有地形模式中气压梯度力误差扣除法   总被引：4，自引：0，他引：4  

钱永甫  周天军 《高原气象》1995,(1)

：在现有有地形的数值模式中，陡峭地形区气压梯度力的计算存在一个普遍问题，即计算精度较高的格式比较繁琐而费时，简单省时的格式又不精确和不稳定。为解决这个问题，作者等在最近提出了一种方法，称为气压梯度力的误差扣除法。该方法假定：气压梯度力的计算误差主要来自地形而与气压形势关系较小。用理想场对该方法进行检验后表明，这一方法是成功的。本文则用气候模式对作者提出的有地形数值模式中气压梯度力的误差扣除法进行了模拟检验。所用模式是作者等使用多年的Ｐ－混合坐标系５层模式，选用了四种气压梯度力的计算格式，即ＤＤＤ格式、Ｃｏｒｂｙ格式、平均温度格式和经典中央差格式。比较了这四种格式在有无误差扣除时的模拟结果，发现：对于计算精度较高的格式，如ＤＤＤ格式、Ｃｏｒｂｙ格式及平均温度格式，有无误差扣除的结果相差不大，但误差扣除法仍可在一定程度上改善模拟效果。对于计算精度差的格式，如经典中央差格式，在无误差扣除时计算不稳定，得不到模拟结果，进行误差扣除后，从根本上提高了其计算精度，因而也提高了计算的稳定性，达到了较满意的模拟效果。而且与其它格式的模拟结果相当接近。本文提出的误差扣除法可同时用于格点模式和谱模式。  相似文献   

北大西洋年际变率的海气耦合模式模拟II：热带太平洋强迫     

周天军  宇如聪  郜永祺  Helge Drange 《气象学报》2006,64(1):18-30

利用一个全球海气耦合模式(BCM),结合观测资料,讨论了热带太平洋强迫对北大西洋年际气候变率的影响。研究表明,BCM能够相对合理地模拟赤道太平洋的年际变率模态及相应的海温距平型和大气遥相关型,尽管其准3年的振荡周期过于规则。来自数值模式和观测上的证据都表明,北大西洋冬季海温的主导性变率模态,即自北而南出现的“- -”的海温距平型,受到来自热带太平洋强迫的显著影响,其正位相与赤道中东太平洋冷事件相对应。换言之,赤道太平洋暖事件的发生,在太平洋-北美沿岸激发出PNA遥相关型,进而通过在北大西洋产生类似NAO负位相的气压距平型,削弱本来与NAO正位相直接联系的三核型海温距平。北大西洋三核型海温距平对热带太平洋强迫的响应,要滞后2—3个月的时间。  相似文献   

THE INTERBASIN TRANSPORT OF ATMOSPHERIC MOISTURE EVALUATED FROM NCEP/NCAR REANALYSIS DATA          下载免费PDF全文

周天军  张学洪  王绍武 《Acta Meteorologica Sinica》2000,(2)

With the objective of providing a relatively accurate and complete diagram,the global scaleinterbasin transport of atmospheric moisture on the basis of the NCEP/NCAR reanalysis data for theperiod 1980 to 1994 is evaluated.The results show that the net zonal vapor flux for the Pacific,theAtlantic and the Indian Oceans is 0.25 Sv,—0.68 Sv and —0.29 Sv respectively.The markingdifferences in the zonal moisture budget among individual basins are speculated as the reason thatdominates the differences in the salinity between the Pacific and the Atlantic Oceans.Though currentevaluation on the net zonal moisture flux for the Atlantic basin is generally in qualitative agreementwith the previous estimate,quantitative discrepancy is found to exist.According to current statistics,the tropical easterlies carry water vapor of 0.43 Sv from the Atlantic basin across Central Americainto the Pacific,and the northern westerlies allow water vapor of 0.25 Sv to escape from the Pacific.Quantitative analyses also reveal that the seasonal variation of net zonal vapor flux for the Pacific andthe Indian Oceans is stronger than that for the Atlantic,which may be favorable for the maintenanceof high salinity feature of the Atlantic Ocean.  相似文献   

