Object-Based Evaluation of Tropical Precipitation Systems in DYAMOND Simulations over the Maritime Continent

Abstract

The present study uses an object-based evaluation metric to examine the precipitation bias over the MaritimContinent in the global cloud-resolving models. We specifically focus on the difference between the models thdirectly resolve convection and those using convection parameterization. The 40-day hindcast experiments of thDYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domain (DYAMOND) intercom-parison project are evaluated against the high-resolution satellite rainfall products. The hindcast of the CentrWeather Bureau Global Forecast System (CWBGFS) under the DYAMOND protocol is also included. The resulindicate that most models simulate insufficient numbers of large precipitation system [object-based precipitatiosystem (OPS), > 370 km in scale], indicating weaker convection organization. The observation indicates ththe maximum precipitation within the OPS intensifies with increasing object size. All of the models capture thpositive relationship, but most of them overestimate the sensitivity. Most of the models overestimate both thfrequency and intensity of small OPS (< 160 km), except for the models with convection parameterization [i.eCWBGFS, European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (IFS)-9 kmAlthough most of the models can reproduce the observed peak time of diurnal precipitation over the land area ithe Maritime Continent, the simulated fractional contribution of different sizes of OPS to the total precipitatiovaries from model to model, and their peak times do not follow the observed ones with delayed peak times athe size of OPS increases from small, mid-size, to large categories. Most of the models reasonably capture thmean diurnal cycle peak time, but only the models with convection parameterization and Model for PredictioAcross Scales (MPAS) can represent the diurnal evolution of fractional contribution from different OPSs. The implications of the current results to the upscale processes of the tropical convection systems in the global modeare also discussed.