Biases of the wintertime Arctic Oscillation in CMIP5 models

Abstract

Distinct biases are found in the pattern and teleconnections of the Arctic Oscillation (AO) in 32 climate models that participate the Coupled Model Intercomparison Project Phase 5 (CMIP5). Compared with observations, the Pacific (Atlantic) center of AO is excessively strong (weak) in most of the 32 CMIP5 models, and the AO-related surface air temperature anomalies are generally weak over the Eurasian continent and North America. These biases are closely tied to the excessively strong linkage, which is marginal in observations, between AO and the North Pacific mode (NPM)-the leading variability of the North Pacific sea level pressure. It implies that the AO in CMIP5 models may be compounded with some regional mode over the North Pacific. Accordingly, a bias-correction method was proposed via correcting the AO index (AOI) to improve the diagnostic estimates of the AO teleconnections. The results suggest that the biases in the pattern and teleconnections of AO can be significantly reduced when the NPM variability is linearly removed from the AOI.

Attribution of the East Asian Winter Temperature Trends During 1979–2018: Role of External Forcing and Internal Variability

“…Thus, a reasonable projection of the multidecadal changes of AO should be helpful to predict a more realistic SAT change in the NEA on the time scale of 30-50 years. Previous studies show that the circulation and SAT variations in the SEA are less affected by AO (e.g., Gong et al, 2017;Gong, Wang, Chen, & Nath, 2018;Gong, Wang, Zhou, et al, 2018;He et al, 2017), and thus, the reasons for decreasing SLP trend and corresponding increasing SAT in the SEA including the TP need to be further investigated in future studies. It is noted that the time period analyzed in this study is 40 years, and thus, to what extent internal variability contributes to the SAT trend in East Asia in a longer or shorter time scale should be further investigated in the future.…”

Impacts of 1.5 and 2.0 °C Warming on Pan‐Arctic River Discharge Into the Hudson Bay Complex Through 2070

“…Interannual and interdecadal variability in discharge into the HBC is largely explained by the Arctic Oscillation (AO; Déry & Wood, 2004), which brings relatively cool and dry air during its positive phase and relatively warm and moist air during its negative phase. The CMIP5 GCMs have demonstrated mixed skill in simulating the AO (Gong et al, 2017;Zuo et al, 2013). Therefore, simulations of discharge trends into the HBC may be improved with better representations of the AO in GCMs, particularly in light of projected Arctic amplification by 2100 (Barnes & Polvani, 2015).…”

Modulation of the southern Indian Ocean dipole on the impact of El Niño–Southern Oscillation on Australian summer rainfall

“…This result further suggests that the SST over the SIO may explain the different responses of ASR to similar ENSO events and may also contribute to the formation of the dominant patterns of ASR variation. To further reveal other possible climate factors determining the dominant variability of ASR, the ENSO‐independent PC1 (PC1 EX_NINO3.4 ) and PC2 (PC2 EX_NINO3.4 ) are obtained through linear regression to exclude ENSO variability (Cai and Rensch, ; Gong et al ., ; Liu et al ., ). The wind anomalies associated with PC1 EX_NINO3.4 and PC2 EX_NINO3.4 are quite similar to those related to the original PC1 and PC2 over the SIO and Australia, although ENSO variability has been linearly removed.…”