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1.
The Grid-point Atmospheric Model of IAP LASG version 2 (GAMIL2) has
been developed through upgrading the deep convection parameterization, cumulus
cloud fraction and two-moment cloud microphysical scheme, as well as changing
some of the large uncertain parameters. In this paper, its performance is
evaluated, and the results suggest that there are some significant improvements
in GAMIL2 compared to the previous version GAMIL1, for example, the components
of the energy budget at the top of atmosphere (TOA) and surface; the geographic
distribution of shortwave cloud radiative forcing (SWCF); the ratio of
stratiform versus total rainfall; the response of atmospheric circulation to
the tropical ocean; and the eastward propagation and spatiotemporal structures
of the Madden Julian Oscillation (MJO). Furthermore, the indirect aerosols
effect (IAE) is -0.94 W m-2, within the range of 0 to -2 W m-2
given by the IPCC 4th Assessment Report (2007). The influence of uncertain
parameters on the MJO and radiation fluxes is also discussed. 相似文献
2.
GAMIL2.0 is the newly released version of the Grid-point Atmospheric Model of IAP LASG(GAMIL),in which the major modifications from GAMIL1.0 include an updated deep convection scheme and the incorporation of a two-moment bulk stratiform cloud microphysics scheme.This study evaluates the performances of both versions on Madden Julian Oscillation(MJO) simulations.The results show that GAMIL2.0 obtains an enhanced MJO eastward and northward propagation,which is weak in GAMIL1.0,and it reproduces a more reasonable MJO major structure coupling upper level wind,lower level wind,and outgoing long wave radiation.The contributions of each scheme and factor to the improvement of GAMIL2.0 simulations need further study. 相似文献
3.
CAPT(Climate Change Prediction Program and Atmospheric Radiation Measurement Program(CCPP-ARM) Parameterization Testbed) has been a valuable tool to assess climate models in recent years,and the Tropical Warm Pool-International Cloud Experiment(TWP-ICE) has collected comprehensive measurements to verify its physical parameterizations.The present study evaluates the performances of the two GAMIL(grid-point atmospheric model of IAP LASG) versions during TWP-ICE using CAPT.The results indicate that GAMIL2.0 reproduced better shifts of clouds and rainfall during three distinct monsoon phases than GAMIL1.0,although both of them simulated the large-scale dynamical states well,which are mainly attributable to the different convective parameterizations. 相似文献
4.
Prediction of the Asian-Australian Monsoon Interannual Variations with the Grid-Point Atmospheric Model of IAP LASG （GAMIL） 总被引：8，自引：2，他引：6
Seasonal prediction of Asian-Australian monsoon （A-AM） precipitation is one of the most important and challenging tasks in climate prediction. In this paper, we evaluate the performance of Grid Atmospheric Model of IAP LASG （GAMIL） on retrospective prediction of the A-AM interannual variation （IAV）, and determine to what extent GAMIL can capture the two major observed modes of A-AM rainfall IAV for the period 1979-2003. The first mode is associated with the turnabout of warming （cooling） in the Nifio 3.4 region, whereas the second mode leads the warming/cooling by about one year, signaling precursory conditions for ENSO.
We show that the GAMIL one-month lead prediction of the seasonal precipitation anomalies is primarily able to capture major features of the two observed leading modes of the IAV, with the first mode better predicted than the second. It also depicts the relationship between the first mode and ENSO rather well. On the other hand, the GAMIL has deficiencies in capturing the relationship between the second mode and ENSO. We conclude： （1） successful reproduction of the E1 Nifio-excited monsoon-ocean interaction and E1 Nifio forcing may be critical for the seasonal prediction of the A-AM rainfall IAV with the GAMIL; （2） more efforts are needed to improve the simulation not only in the Nifio 3.4 region but also in the joining area of Asia and the Indian-Pacific Ocean; （3） the selection of a one-tier system may improve the ultimate prediction of the A-AM rainfall IAV. These results offer some references for improvement of the GAMIL and associated seasonal prediction skill. 相似文献
We show that the GAMIL one-month lead prediction of the seasonal precipitation anomalies is primarily able to capture major features of the two observed leading modes of the IAV, with the first mode better predicted than the second. It also depicts the relationship between the first mode and ENSO rather well. On the other hand, the GAMIL has deficiencies in capturing the relationship between the second mode and ENSO. We conclude： （1） successful reproduction of the E1 Nifio-excited monsoon-ocean interaction and E1 Nifio forcing may be critical for the seasonal prediction of the A-AM rainfall IAV with the GAMIL; （2） more efforts are needed to improve the simulation not only in the Nifio 3.4 region but also in the joining area of Asia and the Indian-Pacific Ocean; （3） the selection of a one-tier system may improve the ultimate prediction of the A-AM rainfall IAV. These results offer some references for improvement of the GAMIL and associated seasonal prediction skill. 相似文献
5.
