This study mainly introduces the development of the Flexible Global Ocean-Atmosphere-Land System Model: Grid-point Version 2 (FGOALS-g2) and the preliminary evaluations of its performances based on results from the pre-industrial control run and four members of historical runs according to the fifth phase of the Coupled Model Intercomparison Project (CMIP5) experiment design. The results suggest that many obvious improvements have been achieved by the FGOALS-g2 compared with the previous version,FGOALS-g1, including its climatological mean states, climate variability, and 20th century surface temperature evolution. For example,FGOALS-g2 better simulates the frequency of tropical land precipitation, East Asian Monsoon precipitation and its seasonal cycle, MJO and ENSO, which are closely related to the updated cumulus parameterization scheme, as well as the alleviation of uncertainties in some key parameters in shallow and deep convection schemes, cloud fraction, cloud macro/microphysical processes and the boundary layer scheme in its atmospheric model. The annual cycle of sea surface temperature along the equator in the Pacific is significantly improved in the new version. The sea ice salinity simulation is one of the unique characteristics of FGOALS-g2, although it is somehow inconsistent with empirical observations in the Antarctic.

The Flexible Global Ocean-Atmosphere-Land System Model, Grid-point Version 2: FGOALS-g2

This paper introduces the Flexible Global Ocean–Atmosphere–Land System Model: Grid-Point Version 3 (FGOALS-g3) and evaluates its basic performance based on some of its participation in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) experiments. Our results show that many significant improvements have been achieved by FGOALS-g3 in terms of climatological mean states, variabilities, and long-term trends. For example, FGOALS-g3 has a small (–0.015°C/100 yr) climate drift in 700-yr pre-industrial control (piControl) runs, and smaller biases in climatological mean variables, such as the land/sea surface temperatures (SST), seasonal soil moisture cycle , compared with its previous version FGOALS-g2 during the historical period. The characteristics of climate variabilities, e.g., MJO eastward/westward propagation ratios, spatial patterns of interannual variability of tropical SST anomalies, and relationship between the East Asian Summer Monsoon and El Niño-Southern Oscillation (ENSO), are well captured by FGOALS-g3. In particular, the cooling trend of globally averaged surface temperature during 1940–1970, which is a challenge for most CMIP3 and CMIP5 models, is well reproduced by FGOALS-g3 in historical runs. In addition to the external forcing factors recommended by CMIP6, anthropogenic groundwater forcing from 1965 to 2014 was incorporated into the FGOALS-g3 historical runs. Plain Language Summary The sixth phase of the Coupled Model Intercomparison Project (CMIP6) is a crucial support for the sixth Assessment Report of Intergovermental Panel on Climate Change (IPCC AR6), and will also provide important foundation for research in climate change in the next few years. This paper gives the description of FGOALS-g3 model, its experiment configures and the experiments conducted according to the experimental design of CMIP6, and evaluates the preliminary performance of model simulation. This work offers references to CMIP6 data users and provides enormous output datasets for assessing and understanding climate change.

The Flexible Global Ocean-Atmosphere-Land System Model Grid-Point Version 3 (FGOALS-g3): Description and Evaluation

[1] We estimate the contributions of natural and anthropogenic forcings to the observed summer cooling over the Eastern China through a set of controlled experiments of an atmospheric general circulation model. The control run is forced by historical natural and anthropogenic agents, as well as by the Hadley Center global sea surface temperature. The model suggests a weak influence by the solar radiation change on this cooling, but a significant contribution by the sulfate aerosol to this cooling, through both dynamic and thermal processes. The inclusion of the sulfate aerosol induces a positive gradient of air temperature in the middle-upper troposphere, which results in a northward shift in the 200 hPa East Asian westerly jet stream and an increase of the East Asian summer monsoon, leading to more cloud cover and precipitation in the Eastern China therefore surface cooling over the region.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2007GL030541

Contributions of natural and anthropogenic forcings to the summer cooling over eastern China: An AGCM study

The radioactive species radon ( 222 Rn) has long been used as a test tracer for the numerical simulation of large scale transport processes. In this study, radon trans- port experiments are carried out using an atmospheric GCM with a finite-difference dynamical core, the van Leer type FFSL advection algorithm, and two state-of-the-art cumulus convection parameterization schemes. Measurements of sur- face concentration and vertical distribution of radon collected from the literature are used as references in model evaluation. The simulated radon concentrations using both convection schemes turn out to be consistent with earlier studies with many other models. Comparison with measurements indi- cates that at the locations where significant seasonal varia- tions are observed in reality, the model can reproduce both the monthly mean surface radon concentration and the annual cycle quite well. At those sites where the seasonal variation is not large, the model is able to give a correct magnitude of the annual mean. In East Asia, where radon simulations are rarely reported in the literature, detailed analysis shows that our results compare reasonably well with the observations. The most evident changes caused by the use of a differ- ent convection scheme are found in the vertical distribution of the tracer. The scheme associated with weaker upward transport gives higher radon concentration up to about 6 km above the surface, and lower values in higher altitudes. In the lower part of the atmosphere results from this scheme does not agree as well with the measurements as the other scheme. Differences from 6 km to the model top are even larger, al- though we are not yet able to tell which simulation is better due to the lack of observations at such high altitudes.

/pdf/evaluation-of-the-atmospheric-transport-in-a-gcm-using-radon-17dzmjq45b.pdf

Evaluation of the atmospheric transport in a GCM using radon measurements: sensitivity to cumulus convection parameterization

A new coupled climate system model (CSM) has been developed at the Chinese Academy of Meteorological Sciences (CAMS) by employing several state-of-the-art component models. The coupled CAMS-CSM consists of the modified atmospheric model [ECmwf-HAMburg (ECHAM5)], ocean model [Modular Ocean Model (MOM4)], sea ice model [Sea Ice Simulator (SIS)], and land surface model [Common Land Model (CoLM)]. A detailed model description is presented and both the pre-industrial and “historical” simulations are preliminarily evaluated in this study. The model can reproduce the climatological mean states and seasonal cycles of the major climate system quantities, including the sea surface temperature, precipitation, sea ice extent, and the equatorial thermocline. The major climate variability modes are also reasonably captured by the CAMS-CSM, such as the Madden–Julian Oscillation (MJO), El Nino–Southern Oscillation (ENSO), East Asian Summer Monsoon (EASM), and Pacific Decadal Oscillation (PDO). The model shows a promising ability to simulate the EASM variability and the ENSO–EASM relationship. Some biases still exist, such as the false double-intertropical convergence zone (ITCZ) in the annual mean precipitation field, the overestimated ENSO amplitude, and the weakened Bjerknes feedback associated with ENSO; and thus the CAMS-CSM needs further improvements.

The CAMS Climate System Model and a Basic Evaluation of Its Climatology and Climate Variability Simulation

This paper proposes a new two-step non-oscillatory shape-preserving positive definite finite difference advection transport scheme, which merges the advantages of small dispersion error in the simple first-order upstream scheme and small dissipation error in the simple second-order Lax-Wendroff scheme and is completely different from most of present positive definite advection schemes which are based on revising the upstream scheme results. The proposed scheme is much less time consuming than present shape-preserving or non-oscillatory advection transport schemes and produces results which are comparable to the results obtained from the present more complicated schemes. Elementary tests are also presented to examine the behavior of the scheme.

宇如聪

Papers

A Two-Step Shape-Preserving Advection Scheme