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1.
Although the annual global sea-air CO2 flux has been estimated extensively with various wind-dependent-k parameterizations, uncertainty still exists in the estimates. The sea-state-dependent-k parameterization is expected to improve the uncertainty existing in these estimates. In the present study, the annual global sea-air CO2 flux is estimated with the sea-state-dependent-k parameterization proposed by Woolf (2005), using NOAA/NCEP reanalysis wind speed and hindcast wave data from 1998 to 2006, and a new estimate, −2.18 Gt C year−1, is obtained, which is comparable with previous estimates with biochemical methods. It is interesting to note that the averaged value of previous estimates with various wind-dependent-k parameterizations is almost identical to that of previous estimates with biochemical methods by various authors, and that the new estimate is quite consistent with these averaged estimates.  相似文献   

2.
Partial pressure of CO2(pCO2) was investigated in the Changjiang(Yangtze River) Estuary,Hangzhou Bay and their adjacent areas during a cruise in August 2004,China.The data show that pCO2 in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago.The pCO2 varied from 168 to 2 264 μatm,which fell in the low range compared with those of other estuaries in the world.The calculated sea-air CO2 fluxes decreased offshore and varied from -10.0 to 88.1 mmol m-2 d-1 in average of 24.4 ± 16.5 mmol m-2 d-1.Although the area studied was estimated only 2 × 104 km2,it emitted(5.9 ± 4.0) × 103 tons of carbon to the atmosphere every day.The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle.  相似文献   

3.
Role of sea ice in air-sea exchange and its relation to sea fog   总被引：1，自引：0，他引：1  
Synchronous or quasi-synchronous stereoscopic sea-ice-air comprehensive observation was conducted during the First China Arctic Expedition in summer of 1999. Based on these data, the role of sea ice in sea-air exchange was studied. The study shows that the kinds, distribution and thickness of sea ice and their variation significantly influence the air-sea heat exchange. In floating ice area, the heat momentum transferred from ocean to atmosphere is in form of latent heat; latent heat flux is closely related to floating ice concentration; if floating ice is less, the heat flux would be larger. Latent heat flux is about 21 23.6 W*m-2, which is greater than sensible heat flux. On ice field or giant floating ice, heat momentum transferred from atmosphere to sea ice or snow surface is in form of sensible heat. In the floating ice area or polynya, sea-air exchange is the most active, and also the most sensible for climate. Also this area is the most important condition for the creation of Arctic vapor fog. The heat exchange of a large-scale vapor fog process of about 500000 km2 on Aug. 21 22,1999 was calculated; the heat momentum transferred from ocean to air was about 14.8×109 kW. There are various kinds of sea fog, radiation fog, vapor fog and advection fog, forming in the Arctic Ocean in summer. One important cause is the existence of sea ice and its resultant complexity of both underlying surface and sea-air exchange.  相似文献   

4.
MODIS数据的云顶高度反演   总被引：2，自引：0，他引：2  
云的辐射特性和它的高度影响到辐射的收支可以导致地球的变暖或变冷,在地球大气能量收支平衡中．云具有特别显著的调节作用,是影响气候变化的一个重要因子。云顶性质包括云顶气压、云顶温度和有效云量或有效比辐射率。很多方法被用来从多光谱资料中估计云参数,而CO2薄片算法(截断法)则是使用被动遥感资料反演云顶性质的重要方法之一。利用15μmCO2吸收带的几个吸收不同的MODIS红外波段,对于大气不同高度层次的不同敏感度,通过从地球大气系统的几个CO2波段同时测量向上红外辐射,以及大气的温度和透射率廓线的基础上,可以推断出云顶气压。这项技术应用于HIRS资料上已经有20年的历史,而EOS系列地球环境卫星的升空,使EOS上搭载的MODIS探测器成为第一个拥有CO2薄片波段的高空间分辨率探测器。本文依据CO2薄片算法(截断法)的理论模型结合实例讨论算法的特点及不足,同时分析其误差以利改进。  相似文献   

