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区域气候模拟中侧边界嵌套误差的研究
ANALYSIS OF LATERAL BOUNDARY NESTING ERRORS IN REGIONAL CLIMATE MODELING
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摘要: 在复杂地形条件下嵌套细网格模式的基础上，建立了与球圈模式相嵌套的区域模式系统，对几种不同条件下的嵌套误差进行了比较分析，研究了区域模式嵌套误差的特征分布及时空演变特征。初步分析表明：区域模式嵌套造成的误差在不同区域的分布不同，且不同的物理量在时空的分布也不同；动能场的误差主要在边界区上层的流入区，感热场的误差在边界区上层，水汽的误差在边界区上层的流入区；侧边界输入时间间隔对模式嵌套误差有一定的影响。有限区细网格模式在上层长波误差大于粗网格环圈模式上层误差，在下层短波模拟的误差比粗网格环圈模式的下层误差要小。相速误差对侧边界嵌套误差的影响在下层很严重，嵌套误差的大小与大小模式的网格距之比有关；在大小模式物理参数化过程一致的条件下，无日变化的区域模式其嵌套误差远大于有日变化的区域模式嵌套误差。Abstract:
In order to study the characteristics of errors associated with the lateral boundary conditions used in regional modeling, especially the regional climate modeling, based on the YH model, a regional model system nested with a spherical-belt type model is established and a set of error diagnosis tools are developed. By means of the software Excel, a series of comparative studies are carried out to analyze the spatial and temporal distribution of the errors due to the different lateral boundary conditions. The results show that the basic methodology for detecting the errors associated with lateral boundary conditions in regional modeling is rational, and the tools are quite useful. Moreover, it might also be applied to other studies, such as for diagnosing other types of errors in the model or developing some new schemes. The preliminary results indicated that the lateral boundary error of a regional model varies with the location in the model domain, and the spatial and temporal distribution of the error associated with different variables is rather different. Relatively, the errors of mass and potential vorticity fields are smaller in the YH model. The errors of kinetic energy and water vapor field are found mainly in the influent part of upper layers in the near-boundary region, while the error of sensitive heat field was in the upper layers of near-boundary region. The fixed lateral boundary conditions cause more serious errors than the nested ones, and the time interval updating the lateral boundary also has some impact on the error. It is interesting to mention that the errors of upper layers in the fine mesh regional model where the long wave motion dominates are larger than the errors found in the coarse mesh spherical-belt one. On the other hand, the errors of lower layers in the same fine mesh regional model where the short wave motion dominates are smaller than the errors found in the coarse mesh spherical-belt one.The impact of phase velocity error on lateral boundary errors is more significant in the lower layer, which is related to when the ratio of grid lengths of fine-mesh vis-à-vis coarse-mesh. The errors became much more serious when the diurnal variation cycle is turned off in the regional model.
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Key words:
- Ci rculation model;
- Nested erro r;
- Lateral boundary;
- Phase velocity error
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图 6 无地形干绝热模式动能场误差绝对值5天滑动平均分布(a)环圈粗网格模式与区域细网格模式误差比较,(b)区域细网格模式与区域粗网格模式误差比较,(c)不同分辨率侧边界资料造成的区域模式误差比较
表 1 诊断方案的设计
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[1] 曾庆存,李荣风.不等距差分格式的计算紊乱问题.大气科学,1982,6(4): 345～354. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXK198204000.htm [2] 廖洞贤,陆维松.有限区域预报中的一些问题.气象学报,1982,40(4): 387～397. http://www.cnki.com.cn/Article/CJFDTOTAL-QXXB198204000.htm [3] 颜宏.单向影响嵌套侧边界技术的研究(一) 研究现状和C型跳点网格模式侧边界方案的设计.高原气象,1987,6(2): 192～204. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX1987S1008.htm [4] Anthes R A, Kuo Y H, Hsie E Y, et al. Estimation of skill and uncertainty in regional numerical models. Quart J Roy Meteor Soc., 1989,115: 763～806. [5] 刘永强,丁一汇. 区域气候模拟研究. 应用气象学报,1995,6(2):228～239. http://qk.cams.cma.gov.cn/jams/ch/reader/view_abstract.aspx?file_no=19950236&flag=1 [6] 苗峻峰,徐祥德.气候模式一重、二重区域嵌套方案的试验研究.气象科学,1993,13(3): 269～280. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKX199303005.htm [7] 颜宏. 复杂地形条件下嵌套细网格模式的设计(一) 数值模式的基本原理. 高原气象,1987,6(2): 1～62. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX1987S1001.htm [8] 颜宏. 复杂地形条件下嵌套细网格模式的设计(二) 数值模式中次网格物理过程参数化.高原气象,1987, 6(2): 63～138. -
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