Decrease In Altitude Research Articles

Observation of clouds macrophysical characteristics in China by CALIPSO

Clouds’ macrophysical characteristics play an important role in the climate system and dramatically vary because of the diverse climatic and geographic factors in China. We analyze cloud macrophysical characteristics and the differences between subregions in China (18°–54°N, 73°–135°E) from March 2012 to February 2015 based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations, including cloud fractions, cloud vertical distribution, and cloud geometrical properties with the perspective of daytime and nighttime. We found that annual single layer, multilayer (ML), and total cloud fractions are 40.4±1.1%, 22.4±0.4%, and 62.8±1.5%, respectively, and clouds are generally located between 6 and 12 km. The cloud fractions in daytime are less than that in nighttime over the south while that of Tibet shows the reverse trend. In the vertical direction, except for Tibet, the clouds in nighttime have larger spatial coverage and are higher in altitude than that in daytime. The regional average values of cloud macrophysical characteristics in the south are highest, followed successively by Tibet, north, and northwest. Cloud geometrical depth and spacing show a gradually declining trend with the increase in layers and decrease of altitude in ML cloud system.

Solar cycle variations in ion composition in the dayside ionosphere of Titan

AbstractOne Titanian year spans over two complete solar cycles, and the solar irradiance has a significant effect on ionospheric densities. Solar cycle 24 has been one of the quietest cycles on record. In this paper we show data from the Cassini ion and neutral mass spectrometer (INMS) and the radio and plasma wave science Langmuir probe spanning the time period from early 2005, at the declining phase of solar cycle 23, to late 2015 at the declining phase of solar cycle 24. Densities of different ion species measured by the INMS show a consistent enhancement for high solar activity, particularly near the ionospheric peak. The density enhancement is best seen in primary ion species such as CH3+ rather than heavier ion species such as HCNH+. Unlike at Earth, where the ionosphere and atmosphere thermally expand at high solar activity, at Titan the altitude of the ionospheric peak decreases, indicating that the underlying neutral atmosphere was less extensive. Among the major ion species, CH5+ shows the largest decrease in peak altitude, whereas heavy ions such as C3H5+ show very little decrease. We also calculate the ion production rates using a theoretical model and a simple empirical model using INMS data and show that these effectively predict the increased ion production rates at high solar activity.

Effect of tropical cyclones on the stratosphere–troposphere exchange observed using satellite observations over the north Indian Ocean

Abstract. Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere–troposphere exchange (STE) processes in the upper troposphere and lower stratosphere (UTLS) region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS) radio occultation (RO) measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS) satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase) in the tropopause altitude (temperature) up to 0.6 km (3 K), and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL) thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and consequentially the STE in the UTLS region.

Evaluation of TRMM multi-satellite precipitation analysis (TMPA) against terrestrial measurement over a humid sub-tropical basin, India

To support the GPM mission which is homologous to its predecessor, the Tropical Rainfall Measuring Mission (TRMM), this study has been undertaken to evaluate the accuracy of Tropical Rainfall Measuring Mission multi-satellite precipitation analysis (TMPA) daily-accumulated precipitation products for 5 years (2008–2012) using the statistical methods and contingency table method. The analysis was performed on daily, monthly, seasonal and yearly basis. The TMPA precipitation estimates were also evaluated for each grid point i.e. 0.25° × 0.25° and for 18 rain gauge stations of the Betwa River basin, India. Results indicated that TMPA precipitation overestimates the daily and monthly precipitation in general, particularly for the middle sub-basin in the non-monsoon season. Furthermore, precision of TMPA precipitation estimates declines with the decrease of altitude at both grid and sub-basin scale. The study also revealed that TMPA precipitation estimates provide better accuracy in the upstream of the basin compared to downstream basin. Nevertheless, the detection capability of daily TMPA precipitation improves with increase in altitude for drizzle rain events. However, the detection capability decreases during non-monsoon and monsoon seasons when capturing moderate and heavy rain events, respectively. The veracity of TMPA precipitation estimates was improved during the rainy season than during the dry season at all scenarios investigated. The analyses suggest that there is a need for better precipitation estimation algorithm and extensive accuracy verification against terrestrial precipitation measurement to capture the different types of rain events more reliably over the sub-humid tropical regions of India.