5.
Pco2 of air and seawater samples from the East China Sea(ECS) were measured in situ in autumn, 1994,Ocean currents,terrestrial fluviation,biological activities,etc.,Pco2 char-acters in air and seawater were investigated,CO2 flux and its character in the East China Sea are discussed on the basis of the Pco2 profiles of air and seawater,It was clear that the nearshore was the source of CO2;and tht the oulter sea area was the sink of CO2; and that the shelf area of the EXS is a net sink for atmospheric CO2 in autumn.  相似文献   

6.
This study on the sectional and vertical distribution of dissolved oxygen (DO) and the O2 fluxes across the sea-air interface in East China Sea (ESC) waters shows that the waters were in steady state and that the difference of DO was great in upper and bottom waters in Apr. 1994; but that seawater mixing was strong and the difference of DO was small in upper and bottom waters in Oct. 1994. The above conclusions were specially obvious in continental shelf waters under 100 m. The DO maximum in subsurface layer waters appeared only at several stations and in general the DO in the waters decreased with depth. The horizontal distributions of O2 fluxes across the sea-air interface appeared in stripes in Leg 9404 when most regions covered were supersaturated with O2 seawater to air flux was large, and that on section No. 1 was 1.594 L/m2·d. The horizontal distribution of O2 fluxes across the sea-air interface appeared lumpy in Leg 9410, when most regions covered were unsaturated with O2·O2 was dissolved from air to seawater, and the fluxes were 0.819 L/m2·d on section No. 1 in Leg 9310, 0.219 L/m2·d in Leg 9410. The main reasons for DO change in surface layer seawater were the mixture of upper and bottom layer water, and the exchange of O2 across the sea-air interface. The variation of DO by biological activity was only 20% of total change of DO. Contribution No. 2716 from Institute of Oceanology, Chinese Academy of Sciences.  相似文献   

7.
1 Introduction From July 10th to September 26, 2003,“Xuelong”scientific expedition icebreaker executed the 2nd Chinese Arctic Research Expedition (CHINARE2003). The voyage star- ted from Shanghai to Dalian via Yellow Sea and Bo Hai and the cruising rout…  相似文献   

8.
ChinaFLUX CO2通量数据处理系统与应用   总被引：4，自引：0，他引：4  
CO2通量观测数据的规范处理及其高质量数据产品的发布,是CO2通量及其相关领域研究的前提和基础。为解决目前通量观测数据处理工作中存在的过程繁琐、方法不统一、处理不及时等问题,本研究以MATLAB为开发工具,利用其强大的数学计算功能和可视化GUI技术,集成目前主要的通量数据处理方法,开发了一套具有自主知识产权的中国通量网(ChinaFLUX)通量观测数据处理系统。该系统的处理对象为30min的CO2通量观测数据,其主要处理步骤包括湍流通量计算、观测数据的质量控制/质量保证、缺失观测数据的插补,以及不同时间尺度下碳交换量的分解和计算等。该系统自动化程度高、可视化程度强,为ChinaFLUX通量观测数据处理及服务提供了一个良好的平台。  相似文献   

9.
利用GRACE监测全球海水质量变化时滤波处理的影响分析   总被引：1，自引：0，他引：1  
利用CSR公布的GRACE RL05月重力场数据,采用多种滤波方法推算全球平均海水质量变化,并与GFZ公布的已滤波数据DDK1~DDK5估算结果进行比较。结果表明,不同的滤波方法对估算全球平均海水质量变化结果的影响是显著的,主要体现在信号的空间分布、时间序列以及拟合的趋势项3个方面。 2002~2014年CSR RL05数据多种滤波估算的全球海水质量变化速率为1.17~1.26 mm/a,GFZ DDK数据显示的速率为1.29~1.45 mm/a,两组数据给出的加速度项分别为0.1 mm/a2、0.07 mm/a2。  相似文献   

