Taiwan Earth System Model Version 1: description and evaluation of mean state

Lee, Wei‐Liang; Wang, Yi‐Chi; Shiu, Chengshi; Tsai, I‐Chun; Tu, Chih Yen; Lan, Yung-Yao; Chen, Jen‐Ping; Pan, Hua-Lu; Hsu, Huang‐Hsiung

doi:10.5194/gmd-13-3887-2020

Cited by 96 publications

(19 citation statements)

References 57 publications

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“…Improving model CPS is beyond the scope of this paper. However, many CMIP6 models have put significant efforts in CPS developments and reported improvements with respect to diurnal cycles (e.g., Lee et al 2020;Lin et al 2019;Park et al 2019). Our results confirm their hard work of model developers has paid off in this new generation of climate models.…”

Section: Discussionsupporting

confidence: 74%

Evaluating Diurnal Rainfall Signal Performance from CMIP5 to CMIP6

Lee

Wang

2021

Journal of Climate

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This study provides a comprehensive overview of diurnal rainfall signal performance within the current collection of models in Phase 6 of the Coupled Model Inter-comparison Project (CMIP6). The results serve as a reference for understanding model physics performance to represent precipitating processes and atmosphere–land–ocean interactions in response to the diurnal solar radiation cycle. Performance metrics are based on the phase, amplitude, and two empirical orthogonal function (EOF) modes of the climatological diurnal rainfall cycle derived from a Tropical Rainfall Measurement Mission observational dataset. We found that the ensemble model biases of diurnal phase and amplitude over lands improved from CMIP5 to CMIP6; however, those over oceans are still highly uncertain among CMIP6 models. Evaluation with observed EOF modes shows that the CMIP6 models are bifurcated based on the second EOF (EOF2), which represents diurnal rainfall contrast of coastal regimes where large biases of phase and amplitude reside. While the model ensemble suggests models are benefited from higher resolution in simulating phase and amplitude biases, the most distinct difference between the bifurcations is that one group successfully captures prevailing nighttime rainfall over tropical islands and coasts, especially over the Maritime Continent. Convective rainfall diagnosed by cumulus parameterization is found to be responsible for such biases. Our results suggest that CMIP6 models have generally been improved in their representation of diurnal rainfall cycles; however, for coastal diurnal regimes, more study is needed to improve the model parameterization of precipitation processes interacting with islands and coastal regions as current model resolution is still too coarse to resolve them.

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Section: Discussionsupporting

confidence: 74%

Evaluating Diurnal Rainfall Signal Performance from CMIP5 to CMIP6

Lee

Wang

2021

Journal of Climate

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“…The parameterization scheme developed by Lee et al (2011) is computationally efficient because the domain-averaged topographic factors can be calculated a priori based on high-resolution DEM. This parameterization has been successfully applied in the Weather Research and Forecasting (WRF) model (Gu et al, 2012;Liou et al, 2013), CLM4.0 (Lee et al, 2015(Lee et al, , 2019, and Taiwan Earth System Model Version 1 (TaiESM) (Lee et al, 2020) and is promising for incorporation in ELM.…”

Section: Introductionmentioning

confidence: 99%

A parameterization of sub-grid topographical effects on solar radiation in the E3SM Land Model (version 1.0): implementation and evaluation over the Tibetan Plateau

Hao

Bisht

Gu³

et al. 2021

Geosci. Model Dev.