The First Russian Orbit-Borne Scatterometer: Numerical Simulation

We have chosen a “SeaWinds” scatterometer with an orbital altitude of about 800 km as a prototype of the first Russian orbital scatterometer. An involuntary decrease in the orbit altitude to 650 km made us choose between conservation of the initial swath width 1800 km or the incidence angles with the swath-width decrease to 1500 km. A wider swath width has the advantage of a better coverage of the world-ocean surface. However, it leads to an increase in the local incidence angles and, hence, a decrease in the reflected-signal power. As a result, the signalto-noise ratio decreases and an error in the wind velocity and direction reconstruction because of the equipment noise increases. The error of the wind-velocity vector reconstruction for the same drive and antenna is the choice criterion. During the study, the mathematical model of the scatterometer is developed, the numerical simulation for both swath widths is performed, the data are processed, and the reconstruction accuracies of the wind velocity and direction are compared. It is shown that the reconstruction accuracy can significantly be improved if the measurement for two polarizations is used. The results obtained also show that the wind velocity is sufficiently well reconstructed for both swaths, while the wind-direction reconstruction accuracy in the case of a wider swath is worse than that required by the technical specifications for the scatterometer. Therefore, the swath width of the new scatterometer should be 1500 km.

Altitudinal variation in pharmacologically active compounds of wild and cultivated populations of Epimedium elatum

Epimedium is a well known genus of Chinese pharmacopoeia, possessing various medicinal properties such as aphrodisiac, antioxidant, immunomodulatory, vasodilatory, hepatoprotective, cardioprotective, antidepressant, anticancerous and antiosteoporosis activities. The active principle has been found to be its flavonoid glycosides, especially Icariin and Icariside-II. In the present study, Epimedium elatum, the only species of this genus growing in Indian subcontinent and endemic to Kashmir Himalayas, has been studied for its active principle content at different habitats. The plants were collected from wild populations (W-I W-II &W-III) growing at three different sites of different altitudes and cultivated at low altitudes of Central Kashmir. After two years, the plants from wild populations as well as cultivated populations were collected, shade dried, grinded and prepared for HPLC analysis. The results showed that the content of active principles in leaves vary significantly between plants growing at different habitats. The Icariin and Icariside-II yield (per plant) of wild populations significantly increased with a decrease in altitude of habitat. Cultivated population growing at higher altitude had significantly more yield than all other populations, except the W-III. The content of active principles as a percentage of leaf dry mass increased with increase in altitude. However, the harvest index of wild populations showed a decreasing trend with increasing altitude. The content of active principles as a percentage of dry mass of whole plant was comparable in all the habitats, including the cultivated populations. The present study suggests that Epimedium plants cultivated at lower altitudes are equally or more productive in terms of Icariin and Icariside-II content than that of wild plants growing at higher altitudes.

Evidence for lightning‐associated enhancement of the ionospheric sporadic E layer dependent on lightning stroke energy

AbstractIn this study we analyze the lightning data obtained by the World‐Wide Lightning Location Network (WWLLN) and hourly ionospheric data observed by ionosondes located at Sanya and Beijing, to examine the changes in ionospheric electron density in response to the underlying thunderstorms and to investigate the possible connection between lightning discharges and the enhancement of the ionospheric sporadic E(Es) layer. We identify a statistically significant enhancement and a decrease in altitude of the Es layer at Sanya station, in agreement with the results found at Chilton, UK. However, the lightning‐associated modification of the Es layer investigated using the same approach is not evident at Beijing station. Furthermore, we compare the responses to weak and strong lightning strokes using WWLLN‐determined energies at Sanya in 2012. The lightning‐associated enhancement of the Es layer is predominantly attributed to powerful strokes with high stroke energy. A statistically significant intensification of the Es layer with higher‐energy strokes at Sanya, along with the statistical dependence of lightning‐associated enhancement of the Es layer on stroke energy, leads us to conclude that the magnitude of the enhancement is likely associated with lightning stroke energy.

Variations in Firn Line Altitude and Firn Zone Area on Qiyi Glacier, Qilian Mountains, Over the Period of 1990 to 2011

Firn line altitude is an indicator of equilibrium line altitude (ELA) and plays an important role in predicting climate behavior and global change. Landsat 30-m resolution data from clear sky at the end of 21 summer melt seasons (July and August, 1990–2011) were used to obtain the firn lines and extract the glacier boundary at Qiyi Glacier in the Qilian Mountains of China. High-resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer 30-m resolution Global Digital Elevation Model (ASTER GDEM) was employed to obtain the firn line altitudes. The firn line altitudes on the Qiyi Glacier increased from 4540 m a.s.l. to 5000 m a.s.l. during the study period, a rise of 460 m. Changes in firn line altitudes had good positive correlations with air temperature data and were in good agreement with measured and simulated ELA changes. The calculated firn zone area decreased (increased) with the increase (decrease) of firn line altitude. Linear regression was used to fit the variational trend, indicating that the firn zone area decreased by ∼1.19 km2, with a change rate 0.057 km2 a-1, during the study period. The firn zone area ratio decreased from 76.2% to 18.1% during the same time.