Performances of two LASG/IAP(State Key Laboratory of Numerical Modeling for Atmospheric Sci- ences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics)Atmospheric General Circulation Models(AGCMs),namely GAMIL and SAMIL,in simulating the major characteristics of the East Asian subtropical westerly jet(EASWJ)in the upper troposphere are examined in this paper.The mean vertical and horizontal structures and the correspondence of the EASWJ location to the meridional temperature gradient in the upper troposphere are well simulated by two models.However,both models underestimate the EASWJ intensity in winter and summer,and are unable to simulate the bimodal distribution of the ma- jor EASWJ centers in mid-summer,relative to the observation,especially for the SAMIL model.The biases in the simulated EASWJ intensity are found to be associated with the biases of the meridional temperature gradients in the troposphere,and furthermore with the surface sensible heat flux and condensation latent heating.The models capture the major characteristics of the seasonal evolution of the diabatic heating rate averaged between 30°-45°N,and its association with the westerly jet.However,the simulated maximum diabatic heating rate in summer is located westward in comparison with the observed position,with a rela- tively strong diabatic heating intensity,especially in GAMIL.The biases in simulating the diabatic heating fields lead to the biases in simulating the temperature distribution in the upper troposphere,which may further affect the EASWJ simulations.Therefore,it is necessary to improve the simulation of the meridional temperature gradient as well as the diabatic heating field in the troposphere for the improvement of the EASWJ simulation by GAMIL and SAMIL models. 相似文献
6.
Recently, a new atmospheric general circulation model （GAMIL： Grid-point Atmospheric Model of IAP LASG） has been developed at the Institute of Atmospheric Physics （IAP）, Chinese Academy of Sciences （CAS）, which is based on the Community Atmospheric Model Version 2 （CAM2） of the National Center for Atmospheric Research （NCAR）. Since the two models have the same physical processes but different dynamical cores, the interannual variability simulation performances of the two models are compared. The ensemble approach is used to reduce model internal variability. In general, the simulation performances of the two models are similar. Both models have good per- formance in simulating total space-time variability and the Southern Oscillation Index. GAMIL performs better in the Eastern Asian winter circulation simulation than CAM2, and the model internal variability of GAMIL has a better response to external forcing than that of CAM2. These indicate that the improvement of the dynamic core is very important. It is also verified that there is less predictability in the middle and high latitudes than in the low latitudes. 相似文献
7.
Analysis on the 10-yr Simulation of the Meiyu Precipitation and Its Associated Circulation with the GAMIL Model 
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下载免费PDF全文 ZHUO Dongqi ZHANG Yaocun WANG Bin LI Lijuan HUANG Ying 《Acta Meteorologica Sinica》2010,24(3):328-339
The major features of Meiyu precipitation and associated circulation systems simulated by the grid-point atmospheric model of IAP LASG (GAMIL) with Zhang-McFarlane and Tiedtke cumulus parameterization schemes are examined in this paper. The results show that the model with both schemes can reproduce the heavy precipitation center over the Yangtze-Huai River Basin (YHRB) during the Meiyu period. The horizontal and vertical structures of the circulation systems during the Meiyu period are also well simulated,such as the intensive meridional gradients of moisture and μse (pseudo-equivalent temperature), the strong low-level southwesterly flow in the lower troposphere over East China, the location of the westerly jet stream in the upper troposphere, the strong ascending motion in heavy precipitation zone, and compensation downward motion on the northern and southern sides of the heavy precipitation belt. However, obvious discrepancies occur in the simulated temperature field in the mid-lower troposphere,especially with the Zhang-McFarlane scheme. In addition, the simulated Meiyu period (onset and duration) is found to be associated with the temperature difference in the lower atmosphere over the land and ocean, and with the cumulus parameterization schemes. The land-sea thermal contrast (LSTC) simulated by the Zhang-McFarlane scheme increases faster than that in the reanalysis from April to July, and changes from negative to positive at the end of May. Consequently, the simulated Meiyu onset begins in May, one month earlier than the observation. On the other hand, since the LSTC simulated by the Tiedtke scheme is in agreement with the reanalysis during June and July, the simulated Meiyu period is similar to the observation. The different LSTCs simulated by the GAMIL model with the two cumulus parameterization schemes may affect the Meiyu period simulations. Therefore, it is necessary to refine the cumulus parameterization scheme in order to improve the Meiyu precipitation simulation by the GAMIL model. 相似文献
8.
The Cloud Feedback Model Intercomparisons Project (CFMIP) Observation Simulator Package (COSP) is adopted in the Grid-point Atmospheric Model of IAP LASG (GAMIL2) during CFMIP at Phase II to evaluate the model cloud fractions in a consistent way with satellite observations. The cloud simulation results embedded in the Atmospheric Model Intercomparison Project (AMIP) control experiment are presented using three satellite simulators: International Satellite Cloud Climatology Project (ISCCP), Moderate Resolution Imaging Spectroradiometer (MODIS), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar onboard the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Overall, GAMIL2 can produce horizontal distributions of the low cloud fraction that are similar to the satellite observations, and its similarities to the observations on different levels are shown in Taylor diagrams. The discrepancies among satellite observations are also shown, which should be considered during evaluation. 相似文献
9.
An Assessment of MJO and Tropical Waves Simulated by Different Versions of the GAMIL Model 下载免费PDF全文
下载免费PDF全文 Simulated outgoing longwave radiation (OLR) outputs by two versions of the grid-point atmospheric general circulation model (GAMIL) were analyzed to assess the influences of improvements in cloud microphysics and convective parameterization schemes on the simulation of the Madden-Julian oscillation (MJO) and other tropical waves. The wavenumber-frequency spectral analysis was applied to isolate dominant modes of convectively coupled equatorial waves, including the MJO, Kelvin, equatorial Rossby (ER), mixed Rossby-gravity (MRG), and inertio-gravity (IG) waves. The performances of different versions of the GAMIL model (version 1.0 (GAMIL1.0) and version 2.0 (GAMIL2.0)) were evaluated by comparing the power spectrum distributions of these waves among GAMIL1.0, GAMIL2.0, and observational data. GAMIL1.0 shows a weak MJO signal, with the maximum variability occurring separately at wavenumbers 1 and 4 rather than being concentrated on wavenumbers 1–3, suggesting that GAMIL1.0 could not effectively capture the intraseasonal variability. However, GAMIL2.0 is able to effectively reproduce both the symmetric and anti-symmetric waves, and the significant spectra of the MJO, Kelvin, and MRG waves are in agreement with observational data, indicating that the ability of GAMIL2.0 to simulate the MJO and other tropical waves is enhanced by improving the cloud microphysics and convective parameterization schemes and implying that such improvements are crucial to further improving this model’s performance. 相似文献
10.
This paper documents a study to examine the sensitivity to cloud droplet effective radius and liquid water path and the alleviation the energy imbalance at the top of the atmosphere and at the surface in the latest version of the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP） （GAMIL1.1.0）. Considerable negative biases in all flux components, and thus an energy imbalance, are found in GAMIL1.1.0. In order to alleviate the energy imbalance, two modifications, namely an increase in cloud droplet effective radius and a decrease in cloud liquid water path, have been made to the cloud properties used in GAMIL. With the increased cloud droplet effective radius, the single scattering albedo of clouds is reduced, and thus the reflection of solar radiation into space by clouds is reduced and the net solar radiation flux at the top of the atmosphere is increased. With the reduced cloud optical depth, the net surface shortwave radiation flux is increased, causing a net warming over the land surface. This results in an increase in both sensible and latent heat fluxes over the land regions, which is largely balanced by the increased terrestrial radiation fluxes. Consequently, the energy balance at the top of atmosphere and at the surface is achieved with energy flux components consistent with available satellite observations. 相似文献