Evaluation of the Paleoclimate Modelling Intercomparison Project Phase 4 (PMIP4) Models in Simulating the Contraction of Indo-Pacific Warm Pool Between the Mid-Holocene and Pre-Industrial
Fitri Wulan Darojati (a*), Yudha Setiawan Djamil (b), Rima Rachmayani (c), Marfasran Hendrizan (b), Sri Yudawati Cahyarini (b)

a) Study Program of Oceanography, Faculty of Earth Science and Technology, Bandung Institute of Technology, Jl. Ganesa 10 40132, Bandung, Indonesia

b) Research Center for Climate and Atmosphere (PRIMA), National Research and Innovation Agency (BRIN), Jl. Sangkuriang 1-9, Bandung, Indonesia

c) Research Group of Environmental and Applied Oceanography, Faculty of Earth Science and Technology, Bandung Institute of Technology, Jl. Ganesa 10 40132, Bandung, Indonesia

Abstract

Sea surface temperature (SST) proxy indicates a contraction of the Indo-Pacific Warm-Pool (IPWP) occurred during mid-Holocene as relative to the recent time. The contraction is in the form of cooling in the western and eastern parts of the IPWP and warming in the central region. The underline mechanisms of such contraction can only be revealed by well-performed climate models. Thus, our study verified sea surface temperature (SST) changes in the IPWP during the mid-Holocene relative to pre-industrial conditions simulated by models from Paleoclimate Modelling Intercomparison Project phase 4 (PMIP4) with SST proxy dataset by calculating their Weighted Cohen Kappa scores. Unlike SST proxy, annual-mean simulations from all models show cooling across the IPWP, likely due to greenhouse gas forcing. However, for the December-January-February (DJF) seasonal average, some models simulate warming in the central IPWP, while most models simulate cooling in the March-April-May (MAM) and June-July-August (JJA) seasons across the IPWP. During September-October-November (SON), most areas in IPWP show warming. Climate Earth System Model, version 2 (CESM2) in DJF showed the best simulation results of all models with Kappa=0,4088. Nevertheless, the low value of Cohen Kappa for the annual mean indicates that the PMIP4 models are unable to adequately capture the contraction of the IPWP between the two eras.

Keywords: IPWP, Mid-Holocene, proxy, PMIP4, Cohen Kappa

Topic: Ocean Sciences