10.
CO2地质封存是减少CO2向大气排放,缓解温室效应的有效手段之一。由于构造和成岩作用,倾斜地层在自然界中普遍存在,研究倾斜地层对CO2封存量及安全性的影响具有实际意义。依托新疆准噶尔盆地阜康凹陷某CO2地质封存示范工程,采用数值模拟方法,分析了中高渗CO2储层地层倾角变化对CO2地质封存过程的影响。结果表明:CO2注入将导致近井区域地层压力显著升高;中高渗倾斜地层与水平地层相比,在地层压力分布、CO2侧向运移距离、CO2注入速率和总封存量等方面均存在明显差异。相比于水平地层,由于地层倾角的存在,倾斜地层压力呈不对称分布,CO2侧向运移距离显著加大。倾斜地层中压力传递和消散过程与水平地层差异显著,受此影响,倾斜地层与水平地层CO2的总注入量差值随时间呈非单调性变化。在注入初期,倾斜地层CO2的总注入量小于水平地层,随着注入时间延长,倾斜地层CO2的总注入量逐渐接近并超过水平地层;注入20年后,相较于水平地层,倾斜地层倾角越大越有助于增加CO2的总注入量,这一研究结果与前人基于低渗倾斜地层的研究结论正好相反。地层倾角的存在会促进CO2向浅部运移,倾角越大,CO2向浅部含水层和大气泄露的风险越大。因此,在CO2地质封存场地选址中,应充分考虑倾斜地层对封存效率及安全性的影响。  相似文献   

11.
An Acoustic Doppler Current Profiler (ADCP) was used in Nov. 1990 measure the seawaterfluxes in a southeast-northwest cross-section in the Bashi Strait to a depth of 400 m. Measuredconcentrations of dissolved oxygen (DO), phosphate (PO_4), nitrate (NO_3), silicate (SiO_2), total alkalinity(TA) and calculated total CO_2, (TCO_2) and the current speed were used to estimate the flux densities(concentration times current speed) of seawater and chemicals.The fluxes of nutrients were near zero near surface and increased with depth. For oxygen andcarbonates, the distributions of flux had structures similar to that of the curmt speed field.  相似文献   

12.
In the mid-eastern China,there are few or no lakes which are in the absence of anthropogenic disturbances,or their sediments remain undisturbed.As a result,the reference lakes distribution and paleolimnological reconstruction approaches usually are inappropriate to estimate lake reference conditions for nutrients.This yields the necessity of using the extrapolation methods to estimate the lake reference conditions for nutrients within those regions.The lake reference conditions for nutrients could be inferred inversely from the law of mass conservation,current lake nutrient concentration,and the loadings from watershed.Considering the scarcity of hydrological and water quality data associated with lakes and watersheds in China,as well as the low requirement of the watershed nutrient loadings models for these data,the soil conservation service(SCS) distributed hydrological model and the universal soil loss equation(USLE) were applied.The SCS model simulates the runoff process of the watershed,thereby calculating dissolved nutrients annually.The USLE estimates the soil erosion and particulate nutrients annually in a watershed.Then,with the loadings from atmospheric deposition and point source,the previous annual average nutrient concentrations could be acquired given the current nutrient concentrations in a lake.Therefore,the nutrient reference conditions minimally impacted by human activities could be estimated.Based on the proposed model,the reference conditions for total nitrogen and total phosphorus of Chaohu Lake,Anhui Province,China are 0.031 mg/L and 0.640 mg/L,respectively.The proposed reference conditions estimation model is of clear physical concept,and less data required.Thus,the proposed approach can be used in other lakes with similar circumstances.  相似文献   

