RIEMS2.0模式提高分辨率对中国气温模拟能力的影响

利用区域环境集成系统模式（RIEMS2.0）在60 km和30 km两种分辨率下进行中国区域的长期模拟试验（1991～2000年），开展不同分辨率下中国气温平均气候态和年际变率的模拟能力分析研究。结果表明：（1） RIEMS2.0能较好模拟出多数分区多年平均气温的空间分布，与观测空间分布较接近。随着水平分辨率的提高，模式模拟的气温空间分布模拟更精细，使得平均气温的模拟冷偏差减小，模拟结果更趋于实测。对年均温和冬季气温来说，中国及多数分区模拟与观测的偏差减少，且通过显著性检验（P＜0.01）；对夏季气温来说，中国及多数分区的偏差增加，气温的模拟能力没有明显提高。（2）对年际变率来说，随着水平分辨率的提高，大部分区域模拟能力有一定程度的提高。特别是年均温和冬季气温的年际变率，多数地区模拟改进效果较好；而夏季气温年际变率的模拟在中国大部分地区没有明显改善。

Comparisons on RIEMS2.0's Ability to Simulate Multi-Year Mean Climate in Northern China with Two Model Domains

Regional Integrated Environment Modeling System Version 2.0 (RIEMS2.0) is now being developed by the Key Laboratory of Regional Climate-Environment for Temperate East Asia, Chinese Academy of Sciences. In order to test the sensitivity of the RIEMS2.0 model domain to simulate long-term climate and its change, and provide a basis for the further development and application of the model, the authors compared results between simulated and observed precipitation and surface-airtemperature using two model domains under different cumulus parameterization schemes. The model was driven by NCEP/NCAR re-analysis data with a simulation duration ranging from 1 January 1979 to 31 December 2007. There were no significant differences found in the spatial distributions of the simulated precipitation and surface-air-temperature, or interannual variations between the two model domains. There were, however, differences observed between the two model domain simulations of local sub-regions. The smaller model domain more accurately simulated precipitation, especially in summer (June, July, and August), and decreased the bias of surface-airtemperature, especially in winter (December, January, and February). The weak summer and winter monsoons simulated by the smaller model domain was a result of boundary forcings and may partially account for the improvements of this model.

Testing the ability of RIEMS2.0 to simulate multi-year precipitation and air temperature in China

RIEMS2.0 (Regional Integrated Environment Modeling System, Version 2.0) is now being developed starting from RIEMS1.0 by the Key Laboratory of Regional Climate Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, China. In order to test RIEMS2.0’s ability to simulate long-term climate and its changes, as well as provide a basis for further development and applications, we compare simulated precipitation and air temperature from 1980 to 2007 (simulation duration from Jan. 1, 1979 to Dec. 31, 2007) under different cumulus parameterization schemes with the observed data. The results show that RIEMS2.0 can reproduce the spatial distribution of precipitation and air temperature, but that the model overestimates precipitation with the rainfall center moving northwestward and underestimates air temperature for annual simulations. Annual and interannual variations in precipitation and air temperature for different climate subregions are well captured by the model. Further analysis of summer and winter simulations shows that precipitation is overestimated, except for the Jianghuai-Jiangnan subregions in the winter, and the air temperature bias in the summer is weaker than in the winter. There are larger biases for precipitation and air temperature in semiarid subregions. Anomalies in precipitation and air temperature are also well captured by the model. Although a similar distribution can be found between observed data and simulated results under different cumulus parameterization schemes, these show differences in intensity and location. In sum, RIEMS2.0 shows good stability and does well in simulating the long-term climate and its changes in China.

中国不同排放情景下人为气溶胶的气候效应

本文利用区域气候模式RIEMS2.0(Regional Integrated Environmental Model System)和2006年以及2020年三种排放情景下的排放资料,研究了2006年气候背景下的人为气溶胶的浓度分布特征及辐射效应,估算了未来不同排放情景下人为气溶胶的主要成分硫酸盐、硝酸盐、黑碳、有机碳(含二次有机碳)的综合气候效应.结果表明:(1)2006年中国地区人为气溶胶浓度硫酸盐>有机碳>硝酸盐>黑碳,其区域柱浓度平均值分别为6.0、4.0、1.3和0.3mg/m2.(2)2006年硫酸盐、硝酸盐、有机碳和黑碳的平均辐射强迫分别为-1.32、-0.60、-0.40和0.28W/m2.硫酸盐、硝酸盐和有机碳的负辐射强迫超过黑碳的正辐射强迫,人为气溶胶总辐射强迫为-1.96W/m2.(3)人为气溶胶的辐射效应及引起的地面气温变化对排放源非常敏感,未来采取不同排放政策导致的人为气溶胶的含量及辐射效应有较大差异.在未来排放增加的情景下,各区域的气溶胶浓度、辐射强迫、气温下降幅度和降水减少幅度也相应加大.