Distribution and elevated soil pools of mercury in an acidic subtropical forest of southwestern China

Tieshanping catchment in southwest China was supposed to a large pool of atmospheric mercury. This work was aimed to examine THg (total mercury) concentrations, pools and influence factors in the acidic forest. THg concentrations were highly elevated in the study area, which was significantly depended on TOM (total organic matter) concentrations and altitudinal elevation, whereas negatively correlated with soil pH. The pools of mercury accumulated in soils were correlated strongly with the stocks of TOM and altitude, ranged from 5.9 to 32 mg m−2 and averaged 14.5 mg m−2, indicating that the acidic forest was a great sink of atmospheric mercury in southwest China. THg concentrations in stream waters decreased with altitude increasing and regression analyses showed that soil/air exchange flux would be increased with the decrease of altitude. Present results suggest that elevation increasing decreases THg losses as low THg concentrations in runoffs and volatilization from soils.

Effect of Cynodon dactylon community on the conservation and reinforcement of riparian shallow soil in the Three Gorges Reservoir area

IntroductionRiparian vegetation plays a crucial role in soil conservation and riverbank reinforcement. The Three Gorges hydrologic project has significantly changed the pattern of water-level fluctuation and riparian environment, which significantly influenced plant community development and its effect on soil conservation and riverbank protection. Cynodon dactylon, a perennial grass with developed root system and creeping stems, has become a dominant riparian species in the Three Gorges area after the completion of the dam. We aimed to characterize how the soil-root system under the C. dactylon community responded to environmental changes and effects of the soil-root system on shallow soil conservation and riverbank reinforcement through field investigation and laboratory test.MethodsWe conducted a field survey and experimental research. Quadrates of a natural C. dactylon community were set up on a riverbank along an altitude gradient. Plants were sampled randomly for the measurements of spatial structure and tensile strength of roots. Soil erosion resistance, soil scour resistance, and shear strength of sampled soil-root systems and control soil were tested in the laboratory.ResultsRoots of the C. dactylon community significantly increased soil erosion resistance, soil scour resistance, and shear strength, enhancing the stability of shallow soil and riverbank. Due to water-level fluctuation, C. dactylon at lower altitudes was subjected to less time exposed to air. As a result, the soil-root systems at lower altitudes were characterized by reduced biomass with reduced capacity for soil reinforcement as measured through erosion resistance, soil scour resistance, and shear strength. The correlation analysis indicated that root biomass had a significant positive linear correlation with the enhancement of erosion resistance and scour resistance, and shear strength, respectively.ConclusionsRoots of the C. dactylon community effectively enhanced the stability of riparian shallow soil and riverbank. The fluctuation in water level caused the difference of root growth as the exposed time of plants decreases with the decrease of altitude. The difference of root structure resulted in the variation of the soil-root system in soil conservation and reinforcement.

