西北太平洋海域风浪、涌浪、混合浪波浪能资源特征   总被引：1，自引：0，他引：1  

郑崇伟  游小宝  陈晓斌  李燕 《气象科学》2014,34(4):408-413

用ECMWF的ERA-40海浪再分析资料,应用波浪能流密度计算方法,对西北太平洋海域的风浪能、涌浪能、混合浪能展开研究。结果表明:(1)波浪能流密度呈现出显著季节性差异。混合浪能流密度表现为冬高夏低;春、夏、秋季的涌浪能流密度明显大于风浪能流密度,冬季相反;(2)混合浪能流密度的大值区主要分布于阿留申群岛附近海域,高值中心可达60 kW/m以上;近海的大值区主要分布于琉球群岛—巴士海峡—传统的南海大风区一带,年平均值在4 kW/m以上,南海北部可达12 kW/m以上;(3)黄渤海的涌浪和混合浪能流密度峰值出现在8—9月,波谷出现在6月。风浪能流密度峰值出现在11月—次年3月,波谷出现在6—8月,均呈现双峰型月变化特征。东海、南海北部、南海中南部海域能流密度的月变化特征相似,都为双峰型,12月—次年4月的能流密度整体较高,波峰出现在12月,波谷出现在5—7月;(4)2 kW/m以上混合浪能流密度出现的频率较高,近海低于大洋;(5)0.5 m以上有效波高出现的频率都非常高,中国近海稍低于大洋;(6)涌浪能流密度的稳定性明显好于风浪能流密度;大洋的能流密度稳定性明显强于近岸。1月份能流密度的稳定性最好,4月和7月次之,10月的稳定性最差。  相似文献   

基于非均匀水体对比度传输方程的海水透明度计算试验          下载免费PDF全文

李妍  陈希  于斌  钟奕飞 《大气科学学报》2014,37(6):767-771

针对均匀水体假设的海水透明度经验计算公式不具有普适性的缺点,将海水在垂直方向上分为若干光学性质相近的均匀层,推导出非均匀水体中目标对比度传输方程,在此基础上,建立了海水透明度的计算模型。利用BROKE_WEST_ACS实测的海水固有光学性质数据和透明度盘观测数据,对计算模型进行了数值试验和效果分析。结果表明:模型计算值与透明度盘实测值平均相对误差为9.1%;该模型既克服了透明度盘测量易受天气状况和人眼差异影响较大的缺点,又突破了均匀水体透明度计算方法的局限性。  相似文献   

The Seasonal Variabilities in the Concentration of Atmospheric Aerosols over Qingdao, China   总被引：2，自引：0，他引：2  

SHENG Lifang FU Ying QIU Mingyan GAO Huiwang 《中国海洋大学学报(英文版)》2005,4(4):383-390

Mass concentrations of Total Suspended Particles （TSP） and size-segregated particles were obtained from July 2001 to June 2002 in Qingdao to characterize the seasonal variations of atmospheric aerosols and to show the impact of dust events on the air quality in Qingdao. Data on size-segregated aerosols show that 73.74% of the TSP mass concentration is contributed by particles with diameters less than 11 μm. Particles with diameters less than 1.1μm have a higher concentration during the winter. In spring, larger particles tend to have higher mass concentrations. Bimodal particle size distributions have been observed, with maxima around 4.7-7 μand 0.43-0.65 μm in the winter season, and 7-11 μm and 0.65-1.1 μm in the autumn season. Measurements made during the dust events in March 2002 show high concentrations of particles in the size range 2.1-7μm.  相似文献   

双基地激光测风雷达回波信号仿真研究          下载免费PDF全文

李绍辉  孙学金  邵连军  易欣  张传亮 《气象科学》2023,43(4):523-533

本文针对传统的体散射模型并未考虑大气不均匀性对信号传输的影响等问题,通过引入垂直非均匀的大气参数改进了模型,并利用其建立了体目标的双基地激光测风雷达方程,仿真了侧向散射回波信号,并与单基地雷达进行了对比分析。研究表明:水平方向上,双基地激光测风雷达的回波信号分布特征与单基地雷达差异较大,其回波信号等值线在近地面为卵形线,随着探测高度的增加,回波信号等值线逐渐变为以主、被动雷达为焦点的椭圆形,并最终趋近于圆形;垂直方向上,双基地激光测风雷达的回波信号随高度衰减剧烈,近地面的回波能量约为10^-10 J,4 km高度的回波能量约为10^-15J,在中低层大气(0~10 km),回波信号中气溶胶散射占比大,在高层大气(10 km以上),分子散射占比大。  相似文献   

非洲地形对印度夏季风影响的数值试验   总被引：1，自引：0，他引：1  

余沛龙  王丽琼  张立凤  左瑞亭 《干旱气象》2013,(1):10-17

利用IAP9L AGCM模式对印度夏季风风场进行了数值模拟,基本上模拟出了印度夏季风系统中各风系分布;在此基础上,通过改变模式中非洲大陆的地形高度,设计了一组地形敏感性试验,对比了敏感性试验和控制试验的结果,分析非洲地形高度对印度夏季风的影响。结果表明,非洲地形高度升高使得阿拉伯海热带区域、南印度洋副热带区域和非洲大陆东南部在低层分别出现异常反气旋、气旋和反气旋环流,这些异常环流使非洲大陆东岸的越赤道气流增强,阿拉伯海热带地区的西风气流增强;地形升高也会使印度半岛区域低层水汽通量辐合增强,整层垂直上升速度加强,降水增加,故非洲地形升高最终导致了印度夏季风增强;而非洲地形高度降低,则情况相反,这充分说明了非洲大陆地形是印度夏季风形成的关键因子。  相似文献   

