全球大洋季节内尺度上海-气相互作用特征分析

判定局地海-气相互作用的特征对海-气耦合模式中应用哪种形式的“强迫模拟”具有重要指导作用。本文根据海表热通量异常与海表温度异常及海表温度变率之间的相关关系,对全球大洋季节内尺度上的海-气相互作用特征进行了综合分析。结果表明:(1)南、北半球亚热带地区海-气相互作用的特征主要表现为大气对海洋的强迫,且在夏季(北半球为6—8月,南半球为12—翌年2月)强迫作用的范围最大,冬季强迫作用的范围最小;(2)赤道中、东太平洋及赤道大西洋地区海-气相互作用的特征全年表现为海洋对大气的强迫,印度洋索马里沿岸、阿拉伯海以及孟加拉湾地区仅在6—8月表现出海洋强迫大气的现象,而孟加拉湾则在9—11月表现为大气强迫海洋;(3)45°N(S)以上的高纬度地区海表温度的异常和变率无法用局地热通量的交换来解释,这是因为该区域海表温度的变化主要由平流等海洋内部动力过程决定,因此海-气之间在季节内尺度上的相互作用不明显。在某些海区,季节内尺度上的海-气相互作用关系与季节以上时间尺度的这种关系可能会有明显不同。     

Albedo of clouds and radiation conditions in the oceans

On the basis of the satellite and ship data of many-year observations, we parametrize the albedo of the ocean-atmosphere system both for the conditions of “fair weather” and for the maximum and climatic optical thicknesses of oceanic clouds. These results are used to develop a procedure of practically exact reconstruction of the monthly average fluxes of integral solar radiation and the radiation budget over the ice-free surface of the oceans according to the data of satellite measurements of albedo (Nimbus NOAA satellite, 1974–1983) for arbitrary conditions of transparency of the atmosphere and cloudiness. We determine the current and climatic monthly average values and the characteristics of interannual variability of all components of the radiation mode of the ocean-atmosphere system with a spatial resolution of 500×500 km. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

一种新型海-气湍流通量参数化方案的模式测试

将一种新型湍流通量参数化方案代入到大气环流模式CAM3中,对比分析了模式改进前后模拟的风应力、感热通量、潜热通量和降水的全球分布,以及风应力、潜热通量和降水的纬向平均。结果表明:改进后模式的模拟结果更接近ERS、ERA40湍流通量数据和CMAP综合降水数据,其中对西风带上洋面风应力、亚洲季风区的潜热通量和降水改进明显。由于该新型湍流通量参数化方案直接由整体理查逊数、空气动力学粗糙度和热力学粗糙度参数化稳定度参数,避免了通过循环迭代计算Obukhov长度,计算效率得到提高。     

基于CMIP5资料的热带大洋非均匀增暖及其成因的分析

利用第五次耦合模式比较计划(coupled model intercomparison project phase 5,简称CMIP5)中的月平均资料,基于合成分析、相关分析等现代气象统计方法,对热带太平洋、印度洋和大西洋年平均海温增暖不均匀特征及其成因进行分析。9个海洋模式集合的平均结果表明:在全球增暖背景下,3个热带大洋的海温增暖均表现出不均匀性,且增暖原因存在较大差异。热带太平洋赤道及其以北地区以海洋动力作用为主,赤道以南地区则以大气热力作用为主,而且海水上翻/下沉运动对海温增暖的作用在东、西太平洋之间存在明显差异;热带印度洋大面积海域的海温变化难以通过海气热通量交换来解释,海水上翻/下沉运动与温度平流对海温增暖的作用比较一致(二者同时利于海温增暖);热带大西洋赤道附近地区的海温增暖是表层温度平流和上翻/下沉运动共同作用的结果,赤道以北的大西洋海温变化则以温度平流的作用为主,而赤道以南的大西洋海温的变化主要是海水上翻/下沉作用引起的。     

Performance of a numerical short-wave model

A numerical short-wave model system based on the Boussinesq equations is verified against analytical as well as experimental results for shoaling, refraction, diffraction and partial reflection processes. It is shown that engineers can confidently and responsibly apply such a model system to the study of wave disturbance in coastal regions.     

