As concluded from physical theory and laboratory experiment,it is widely accepted that nonlinearities of sea state play an important role in the formation of rogue waves;however,the sea states and corresponding nonlin...As concluded from physical theory and laboratory experiment,it is widely accepted that nonlinearities of sea state play an important role in the formation of rogue waves;however,the sea states and corresponding nonlinearities of real-world rogue wave events remain poorly understood.Three rogue waves were recorded by a directional buoy located in the East China Sea during Typhoon Trami in August 2013.This study used the WAVEWATCHⅢmodel to simulate the sea state conditions pertaining to when and where those rogue waves were observed,based on which a comprehensive and full-scale analysis was performed.From the perspectives of wind and wave fields,wave system tracking,High-Order Spectral method simulation,and some characteristic sea state parameters,we concluded that the rogue waves occurred in sea states dominated by second-order nonlinearities.Moreover,third-order modulational instabilities were suppressed in these events because of the developed or fully developed sea state determined by the typhoon wave system.The method adopted in this study can provide comprehensive and full-scale analysis of rogue waves in the real world.The case studied in this paper is not considered unique,and rules could be found and confirmed in relation to other typhoon sea states through the application of our proposed method.展开更多
During the summer of 2008, the third CHINARE Arctic Expedition was carried out on board of Xuelong Icebreaker in the central Chukchi Sea. A submersible mooring system was deployed and recovered at Station CN-01 （71.4...During the summer of 2008, the third CHINARE Arctic Expedition was carried out on board of Xuelong Icebreaker in the central Chukchi Sea. A submersible mooring system was deployed and recovered at Station CN-01 （71.40.024＇N, 167.58.910＇W） with 33 days of the current profile records, and continuous observation of temperature and salinity data were collected. This mooring station locates in the blank of similar observation area and it is the first time for our Chinese to finish this kind of long-term mooring work in this area. This mooring system finished integrated hydrological observations with long-term continuous record of the whole profile velocity for the first time. Based on time series analysis of temperature, salinity, velocity and flow direction, we get the following main results. （1） During the observation period, the mean surface current velocity is 70.2 cm/s eastward, and velocity reaches its maximum in average at 3 m level with magnitude 90.0 cm/s, direction 206.. （2） In 9-30 m layers, the semidiurnal period variation is the most obvious, the flow direction is quite stable, and the flow is synchronous and consistent vertically. （3） Besides the semidiurnal period variation, the main variation in the upper layer is in 11-d period, with variations in period 5.5, 5.5, and 3.7 d, which reflect the influences of sea surface wind change and maintenance. （4） Near the bottom the temperature change is correlated and synchronized with the conductivity.展开更多
In this study, the simulating waves nearshore (SWAN) model with a locally refined curvilinear grid system was constructed to simulate waves in Jervis Bay and the neighbouring ocean of Australia, with the aim of examin...In this study, the simulating waves nearshore (SWAN) model with a locally refined curvilinear grid system was constructed to simulate waves in Jervis Bay and the neighbouring ocean of Australia, with the aim of examining the wave characteristics in an area with special topography and practical importance. This model was verified by field observations from buoys and acoustic Doppler profilers (ADPs). The model precisions were validated for both wind-generated waves and open-ocean swells. We present an approach with which to convert ADP-observed current data from near the bottom into the significant wave height. Our approach is deduced from the Fourier transform technique and the linear wave theory. The results illustrate that the location of the bay entrance is important because it allows the swells in the dominant direction to propagate into the bay despite the narrowness of the bay entrance. The wave period T p is also strongly related to the wave direction in the semi-enclosed bay. The Tp is great enough along the entire propagating direction from the bay entrance to the top of the bay, and the largest Tp appears along the north-west coast, which is the end tip of the swells’ propagation.展开更多
