Meeting Documents

Diagnosing the Internal Variability of Arctic Sea Surface Temperature, Salinity, Stratification, and Transports in Historical CMIP6

Abstract

The Arctic Ocean has changed drastically over the last several decades, with decadal warming and freshening of the sea surface being clear proxies for anthropogenic forcing. The competing influences of Pacification in the Eurasian Basin and Atlantification in the Amerasian Basin further contribute to this change by modulating water column stratification, thus altering the vertical distribution and transport of heat and freshwater. While the role of anthropogenic forcing in these trends have been made evident by previous studies, it remains unclear to what extent they can be attributed explicitly to forcing versus internal variability. Techniques in model intercomparison and large ensemble analyses have been demonstrated as powerful tools for parsing one from the other. However, to date, none such assessments of internal variability have been performed over the full suite of state-of-the-art climate models and large ensembles in the Coupled-Model Intercomparison Project’s sixth phase. Here, we diagnose the historical (1850-2015) internal variability of regional and pan-Arctic sea surface temperature (SST), salinity (SSS), upper-ocean stratification, and volume transports across CMIP6 models with at least ten ensemble members. Each model’s representation of internal variability is compared with that of ‘observational’ data products (e.g., ECCOV4r4 and GLORYS12V1), via synthetic ensembles generated from the individual datasets.View Document (OSM26) »