Submesoscale eddies in Peter the Great Bay of the Japan/East Sea in winter

Ocean Dynamics - Cold-core (T < 0 °C) domes of dense water σθ > 27.24 kg/m3 were observed in the near-bottom layer at the...     

High efficient parallel numerical surface wave model based on an irregular quasi-rectangular domain decomposition scheme

To achieve high parallel efficiency for the global MASNUM surface wave model, the algorithm of an irregular quasi-rectangular domain decomposition and related serializing of calculating points and data exchanging schemes are developed and conducted, based on the environment of Message Passing Interface (MPI). The new parallel version of the surface wave model is tested for parallel computing on the platform of the Sunway BlueLight supercomputer in the National Supercomputing Center in Jinan. The testing involves four horizontal resolutions, which are 1°×1°, (1/2)°×(1/2)°, (1/4)°×(1/4)°, and (1/8)°×(1/8)°. These tests are performed without data Input/Output (IO) and the maximum amount of processors used in these tests reaches to 131072. The testing results show that the computing speeds of the model with different resolutions are all increased with the increasing of numbers of processors. When the number of processors is four times that of the base processor number, the parallel efficiencies of all resolutions are greater than 80%. When the number of processors is eight times that of the base processor number, the parallel efficiency of tests with resolutions of 1°×1°, (1/2)°×(1/2)° and (1/4)°×(1/4)° is greater than 80%, and it is 62% for the test with a resolution of (1/8)°×(1/8)° using 131072 processors, which is the nearly all processors of Sunway BlueLight. When the processor’s number is 24 times that of the base processor number, the parallel efficiencies for tests with resolutions of 1°×1°, (1/2)°×(1/2)°, and (1/4)° ×(1/4)° are 72%, 62%, and 38%, respectively. The speedup and parallel efficiency indicate that the irregular quasi-rectangular domain decomposition and serialization schemes lead to high parallel efficiency and good scalability for a global numerical wave model.     

Retrospective Study on the Predictability of Pattern Informatics to the Wenchuan M8.0 and Yutian M7.3 Earthquakes

Two large earthquakes occurred in the western part of China in 2008, one of them being the Yutian (35.6°N, 81.6°E) M7.3 earthquake that occurred on March 21 (BJT) and the other the Wenchuan (31.0°N, 103.4°E) M8.0 earthquake that occurred on May 12 (BJT). In this paper, the West Continental China (included in 20.0°–50.0°N, 70.0°–110.0°E region) was the study region for verifyong the predictability of the pattern informatics (PI) method using the receiver-operating characteristic curve (ROC) test and R score test. Different forecasting maps with different calculating parameters were obtained. The calculating parameters were the grid size Δx, base time t _b, reference interval t _b to t ₁, change interval t ₁ to t ₂, and forecasting interval t ₂ to t ₃. In this paper, the base time t _b fixed to June 1, 1971, the ending forecast time t ₃ fixed to June 1, 2008, and the forecasting interval t ₂ to t ₃ changed from 1 to 10 years, and the grid sizes were chosen as 1° × 1° and 2° × 2°, respectively. The results show that the PI method could forecast the Yutian M7.3 and Wenchuan M8.0 earthquakes only using suitable parameters. Comparing the forecast results of grid sizes 1° × 1° and 2° × 2°, the models with 2° × 2° grids were better. Comparing the forecast results with different forecasting windows from 1 to 10 years, the models with forecasting windows of 4–8 years were better using the ROC test, and the models with forecasting windows of 7–10 years were better using the R score test. The forecast efficiency of the model with a grid size of 2° × 2° and forecast window of 8 years was the best one using either the ROC test or the R score test.     