中国农田下垫面变化对气候影响的模拟研究

使用同期的美国国家环境预报中心/能源部(NCEP/DOE)再分析资料驱动区域气候耦合模式AVIM-RIEMS2.0,从遥感卫星图像资料中获取3期中国土地利用/覆盖数据中的农田植被类型,将其分别引入到AVIM-RIEMS2.0模式进行积分,研究中国农田下垫面变化对东亚区域气候的影响。结果表明:中国农田变化对气候影响具有冬季弱、夏季强的季节性变化,夏季气温和降水的差异在一些地区通过了95%的显著性检验;20世纪80年代农田扩张,林地、草地为主的植被类型转化为农田,植被变化区域的叶面积指数降低,反照率升高,且通过了95%的显著性检验,使得中国东部地区的气温由南到北呈现增加—减少—增加—减少的相间变化趋势,而降水的变化趋势大体相反;20世纪90年代农田面积减少,除东北地区外,农田变化引起的植被变化与80年代基本相反,叶面积指数变化、反照率以及由此导致的气候各要素也呈现大体相反的变化趋势;不同时期农田变化引起的植被类型转化的差异,使850 hPa风场变化趋势基本相反,可能是导致气温和降水变化趋势差异的主要原因之一。

区域环境系统集成模式对1997/1998年夏季中国两个极端气候事件模拟能力分析

区域环境系统集成模式(RIEMS2.0,Regional Integrated Environment Modeling System Version 2.0)是由中国科学院大气物理研究所东亚区域气候环境重点实验室在RIEMS1.0基础上发展的区域气候模式。为了检验RIEMS2.0对短期气候的模拟能力,利用降水和气温(2 m)观测资料检验RIESM2.0不同物理过程和初始条件集合模拟1997/1998年夏季中国华北地区高温干旱和长江流域洪涝两个连续极端气候事件的能力(连续积分时间(1997年3月1日—1998年8月31日)共18个月),比较模拟和观测的1997/1998年夏季降水和气温。集合模拟结果表明RIEMS2.0能很好模拟1997/1998年夏季降水和气温及其两年差值分布;模拟和观测的日降水和平均气温结果有很好的相关性,但是降水模拟总体高估,干旱和江淮及江南区气温模拟偏高而半干旱和湿润区气温模拟偏低。在不同物理过程集合模拟中,虽然集合平均距平相关系数(ACC)和均方根误差(RMSE)并不是优于所有集合成员值,但集合模拟能减小模式的不确定性,在一定程度上提高模拟精度。不同显式水汽方案和积云参数化方案对降水、气温模拟效果表现出很好的一致性,湿润区一致性最好。因此,RIEMS2.0模拟能揭示1997/1998年两个连续极端气候事件夏季降水和气温空间分布,反映不同子区域降水和气温分布特征,各集合成员的模拟结果存在差异的同时也保持了很好的稳定性,选择合适的物理过程可以提高模式对区域气候的模拟能力。

区域气候模式与陆面模式的耦合及其对东亚气候模拟的影响

将大气—植被相互作用模式AVIM(Atmosphere–Vegetation Interaction Model)与区域环境系统集成模式RIEMS2.0(Regional Integrated Environment Modeling System Version 2.0)耦合,利用耦合后的AVIM-RIEMS2.0模式在东亚区域选定典型年份进行积分试验,通过模拟结果与观测资料对比分析,从整体上评估耦合模式对东亚区域的模拟能力。结果表明:模式能够较好地模拟850 hPa风场、500 hPa位势高度、气温、降水以及地表热通量空间分布型和季节变化。双向耦合具有动态植被过程的AVIM模式后,RIEMS2.0模拟能力有一定程度的提高。850 hPa风场在冬季的中国东北、华北地区以及夏季的中国东部地区,模拟偏差都减小;500 hPa高度场模拟在中国北方地区改进明显,而在中国南方地区的夏季并没表现出明显的改进趋势。耦合模式改进了RIEMS2.0模式冬季气温模拟偏低而夏季偏高的现象。从区域平均看,耦合模式改善了降水模拟偏多的现象,并使得潜热通量的模拟效果有明显的改进,对感热通量模拟在大部分地区也有改进。总的来看,AVIM-RIEMS2.0耦合模式对中国北方地区模拟改进较为明显,而对中国南方地区,特别是华南地区没有明显的改进。