13.
Quantification of greenhouse gases[nitrous oxide(N2O)and methane(CH4)]and nitric oxide(NO)emissions from subtropical conventional vegetable systems through multi-site field measurements are needed to obtain accurate regional and global estimates.N2 O,NO and CH4 emissions from subtropical conventional vegetable systems were simultaneously measured at two different sites with hilly topography in the Sichuan basin,southwest China by using the static chamber gas chromatography technique.Results showed that annual soil N2O and NO fluxes for the treatment receiving N fertilizer ranged from 6.34-7.71 kg N ha-1 yr-1 and 0.69-0.85 kg N ha-1 yr-1,respectively,while decreased soil CH4 uptakes by 26.4%as compared with no N fertilizer addition across our two sites of experiment.Overall,the average direct N2 O and NO emission factor(EFd)were 0.71%and 0.12%,respectively,which were both lower than the available EFd for subtropical conventional vegetable systems.This finding indicates that current regional and global estimates of N2O and NO emissions from vegetable fields are likely overestimated.Background N2O emissions(3.42-3.62 kg N ha-1 yr-1)from the subtropical conventional vegetable systems were relatively high as compared with available field measurements worldwide,suggesting that background N2O emissions cannot be ignored for regional estimate of N2O emissions in subtropical region.Nevertheless,the significantly intra-and inter-annual variations in N2O,CH4 and NO emissions were also observed in the present study,which could be explained by temporal variations of environmental variables(i.e.soil temperature and moisture).The differences in N2O and NO EFd and CH4emissions between various vegetable systems in particular under subtropical conditions should be taken into account when compiling regional or global inventories and proposing mitigation practices.  相似文献   

14.
The estimation of gear selectivity is a critical issue in fishery stock assessment and management. Several methods have been developed for estimating gillnet selectivity, but they all have their limitations, such as inappropriate objective function in data fitting, lack of unique estimates due to the difficulty in finding global minima in minimization, biased estimates due to outliers, and estimations of selectivity being influenced by the predetermined selectivity functions. In this study, we develop a new algorithm that can overcome the above-mentioned problems in estimating the gillnet selectivity. The proposed algorithms include minimizing the sum of squared vertical distances between two adjacent points and minimizing the weighted sum of squared vertical distances between two adjacent points in the presence of outliers. According to the estimated gillnet selectivity curve, the selectivity function can also be determined. This study suggests that the proposed algorithm is not sensitive to outliers in selectivity data and improves on the previous methods in estimating gillnet selectivity and relative population density of fish when a gillnet is used as a sampling tool. We suggest the proposed approach be used in estimating gillnet selectivity.  相似文献   

15.
Surface water can be divided into three layers from top downward: surface microlayer (SML, thickness≤50 μm), subsurface layer (SSL, ≈25 cm) and surface layer (SL, 1–5m), among which the SML plays an important role on sea-air interaction because of its unique physical-chemical property. Carbon dioxide system including DIC (dissolved inorganic carbon), Alk (alkalinity), pH and pCO2 (partial pressure of CO2) in multilayered waters of the Yellow Sea was studied for the first time in March and May 2005. The results show that: DIC and Alk are obviously enriched in SML. The contents of DIC, Alk and pCO2 become lower in turn from SML, SSL to SL, higher in March and lower in May, whereas for pH it was opposite. The relationship between DIC and Alk is clearly positive, but negative between pH and pCO2. Meanwhile, pCO2 and temperature/salinity is also in positive relation, pCO2 decreases with latitude increase. DIC and Alk show a similar variation trend with the maximum at 02:00–03:00, but pH and pCO2 show an opposite pattern. In addition, the distribution patterns are similar to each other in the three layers. The Yellow Sea is shown to be a sink of atmospheric CO2 in spring by two methods: (1) comparing pCO2 in seawater and atmosphere; (2) turning direction of “pH-depth” curve. Calculation on the base of pCO2 data in SML in four models shows that carbon flux in spring in the area was about -6.96×106 t C.  相似文献   

