【作者】 姜华；

【导师】 吴德星；

【作者基本信息】 中国海洋大学 ， 物理海洋学， 2003， 博士

【摘要】 海表潜热和感热通量的时空变化研究是全球气候变化研究和气候系统能量平衡和淡水收支的重要方面。但受热通量资料质量的局限，目前关于热通量的时空变化的研究不多。基于海表潜热和感热通量的时空变化在全球变化中的重要性和海表潜热和感热通量研究对热通量资料产品精度的依赖性，本文重点就现有热通量资料产品的质量和热带大西洋海表潜热和感热通量的季节和年际变化开展较深入的研究。 以基于船测资料的SOC(Southampton Oceanography Center)和基于锚定浮标观测的PIRATA(Pilot Research Moored Array in the Tropical Atlantic)热通量产品为参照，对WHOI(Woods Hole Oceanography Institute)综合分析、NCEP1(NCEP/NCAR Reanalysis)和NCEP2(NCEP/DOE AMIP-Ⅱ Reanalysis)再分析热通量产品在热带大西洋的精度进行了评估。结果认为NCEP1和NCEP2产品中，由算法所带来的误差在信风区远远大于赤道区；在信风区，由算法所带来的误差是基本变量所带来的误差的3-4倍，在赤道区，为1-2倍。在热带大西洋大部分区域内，WHOI对湍动热通量的平均场和时间变化的估计精度要高于NCEP1和NCEP2产品。WHOI在信风区内对潜热通量的量值和时间变化的估计要好于赤道区。在赤道区，WHOI对海气湿度差的估计相对于PIRATA偏高，直接导致其对潜热通量的估计偏差。综合分析认为，WHOI热通量资料产品是目前各资料产品中最适合使用和值得信赖的资料产品。 分析确定了热带大西洋海表潜热和感热通量的季节变化的主要特征及其成因。发现在南北两信风区，风速和海气湿度差的变化几乎是同位相的，平均背景风速和海气湿度差都较大，他们互相加强彼此对潜热通量变化的贡献，所以海洋潜热损失最大是发生信风南北两区的各自风速和海气湿度差都较大的冬季。在赤道冷舌区，平均的背景海气湿度差比较小，所以平均风速背景下的海气湿度差的热带大西洋海表潜热和感热通量的季节和年际变化研究变化主导该区的潜热通量的变化。赤道冷舌区海表温度又主导着海气湿度差的变化，所以该区海洋的潜热损失最大发生海表温度最高的3一5月份。在气候平均的工TCZ区，平均的背景海气湿度差比较大，所以平均海气湿度差背景下风速的变化主导潜热通量的变化，因此该区潜热损失最大值发生在风速最大的6一8月份。在巴西以北的暖水区，尽管海气湿度差的变化和风速的变化都较大，但二者在区域内总是反相，彼此削弱了对潜热通量变化的贡献，所以该区潜热通量的变化振幅较小，最终由风速的变化主导潜热通量的变化。感热通量的变化主要由海气温差的变化主导。 借助SVD、EOF和MTM谱分析等分析方法，分析了热带大西洋潜热和感热通量年际变化的主要特征。发现湍动热通量的前两个EOF模态主要描述的是位于ITCZ南北两侧的信风区的湍动热通量的变化。第一模态EOF时间系数的M翎谱给出了约两个半月的周期变化和2一3年的准周期变化。第二模态给出了2一3年的变化信号。在赤道冷舌区，SST变化对湍动热通量的变化起主要作用，赤道冷舌区以外风速变化对潜热通量变化影响最大。基于图像分析，认为ITCZ位置和强度存在2一3年的变化周期，El Nino年ITCZ变化的南北跨度最小，推断Walker环流异常可能是ITCZ位置和强度年际变化的主要作用。 热带太平洋ENSO事件通过对Walker环流的调整减小热带大西洋ITCZ区的风速值，湍动热通量亦随之减小。热带大西洋的增暖事件中，东风减弱，西风加强，赤道冷舌区海洋的潜热和感热损失随SST的增暖而增大，ITCZ区海洋的潜热和感热损失则伴随着风速的减小而减小。SST Dipole年北半球异常的西南风导致湍动热通量在中非西海岸至ITCZ区的双倍减小，它会进一步扩大北半球的SST异常。 SST和湍动热通量的祸合场的第一模态所表征的是西风加强一冷舌区SST升高一海表潜热和感热损失在冷舌区增大的湍动热通量变化的驱动过程。在第二模态中，由SST Dipole驱动的越赤道的异常风，只在SST梯度较大的北半球ooN一10ON的区域较强。此异常风在柯氏力的作用下，在北半球形成与背景的东风反向的异常西风，使得ooN一10oN的风速减小，潜热通量减小，于是在该区域内形成的正的海表温度异常振幅被放大。 本文主要创新和贡献主要有以下几点。确定了各热通量资料产品的误差范围和其适用的对象，确定了计算误差和基本变量场存在误差间的比例;首次揭示了热带大西洋海表潜热和感热通量的季节和年际变化研究潜热和感热通量在热带大西洋5个不同的气候敏感区域的变化特征及成因:揭示了热带大西洋湍动热通量、SST和湍动热通量祸合模态及ITCZ位置和强度存在2一3年的年际变化，并确定出EI Nino年ITCZ变化南北跨度最小的现象;提出了热带大西洋类El Nino事件中，西风加强分冷舌区SST升高斗冷舌区海表潜热和感热热损失增加的湍动热通量变化的驱动过程。更多还原

