权重分布法集成预报试验

该工作提出了以历史预报评估参数为权重的权重分布客观集成预报方法 ,用该方法对 6种汛期预报方法 1 984～ 1 998年和 8个单位 1 995～ 1 998年的汛期预报进行了集成预报试验 .结果表明 ,经权重分布集成预报以后预测水平有明显提高 ,而且效果相对稳定 .权重分布集成预报方法指导思想明确 ,可行性强 ,可用于实际业务预报     

南海北部陆坡海域内波谱特征

本文对1998年南海季风实验中定点观测的声学多普勒流速剖面仪（Acoustic Doppler Current Profiler,ADCP）海流数据进行频谱分析,结果表明南海北部地区内波之间的非线性作用的强弱影响着该海域的内波谱特征。在季节性温跃层（水深22m和58m）中,由于存在着强的非线性作用,内波带的谱斜率趋于σ^-1和σ^-2之间,而且较高能量的潮谐波频率的峰值随着频率呈现少见的一。递减。在季节性温跃层（水深130m）以下,内波非线性相互作用较弱,观测的内波带谱特征与标准Garrett-Munk内波谱相似,均显示了σ^-2的谱斜率。     

南海东北部内潮的模态结构和传播

The evolution of energy, energy flux and modal structure of the internal tides(ITs) in the northeastern South China Sea is examined using the measurements at two moorings along a cross-slope section from the deep continental slope to the shallow continental shelf. The energy of both diurnal and semidiurnal ITs clearly shows a～14-day spring-neap cycle, but their phases lag that of barotropic tides, indicating that ITs are not generated on the continental slope. Observations of internal tidal energy flux suggest that they may be generated at the Luzon Strait and propagate west-northwest to the continental slope in the northwestern SCS. Because the continental slope is critical-supercritical with respect to diurnal ITs, about 4.6 kJ/m~2 of the incident energy and 8.7 kW/m of energy flux of diurnal ITs are reduced from the continental slope to the continental shelf. In contrast, the semidiurnal internal tides enter the shelf because of the sub-critical topography with respect to semidiurnal ITs.From the continental slope to the shelf, the vertical structure of diurnal ITs shows significant variation, with dominant Mode 1 on the deep slope and dominant higher modes on the shelf. On the contrary, the vertical structure of the semidiurnal ITs is stable, with dominant Mode 1.     

1993年北半球环流特征及其对我国天气气候的影响

１９９３年北半球主要环流特征表现为：５００ｈＰａ副产持续加强西伸，位置偏南；亚洲中纬度春，夏经向环流发展，东亚太平洋遥相关型稳定；西藏高原５００ｈＰａ位势高度持续偏高，印缅槽持续偏弱；１００ｈＰａ位势高度场低纬持续偏高，中，高纬持续偏低，夏季南亚高压位置异常偏高。热带海洋出现明显异常，一次新的厄尔尼诺现象发生。热带海洋和北半球大气环流的异常对我国天气气候产生明显影响。     

Rossby波临界周期与海面高度异常能谱临界周期在南海的空间分布特征

本文利用WOA01(the Word Ocean Atlas 2001)海水各层气候态温盐数据计算南海Rossby波临界周期,并与其在同纬度西北太平洋中的分布对比.结果显示,在南海中Rossby波临界周期随纬度增加而逐渐增加,并且由于南海的特殊地形,海盆中Rossby波临界周期呈北东-南西向分布,与其在大洋中呈纬向带状分布不同.通过分析南海各网格点上海面高度异常(SSHA,the sea surface height anomaly)的能谱,我们发现在海盆中部其临界周期与当地Rossby波临界周期基本相同,其值也随纬度增加而逐渐增加,因而从观测上验证了模式结果,即在海面风应力旋度能谱临界周期小于等于当地Rossby波临界周期的条件下,海洋响应能谱临界周期等于当地Rossby波临界周期.     

不同来源月平均环流资料的差异

本文对1987年7—12月来源于B模式,欧溯中心、美国华盛顿数值预报客观分析和人工读数的北半球海平面气压(SLP)、500、100hPa月平均环流资料的差异作了统计分析。结果表明,从大范围和总趋势来看,不同来源的资料基本上是一致的,但洋面上和低纬、高凉地区差别比较明显,其中100hPa的差异最失,使用时需加以注意。     

海洋中尺度涡的机械能及其源汇研究*

由于观测手段的限制,海洋中尺度涡的能量输送及生成与耗散动力过程一直是世界大洋能量循环中悬而未决的一个问题,而中尺度涡在海洋中又广泛存在,它不仅占据海洋表层动能的绝大部分,而且是能量级串中连接大尺度和小尺度的中间环节,在大洋能量传输中扮演着重要的角色。文章以中尺度涡场机械能的大小、分布、源汇为主线,结合作者在这方面的最新研究成果,综述当前对中尺度涡机械能及其源汇的研究进展。     

Nonlinear interactions among internal tidal waves in the northeastern South China Sea

We used a set of 75-day long ADCP data from the northeastern South China Sea (SCS) to investigate nonlinear interactions among freely propagating internal tidal waves. The kinetic energy spectra displayed significant peaks at some higher tidal frequencies, such as O₁M₂ (O₁+M₂), and M₄ (M₂+M₂), where O₁ is the lunar diurnal internal tide, M₂ is the lunar semidiurnal internal tide, and M₄ is the first higher harmonic frequency of M₂. These higher tidal harmonic frequency peaks, as well as the fundamental tidal harmonic peaks, show a σ ^−2.3 spectral falloff rate with frequency. In addition, we explored the possible generation mechanism of higher tidal harmonics. Analysis on the rotary and bicoherence spectra suggests that strong forced non-resonant interaction induced by nonlinear advections was the dominant physical mechanism that induced these higher tidal harmonics. Moreover, the energetic, freely propagating semidiurnal (M₂) internal tidal wave played the most crucial role in these interactions. These results indicate that strong nonlinear forced non-resonant interactions among internal tides can be one of the processes responsible for the redistribution of energy in the internal wave spectrum.     

南海北部相干内潮和非相干内潮演变特征

通过南海北部跨越陆坡和陆架区的3套潜标数据,对全日和半日相干、非相干内潮的动能变化特征进行了研究。研究表明,全日内潮沿陆坡区向陆架区传播的过程中,在陆坡区主要以全日相干内潮生成为主,平均动能生成率为2.32 J/（m3·s）;在陆架区以全日相干内潮耗散为主,平均动能耗散率为0.44 J/（m3·s）。全日非相干内潮动能在陆坡和陆架区均增长,平均动能生成率分别为0.39 J/（m3·s）和0.03 J/（m3·s）。全日与半日相干内潮动能在陆坡和陆架区的表现不同,陆坡区的全日相干内潮动能明显大于陆架区的全日相干内潮动能,而半日相干内潮动能在陆坡和陆架区没有明显差别;陆架区的全日和半日非相干内潮动能要大于陆坡区的全日和半日非相干内潮动能。