2013年南斯科舍海岭MW7.8地震的多点震源机制反演

2013年11月17日,在南极南奥克尼群岛北、南极板块与斯科舍板块之间发生了一次M_W7.8级地震（2013年南斯科舍海岭M_W7.8地震）,我们利用全球分布的长周期和宽频带地震记录反演确定了这次地震随时间和空间变化的震源机制,验证了提出的一种多点震源机制反演的新方法.首先利用长周期记录的W震相反演了这次地震的矩心矩张量解并利用体波提取了视震源时间函数,同时利用台阵反投影技术从宽频带记录中获得了这次地震的高频源的时空分布,然后基于矩心矩张量解、视震源时间函数以及高频源的时空分布,实现了采用新方法对2013年南斯科舍海岭M_W7.8地震的多点震源机制反演.矩心矩张量解表明,地震矩心在44.50°W/60.18°S,矩心深度19 km,半持续时间49 s,释放标量地震矩4.71×10²⁰ N·m,发震断层走向104°,倾角54°,滑动角8°.视震源时间函数清楚地揭示了地震矩随时间变化的方位依赖性,总体上可以将时间过程分为前60 s和后50 s两个阶段,但前60 s可细分为两次子事件.根据台阵反投影结果,这次地震为沿海沟从西到东的单侧破裂,破裂长度达311 km,可以分为5次子事件,能量释放的峰值点依次为13 s、30 s、51 s、64 s和84 s,平均破裂速度分别为0.6 km·s^-1、2.6 km·s^-1、2.3 km·s^-1、2.8 km·s^-1和3 km·s^-1.多点震源机制反演显示,5次子事件的矩震级分别为M_W7.57,M_W7.48,M_W6.80,M_W7.53和M_W7.08,半持续时间依次为21 s,17 s,6 s,16 s和8 s,走向分别为95°,105°,81°,98°和98°,倾角依次为57°,49°,86°,46°和64°,滑动角-9°,1°,-17°,13°和-4°.这些在震源机制、能量释放以及持续时间方面的变化都是当地构造和应力环境复杂性的反映.     

Kinetik der Methanfermentation des Klärschlammes

Zusammenfassung In der vorliegenden Arbeit wird die Fermentation der organischen Stoffe des Kl?rschlammes vom kinetischen Standpunkt untersucht. Für die Faulgasproduktion ist die T?tigkeit der Methanbakterien entscheidend. Bei der ?batch?-Fermentation des Kl?rschlammes mit Trockensubstanzgehalt von 5% wurde die maximale Wachstumsrate der Methanbakterien für die folgenden Inkubationstemperaturen bestimmt: für 20°C 0,02 Tage⁻¹, für 30°C 0,09 Tage⁻¹, für 50°C 0,17 Tage⁻. Im semikontinuierlichen Prozess wurde der spezifische Wirkungsgrad als Quotient der aus 1 Liter Faulraum produzierten Faulgasmenge (im ml) zum Inhalt der organischen Stoffe im Rohschlamm (in g/l) ausgedrückt. Die Abh?ngigkeit des spezifischen Wirkungsgrades von der Raumbelastung für Temperaturen von 20°C, 30°C und 50°C wurde graphisch dargestellt. Die Verdünnungsrate, bei der die maximalen Werte des spezifischen Wirkungsgrades erreicht wurden, sind für 20°C 0,12 Tage⁻¹, für 30°C 0,21 Tage⁻¹ und für 50°C 0,28 Tage⁻¹. Entsprechende Werte des spezifischen Wirkungsgrades waren der Reihe nach: 20 ml/g pro Tag, 63 ml/g pro Tag und 100 ml/g pro Tag. Die minimale Generatinsdauer der Methanbakterin betr?gt für 20°C 3,1 Tage, für 30°C und 50°C weniger als 2,5 Tage. Aus dem Vergleich des ein- und zwistufigem Betriebs geht hervor, dass bei einer l?nger als 10 Tage w?hrenden Aufenthaltsdauer der spezifische Wirkungsgrad der beiden Systeme identisch ist, bei kürzerer Aufenthaltsdauer leistet jedoch der einstufige Betrieb mehr.

