Implications of CMIP3 model biases and uncertainties for climate projections in the western tropical Pacific

Abstract

Regional climate projections in the Pacific region are potentially sensitive to a range of existing model biases. This study examines the implications of coupled model biases on regional climate projections in the tropical western Pacific. Model biases appear in the simulation of the El Niño Southern Oscillation, the location and movement of the South Pacific Convergence Zone, rainfall patterns, and the mean state of the ocean-atmosphere system including the cold tongue bias and erroneous location of the edge of the Western Pacific warm pool. These biases are examined in the CMIP3 20th century climate models and used to provide some context to the uncertainty in interpretations of regional-scale climate projections for the 21st century. To demonstrate, we provide examples for two island nations that are located in different climate zones and so are affected by different biases: Nauru and Palau. We discuss some of the common approaches to analyze climate projections and whether they are effective in reducing the effect of model biases. These approaches include model selection, calculating multi model means, downscaling and bias correcting.

Will a Warmer World Mean a Wetter or Drier Australian Monsoon?

“…The Australian monsoon is very strongly modulated by Pacific sea surface temperature (SST) changes, and in particular El Niño-Southern Oscillation (ENSO) events (e.g., Drosdowsky 1996;Smith et al 2008;Zhang 2010), and projected changes in ENSO are uncertain (Collins et al 2010). Critically too, models are subject to significant and persistent biases in equatorial Pacific SSTs, which may have a large influence on their ability to simulate both current and future climates (e.g., Xie et al 2010;J. N. Brown et al 2013;Li and Xie 2014;Grose et al 2014a,b).…”

Climate change projection for the western tropical Pacific Ocean using a high-resolution ocean model: Implications for tuna fisheries

“…We shall compare the HOM and CSIRO35 simulations with each other and with recent analyses of global climate model projections (e.g. Brown et al, 2013a;Ganachaud et al, 2013) as well as observed multi-decadal trends in the region. We will also use the HOM simulation with windstress feedback to assess how interactions between the ocean and the atmosphere could modify future climate change projections.…”

“…Coupled global circulation models (CGCMs) have common spatial biases in the western tropical Pacific, such as a Warm Pool eastern edge that is too far west (Brown et al, 2013a), which can potentially affect their future climate projections for the tropical Pacific (Brown et al, 2013b). To investigate the impact of climate change on the western tropical Pacific, we use simulations from a high-resolution ocean model (HOM) that gives a good representation of the present-day western tropical Pacific ocean state to make a climate projection for the 2060s .…”

Optimising fisheries management in relation to tuna catches in the western central Pacific Ocean: A review of research priorities and opportunities

“…This limits investigation of changes to modes of variability such as ENSO (e.g. 183 Guilyardi et al 2012) and changes to the position of ocean provinces (Brown et al 2013) via the use 184 of climate models. 185…”