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961.
962.
AbstractBased on hydrological data obtained during the 7th to 9th Chinese National Arctic Research Expeditions in the summers of 2016–2018, the main water structure on the shelf of the northern Bering Sea and the volume and heat fluxes of the Bering Strait throughflow were analyzed. Distinct variability was identified in the three Pacific water masses feeding the strait - Anadyr Water (AW), Bering Shelf Water (BSW) and Alaskan coastal water (ACW). Overall, the temperature and salinity of the entire section increased each year, with 2018 showing significant anomalies, i.e., a temperature anomaly of up to 1?°C and a maximum salinity anomaly of 2. From 2016 to 2018, the extent of the ACW gradually narrowed in the eastern part of this section, while the AW expanded eastward each year. The net volume transport through each of the three sections increased poleward from 1.65?Sv to 2.76?Sv, with the AW increasing from 0?Sv to 1.03?Sv, the BSW varying between 0.52–1.65?Sv, and the ACW gradually decreasing from 1.04?Sv to disappearing completely. The net heat fluxes were also poleward, varying between 25.77 TW and 61.50 TW, and showing a significant increase. Significant variations in magnitude and extent were observed in each water mass of the Bering Strait throughflow, which could produce widespread effects in the Arctic Ocean and the global ocean beyond. 相似文献
963.
使用DYYZⅡ型自动气象站,提高了观测时效,消除了人工读数误差,减轻了观测人员的劳动强度。在4个月的使用过程中,我们发现一些问题,这些问题在使用中我们是如何解决的,下面做一阐述,供大家参考。 相似文献
964.
Magmatism and tectonic processes in Area A hydrothermal vent on the Southwest Indian Ridge 总被引:5,自引:0,他引:5
The hydrothermal vent in Area A(37.78°S,49.65°E)is the first active hydrothermal vent discovered on the Southwest Indian Ridge(SWIR).Heat source and adequate bulk permeability are two necessary factors for the formation of a hydrothermal vent.Along the SWIR 49.3°E to 51.2°E,the gravity-derived crustal thickness is up to 9.0 km,much thicker than the average thickness of the global oceanic crust.This characteristic indicates that the magma supply in this area is robust,which is possibly affected by a hotspot.The large-scale residual mantle Bouguer anomalies(RMBA)reveal prominent negative-gravity anomalies between the first-order ridge segment(from Indomed to Gallieni,46.0°E to 52.0°E)and the Marion-Del Cano-Crozet region.These anomalies indicate the channel of the hotspot-ridge interaction.The tomography data corrected with theoretical thermal model indicate that the low-velocity anomalies corresponding to this channel can reach the base of the lithosphere.Near the hydrothermal vent area,the topography and crustal thickness at the off-axis area are extremely asymmetrical.South of the SWIR,the high topography corresponds to the thinning crustal thickness.The residual isostatic topography anomalies indicate that Area A is a deviation from the local isostatic equilibrium,similar to the characteristics of the transform fault inside corner.The forward profiles of the magnetic data indicate that the thinning magnetic layer at the south side of Area A corresponds to the shallow,high-velocity area revealed by the OBS,which is the result of tectonic extension of a detachment fault.The active tectonic processes in Area A can provide sufficient crustal permeability to the hydrothermal circulation and may form massive sulfide deposits. 相似文献
965.
966.
温室气体浓度增加情景下大西洋温盐环流的演变 总被引:2,自引:0,他引:2
温室气体浓度增加(以CO2为主)引起的温盐环流演变在未来气候系统中扮演非常重要的角色.在最新的温室气体排放情景下,利用基于德国马普气象研究所为IPCC第四次评估报告而最新发展的气候模式(ECHAM5/MPIOM),对3种不同的温室气体排放假设(B1,A1B,A2)进行了可靠的数值模拟.在此基础上,就大西洋温盐环流和北大西洋深层水形成的变化,以及北大西洋不同海区的温盐环流对温室气体浓度增加的响应,对模拟结果进行了分析.研究揭示,到21世纪末,在3种CO2排放情景下,温盐环流强度分别减弱了4Sv(1Sv=106m3/s)、5.1Sv、5.2Sv,大体相当于减弱了20%、25%、25.1%.由于全球变暖引起副极地海区表层海水变暖变淡,拉不拉多海(LabradorSea)和丹麦海峡(DenmarkStrait)以南区域的深层对流有所减弱.而在格陵兰-冰岛-挪威海(GINSea)的情况相反,由于北大西洋暖流的增强,通过法鲁海峡(Faro-BankChannel)进入GIN海域的高盐水增加,导致GIN海域上层盐度(密度)增加,进而深层对流加强.在A1B情景下,由于全球变暖北大西洋的深层水生成率从16.2Sv降到了12.9Sv. 相似文献
967.
Gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM) were measured over 2-week seasonal field campaigns near Salmon Falls Creek Reservoir in south-central Idaho from the summer of 2005 through the fall of 2006 and over the entire summer of 2006 using automated Tekran Hg analyzers. GEM, RGM, and particulate Hg (HgP) were also measured at a secondary site 90 km to the west in southwestern Idaho during the summer of 2006. The study was performed to characterize Hg air concentrations in the southern Idaho area for the first time, estimate Hg dry deposition rates, and investigate the source of observed elevated concentrations. High seasonal variability was observed with the highest GEM (1.91 ± 0.9 ng m−3) and RGM (8.1 ± 5.6 pg m−3) concentrations occurring in the summer and lower values in the winter (1.32 ± 0.3 ng m−3, 3.2 ± 2.9 pg m−3 for GEM, RGM, respectively). The summer-average HgP concentrations were generally below detection limit (0.6 ± 1 pg m−3). Seasonally averaged deposition velocities calculated using a resistance model were 0.034 ± 0.032, 0.043 ± 0.040, 0.00084 ± 0.0017 and 0.00036 ± 0.0011 cm s−1 for GEM (spring, summer, fall and winter, respectively) and 0.50 ± 0.39, 0.40 ± 0.31, 0.51 ± 0.43 and 0.76 ± 0.57 cm s−1 for RGM. The total annual RGM + GEM dry deposition estimate was calculated to be 11.9 ± 3.3 μg m−2, or about 2/3 of the total (wet + dry) deposition estimate for the area. Periodic elevated short-term GEM (2.2–12 ng m−3) and RGM (50–150 pg m−3) events were observed primarily during the warm seasons. Back-trajectory modeling and PSCF analysis indicate predominant source directions to the SE (western Utah, northeastern Nevada) and SW (north-central Nevada) with fewer inputs from the NW (southeastern Oregon and southwestern Idaho). 相似文献
968.
969.
小试金光谱法同时测定地质样品中超痕量铂钯金 总被引:9,自引:2,他引:9
用小试金光谱法同时测定地质样品中低至0·x×10~(-9)级Pt、Pd和Au,包括先用小试金熔炼和灰吹预富集10g样品中的Pt、Pd和Au于1mg的银合粒中,然后把银合粒装入石墨电极同锇-锑合金(ω(Os)=0.06)一起激发,以发射光谱法同时测定它们的含量。小试金法类同经典火试金,但采用纯化过的2PbCO_3·Pb(OH)_2(Pt、Pd和Au的含量皆<0.05 ×10~(-9)代替商品PbO,并且用50ml高铝坩埚在950℃进行熔炼。方法的检出限是Pt0.2×10~(-9),Pd和Au均为0.1×10 相似文献
970.
Wang Shujuan Yan Yihua Zhao Ruizhen Fu Qijun Tan Chengming Xu Long Wang Shijin Lin Huaan 《Solar physics》2001,204(1-2):153-164
25 MHz–7.6 GHz global and detailed (fine structure – FS) radio spectra are presented, which were observed in the NOAA 9077
active region for the Bastille Day (14 July 2000) flare at 10:10–11:00 UT. Besides broadband radio bursts, high-resolution
dynamic spectra reveal metric type II burst, decimetric type IV burst and various decimetric and microwave FSs, such as type III
bursts, type U bursts, reverse-slope (RS)-drifting burst, fiber bursts, patch and drifting pulsation structure (DPS). The
peak-flux-density spectrum of the radio bursts over the range 1.0–7.6 GHz globally appears as a U-shaped signature. Analyzing
the features of backbone and herringbones of the type II burst, the speeds of shock and relevant energetic electron beams
were estimated to be 1100 km s−1 and 58 500 km s−1, respectively. Also the time sequence of the radio emission is analyzed by comparing with the hard X-rays (HXRs) and the
soft X-rays (SXRs) in this flare. After the maxima of the X-rays, the radio emission in the range 1.0–7.6 GHz reached maxima
first at the higher frequency, then drifted to the lower frequency. This comparison suggested that the flare included three
successive processes: firstly the X-rays rose and reached maxima at 10:10–10:23 UT, accompanied by fine structures only in
the range 2.6–7.6 GHz; secondly the microwave radio emission reached maxima accompanied by many fine structures over the range
1.0–7.6 GHz at 10:23–10:34 UT; then a decimetric type IV burst and its associated FSs (fibers) in the range 1.0–2.0 GHz appeared
after 10:40 UT. 相似文献