The Bohai Rim region is one the most important bases for commodity grain production in China. With the rapid pace of agricultural industrialization, nitrogenous fertilizer has been used at an ever increasing rate, whi...The Bohai Rim region is one the most important bases for commodity grain production in China. With the rapid pace of agricultural industrialization, nitrogenous fertilizer has been used at an ever increasing rate, which resulted in the trace of accumulative nitrogen in the soil and caused serious environmental problems. In this study we made use of the farmland nitrogen balance model to assess the spatial difference of farmland nitrogen nutrient budget in the Bohai Rim region in 2008 with the assistance of GIS. Our results indicated that： 1） Farmland in this region has a nitrogen surplus totaling 5.0822 million tons, or an average of 288.54 kg/ha. 2） In the Bohai Rim region, farmland nitrogen input and farmland nitrogen budget both show a spatial differentiation. Major grain-producing areas have a higher nitrogen input than that of the grazing-farming areas. The main sources of nitrogen input include chemical fertilizer, organic fertilizer, deposition from atmospheric drying and wetting, and biological fixation, which account for 79.47%, 9.53%, 4.62%, and 3.58% of the total input, respectively. Therefore, chemical fertilizer is the predominant source of nitrogen input to farmland. 3） A total of 3.3398 million tons of nitrogen were output from the farmland via harvested crops and it accounts for 52.36% of the total nitrogen output from farmland in this region. On average, the amount of nitrogen output from unit farmland is equal to 176.65kg/ha. This study has shed light on farmland nitrogen budget and its spatial variation in the study area, may provide scientific evidences for rationalizing the use of chemical fertilizer and managing agricultural operation on the regional scale and is also valuable for improving the economic and ecological efficiency of fertilizer use at the regional scale.展开更多
基金Supported by the National Key Research and Development Program of China(Nos.2016YFC1402004,2016YFC1401805)
文摘As concluded from physical theory and laboratory experiment,it is widely accepted that nonlinearities of sea state play an important role in the formation of rogue waves;however,the sea states and corresponding nonlinearities of real-world rogue wave events remain poorly understood.Three rogue waves were recorded by a directional buoy located in the East China Sea during Typhoon Trami in August 2013.This study used the WAVEWATCHⅢmodel to simulate the sea state conditions pertaining to when and where those rogue waves were observed,based on which a comprehensive and full-scale analysis was performed.From the perspectives of wind and wave fields,wave system tracking,High-Order Spectral method simulation,and some characteristic sea state parameters,we concluded that the rogue waves occurred in sea states dominated by second-order nonlinearities.Moreover,third-order modulational instabilities were suppressed in these events because of the developed or fully developed sea state determined by the typhoon wave system.The method adopted in this study can provide comprehensive and full-scale analysis of rogue waves in the real world.The case studied in this paper is not considered unique,and rules could be found and confirmed in relation to other typhoon sea states through the application of our proposed method.
基金The National Key Basic Research and Development Plan under contract No. 2010CB950301:"Sea-ice-air interaction in the Southern Ocean and its influence on the south Indian Ocean",International Polar Year Chinese action plan project:"Chukchi Sea & Beaufort Sea ice anomaly variation and its impact on the winter climate of China"National Science and Technology Support Program under contract No.2006BAB18B02:"Water masses and circulation monitoring technology and its application in the southern ocean"The Basic Research Fund Project under contract No.FIO SOA 2010T01:"Key technology research of polar mooring observation system"
文摘During the summer of 2008, the third CHINARE Arctic Expedition was carried out on board of Xuelong Icebreaker in the central Chukchi Sea. A submersible mooring system was deployed and recovered at Station CN-01 （71.40.024＇N, 167.58.910＇W） with 33 days of the current profile records, and continuous observation of temperature and salinity data were collected. This mooring station locates in the blank of similar observation area and it is the first time for our Chinese to finish this kind of long-term mooring work in this area. This mooring system finished integrated hydrological observations with long-term continuous record of the whole profile velocity for the first time. Based on time series analysis of temperature, salinity, velocity and flow direction, we get the following main results. （1） During the observation period, the mean surface current velocity is 70.2 cm/s eastward, and velocity reaches its maximum in average at 3 m level with magnitude 90.0 cm/s, direction 206.. （2） In 9-30 m layers, the semidiurnal period variation is the most obvious, the flow direction is quite stable, and the flow is synchronous and consistent vertically. （3） Besides the semidiurnal period variation, the main variation in the upper layer is in 11-d period, with variations in period 5.5, 5.5, and 3.7 d, which reflect the influences of sea surface wind change and maintenance. （4） Near the bottom the temperature change is correlated and synchronized with the conductivity.