On the parameterization of drag coefficient over sea surface

Six parameterization schemes of roughness or drag coefficient are evaluated on the basis of the data from six experiments. They present great consistency with measurement when friction velocity u*<0.5 m/s (approximately corresponding to 10 m wind speed U10 <12 m/s) and large deviation from measurement when u*≥0.5 m/s (approximately U10≥12 m/s). In order to improve the deviation, a new parameterization of drag coefficient is derived on the basis of the similarity theory, Charnock relationship and Toba 3/2 power law. Wave steepness and wind-sea Reynolds number are considered in the new parameterization. Then it is tested on the basis of the measurements and shows significant improvement when u*≥0.5 m/s. Its standard errors are much smaller than the ones of the other six parameterizations. However, the new parameterization still needs more tests especially for high winds.     

Observation of clouds and solar radiation over the Pacific Ocean as relation to global climate

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Effects of vertical mixing parameterization on the mixed layer depth over the North Pacific in a global OGCM

We present MLD variability over the North Pacific Ocean in a global ocean general circulation model and impacts of three different vertical mixing schemes on it, based on statistical measures (annual mean difference, root-mean-square difference and correlation coefficient). The constant vertical mixing scheme tends to underestimate MLD over the whole basin. The Pacanowski-Philander scheme tends to overestimate MLD (> 20 m) in the mid- to high latitude during summer, implying that vertical mixing in the mid- to high latitude may not be represented properly by simple internal mixing mechanisms such as stratification or vertical shear of horizontal velocity. On the other hand, the new vertical mixing scheme (Noh et al. 2002) gives the most consistent MLD and its seasonal and spatial variability when compared with observation. These results suggest that parameterization of vertical mixing has significant effects on simulation of the seasonal and spatial variability of MLD over the North Pacific Ocean.     

Synthesis of symmetric flattop radiation patterns

In this communication, the design of ring arrays that produce symmetric flattop radiation patterns with low sidelobes is presented. The equivalent linear array approach is used in the design of the array. A newly developed iterative algorithm is employed to obtain a prototype linear array that generates a desired flattop pattern. A new concept of common scale factor of ring arrays is introduced, which not only adds flexibility to the design, but also reduces the complexity of the array. In the design examples presented, it is shown that an almost flattop pattern with maximum ripple less than 0.075 dB and sidelobe levels less than 28 dB can be achieved using only 10 ring radiators     

WRF模式中台风"启德"模拟对 参数化方案的敏感性分析

为准确模拟台风路径和强度,采用WRF模式比较不同微物理过程和积云对流过程参数化方案对台风路径和强度模拟的影响,并基于集合预报方法考虑对台风预报系统误差进行优化。选用4种微物理过程方案和3种积云对流参数化方案,针对1213号台风“启德”进行模拟,结果表明不同的参数化方案对台风路径和强度的预报结果有明显影响,积云对流过程参数化方案相对于微物理过程参数化方案更加敏感。基于不同参数化方案扰动成员的集合平均预报方法,对于台风路径和强度的模拟误差均有明显改善,台风路径误差随时间增幅较小,其结果优于全部12个单方案试验的模拟结果;从台风强度方面来看,基于集合预报方法模拟得到的台风强度变化趋势与实况结果一致,且误差较小,优于大多数试验方案。结果表明:采用不同微物理过程和积云对流过程参数化方案的组合构建的集合预报模型,对于台风路径和强度的模拟均有一定程度改善,减小了采用不同参数化方案产生的路径不确定性,使其在台风“启德”的路径模拟上与实况更为接近,可为提升台风预报能力提供科学参考。     

A new parameterization of surface drag in the marginal sea ice zone

A parameterization of subgridscale surface fluxes over the marginal sea ice zone which has been used earlier in several studies is modified and applied to a nonhydrostatic mesoscale model. The new scheme accounts for the form drag of ice floes and is combined with a so-called flux averaging method for the determination of surface fluxes over inhomogeneous terrain. Individual fluxes over ice and water are calculated as a function of the blending height. It is shown by comparison with observations that the drag coefficients calculated with the new parameterization agree well with data. The original scheme strongly overestimates the form drag effect. An improvement is mainly obtained by an inclusion of stratification and by use of a more adequate coefficient of resistance for individual ice floes. The mesoscale model is applied to off-ice flows over the polar marginal sea ice zone. The model results show that under certain meteorological conditions the form drag can have a strong influence on the near-surface wind velocity and on the turbulent fluxes of momentum. Four case studies are carried out. The maximum influence of form drag occurs in the case with strong unstable stratification and with wind oblique to the ice edge. Under these conditions the wind stress on sea ice is modified by at least 100% for ice concentrations less than 50% if form drag is taken into account.     