Uncertainty in the 2°C warming threshold related to climate sensitivity and climate feedback     

周天军  陈晓龙 《Acta Meteorologica Sinica》2015,29(6):884-895

Climate sensitivity is an important index that measures the relationship between the increase in greenhouse gases and the magnitude of global warming. Uncertainties in climate change projection and climate modeling are mostly related to the climate sensitivity. The climate sensitivities of coupled climate models determine the magnitudes of the projected global warming. In this paper, the authors thoroughly review the literature on climate sensitivity, and discuss issues related to climate feedback processes and the methods used in estimating the equilibrium climate sensitivity and transient climate response (TCR), including the TCR to cumulative CO₂ emissions. After presenting a summary of the sources that affect the uncertainty of climate sensitivity, the impact of climate sensitivity on climate change projection is discussed by addressing the uncertainties in 2°C warming. Challenges that call for further investigation in the research community, in particular the Chinese community, are discussed.  相似文献   

对流层和平流层温度中ENSO信号的多种资料比较   总被引：2，自引：0，他引：2  

于超越  周天军  李博 《大气科学》2011,35(6):1020-1032

本文利用1980～1999年卫星资料Microwave Sounding Unit (MSU)和5种再分析资料(ERA40、JRA25、NCEP1、NCEP2、MERRA),分析了北半球冬季全球对流层中层和平流层低层温度变化中的ENSO信号,讨论了ENSO暖冷位相时温度异常的对称性和非对称性,并以MSU卫星资料为标准,...  相似文献   

东亚副热带西风急流及其年际变率的海气耦合模式模拟   总被引：6，自引：0，他引：6  

蔡琼琼  周天军  吴波  李博  张丽霞 《海洋学报》2011,33(4):38-48

分析了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)快速耦合气候系统模式FGOALS_gl模拟的东亚副热带西风急流,并讨论了ENSO对东亚夏季副热带西风急流位置的影响.FGOALS_gl能较好模拟东亚副热带西风急流的空间分布以及季节演变,但较之再分析资料,模式模拟的急流强度偏弱...  相似文献   

Variation of surface temperature during the last millennium in a simulation with the FGOALS-gl climate system model     

张洁  周天军  辛晓歌 《大气科学进展》2013,30(3):699-712

A reasonable past millennial climate simulation relies heavily on the specified external forcings, including both natural and anthropogenic forcing agents. In this paper, we examine the surface temperature responses to specified external forcing agents in a millennium-scale transient climate simulation with the fast version of LASG IAP Flexible Global Ocean-Atmosphere-Land System model (FGOALS-gl) developed in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). The model presents a reasonable performance in comparison with reconstructions of surface temperature. Differentiated from significant changes in the 20th century at the global scale, changes during the natural-forcing-dominant period are mainly manifested in the Northern Hemisphere. Seasonally, modeled significant changes are more pronounced during the wintertime at higher latitudes. This may be a manifestation of polar amplification associated with sea-ice-temperature positive feedback. The climate responses to total external forcings can explain about half of the climate variance during the whole millennium period, especially at decadal timescales. Surface temperature in the Antarctic shows heterogeneous and insignificant changes during the preindustrial period and the climate response to external forcings is undetectable due to the strong internal variability. The model response to specified external forcings is modulated by cloud radiative forcing (CRF). The CRF acts against the fluctuations of external forcings. Effects of clouds are manifested in shortwave radiation by changes in cloud water during the natural-forcing-dominant period, but mainly in longwave radiation by a decrease in cloud amount in the anthropogenic-forcing-dominant period.  相似文献   

The flexible global ocean-atmosphere-land system model, Grid-point Version 2: FGOALS-g2   总被引：3，自引：0，他引：3  

