Perturbing the Surface Energy Balance to Emulate the Historical Pattern of Tropical Pacific Sea Surface Temperature Trends

Details

• Journal Title:
  Journal of Climate
• Personal Author:
  Merlis, Timothy M.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CIMES (Cooperative Institute for Modeling the Earth System)
• Description:
  The strengthening of the zonal sea surface temperature (SST) gradient observed in the tropical Pacific in recent decades is a regional climate change signal that may be outside the range of historical simulations with comprehensive climate models. Given the important role that this change has on other aspects of climate, a series of idealized surface energy balance calculations with imposed parameters are performed to build a baseline understanding of the sensitivities that govern these changes. I quantify the requisite magnitudes of five perturbations that reach a new equilibrium with a mean SST warming of about 0.5 K and about 0.4 K more west Pacific warming than east Pacific warming, based approximately on the observed trends. A characteristic magnitude of zonal asymmetry in a surface energy tendency that can bring changes in line with observed trends is ≈3 W m−2. Strengthened zonal SST gradients can arise from a more zonally asymmetric ocean heat flux that increases by ≈20% K−1 using that implied by ERA5’s surface fluxes, a spatially varying radiative forcing with a west–east contrast of ≈3.3 W m−2, a more amplifying surface radiative feedback in the west than in the east with a contrast of ≈4 W m−2 K−1, a surface-air relative humidity (RH) contrast that increases RH in the west and decreases it in the east by ≈0.5% K−1, or a more zonally asymmetric wind speed that increases by ≈16% K−1. The “storylines” of forced surface energy budget change identified here are valuable in determining the plausibility of mechanisms that may be absent or underestimated in coupled climate model simulations.
• Keywords:
  Climatic Changes Ocean Temperature Climatic Changes Ocean Temperature Atmosphere-ocean Interaction Climate Change Climate Sensitivity Sea Surface Temperature (SST)
• Source:
  J. Climate, 38, 6193–6206
• DOI:
  https://doi.org/10.1175/JCLI-D-24-0496.1
• Format:
  PDF
• Document Type:
  Journal Article
• Funding:
  Grant no. NA18OAR4320123 ; Grant no. NA23OAR4320198
• Place as Subject:
  Pacific Ocean
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:5b02c1112bb054ab19a2334c7b7b5376ef3fced4964fcf01b8a8e4784a4b8101b410d09bb8ca853fa3c108ca48909a1ac574447498b950793f7a9521ba52f6c7
• File Type: