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1998 Vol. 15, No. 1

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Simulation of the Asian Monsoon by IAP AGCM Coupled with an Advanced Land Surface Model (IAP94)
Zeng Qingcun, Dai Yongjiu, Xue Feng
1998, 15(1): 1-16. doi: 10.1007/s00376-998-0013-9
In this paper, the global and regional features of the seasonal variation of general circulation, and especially the Asian monsoon simulated by the Institute of Atmospheric Physics Two-level AGCM coupled with a sophisticated land-surface model (IAP94-GCM) are presented and compared with the observation. The comparison is made by using the equilibrium multiyear seasonal cycle climate from a 100-year integration. In the integration sea surface temperature (SST) and sea ice are taken from the observed climatological data (with seasonal variation) because our purpose is to see the improvement of simulation due to the coupling with an advanced land surface model. Overall, the IAP94-GCM provides a reasonably realistic simulation of the interseasonal and intraseasonal climatology of the Asian monsoon and yields an important information that sheds light on the thermal underpinning and the thermodynamics of the seasonal and even multiscale variabilities associated with the Asian summer monsoon.
A Method for Spaceborne Synthetic Remote Sensing of Atmospheric Aerosol Optical Depth and Vegetation Reflectance
Qiu Jinhuan
1998, 15(1): 17-30. doi: 10.1007/s00376-998-0014-8
Spaceborne synthetic remote sensing of atmospheric aerosol optical depth and vegetation reflectance is very sig-nificant, but it remains to be a question unresolved yet. Based on the property of vegetation reflectance spectra from near ultra-violet to near infrared and the sensitivity of outgoing radiance to vegetation reflectance and atmospheric aerosol optical depth, a new method for spaceborne synthetic remote sensing of the reflectance and the depth is pro-posed, and an iteration-correlation inversion algorithm is developed in this paper. According to numerical experi-ment, effects of radiance error, error in aerosol imaginary index and vegetation medium inhomogeneity on retrieved result are analyzed. Inversion results show that the effect of error in aerosol imaginary index is very important. As the error of aerosol imaginary index is within 0.01, standard errors of aerosol optical depth and vegetation reflectance so-lutions for 14 spectral channels, from 410 nm to 900 nm are respectively less than 0.063 and 0.023. And as the radiance error is within 2%, the standard errors are less than 0.023 and 0.0056.
The Quasi-Decadal Oscillation of Air-Sea System in the Northwestern Pacific Region
Li Chongyin
1998, 15(1): 31-40. doi: 10.1007/s00376-998-0015-7
The data analyses found at first that the air-sea system in the northwestern Pacific region has clear systematical quasi-decadal oscillation, such as the surface air temperature, the subtropical high activities over the northwestern Pacific and the SSTA which has different time-scale features from the temporal variation with 3-4 years period of SSTA in the equatorial Pacific. In East Asia, the climate variations, such as the surface air temperature, the precipitation and the beginning date of Mei-yu in the Yangtze River basin, also have clear quasi-decadal oscillation. They can be regarded as the influ?ences of quasi-decadal oscillation of air-sea system in the northwestern Pacific region.
Influences of Vorticity Source and Momentum Source on Atmospheric Circulation
Fang Juan, Wu Rongsheng
1998, 15(1): 41-46. doi: 10.1007/s00376-998-0016-6
A simplified one-dimensional barotropic vorticity equation is used to study the influences of the vorticity and the momentum source on the large scale wave. Both vorticity source and momentum source can cause the formation of the large scale wave, but the former can produce large scale wave only under the condition that there is apparent basic flow acting on it, while the latter can produce the large scale wave even when ū tends to be zero. Furthermore, the amplitude of steady wave caused by the former is proportional to √ū, while the amplitude caused by the latter has no relation to ū, instead it depends only on the magnitude of the perturbation of momentum.
A Land Surface Model (IAP94) for Climate Studies Part II: Implementation and Preliminary Results of Coupled Model with IAP GCM
Dai Yongjiu, Xue Feng, Zeng Qingcun
1998, 15(1): 47-62. doi: 10.1007/s00376-998-0017-5
The Institute of Atmospheric Physics Land Surface Model (IAP94) has been incorporated into the IAP two-level atmospheric general circulation model (IAP GCM). Global and regional climatology averaged over the last 25 years of 100 year integrations from the IAP GCM with and without IAP94 (“bucket” scheme) is compared. The simulated results are also compared with the reanalysis data. Major findings are:(1) The IAP GCM simulation without IAP94 has extensive regions of warmer than observed surface air tempera?tures, while the simulation with IAP94 very much improves the surface air temperature.(2) The IAP GCM simulation with IAP94 gives improvement of the simulated precipitation pattern and intensity, especially the precipitation of East Asian summer monsoon and its intraseasonal migration of the rainbelts.(3) In five selected typical regions, for most of the surface variables such as surface air temperature, precipitation, precipitation minus evaporation, net radiation, latent heat flux and sensible heat flux, the IAP GCM with IAP94 pro?vides better simulations.
A Numerical Simulation of “5.5” Super-Duststorm in Northern China
Li Xingsheng, Zhou Jianqiang, Li Zhe, Fang Xiumei, He Zhuanshi, Farn Parungo
1998, 15(1): 63-73. doi: 10.1007/s00376-998-0018-4
Combining the Penn State/NCAR mesoscale (MM4) model, the dust transport model and an atmospheric radiative transfer model, a super duststorm process occurred in the Gansu province on 5 May 1993 has been simu-lated. Based on the observations of duststorms occurred in the northern China and the field measurements of dust particles’ physical and optical properties, model simulating dust plume transport processes and dust particle radiative forcing have been developed. The models are described and verified with real cases of duststorms.
The Regional Dynamical Model of the Atmospheric Ozonosphere
Wang Weiguo, Xie Yingqi, Qiu Jinhuan, Liu Qing
1998, 15(1): 74-82. doi: 10.1007/s00376-998-0019-3
The TOMS zonal average total ozone data in the Northern Hemisphere are decomposed with the empirical orthogonal function (EOF) method. According to the features of the spatial characteristic vectors, the characteristic vectors that have been obtained with EOF method can be used as the ordered orthogonal radixes to unfold the phase space. After the corresponding time functions are embedded in phase space, the traces of the state vectors of the re-gional ozonosphere dynamical system alt constructed, and can be used to describe the attractor integral information of the asymptotic state of the regional ozonosphere system and the dynamical features of the regional ozonosphere system, and then the embedded saturation dimension of the regional ozonosphere system attractor is successfully ob?tained. Based on these works mentioned above, by using the time function series we solve a problem contrary to the numerical solution and retrieve the control parameters of the state equations in which quadratic nonlinear terms are included, and then the dynamical models that can objectively reflect the temporal variation of the regional ozonosphere system are finally established.
Topographically Forced Three-Wave Quasi-Resonant and Non-Resonant Interactions among Barotropic Rossby Waves on an Infinite Beta-Plane
Luo Dehai
1998, 15(1): 83-98. doi: 10.1007/s00376-998-0020-x
In this paper, we first apply the assumption h=εh` of topographic variation (h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant and non-resonant interactions among Rossby waves for zonal wavenumbers 1-3 over a wavenumber-two bottom topography (WTBT). Some numerical calculations are made with the fourth-order Rung-Kutta Scheme. It is found that for the case without topographic forcing, the period of three-wave quasi-resonance (TWQR) is found to be in-dependent of the zonal basic westerly wind, but dependent on the meridional wavenumber and the initial amplitudes. For the fixed initial data, when the frequency mismatch is smaller and the meridional wavelength is moderate, its pe-riod will belong to the 30-60-day period band. However, when the wavenumber-two topography is included, the pe-riods of the forced quasi-resonant Rossby waves are also found to be strongly dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind reaches a moderate extent, intraseasonal oscillations in the 30-60-day period band can be found for zonal wavenumbers 1-3. On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction over a WTBT can occur in this case. When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the presence of a WTBT, the three Rossby waves oscillate with the identical period. The period, over a moder-ate range of the zonal basic westerly wind, is in the intraseasonal, 30-60-day range.
The Numerical Simulation on the PBL Structure and Its Evolution over Small-Scale Concave Terrain
Shi Yong, Jiang Weimei
1998, 15(1): 99-106. doi: 10.1007/s00376-998-0021-9
A high-resolution, nonhydrostatic, three-dimensional diagnostic PBL model over small-scale concave terrain was established in this paper. A two-dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy (E-ε) closure scheme was used in both mod-els. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteris-tic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.
Analysis of the Ability of Infrared Water Vapor Channel for Moisture Remote Sensing in the Lower Atmosphere
Zhao Gaoxiang
1998, 15(1): 107-112. doi: 10.1007/s00376-998-0022-8
The ability of HIRS / 2 and GOES 1 / M infrared water wapor channels for moisture remote sensing in the lower atmosphere has been analyzed. It is found that the HIRS / 2 channel 10 seems not to be an optimal channel for water vapor remote sensing in the lower part of the atmosphere, we can find other channels that are more sensitive to mois-ture variation in the lower atmosphere and might be more useful for low level atmospheric moisture remote sensing.
On the Evolution of Finite-amplitude Disturbance to the Barotropic and Baroclinic Quasigeostrophic Flows
Mu Mu, Xiang Jie
1998, 15(1): 113-123. doi: 10.1007/s00376-998-0023-7
Some new results on the evolution of finite-amplitude disturbances to the nonlinearly stable and unstable quasigeostrophic flows are presented. Both barotropic and multilayer haroclinic problems are investigated. The upper (lower) bounds on the energy and potential enstrophy of disturbances to the nonlinearly stable(unstable) basic flows are established.
Atmospheric Refractive Turbulence Effect on Diffraction-Limited Infrared Coherent Lidar
Chen Wuhe, Situ Da, Zhong Xubin
1998, 15(1): 124-134. doi: 10.1007/s00376-998-0024-6
This paper, based on the Kavaya-Suni format, discusses the signal-to-noise ratio equation of the diffraction-limited coherent CO2 lidar in detail, which is applied to atmospheric turbulence. The cumulative SNR and relative SNR, which are all affected by the nonlinear effects of the diffraction-limited Gaussian beam, atmos-pheric molecule and atmospheric turbulence, are simulated by microcomputer. Six instructions for the optimal design of IR CO2 Coherent Lidar System, are provided.