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Abstract. Topography exerts significant influences on the incoming solar radiation at the land surface. A few stand-alone regional and global atmospheric models have included parameterizations for sub-grid topographic effects on solar radiation. However, nearly all Earth system models (ESMs) that participated in the Coupled Model Intercomparison Project (CMIP6) use a plane-parallel (PP) radiative transfer scheme that assumes that the terrain is flat. In this study, we incorporated a well-validated sub-grid topographic (TOP) parameterization in the Energy Exascale Earth System Model (E3SM) Land Model (ELM) version 1.0 to quantify the effects of sub-grid topography on solar radiation flux, including the shadow effects and multi-scattering between adjacent terrain. We studied the role of sub-grid topography by performing ELM simulations with the PP and TOP schemes over the Tibetan Plateau (TP). Additional ELM simulations were performed at multiple spatial resolutions to investigate the role of spatial scale on sub-grid topographic effects on solar radiation. The Moderate Resolution Imaging Spectroradiometer (MODIS) data was used to compare with the ELM simulations. The results show that topography has non-negligible effects on surface energy budget, snow cover, snow depth, and surface temperature over the TP. The absolute differences in surface energy fluxes for net solar radiation, latent heat flux, and sensible heat flux between TOP and PP exceed 20, 10, and 5 W m−2, respectively. The differences in land surface albedo, snow cover fraction, snow depth, and surface temperature between TOP and PP exceed 0.1, 0.1, 10 cm, and 1 K, respectively. The magnitude of the sub-grid topographic effects is dependent on seasons and elevations and is also sensitive to the spatial scales. Although the sub-grid topographic effects on solar radiation are larger with more spatial details at finer spatial scales, they cannot be simply neglected at coarse spatial scales. When compared to MODIS data, incorporating the sub-grid topographic effects overall reduces the biases of ELM in simulating surface energy balance, snow cover, and surface temperature, especially in the high-elevation and snow-covered regions over the TP. The inclusion of sub-grid topographic effects on solar radiation parameterization in ELM will contribute to advancing our understanding of the role of the surface topography on terrestrial processes over complex terrain.

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“…Our past experiences in tuning GCMs also show that implementing strong tuning sometimes will indeed offset the improvements resulted from physical parameterizations with less tuning. In fact, to avoid the situation, we used the T_pdf of GTS scheme (with tuning as discussed below) as the stratiform cloud macrophysics scheme of the TaiESM model participating in the CMIP6 project (Lee et al, 2020a).…”

Section: Tuning Parameters Of the Gts Schemementioning

confidence: 99%

“…This modified macrophysics scheme is named the GFS-TaiESM-Sundqvist (GTS) scheme version 1.0 (GTS v1.0). It was first developed for the Global Forecast System (GFS) model at the National Centers for Environmental Prediction (NCEP) and has been further improved for the Taiwan Earth System Model (TaiESM; Lee et al, 2020a) at the Research Center for Environmental Changes (RCEC), Academia Sinica. Park et al (2014) discussed a similar approach wherein a triangular PDF was used to diagnose cloud liquid water as well as the liquid cloud fraction, and suggested that the PDF width could be computed internally rather than specified, to consistently diagnose both CF and cloud liquid water as in macrophysics.…”

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confidence: 99%

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GTS v1.0: a macrophysics scheme for climate models based on a probability density function

et al. 2021

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Abstract. Cloud macrophysics schemes are unique parameterizations for general circulation models. We propose an approach based on a probability density function (PDF) that utilizes cloud condensates and saturation ratios to replace the assumption of critical relative humidity (RH). We test this approach, called the Global Forecast System (GFS) – Taiwan Earth System Model (TaiESM) – Sundqvist (GTS) scheme, using the macrophysics scheme within the Community Atmosphere Model version 5.3 (CAM5.3) framework. Via single-column model results, the new approach simulates the cloud fraction (CF)–RH distributions closer to those of the observations when compared to those of the default CAM5.3 scheme. We also validate the impact of the GTS scheme on global climate simulations with satellite observations. The simulated CF is comparable to CloudSat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Comparisons of the vertical distributions of CF and cloud water content (CWC), as functions of large-scale dynamic and thermodynamic parameters, with the CloudSat/CALIPSO data suggest that the GTS scheme can closely simulate observations. This is particularly noticeable for thermodynamic parameters, such as RH, upper-tropospheric temperature, and total precipitable water, implying that our scheme can simulate variation in CF associated with RH more reliably than the default scheme. Changes in CF and CWC would affect climatic fields and large-scale circulation via cloud–radiation interaction. Both climatological means and annual cycles of many of the GTS-simulated variables are improved compared with the default scheme, particularly with respect to water vapor and RH fields. Different PDF shapes in the GTS scheme also significantly affect global simulations.

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Taiwan Earth System Model Version 1: description and evaluation of mean state

Cited by 96 publications

References 57 publications

Evaluating Diurnal Rainfall Signal Performance from CMIP5 to CMIP6

Evaluating Diurnal Rainfall Signal Performance from CMIP5 to CMIP6

A parameterization of sub-grid topographical effects on solar radiation in the E3SM Land Model (version 1.0): implementation and evaluation over the Tibetan Plateau

GTS v1.0: a macrophysics scheme for climate models based on a probability density function

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