16.
Time-series of chlorophyll-a(CHL),a proxy for phytoplankton biomass,and various satellite-derived climate indicators are compared in a region of the Subantarctic Southern Ocean(40°-60°S,110°-140°E)for years 2012-2014.CHL reached a minimum in winter(June)and a maximum in late summer(early February).Zonal mean CHL decreased towards the south.Mean sea surface temperature(SST)ranged between 8℃and 15℃and peaked in late February.CHL and SST were positively correlated from March to June,negatively correlated from July to September.CHL and wind speed(WIND)were negatively correlated with peak WIND occurred in winter.Wind direction(WIRD)was mostly in the southwest to westerly direction.The Antarctic Oscillation index(AAO)and CHL were negatively correlated(R=−0.58),indicating that as synoptic wind systems move southwards,CHL increases,and conversely when wind systems move northwards,CHL decreases.A genetic algorithm is used to calibrate the biogeochemical DMS model’s key parameters.Under 4×CO2(after year 2100)Regional mean SST increases 12%-17%,WIND increases 1.2ms−1,Cloud Cover increases 4.8%and mixed layer depth(MLD)decreases 48m.The annual CHL increases 6.3%.The annual mean DMS flux increase 25.2%,increases 37%from day 1 to day 280 and decrease 3%from day 288 to day 360.The general increase of DMS flux under 4×CO2 conditions indicates the Subantarctic regional climate would be affected by changes in the DMS flux,with the potential for a cooling effect in the austral summer and autumn.  相似文献   

17.
The physiological responses of Nitzschia palea Kiitzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 μl/L increased the dissolved inorganic carbon (DIC) and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher Ik values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO3- in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO3- and CO2. Although doubled CO2 level would enhance the biomass of N. palea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of N. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.  相似文献   

18.
GPS buoy methodology is one of the main calibration methodologies for altimeter sea surface height calibration.This study introduces the results of the Qinglan calibration campaign for the HY-2 A and Jason-2 altimeters.It took place in two time slices;one was from August to September 2014,and the other was in July 2015.One GPS buoy and two GPS reference stations were used in this campaign.The GPS data were processed using the real-time kinematic(RTK)technique.The final error budget estimate when measuring the sea surface height(SSH)with a GPS buoy was better than 3.5 cm.Using the GPS buoy,the altimeter bias estimate was about-2.3 cm for the Jason-2 Geophysical Data Record(GDR)Version 'D' and from-53.5 cm to-75.6 cm for the HY-2 A Interim Geophysical Data Record(IGDR).The bias estimates for Jason-2 GDR-D are similar to the estimates from dedicated calibration sites such as the Harvest Platform,the Crete Site and the Bass Strait site.The bias estimates for HY-2 A IGDR agree well with the results from the Crete calibration site.The results for the HY-2 A altimeter bias estimated by the GPS buoy were verified by cross-calibration,and they agreed well with the results from the global analysis method.  相似文献   

19.
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20.
OCCAM global ocean model results were applied to calculate the monthly water transport through 7 straits around the East China Sea(ECS)and the South china Sea(SCS).Analysis of the features of velocity profiles and their variations in the Togara Strait,Luzon Strait and Eastern Taiwan Strait showed that;1)the velocity profiles had striped pattern in the Eastern Taiwan Strait,where monthly flux varied from 22.4 to 28.1 Sv and annual mean was about 25.8 Sv;2)the profiles of velocity in the Togara Strait were characterized by core structure,and monthly flux varied from 23.3 to 31.4 Sv,with annual mean of about 27.9 Sv;3)water flowed from the SCS to the ECS in the Taiwan Strait,with maximum flux of 3.1 Sv in July and minimum of 0.9 Sv in November;4)the flux in the Tsushima Strait varied by only about 0.4 Sv by season and its annual mean was about 2.3 Sv;5)Kuroshio water flowed into the SCS in the Luzon Strait throughout the year and the velocity profiles were characterized by multi-core structure.The flux in the Luzon Strait was minimun in June(about 2.4 Sv)and maximum in February(about 9.0 Sv),and its annual mean was 4.8 Sv;6)the monthly flux in the Mindoro Strait was maximum in December(3.0 Sv)and minimum in June(Only 0.1 Sv),and its annual mean was 1.3 Sv;7)Karimata Strait water flowed into the SCS from May to August,with maximum in-flow flux of about 0.75 Sv in June and flowed out from September to April at maximum outflow flux of 3.9 Sv in January.The annual mean flux was about 1.35 Sv.  相似文献   

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