Effects of solar radiation on dimethylsulfide cycling in the western Atlantic Ocean

The influence of solar radiation on springtime rates of photochemical and biological consumption of dimethylsulfide (DMS) in surface waters from the western Atlantic Ocean was examined by exposing 0.2 μm filtered and unfiltered surface seawater to natural sunlight at five depths in the upper 30 m. Parallel deck incubations of 0.2 μm filtered seawater under various long-pass optical filters were also carried out to aid in assessing the wavelength dependence of DMS photolysis. DMS photolysis rate constants for mid-day exposure (∼10:30–17:30 local time) to surface irradiance ranged from 0.026 to 0.086 h⁻¹ and were highest in coastal and shelf waters. Photolysis rate constants decreased with increasing irradiation depth, in accordance with the attenuation of ultraviolet radiation (UVR, 280–400 nm). Total DMS consumption rates (photochemical+biological) in unfiltered surface samples also decreased with increasing incubation depth and were larger than photolysis rates at nearly all depths and all stations. The decrease in photolysis rate constants with exposure depth was mirrored by biological DMS consumption rate constants that were severely inhibited at surface irradiances, and approached or exceeded dark rate constants at deeper exposure depths. Photolysis rates were 2–19 times greater than estimated biological consumption rates in the surface light exposed samples, while biological consumption rates were significantly larger than photolysis rates at incubation depths below the 1% light level for UV–B radiation (280–320 nm). Total DMS loss rates increased up to nine-fold with UVR exposure, but changes in DMS concentrations were not strongly correlated to light dose, presumably due to parallel, light-mediated DMS production processes. The primary loss process for DMS depended mainly on the depth interval considered and the attenuation of UVR; in general, photochemical removal dominated shallow layers characterized by high UV–B intensities, whereas biological removal dominated in deeper layers where UV–B was absent, but UV–A (320–400 nm) and visible (400–700 nm) light fluxes were still relatively high. These results demonstrate that UVR exposure significantly influences the spatial and temporal pattern of DMS production and loss processes, and ultimately the DMS flux to the atmosphere.     

Biorobotic AUV maneuvering by pectoral fins: inverse control design based on CFD parameterization

Biologically inspired maneuvering of autonomous undersea vehicles (AUVs) in the dive plane using pectoral-like oscillating fins is considered. Computational fluid dynamics are used to parameterize the forces generated by a mechanical flapping foil, which attempts to mimic the pectoral fin of a fish. Since the oscillating fins produce periodic force and moment of a variety of wave shapes, the essential characteristics of these signals are captured in their Fourier expansions. Maneuvering of the biorobotic AUV in the dive plane is accomplished by periodically altering the bias angle of the oscillating fin. Based on a discrete-time AUV model, an inverse control system for the dive-plane control is derived. It is shown that, in the closed-loop system, the inverse control system accomplishes accurate tracking of the prescribed time-varying depth trajectories and the segments of the intersample depth trajectory remain close to the discrete-time reference trajectory. The results show that the fins located away from the center of mass toward the nose of the vehicle provide better maneuverability.     

TMI、AMSR-E全球海表温度与Argo近海表温度的比较

本文将TMI（Tropical Rainfall Measuring Mission （TRMM）Microwave Imager）和AMSR-E（Advanced Microwave Scanning Radiometer for the Earth Observing System）卫星观测的全球海表温度与Argo浮标观测的近海表温度进行了比较。并检验了影响海温变化的因素,包括风速、水汽含量、液态云和地理位置。结果显示,TMI、AMSR-E海表温度与Argo近海表温度均明显相关。在低风速时,TMI、AMSR-E海表温度整体比Argo近海表温度高。在低风速时,TMI比AMSR-E海表温度更接近Argo近海表温度,但TMI海表温度在高纬可能没有经过良好校正。温度差异显示,在低水汽含量时,TMI和AMSR-E海表温度显示出暖的差异,代表TMI和AMSR-E海表温度在高纬均没有经过良好校正。黑潮延伸区的海表温度变化要比海潮区明显。春季在黑潮延伸区,卫星观测的海表温度与Argo近海表温度差异较小。在低风速时,TMI和AMSR-E海表温度均经过了良好校正,而TMI比AMSR-E效果更好。     