Forecasting the western Pacific subtropical high index during typhoon activity using a hybrid deep learning model     

Jianyin Zhou  Mingyang Sun  Jie Xiang  Jiping Guan  Huadong Du  Lei Zhou 《海洋学报(英文版)》2022,41(4):101-108

Seasonal location and intensity changes in the western Pacific subtropical high(WPSH) are important factors dominating the synoptic weather and the distribution and magnitude of precipitation in the rain belt over East Asia. Therefore, this article delves into the forecast of the western Pacific subtropical high index during typhoon activity by adopting a hybrid deep learning model. Firstly, the predictors, which are the inputs of the model, are analysed based on three characteristics: the first...  相似文献   

Density currents in the two-layer flow: an example of Dardanelles outflow     

《Oceanologica Acta》2003,26(3):243-253

Observations from hydrographic surveys are used to describe the density current flowing through the Dardanelles strait into the Marmara Sea. Aegean water plunges below the surface and flows into the Marmara Sea. This flow joins into the Marmara Sea as a negatively buoyant plume and sinks through the deeper parts. Seasonal variation in the incoming water density results in the observing mainly two different forms of the density current in this area. These two forms are boundary currents and intrusion. Boundary currents were observed as a dense bottom current during the winter when the inflowing water density attains to annual maxima and as an overflow during the autumn when the inflowing water density drops to annual minimum. Intrusion form of the density current was observed during the summer.  相似文献   

Tropical Atlantic variability and coupled model climate biases: results from the Tropical Atlantic Climate Experiment (TACE)     

W. E. Johns  P. Brandt  P. Chang 《Climate Dynamics》2014,43(11):2887-2887

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PLANETARY BOUNDARY LAYER HEIGHT MEASURED BY A WIND PROFILER BASED ON THE WAVELET TRANSFORM     

艾未华  戈书睿  魏浩  胡明宝 《热带气象学报(英文版)》2017,23(4):396-407

Planetary boundary layer height (PBLH) is an important input parameter for any boundary layer study or model, either climate or atmospheric. The variation of the PBLH is also of great significance to the physical processes of numerical prediction, diagnosis of weather forecasting and monitoring urban pollutants. However, effective ways to monitor the PBLH continuously are lack. Wind profilers are commonly used in monitoring PBLH continuously because of its high temporal and spatial resolution, coupled with capability of continuous detection. In this paper, the covariance wavelet transform (CWT) is used to analyze the range-corrected signal-to-noise ratio (SNR) of the wind profiler to determine the PBLH, which is then compared with the results measured by the gradient method and the radiosonde. The conclusions are as follows: (1) The scaling parameter a and translation parameter b of the wavelet are critical in determination of the PBLH by applying the CWT as different values may get completely different results, which requires to select appropriate values in the calculation carefully. (2) Quality control is crucial in determining the PBLH because good quality control can help remove mutation points, which makes the determined PBLH more consistent with the actual situation. (3) In clear-air, the gradient method is not applicable if the boundary layer turbulence is inhomogeneous and the impact of noise is large for that it is easy to be impacted by the mutation of SNR caused by the atmosphere turbulence instability and other factors, which will cause large errors, while the CWT method as an improvement of the gradient method can determine the PBLH quite well. (4) Through quality control, the PBLHs determined by the CWT are consistent with those of radiosonde, and the correlation coefficient between them is 0.87.  相似文献   

THE CONTRASTS BETWEEN STRONG AND WEAK MJO ACTIVITY OVER THE EQUATORIAL WESTERN PACIFIC IN WINTER     

陈雄  李崇银  谭言科  郭文华 《热带气象学报(英文版)》2017,23(2):133-145

This paper investigates the contrasts between strong and weak Madden-Julian Oscillation (MJO) activity over the equatorial western Pacific during winter using the NCEP reanalysis data. It is shown that the MJO over the equatorial western Pacific in winter shows significant interannual and interdecadal variabilities. During the winters with strong MJO activity, an anomalous cyclonic circulation lies east of the Philippines, strong anomalous easterlies control the equatorial eastern Pacific, and anomalous westerlies extend from the Indian Ocean to the western Pacific in the lower troposphere, which strengthens the convergence and convection over the equatorial western Pacific. The moisture convergence in the lower troposphere is also enhanced over the western Pacific, which is favorable to the activity of MJO. Eastward propagation is a significant feature of the MJO, though there is some westward propagation. The space-time spectral power and center period of the MJO are higher during strong MJO activity winters. The anomalous activity of MJO is closely related to the sea surface temperature (SST) and East Asian winter monsoon (EAWM). During strong MJO activity winters, there are positive/negative anomalies at high/low latitudes in both sea level pressure and 500 hPa geopotential height, and the temperature is lower over the central part of the Chinese mainland, which indicates a strong EAWM. China experiences more rainfall between the Yellow and Yangtze Rivers, but less rainfall south of the Yangtze River. The SSTA is negative near the Taiwan Island due to the impact of strong EAWM and shows a La Ni?a pattern anomaly over the eastern Pacific. During the weak MJO activity winters, the situation is reversed.  相似文献