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Summary The purpose of this study is to estimate the fermentation of the organic matter in sewage sludge from the point of view of kinetics. The activity of methane bacteria seems to be essential for the sludge gas production. In the batch fermentation of sludge containing about 5% of dry solids, the maximal growth rate for methane bacteria at given incubation temperatures was found to be: at 20°C 0,02 days⁻¹, at 30°C 0,09 days⁻¹, and at 50 °C 0,17 days⁻¹. For the semi-continous process, the specific efficiency of the fermentation system was expressed as the relation between the quantity (in ml) of sludge gas produced daily in a one liter digestion area and the volatile solids content in raw sludge (in g/l). The dependence of the specific efficiency upon the volume load at temperatures of 20°C, 30°C, and 50°C was determined graphically. The dilution rate for maximal values of the unit efficiency attained was at 20°C 0,12 days⁻¹, at 30°C 0,21 days⁻¹, and at 50°C 0,28 days⁻¹, corresponding maximal values of specific efficiency were 20 ml/g per day, 63 ml/g per day and 100 ml/g per day. Minimal generation time of methane bacteria is at 20°C 3,1 days, at 30°C and at 50°C less than 2,5 days. Comparison betwen single stage and two-stage operations, with detention periods of more than 10 days, shows that the specific efficiency is very much the same in both systems. However, at shorter detention periods and with the same digestion capacity, the single stage operation is more efficient.

     

Evaluation of the fourth-order tesseroid formula and new combination approach to precisely determine gravitational potential

Calculating topographic gravitational potential (GP) is a time-consuming process in terms of efficiency. Prism, mass-point, mass-line, and tesseroid formulas are generally used to calculate the topographic GP effect. In this study, we reformulate the higher-order formula of the tesseroid by Taylor series expansion and then evaluate the fourth-order formula by numerical tests. Different simulation computations show that the fourth-order formula is reliable. Using the conventional approach in numerical calculations, the approximation errors in the areas of the north and south poles are extremely large. Thus, in this study we propose an approach combining the precise numerical formula and tesseroid formulas, which can satisfactorily solve the calculation problem when the computation point is located in the polar areas or areas very near the surface. Furthermore, we suggest a “best matching choice” of new combination approach to calculate the GP precisely by conducting various experiments. Given the computation point at different positions, we may use different strategies. In the low latitude, we use a precise numerical formula, the fourth-order tesseroid formula, the second-order tesseroid formula, and the zero-order formula, in the 1° range (from the computation point), 1° to 15° range, 15° to 40° range, and the range outside 40°, respectively. The accuracy can reach 2 × 10^?5 m² s^?2. For the high latitude, we use the precise numerical formula, fourth-order tesseroid, second-order tesseroid, and zero-order tesseroid formulas in the ranges of 0° to 1°, 1° to 10°, 10° to 30°, and the zones outside 30°, respectively. However, if an accuracy level of 2 × 10^?5 m² s^?2 is required, the zero-order tesseroid formulas should not be used and the second-order tesseroid formula should be used in the region outside 15° for the low latitude and in the region outside 10° for the high latitude.     

东北地区重力均衡异常特征的初步研究

本文利用地面实测重力资料和地形高程资料,采用普拉特-海福特(Pratt-ttayford)重力均衡理论模型,取1°×1°方格网,通过使用现成改正表格查取改正值与个别计算点用理论公式计算作校核的方法,计算了我国东北地区75个计算点的均衡重力异常值;并对局部第四系覆盖较厚地区作了第四系密度改正;在此基础上,构制了我国东北N39°—49°,E121°—131°大部分地区的均衡重力异常图;结合区域布格重力异常和区域空间重力异常特征以及莫霍界面的起伏特点作了对比分析和讨论     

中国大陆自由空气重力场的初步研究

本文利用地面实测的重力资料计算并构制了从1°×1°到10°×10°平均的中国大陆自由空气重力异常图,并对这套图中所反映出来的基本事实进行了分析和解释,且就这些基本事实与大地构造、地壳均衡、地震活动的关系及其可能的地球动力学过程进行了讨论     

基于中国东港台站的OH气辉成像观测数据对重力波波源的事件分析

利用东港（40°N,124°E）台站于2013年9月15—16日的OH气辉成像观测数据报告了两个重力波事件（1和2）.同时,结合北京十三陵（40.3°N,116.2°E）台站的多普勒流星雷达风场数据和位于39.4°N,130.6°E位置处的SABER/TIMED卫星的温度参数分析发现,观测的两个重力波事件于2013年9月15—16日02∶00—03∶00 LT时间段,和70~110 km高度是自由传播的.利用反射线追踪方法分析表明,重力波事件1和事件2分别产生于（39.3°N,117.2°E）和（47.1°N,121.3°E）.且事件1的波源位置与对流活动和大气向上向下运动过程中产生的不稳定性吻合较好.然而,通过ECMWF再分析资料和MTSAT卫星观测数据分析表明,事件2可能由对流活动或大气向上运动过程中可能产生的不稳定性导致.利用MERRA自地面到约70 km高度的风场数据分析表明,观测的重力波事件1和事件2的水平相速度分别是83.5 m·s^-1（事件1）和80.1 m·s^-1（事件2）,均大于低层-中层大气风速-10~45 m·s^-1.因此,观测的两个重力波事件是可能从低层大气传播到中层-低热层大气的.     