李立娟  林鹏飞  俞永强  王斌  周天军  刘利  刘骥平  包庆  徐世明  黄文誉  夏坤  普业  董理  申思  刘屹岷  胡宁  刘咪咪  孙文奇  史湘军  郑伟鹏  吴波  宋米荣  刘海龙  张学洪  吴国雄  薛巍  黄小猛  杨广文  宋振亚  乔方利 《大气科学进展》2013,30(3):543-560

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.  相似文献   

Relationships between the East Asian-western north pacific monsoon and ENSO simulated by FGOALS-s2   总被引：4，自引：1，他引：3  

吴波  周天军 《大气科学进展》2013,30(3):713-725

The relationships between ENSO and the East Asian-western North Pacific monsoon simulated by the Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 (FGOALS-s2), a state-of-the-art coupled general circulation model (CGCM), are evaluated. For El Nio developing summers, FGOALS-s2 reproduces the anomalous cyclone over the western North Pacific (WNP) and associated negative precipitation anomalies in situ. In the observation, the anomalous cyclone is transformed to an anomalous anticyclone over the WNP (WNPAC) during El Nio mature winters. The model reproduces the WNPAC and associated positive precipitation anomalies over southeastern China during winter. However, the model fails to simulate the asymmetry of the wintertime circulation anomalies over the WNP between El Nio and La Nia. The simulated anomalous cyclone over the WNP (WNPC) associated with La Nia is generally symmetric about the WNPAC associated with El Nio, rather than shifted westward as that in the observation. The discrepancy can partially explain why simulated La Nin a events decay much faster than observed. In the observation, the WNPAC maintains throughout the El Nio decaying summer under the combined effects of local forcing of the WNP cold sea surface temperature anomaly (SSTA) and remote forcing from basinwide warming in the tropical Indian Ocean. FGOALS-s2 captures the two mechanisms and reproduces the WNPAC throughout the summer. However, owing to biases in the mean state, the precipitation anomalies over East Asia, especially those of the Meiyu rain belt, are much weaker than that in the observation.  相似文献   

Impacts of two types of El Niño on atmospheric circulation in the Southern Hemisphere     

孙丹  薛峰  周天军 《大气科学进展》2013,30(6):1732-1742

Based on NCEP/NCAR （National Centers for Environmental Prediction/National Center for Atmo- spheric Research） reanalysis data from 1979 to 2010, the impacts of two types of E1 Nino on atmospheric circulation in the Southern Hemisphere （SH） are analyzed. It is shown thaL when a warming event occurs in the equatorial eastern Pacific （EP E1 Nino）, there is a negative sea level pressure （SLP） anomaly in the east- ern Pacific and a positive one in the western Pacific. Besides, there exists a negative anomaly between 40°S and 60°S and a positive anomaly to the south of 60°S. When a warming event in the central Pacific （CP E1 Nino） occurs, there appears a negative SLP anomaly in the central Pacific and a positive SLP anomaly in the eastern and western Pacific, but the SLP anomalies are not so evident in the SH extratropics. In particular, the Pacific-South America （PSA） pattern induced by the CP E1 Nino is located more northwestward, with a weaker anomaly compared with the EP E1 Nino. This difference is directly related with the different position of heating centers associated with the two types of E1 Nino events. Because the SST anomaly associated with CP E1 Nino is located more westward than that associated with EP El Nino, the related heating center tends to move westward and the response of SH atmospheric circulation to the tropical heating changes accordingly, thus exciting a different position of the PSA pattern. It is also noted that the local meridional cell plays a role in the SH high latitudes during EP E1 Nino. The anomalous ascending motion due to the enhancement of convection over the eastern Pacific leads to an enhancement of the local Hadley cell and the meridional cell in the middle and high latitudes, which in turn induces an anomalous descending motion and the related positive anomaly of geopotential height over the Amundsen-Bellingshausen Sea.  相似文献