A Modeling Study of the Climate Effects of Sulfate and Carbonaceous Aerosols over China

In this paper, the RIEMS 2.0 model is used to simulate the distribution of sulfate, black carbon, and organic carbon aerosols over China （16.2°-44.1°N, 93.4°-132.4°E） in 1998. The climate effects of these three anthropogenic aerosols are also simulated. The results are summarized as follows： （1） The regional average column burdens of sulfate, BC, OC, and SOC were 5.9, 0.24, 2.4, and 0.49 mg m-2, with maxima of 33.9, 1.48, 7.3, and 1.1 mg m-2, respectively. The column burden and surface concentration of secondary organic carbon accounted for about 20% and 7%, respectively, of the total organic carbon in eastern China. （2） The radiative forcings of sulfate, organic carbon, and black carbon at the top of the atmosphere were -1.24, -0.6, and 0.16 W m 2 respectively, with extremes of -5.25, -2.6, and 0.91 W m-2. （3） The surface air temperature changes caused by sulfate, organic carbon, and black carbon were -0.07, -0.04, and 0.01 K, respectively. The air temperature increase caused by black carbon at 850 hPa was higher than that at the surface. The net effect of the three kinds of anthropogenic aerosols together decreased the annual average temperature by -0.075 K; the maximum value was -0.3 K. （4） Black carbon can reduce the precipitation in arid and semi-arid areas of northern China and increase the precipitation in wet and semi-wet areas of southern China. The average precipitation increase caused by black carbon in China was 0.003 mm d^-1. The net effect of the three kinds of anthropogenic aerosols was to decrease the precipitation over China by 0.008 mmd ^-1.

Performance of Regional Integrated Environment Modeling System (RIEMS) in the Simulation of Surface Air Temperature over East Asia

Regional climate models (RCMs) have the potential for more detailed surface characteristic and mesoscale modeling results than general circulation models (GCMs).These advantages have drawn significant focus on RCM development in East Asia.The Regional Integrated Environment Modeling System,version 2.0 (RIEMS2.0),has been developed from an earlier RCM,RIEMS1.0,by the Key Laboratory of Regional ClimateEnvironment for Temperate East Asia (RCE-TEA) and Nanjing University.A numerical experiment covering 1979 to 2008 (simulation duration from 1 January 1978 to 31 December 2008) with a 50-km spatial resolution was performed to test the ability of RIEMS2.0 to simulate long-term climate and climate changes in East Asia and to provide a basis for further development and applications.The simulated surface air temperature (SAT) was compared with observed meteorological data.The results show that RIEMS2.0 simulation reproduced the SAT spatial distribution in East Asia but that it was underestimated.The simulated 30-year averaged SAT was approximately 2.0°C lower than the observed SAT.The annual and interannual variations in the averaged SAT and their anomalies were both well reproduced in the model.A further analysis of three sub-regions representing different longitudinal ranges showed that there is a good correlation and consistency between the simulated results and the observed data.The annual variations,interannual variations for the averaged SAT,and the anomalies in the three sub-regions were also captured well by the model.In summary,RIEMS2.0 shows stability and does well both in simulating the long-term SAT in East Asia and in expressing sub-regional characteristics.

Simulation of a Freezing Rain and Snow Storm Event over Southern China in January 2008 Using RIEMS 2.0

The Regional Integrated Environmental Model System （RIEMS 2.0） with NCEP Reanalysis II is utilized to simulate the severe freezing rain and snow storm event over southern China in January 2008, which caused severe damage in the region. The relationships between the freezing rain process and the large-scale cir- culation, in terms of the westerly and low-level jets, water vapor transportation, and northerly wind area/intensity indices, were analyzed to tmderstand the mechanisms of the freezing rain occurrence. The results indicate the fol- lowing： （1） RIEMS 2.0 reproduced the pattern of precipi- tation in January 2008 well, especially for the temporal evolution of daily precipitation averaged over the Yangtze River valley and southern China; （2） RIEMS 2.0 repro- duced the persistent trough in the South Branch of the westerlies, of which the southwesterly currents trans- ported abundant moisture into southern China; （3） RIEMS 2.0 reasonably reproduced the pattern of frequencies of light and moderate rain, although it overestimated the frequency of rain in southern China. This study shows that RIEMS 2.0 can be feasibly applied to study extreme weather and climate events in East Asia.