SSQ-1 Digital Tape Recording Horizontal Pendulum Tiltmeter

The SSQ-1 Digital Tape Recording Horizontal Pendulum Tiltmeter is an instrument of high sensitivity to detect the changes of ground tilt. It uses a quartz horizontal pendulum held by Z?llner bifilar suspension to sense vertical displacement, the eddy-current transducer on the pendulum converts its displacements into electric signals. Then a microcomputer is used for data acquisition and printing as well as digit tape recording. And at the same time, a filtering pen recorder is used for visible recording. The scale value of the instrument is calibrated by computer using the known tilt angle of the bulging plate — mercury cup. The scale value is 0.3–0.5 m(″)/mV. The following are the testing results for the earth tide observation obtained from the east-west component at Baijiatan Seismic Station, Beijing: r(O₁): 0.6490±0.0179 α(O₁): −3.83°±1.58° r(K₁): 0.8049±0.0128 α(K₁): 1.40°±0.90° r(M₂): 0.6699±0.0040 α(M₂): −0.27°±0.34° r(S₂): 0.7316±0.0075 α(S₂): 2.83°±0.58° r(M₃): 0.8497±0.0964 α(M₃): 1.61°±6.51° The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 353–359, 1993. In this work also participated Mr. Huai-Wen PAN and Wei-Jin ZHANG. And we here give special thanks to Yun-Zao XI, Qin-Wen XI, Bo-Xong TANG, Yi-Hui CHEN and An-Xu WU for their kind help in the development and test of the instrument. This paper is translated by Mr. Zhong ZHENG.     

Estimation of PKP times from ISC data

The International Seismological Centre (ISC) treats reports of the earliest observed core phase arrivals from earthquakes as PKIKP observations and provides residuals based on Jeffreys-Bullen PKIKP times. An analysis of some 30 000 such data from ISC bulletins for the year 1967 has shown that the data include, in addition to PKIKP, many observations of PKP₁ and precursors to PKP. By the use of simple truncation and trimming techniques, travel-time curves (expressed as differences from JB), with standard errors, have been obtained for PKIKP in the ranges 110 to 139° and 152 to 173°, and for PKP₁ in the range 144 to 154°. The PKIKP curve in these ranges agrees quite closely with the curve obtained by Cleary and Hales, and with one derived from model 1066B of Gilbert and Dziewonski, except that the Cleary-Hales curve is up to 0.7 s earlier at distances below 120°, and the 1066B curve is up to 1 s later beyond 152°. The PKP₁ curve is in good agreement with that derived from 1066B.A plot of the number of observations in each 1° distance interval has been used to estimate the positions of the cusps B, C and D on the PKP curve as 144, 152.5 and 115°, again in reasonable agreement with 1066B.     

Paleomagnetic study of Cambrian Potsdam Group sandstones,St. Lawrence Lowlands,Quebec