基金Supported by the National Key R&D Program of China(No.2017YFC1404200)the National Natural Science Foundation of China(No.41406046)+4 种基金the Fundamental Research Funds for National Public Research Institutes of China(No.2014T01)the Overseas Students Science and Technology Activities Project Merit Funding and the ChinaKorea Cooperation Project for Nuclear Safety through the China-Korea Joint Ocean Research Centre(CKJORC)the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-05)the International Cooperative Project on the China-Australia Research Centre for Maritime Engineering of Ministry of Science and Technology(No.2016YFE0101400)the Qingdao National Laboratory for Marine Science and Technology(Nos.2015ASTP,2016ASKJ16,2015ASKJ01)
文摘In this study, the simulating waves nearshore (SWAN) model with a locally refined curvilinear grid system was constructed to simulate waves in Jervis Bay and the neighbouring ocean of Australia, with the aim of examining the wave characteristics in an area with special topography and practical importance. This model was verified by field observations from buoys and acoustic Doppler profilers (ADPs). The model precisions were validated for both wind-generated waves and open-ocean swells. We present an approach with which to convert ADP-observed current data from near the bottom into the significant wave height. Our approach is deduced from the Fourier transform technique and the linear wave theory. The results illustrate that the location of the bay entrance is important because it allows the swells in the dominant direction to propagate into the bay despite the narrowness of the bay entrance. The wave period T p is also strongly related to the wave direction in the semi-enclosed bay. The Tp is great enough along the entire propagating direction from the bay entrance to the top of the bay, and the largest Tp appears along the north-west coast, which is the end tip of the swells’ propagation.
基金National Natural Sciences Foundation of China,No.41130748No.41101162Basic Research Work of Central Scientific Research Institution for Public Welfare,No.202-18
文摘The Bohai Rim region is one the most important bases for commodity grain production in China. With the rapid pace of agricultural industrialization, nitrogenous fertilizer has been used at an ever increasing rate, which resulted in the trace of accumulative nitrogen in the soil and caused serious environmental problems. In this study we made use of the farmland nitrogen balance model to assess the spatial difference of farmland nitrogen nutrient budget in the Bohai Rim region in 2008 with the assistance of GIS. Our results indicated that： 1） Farmland in this region has a nitrogen surplus totaling 5.0822 million tons, or an average of 288.54 kg/ha. 2） In the Bohai Rim region, farmland nitrogen input and farmland nitrogen budget both show a spatial differentiation. Major grain-producing areas have a higher nitrogen input than that of the grazing-farming areas. The main sources of nitrogen input include chemical fertilizer, organic fertilizer, deposition from atmospheric drying and wetting, and biological fixation, which account for 79.47%, 9.53%, 4.62%, and 3.58% of the total input, respectively. Therefore, chemical fertilizer is the predominant source of nitrogen input to farmland. 3） A total of 3.3398 million tons of nitrogen were output from the farmland via harvested crops and it accounts for 52.36% of the total nitrogen output from farmland in this region. On average, the amount of nitrogen output from unit farmland is equal to 176.65kg/ha. This study has shed light on farmland nitrogen budget and its spatial variation in the study area, may provide scientific evidences for rationalizing the use of chemical fertilizer and managing agricultural operation on the regional scale and is also valuable for improving the economic and ecological efficiency of fertilizer use at the regional scale.