【Abstract】 The knowledge of the surface air-sea heat fluxes variability on different space-time scales is vital to understanding the earth’s climate change and the balance of global energy and fresh water budget. The studies of heat flux space-time variability are limited because of the poor qualities of heat fluxes datasets. Based on the importance of heat flux variability to the earth’s climate change and the dependence of the study about heat flux variability on the accuracy of heat flux data, this study will focus on the quality evaluation of heat flux datasets available and seasonal and interannual variability of latent and sensible heat fluxes in the tropical Atlantic Ocean.The turbulent heat fluxes in WHOI (Woods Hole Ocean Oceanography Institute) synthesized fluxes product, NCEP1 and NCEP2 reanalysis fluxes product are evaluated using high-quality SOC flux climatology (Southampton Oceanography Center) which is constructed from ship observations and moored buoy observations PIRATA (Pilot Research Moored Array in the Tropical Atlantic) as the references. It is found that the biases in NCEP1 and NCEP2 turbulent heat fluxes from the biases in the algorithm used in flux calculation in trade wind regions are greater than equatorial regions. In trade wind regions, the biases in fluxes from the biases in algorithm are about 3-4 times of the biases in the fundamental flux-related variables and 1-2 times in equatorial regions. In the most area of tropical Atlantic, the evaluation of magnitude and time series trends of flux in WHOI are more accurate than NCEP1 and NCEP2. In equatorial regions, the air-sea humidity difference is overestimated in WHOI relative to PIRATA, which leads to the biases in latent heat flux. Generally, WHOI flux product is the most reliable and suitable for use.Seasonal variability of latent and sensible in the trade wind regions of tropical Atlantic is examined using WHOI flux product. It is found that the climatological mean of wind speed and air-sea humidity difference are both large, the variation of wind speed are almost in phase with air-sea humidity difference, yielding much larger or smaller latent heat flux. So the ocean release the most latent heat in its own winter of the two hemispheres when both wind speed and air-sea humidity difference are large. In equatorial region, the mean air-sea humidity difference is much smaller, so the variations of air-sea humidity difference under large mean wind speed dominate the variations of latent heat flux. The ocean release the most heat during the period from March to May, when SST is highest in the whole year because SST dominates the variation of air-sea humidity difference. In Climatological ITCZ, the mean air-sea humidity difference is greater relatively so that the variation of wind speed under large mean air-sea humidity difference is the main factor influencing the variation of latent heat flux. The latent heat loss is greatest from June to August when the windspeed is largest in the region. In the region north of Brazil, although both wind speed and air-sea humidity difference have dramatic variations, the variation of latent heat flux is just ordinary in magnitude. The reason is that the variations of wind speed and air-sea humidity difference are out of phase with each other so that they decrease each other greatly. The variation of wind speed dominates the variation of latent heat flux eventually. The variation of sensible heat flux is dominated by air-sea temperature difference.Interannual variability of turbulent heat fluxes is examined using SVD, EOF and MTM methods. It is found that two main EOF modes of turbulent heat fluxes mainly describe the flux variations in two trade wind regions. The MTM spectrum of the first time series of expansion coefficient shows a periodic signal at about two-to-three months and two-to-three years quasi-periodic signal (at the 95% level). The second mode shows a peak at 2-3 years. In equatorial cold tongue region, SST anomalies have great influence on the variation of turbulent heat fluxes. W更多还原