We report paleomagnetic results from oriented drill core samples collected at 10 sites (80 samples) from the Covey Hill and 19 sites (96 samples) from the overlying, fossiliferous Cha?teauguay Formations of the gently dipping Late Cambrian Potsdam Group sandstones exposed in the St. Lawrence Lowlands of Quebec. Stepwise thermal demagnetization analyses ave revealed the presence of two predominant groups of coherent magnetizations C-1 and C-2, after simple correction for bedding tilt. The C-1 group magnetization is a stable direction (D=332°, I=+18°) with unblocking temperatures (T_UB) between 550 and 650°C, present in the older Covey Hill Formation; this direction is probably a chemical remanence acquired during the Covey Hill diagenesis and carried predominantly by hematite. The C-2 group magnetization (D=322°, I=+9°) is present at 13 sites of the younger Cha?teauguay Formation; this is probably carried by magnetite and represents a penecontemporaneous, depositional DRM, characterized by T_UB spectra 400–550°C. We believe that C-2 is relatively younger than C-1 based on a combination of arguments such as the presence of opposite polarities, internal consistency, similarity and common occurrence of C-1 and C-2 respectively in the Covey Hill and Cha?teauguay members. The corresponding paleomagnetic poles C-1 (46°N, 149°E; dp, dm=3°, 5°) and C-2 (37°N, 156°E; dp, dm=2°, 5°) are not significantly different from most of the other Late Cambrian (Dresbachian-Franconian) poles derived from sediments exposed in the southern region (Texas) of the North American craton which are also believed to have been deposited during Croixian Sauk sea transgression similar to the Potsdam sandstones. Although adequate faunal control is lacking (in particular for the Covey Hill Formation), this comparison with the Cratonic poles suggests a Late Cambrian age to the Potsdam poles. The agreement between the results also gives the evidence for internal consistency of cratonic poles at least for Late Cambrian.The incoherent C-3 group remanence (D=250°, I=?15°) is commonly present at 7 sites in both the formations; this may not correspond to a reliable paleomagnetic signal. The other remanence C-4 (D=180°, I=+10°) is found only at 3 sites located in the uppermost stratigraphic levels of the Cha?teauguay Formation; the corresponding paleomagnetic pole (40°N, 107°E) does not differ significantly from the Ordovician and some Late Cambrian poles. The present data are insufficient to resolve a problem in apparent polar wander for Middle and Late Cambrian time posed by the existence of high-latitude poles for some strata of Middle Cambrian age and low-latitude poles for some strata of Late Cambrian age.     

Water flow velocity over frozen and nonfrozen black soil slopes

Ice‐ and snow‐melted water flow over partially thawed frozen soil of cultivated slopes causes serious soil erosion, which results in soil degradation and affects productivity in Northeast China. Water flow velocity over frozen and nonfrozen soil shows importance in understanding meltwater erosion. In this work, a series of laboratory experiments were conducted to measure water flow velocity over frozen and nonfrozen soil slopes. Experiments were performed using the electrolyte trace method under the pulse boundary model, under conditions of 4 slope gradients (5°, 10°, 15°, and 20°), 3 flow rates (1, 2, and 4 L/min), and 7 sensors positioned at 0.1, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 m away from the electrolyte injection point. Results showed that velocities over frozen soil slopes increased with flow rate and slope gradient. Flow velocities over nonfrozen soil slopes increased with flow rate and slope gradients from 5° to 15° and stabilized at 15°. Flow velocities over frozen soil slopes were 30%, 54%, 71%, and 91% higher than those over nonfrozen ones at slope gradients of 5°, 10°, 15°, and 20°. Flow velocities over frozen soil slopes under different flow rates of 1, 2, and 4 L/min were approximately 52%, 59%, and 79% higher than those over nonfrozen soil, respectively. This study can help in assessing the erosion of partially thawed frozen soil by meltwater flow.     

The influence of weathering on the geotechnical properties and slope angles of mudstone in the Mineoka earth-slide area,Japan

Three active earth-slide slopes of Tertiary mudstone were investigated: Slope 1 has an angle of 17 ?4°, Slope 2 of 12.9°, and Slope 3 of 11.6°. Infinite slope analysis indicated that the instability of these three slopes can be well explained by using the residual strength parameters of earth-slide soils near the sliding surface in conjunction with the highest ground water table. The residual angle of shearing resistance, ø'_r, plays an important role in the determination of slope angle because it differs greatly among slopes. Mineralogical studies and X-ray diffraction analyses were performed for the clay minerals included in the slope material. The results showed that illite and chlorite were found in Slope 1, and also in Slopes 2 and 3 together with interstratified illite/montmorillonite and montmorillonite. The degree of weathering is progressive in order of Slopes 1, 2 and 3. The alteration of clay minerals by weathering causes the reduction in ø'_r -values, i.e., 19.4° in Slope 1 (steep, less weathered) and 12.1-9.2° in Slopes 2 and 3 (gentle, much more weathered). This result indicates that the degree of weathering has a great influence on the value of ø'_r, which in turn determines the slope angle.     

