The climatology and interannual variability of the South Asia high and its relationship with ENSO in CMIP5 models

摘要

The present study examines climatology and interannual variability of South Asian high (SAH) and its connection with the ENSO based on 38 coupled models from the Coupled Model Intercomparison Project phase 5 (CMIP5). Results show that multi-model ensemble (MME) can reasonably capture the climatological spatial pattern of the SAH, although its intensity is slightly underestimated. The CCSM4, CESM1-BGC and CESM1-FASTCHEM can well simulate the climatological location and intensity of the SAH. The interannual variability of the SAH is investigated by calculating ratio of the standard deviation of the ten parameters in models with those in observations. The results indicate that the MME can reasonably capture magnitudes of the interannual variability of the area index, intensity index, and longitude of the SAH center. Quasi-4-year period of the SAH intensity index can be well simulated by CMCC-CESM, CMCC-CMS and GFDL-ESM2G, and quasi-5-year period of north-south movement index can be captured by CanCM4, CESM1-CAM5, CESM1-FASTCHEM, CNRM-CM5-2, GFDL-ESM2G and HadCM3. Furthermore, MME can reasonably reproduce seasonal evolution of intensity and location of the SAH except for its east-west movement. The ENSO-SAH relationship is further evaluated. It is found that about two-thirds of the CMIP5 models can capture the observed ENSO-SAH relationship, although the relationship is distinctly exaggerated by several models. The success of these models is attributed to the reasonable simulation of both the "charge" process over the tropical Indian Ocean induced by the ENSO-related anomalous sea surface temperature (SST) over the tropical eastern Pacific (TEP) and longitude extension of the western boundary of the ENSO-related anomalous SST over the TEP.