Evaluating Southern Ocean cloud biases in ACCESS1.3 using hybrid cloud regimes

Introduction

  • Cloud biases in representing current climate, and effects for predicting cloud feedback in warming climate.

  • Use of cloud regimes to aid model evaluation (identifying compensating biases)

  • Use of ISCCP-style cloud regimes to for observational studies and model evaluation.

  • Issues relating to identifying ISCCP-style cloud regimes from models:

    • Identifying inconsistent cloud regimes in each model.

    • Applying modelled clouds to observed cloud regimes.

  • In this study we present a hybrid approach, using both observed and modelled cloud to identify cloud regimes that are common to the model and observations, as well as cloud regimes found only in the models.

  • We evaluate the ACCESS1.3 GCM; a basic comparison of this model against observations using the ISCCP-simulator is given in Figure \ref{fig:hist_sim-obs}: we note that optically thick low and mid-topped cloud are strongly under-represented, while optically thin cloud is over-represented.

  • NOTE: significant under-estimate in cloud about! May be the same problem noticed by John Haynes. Shit.