Paleomagnetism of certain constituents of the Bay St. George sub-basin,western Newfoundland

Paleomagnetic studies have been made of certain constituents of the Bay St. George sub-basin. Specifically, results are reported from the Spout Falls Formation (Tournaisian), the Jeffreys Village Member of the Robinsons River Formation (Visean), and the Searston Formation (Namurian-Westphalian). The following magnetizations have been isolated: Spout Falls A (Tournaisian) with D = 343.5°, I = ?22.7°, k = 61.2, α₉₅ = 7.1° and the corresponding pole at 28.6°N, 139.5°E (4.5°, 8.5°); Spout Falls B (Kiaman) with D = 166.7°, I = 12.2°, k = 51.7, α₉₅ = 10.7° and the corresponding pole at 34.5°S, 42.7°W (5.5°, 10.9°); Jeffreys Village A (Visean) with D = 351.2°, I = ?27.3°, k = 54.0, α₉₅ = 7.6° and the corresponding pole at 26.5°N, 130.7°E (4.5°, 8.3°); Searston A (Namurian) with D = 161.7°, I = 11.7°, k = 107, α₉₅ = 7.4° and the corresponding pole at 33.9°S, 37.2°W (3.8°, 7.5°); and Searston C with D = 111.6°, I = ?13.8°, k = 28.8, α₉₅ = 14.5° and the corresponding pole at 19.6°S, 19.0°E (7.6°, 14.8°). After comparison with paleopoles of similar ages derived from eastern and western Newfoundland rocks, from constituents of the east coast basin and for interior North America, it is concluded that: (1) it is unlikely that any large scale relative motion took place since the Early Carboniferous between eastern and western Newfoundland; (2) it is unlikely that any north-south relative motion took place between the east coast basin and the Bay St. George sub-basin; and (3) the Bay St. George sub-basin results do not support the earlier proposed displaced terrane hypothesis of the northern Appalachians in as much as the motions during the Carboniferous are not supported. There is evidence of the northward motion of the Appalachians and North America as a whole during the Carboniferous. The magnetostratigraphic horizon marker in the Carboniferous separating a dominant normal and reversed magnetization on the older side and an entirely reversed (Kiaman) magnetization on the younger side may be placed in the Bay St. George sub-basin at the base of the Searston Formation.     

震源机制与应力体系关系模拟研究

为理解震源机制和所作用的应力张量之间的关系,模拟了东西向挤压、垂直向拉张的挤压应力体系,南北向挤压、东西向拉张的走滑应力体系和垂直向挤压、东西向拉张的拉张应力体系所产生震源机制及其剪应力和正应力的表现.结果表明:挤压应力体系可以产生逆断型、走滑型和逆走滑型的震源机制,并随着应力形因子R的增大,逆断型震源机制数目逐渐减小,而走滑型和逆走滑型震源机制数目逐渐增加;走滑应力体系兼有各种类型的震源机制,随着R值的增大,正断型和正走滑型震源机制数目逐渐减小,而逆断型和逆走滑型震源机制数目逐渐增加;拉张应力体系兼有正断型、走滑型和正走滑型震源机制,随着R值的增加,正断型震源机制数目逐渐增加,而走滑型和正走滑型震源机制数目逐渐减小.挤压应力体系在震源机制节面上的最大剪应力分布在R=0时沿倾角45°分布,随着R值增大至1,逐渐演变为沿着以(0°,90°)和(180°,90°)为中心的圆弧分布;拉张应力体系的最大剪应力分布则随着R值自0增大至1,最大剪应力自以(0°,90°)和(180°,90°)为中心的圆弧分布逐渐演变为沿倾角45°分布;走滑应力体系则随着R值自0增大至1,最大剪应力自以(0°,90°)和(180°,90°)为中心的圆弧分布逐渐演变为以(90°,90°)为中心的圆弧分布.三种应力体系所表现的震源机制P,T轴分布呈现复杂多样性:R越小,震源机制的T轴分布在拉张主应力周围的区域范围越小,而P轴分布在挤压轴周围的区域范围越大,R=0.5时两者分布区域范围均衡,R超过0.5时越接近1,震源机制的P轴分布在挤压主应力周围的区域范围越小,而T轴分布在拉张轴附近的区域范围越大.     