On the essential differences between the large-scale variations of the surface temperature over the oceans and continents

The characteristic features of the surface temperature variability in the Northern Hemisphere are studied on the secular time scale. The trends of the temperature anomalies over the continents and oceans were found to be opposite. The present global warming is concluded to be caused by the large-scale redistribution of heat in climatic system, indicating a compensative character of the variations observed. The dynamics of the longitudinal and latitudinal gradients of the surface temperature anomalies were analyzed. It was found that the dynamics of these gradients and the changes in the climate phases on the scales of the Northern Hemisphere are correlated. The present state of the climatic system is discussed, and it is concluded that a change in the climatic scenario in the nearest future is possible.     

渤海海冰中太阳辐射的光谱特征观测研究

通过采用多光谱仪器,对渤海营口港一带的近岸固定冰进行了3个站位11个谱段的入射辐射、反射辐射和透射辐射随时间变化过程的观测和研究。结果表明,发生在海冰中的反射辐射和透射辐射与入射太阳辐射的谱分布有明显差别,而且有显著的日变化。文章确立了入射辐射、反射辐射和透射辐射随时间的变化与太阳高度角的正弦成精确的线性关系,海冰的积分反照率与太阳高度角的正弦满足二次函数关系,可将不同时刻的观测值归算到正午时刻的辐射值,使不同时刻的观测结果具有可比性。计算结果表明,海冰只衰减特定强度的辐射,衰减量与入射辐射光谱分布以及辐射的强度无关,导致绿光的透射辐射最强。该文是对渤海海冰透射辐射的初步尝试,所获得的结果对未来大范围海冰光学观测打下了基础。     

影响东海气候的太阳活动信息分析

采用逐次滤波法逐次提取东海气温资料序列中蕴涵的太阳活动影响信息并加以分析,发现东海气候年代际变化特征十分清楚,主要表现为:(1)突变性,东海夏季7月海平面层及对流层大气温度场在过去半个多世纪中发生过一次急剧变化,突变点是1978年7月.从1978年7月由历时30多年的温度偏低时期跃变为持续高温时期,高温期持续至20世纪末,升温幅度超过0.4℃.资料分析表明,整个对流层东海夏季大气温度都具有这种年代际变化特征;(2)高空气候持续增温型,东海夏季7月平流层中部10 hPa大气温度表现为一种波动式的持续升温过程,50多年来温度升高4℃,年升温率超过0.075℃/a.东海平流层底部100 hPa温度也具有持续升温的特点,从1948年至今呈缓慢升高的趋势,53 a升高了1.9℃,升温率为0.036℃/a;(3)周期性,东海不同高度大气温度都具有显著程度不同的22 a周期性年代际变化特征,22 a周期分量的振幅由高空到低空迅速减小,表明22 a周期高空清楚,低空不太明显.东海对流层中部和平流层底部还具有显著的11 a周期性年代际变化.据分析认为22 a周期是太阳黑子磁场磁性变化周期所激发,11 a周期与太阳黑子相对数11 a周期相吻合,二者均为太阳活动在大气气候中的反映.     

Fragmentation in high seas fisheries: Preliminary reflections on a global oceans governance approach

Notwithstanding the wide range of actions taken to strengthen the legal regime of international fisheries, overexploitation and the risk of depletion of stocks have been strong concerns for decades. Indeed, the regime of international fisheries law is currently not rooted in sustainability, and it does not adequately take into consideration the impact of fishing activities on the wider marine environment. One of the main causes lies in fragmentation of international fisheries law: a lack of coordination between instruments and institutions, and gaps in effective coherent structures for fisheries management. Areas beyond national jurisdiction (ABNJ), including the high seas, are particularly prone to this lack of coordination and integration.One alternative to reach a durable management of high seas fisheries might be found in a ‘global oceans governance approach’. This paper explores how this approach could impact the fragmented regime of fisheries. It suggests that governance-based perspectives underline concepts rooted in adaptability and interactions, concepts that suggest to approach international fisheries law not as a static set of rules but as an evolutive process. Reflecting on an overarching goal of coordination and possible management challenges in ABNJ provides an interesting starting point to develop a comprehensive understanding of the impacts of oceans governance on the fragmented legal regime of high seas fisheries. We now need to see how to give effect to governance, a task that remains, at this point, a work in progress.