not able to reproduce the nearshore surface winds, and only a few downscaling studies have been performed by using relatively coarse-grid atmospheric models forced by idealized climate change scenarios. In the present study, the impact of climate change on the PUS upwelling-favorable winds was assessed using a high resolution regional atmospheric model to dynamically downscale the multi-model mean projection of an ensemble of 31 CMIP5 global models under the RCP8.5 worst-case climate scenario. We performed a 10-year retrospective simulation (1994–2003) forced by NCEP2 reanalysis data and a 10-year climate change simulation forced by a climate change forcing (i.e. differences between monthly-mean climatologies for 2080–2100 and 1989–2009) from CMIP5 ensemble added to NCEP2 data. We found that changes in the mean upwelling-favorable winds are weak (less than 0.2 m s−1). Seasonally, summer winds weakly decrease (by 0–5%) whereas winter winds weakly increase (by 0–10%), thus slightly reinforcing the seasonal cycle. A momentum balance shows that the wind changes are mainly driven by the alongshore pressure gradient, except in a local area north of the Paracas peninsula, downstream the main upwelling center, where wind increase in winter is driven by the shoreward advection of offshore momentum. Sensitivity experiments show that the north–south sea surface temperature gradient plays an important role in the wind response along the north and central coasts, superimposed onto the South Pacific Anticyclone large-scale forcing. A reduction (increase) of the gradient induces a wind weakening (strengthening) up to 15% (25%) off the northern coast during summer. This local mechanism is not well represented in global climate models projections, which underlines the strong need for dynamical downscaling of coastal wind in order to study the impact of climate change on the Peruvian upwelling ecosystem.
Volume
57
Issue
February 1
Language
English
OCDE Knowledge area
Ciencias del medio ambiente
Scopus EID
2-s2.0-85101273361
Source
Climate Dynamics
ISSN of the container
09307575
Sponsor(s)
This research is a product of the scientific cooperation between the Peruvian Marine Research Institute (IMARPE) and the Institut de Recherche pour le Developpement (IRD—France) in the framework of the IRD LMI DISCOH program. Numerical simulations were performed on TGCC Curie and Irene SKL High Performance Computers under projects A0050101140 and A0060101140. Nicolas Jourdain is acknowledged for processing the ensemble-mean lateral boundary conditions for the regional atmospheric model simulations. Francis Codron, Jose Rutllant, Pierrick Penven, Claude Estournel and Sebastien Masson are acknowledged for fruitful discussions. J. Tam, D. Gutierrez and A. Chamorro acknowledge finantial support from the Adaptation Fund project “Adaptation to the Impacts of Climate Change on Peru’s Coastal Marine Ecosystem and Fisheries”. J. Tam, F. Colas and A. Chamorro acknowledge financial support from the project Concytec—World Bank, through Fund for Scientific, Technological, and Technological Innovation Development (Fondecyt), for the project “Characterization and forecast of extreme events in the Peruvian ocean using an operational system of oceanic information”. Concytec—World Bank Institut de Recherche pour le Développement - IRD
Sources of information: Directorio de Producción Científica Scopus