The effects of rock uplift and rock resistance on river morphology in a subduction zone forearc,Oregon, USA

Relationships between riverbed morphology, concavity, rock type and rock uplift rate are examined to independently unravel the contribution of along-strike variations in lithology and rates of vertical deformation to the topographic relief of the Oregon coastal mountains. Lithologic control on river profile form is reflected by convexities and knickpoints in a number of longitudinal profiles and by general trends of concavity as a function of lithology. Volcanic and sedimentary rocks are the principal rock types underlying the northern Oregon Coast Ranges (between 46°30′ and 45°N) where mixed bedrock–alluvial channels dominate. Average concavity, θ, is 0·57 in this region. In the alluviated central Oregon Coast Ranges (between 45° and 44°N) values of concavity are, on average, the highest (θ = 0·82). South of 44°N, however, bedrock channels are common and θ = 0·73. Mixed bedrock–alluvial channels characterize rivers in the Klamath Mountains (from 43°N south; θ = 0·64). Rock uplift rates of ≥0·5 mm a⁻¹, mixed bedrock–alluvial channels, and concavities of 0·53–0·70 occur within the northernmost Coast Ranges and Klamath Mountains. For rivers flowing over volcanic rocks θ = 0·53, and θ = 0·72 for reaches crossing sedimentary rocks. Whereas channel type and concavity generally co-vary with lithology along much of the range, rivers between 44·5° and 43°N do not follow these trends. Concavities are generally greater than 0·70, alluvial channels are common, and river profiles lack knickpoints between 44·5° and 44°N, despite the fact that lithology is arguably invariant. Moreover, rock uplift rates in this region vary from low, ≤0·5 mm a⁻¹, to subsidence (<0 mm a⁻¹). These observations are consistent with models of transient river response to a decrease in uplift rate. Conversely, the rivers between 44° and 43°N have similar concavities and flow on the same mapped bedrock unit as the central region, but have bedrock channels and irregular longitudinal profiles, suggesting the river profiles reflect a transient response to an increase in uplift rate. If changes in rock uplift rate explain the differences in river profile form and morphology, it is unlikely that rock uplift and erosion are in steady state in the Oregon coastal mountains. Copyright © 2006 John Wiley & Sons, Ltd.     

临近空间大气扰动变化特性的定量研究

本文利用TIMED/SABER 2002年1月至2013年1月共11年的卫星温度探测数据,通过全球网格化及在网格内作数学统计的方法,得到了20~100km高度上全球网格点上温度的平均值和标准差,实现了对临近空间全球大气扰动进行定量刻画的目的.通过定量分析温度标准差的分布特性,文中得到了临近空间大气扰动的全球分布规律,并讨论了与这些分布规律相关的物理过程.结果表明,在20~70km高度上,温度标准差为1~10K,有显著的冬季/夏季的差异,冬季的温度标准差比夏季大;大气重力波扰动是最主要来源,同时大气传播性行星波引起的扰动也是来源之一.在70~100km高度上,温度标准差常年较强,量值为10~30K,冬季/夏季的差异小,低纬地区的温度标准差高于中高纬度地区,呈现许多局地化的小结构.大气重力波是引起该区域大气总扰动量的主要扰动来源,大气潮汐波、传播性行星波(准2天、准6.5天)也有重要贡献.     

中国大陆区域重力场的基本特征

中国大陆1°×1°空间重力异常和布格重力异常大体以东经104°线为界分为东、西绝然不同的两部分,东部异常变化平缓,线性异常的走向以北北东向为主,西部异常变化急剧,线性异常的走向以北西西向为主,进而还可分成异常特征明显不同的东部、中部、新疆、青藏四大区。文章初步讨论了中国大陆区域重力场与大地构造,地壳均衡和地震活动的关系,认为中国东部线性异常主要反映了北北东向新华夏构造体系,中国西部线性异常主要反映了北西西向西域构造体系,布格重力异常梯度带大都对应断块间的断裂带;布格重力异常和地形高程基本上呈负相关, 中国大陆地壳在大范围内基本处于均衡状态;地震大都发生在重力梯度带上