【作者】 黄昌兴；

【导师】 李维京；

【作者基本信息】 中国气象科学研究院 ， 气象学， 2005， 博士

【摘要】 本文用国家气候中心T63L16大气环流模式,通过实测海温和气候气温(回报时段的平均)强迫,分别进行了20年夏季的回报试验,并对全球尺度和东亚区域的模拟结果进行了系统的检验;在此基础上对该模式的误差演变机制、可预报性和大气初始异常对季节预测的影响等问题进行了一些初步的探讨,得到了一些有意义的结果。 本文的主要结论概括如下: (1) 该模式能够较好地模拟出夏季全球大尺度的平均环流。准确地模拟出了大气环流对流层高、中、低层的大气活动中心,但是对不同的天气气候系统,其中心位置和强度仍然存在一定的误差。模式对温度和降水也有一定的模拟能力,但和实际相差较大。 (2) 模式对东亚降水的模拟,明显偏大,高原东部存在虚假的降水中心;降水误差中,模拟的对流性降水误差占总降水误差的百分之九十以上,而大尺度降水只占很小的一部分。云量、湿度场、感热通量和潜热通量的模拟偏差影响局地降水的误差。 (3) 系统误差和随机误差的量级相同,但随机误差要略大于系统误差。从误差方程中发现,控制系统误差和随机误差的演变因子有,辐合辐散项、转换项、非线性正压生成项和源汇项,并且在不同的预报时段,其影响不同;系统误差和随机误差的演变机制不同,其最大区别是系统误差混合生成项一直是促进系统误差的增长,而在随机误差中却是阻止随机误差误差的增长。系统误差和随机误差之间存在转换作用,总有随机误差向系统误差转换。转换项中,纬向风系统误差起主要作用。 (4) 对海平面气压、500hPa高度场、降水和850hPa温度场以及土壤湿度的可预报性的研究表明,海平面气压场的可预报性集中于热带地区,热带外的可预报性较小;500hPa高度场的可预报性位于热带区域,呈带状分布;降水的可预报性范围较小:850hPa温度场的可预报性位于热带太平洋地区,北美的部分地区也有一定的可预报性;土壤湿度的可预报性集中于东亚和北美大陆地区。以500hPa位势高度场为例,分析了El Nino、La Nina和非ENSO等不同气候背景下的可预报性。结果发现,热带地区,ENSO情况下的可预报性大约要比其它情况大0.2左右;北半球的热带外区域,非ENSO情况下的可预报性要比El Nino、La Nina和ENSO情况下小。在北美地区,ENSO情况下的可预报性分布和非ENSO的差别较大,ENSO情况下的可预报性明显比非ENSO的可预报性大。 (5) 大气初始场异常对夏季季节预测有重要的影响,不同的气象要素不同。海平面气压场,大西洋和南太平洋影响显著。位势高度场,主要影响在北太平洋和大西洋,不过影响范围要比海平面气压场大,且对流层高层的影响要大于中、低层。风场的影响要比海平面气压场和势高度场都小。东亚地区气候异常可预测性的年际变化幅度要比全球大得多,大气初始场异常对东亚气候预测的影响要远大于全球平均的情况。典型年份的个例分析表明,大气初始异常场对夏季季节高度场的预测作用更为明显,模式较好模拟出了热带对流层和平流层风向的年际变化,进一步证实大气初始异常影响在典型的年份更为突出,同时说明热带地区对流层和平流层夏季纬向风的年际变化包含有早期大气初始场的信息。更多还原

【Abstract】 Given observation SST and climate SST(average among hindcasting period), T63L16 GCM model is respectively used to perform numerical experiment of ensemble hindcasting for twenty summer,from 1982 to 2001, then systematical test results of globe and East Asian scale. Basing on those,error evolvement mechanism, atmosphere predictability,and initial atmosphere anomalies impacts on seasonal prediction and other aspect are elementary discussed,getting some interesting results. Primary result are sum up below:(1) This model can preferably simulates summer average circulation of globe scale, well and truly predicts activity center on high, midst and low troposphere of atmosphere circulation, but among different weather climate systems, their location and intensity have some error. For temperature and precipitation, this model has some simulation ability, but results great away from practicality observation data.(2) The precipitation of East area from this model is distinctness excessive,and there exists one nonexistent precipitation center on east Tibet plateau. The error of convective-precipitation makes up to ninety percent of total precipitation error , but large-scale precipitation only very small percents.And results from cloud cover, surface soil water, surface sensible heat flux and surface latent heat flux indicate that their have some effects on local precipitation simulation.(3) Systematic error and random error have the same order of magnitude, but random error is slight more than systematic error. From the error equation, the factors dominate evolvement of systematic error and random error are convergenc-divergence of flux term, mutual conversion term, barotropic generation term and source-sink term. But their effect are different from different simulation phase.The mechanism of evolvement of systematic error and random error aren’t sameness, the most discrepancy is that mix-generation term accelerates systematic error development the whole simulation period, but holds back for random error. There exists conversion between systematic error and random error, and among conversion term, latitude wind systematic error is dominating.(4) Research of the predictability of sea mean pressure, 500hPa geopotential height, precipitation, 850hPa temperature and surface soil indicate predictability of sea mean pressure fastens on tropic, low predictability is extratropical area. Predictability of 500hPa geopotential height locates tropic, exhibiting belt form. The range of predictability of precipitation is narrow. Predictability of temperature is on tropic Pacific ocean area, and some area of north American has some predictability. Predictability of soil is on mostly land of east Asian and north American.Taking the 500hPa geopotential height for example,analysising the predictability from different climate backgrounds indicate, predictability in ENSO year is 0.2 more than other backgrounds on tropic .Predictability on extratropic of the northern hemisphere is smaller than others. Predictability from ENSO year has the same shape from not ENSO but greatly different from not ENSO year.(5) Initial atmosphere anomaly has greatly effect on summer seasonal predict and this effect varies among different variables. To sea mean pressure, greatly influence are Atlantic and south Pacific ocean.Impact on geopotential height most covers north Pacific ocean and Atlantic, but area is wider than sea mean pressure, and its effect on the top of troposphere are greater than of midst and low. Impact on wind is smaller than the former two variables. Effect of initial atmosphere anomaly on east Asian is morer than globe average. Effect on geopotential height is even evident in the year climate varied greatly. Result from typical years shows that model can successfully simulate interannual change of wind direction on tropic troposphere and stratosphere , proving that the effect of Initial atmosphere anomaly is even distinctness in typical year, and interannual change of summer latituide wind on tropic troposphere and stratosphere incl更多还原