山西高原草地景观的数量分类与排序

PDF HTML阅读 XML下载 导出引用 引用提醒 山西高原草地景观的数量分类与排序 DOI: 10.5846/stxb201307291977 作者: 作者单位: 山西林业职业技术学院,山西大学黄土高原研究所;山西省中阳县第一中学,山西大学黄土高原研究所,山西林业职业技术学院 作者简介: 通讯作者: 中图分类号: 基金项目: 山西省自然科学基金项目（2012011033-4）； 山西省林业厅科技创新项目（201021） Classification and ordination of grassland landscape in the Shanxi Plateau Author: Affiliation: Shanxi Forestry Technological college,,Institute of Loess Plateau, Shanxi University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:草地植被空间格局研究是草地景观研究中一项重要的基础工作。空间格局研究不仅限于描述景观的空间特征，而是要深入分析空间格局的分布规律及影响格局形成的原因及机制。以1：50万《山西省草地类型图》、《山西省行政区域图》及《山西省地形图》为主要信息源，借助GIS技术，应用TWINSPAN和DCA对山西高原草地景观的1127个样方进行研究。结果表明：（1）在TWINSPAN分类结果中，31个群丛组从左到右的排列顺序很好地揭示了山西高原草地景观的纬向地带性分布规律。即从40°43’N向34°34’N依次分布着北部草原、中部灌草丛和草丛及南部的暖温带草丛。（2）1127个样方DCA排序图纵轴揭示了明显的海拔梯度，即由上至下海拔逐渐降低，相应地草地景观变化为亚高山草甸、灌草丛、草原及河漫滩草甸；DCA排序图的横轴揭示了明显的水分梯度，即从左到右水分逐渐增加。两大优势群丛组样方及44个优势群丛组物种DCA的排序图都很好地刻画了山西高原水热组合的变化，即从西北向东南由于地形地貌引起的水热组合由冷干向暖湿逐渐变化，水热组合的梯度变化进一步影响了草地景观整体的空间分布格局。（3）GIS技术与数量生态学方法相结合有助于丰富景观生态学研究的技术体系。 Abstract:Spatial pattern is a reflection of the landscape heterogeneity over a region. Research on this pattern is a fundamental work in understanding the landscape structure, and has both theoretical and practical significance for exploring the composition and distribution laws of landscape components and their mechanisms. The key methods for realizing the spatial pattern include the comparison of pattern indices and spatial characteristics; the analysis of transition matrix of Markov Chain, and the dynamic simulation of spatial pattern based on cellular automata model. While these methods are proved to be usefull, the theoretical and technical framework has not yet been formed for the comprehensive research. The methods of quantitative ecology have been successfully used in vegetation pattern analysis on meso\ and mico\ scales. The integrated application of the methods in quantitative ecology and other modern techniques like GIS and RS might enrich the methodology of landscape study. In this study, based on the Grassland Type Map of Shanxi Province (1:500 000), Topography Map of Shanxi Province (1:500 000) and Administration Division Map of Shanxi Province (1:500 000), the Present Grassland Map of Shanxi Plateau (1:500 000) was compiled. Through the GIS techniques, 20mm×20 mm quadrat grids were set up on the Present Map, and then a set of 1127 effective quadrats was obtained. After the calculation of the importance values of individual quadrats, all the 1127 quadrats were analyzed using the quantitative methods of TWINSPAN (Two-Way Indicator Species Analysis) and DCA (Detrended Correspondence Analysis). The results showed that (1) the 31 association groups obtained from the TWINSPAN classification revealed the latitudinal zonality of grassland landscape in the plateau, i.e., the temperate grassland in the north, the shrub-grassland and grassland in the middle, and the warm temperate grassland in the south from 40°43'N to 34°34'N. (2) The vertical axis of DCA ordination plot indicated that, with the decrease in altitude from top to bottom, the grassland landscape changed gradually from the sub-alpine meadow to shrub-grassland, grassland and floodplain meadow; and the horizontal axis exhibited a clear water gradient, i.e., a gradual increase of wetness from left to right. The plots of DCA ordination for the quadrats of two dominant association groups and for the species of 44 dominant association groups reflected the gradient of rainfall and temperature changes, i.e., from the cold-arid conditions in the north-west to warm-wet conditions in the south-east across the plateau. This gradient of water-heat regime further influenced the spatial pattern of grassland landscape. (3) The integrated application of GIS technique and the methods of quantitative ecology could enrich the technical system of landscape ecology. The findings in this study suggest that either TWINSPAN or DCA was very useful for characterizing the distribution patterns of grassland landscape, and for exploring the possible causes of the patterns. The integrated application of GIS technique and quantitative techniques in ecology might have great potential for studies of landscape pattern dynamics, the drivers and the driving mechanisms. Further research on the dynamic characteristics and the driving factors of the grassland landscape in Shanxi Plateau should be conducted. 参考文献 相似文献 引证文献

Numerical Simulation of the Orion CEV Reentry Vehicle

Aerothermodynamics analysis of the Orion crew exploration vehicle (CEV) reentry vehicle at high altitude has been studied numerically. At high altitude in the rarefied flow regime noncontinuum technique such as direct simulation Monte Carlo (DSMC) method is used to solve the Boltzmann equation of kinetic theory. Results are reported at different altitudes in the rarefied regime for ideal gas and real gas model. The effects of nose radius and free stream velocity are presented. The estimation of bow shock strength and peak surface heat flux is higher for ideal gas compared with real gas model. The flow field characteristics have shown significant change with decrease in altitude and increase in free stream velocity. Present results are matching well with the results available in the literature.

Self-consistent retrieval of temperature profiles and cloud structure in the northern hemisphere of Venus using VIRTIS/VEX and PMV/VENERA-15 radiation measurements

Improved radiative transfer simulation and multi-window retrieval procedures (MWR) are described that are applied to investigate thermal structure and cloud features in the nightside atmosphere of Venus over the northern hemisphere. Comparative analyses of spectroscopic data, which were recorded independently in different parts of the infrared spectrum by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M-IR) aboard ESA's Venus Express space probe and the Profile Measuring Instrument for Venus (PMV, Fourier spectrometer FS-1/4) during the earlier Soviet Venera-15 experiment, are combined with self-consistent temperature profile and cloud parameter retrievals. MWR performance is studied using synthetic spectra at different latitudes and for different atmospheric temperature profiles and cloud parameters. VIRTIS and PMV retrieval result comparisons are used to determine constraints on physical state parameter variations, especially on applicability of different cloud models. An analytically parameterized initial model of four-modal cloud altitude distributions is proposed. Together with retrieved cloud parameters, which encompass individual mode factors and cloud upper altitude boundary, it permits optimum fits of measured radiances and brightness temperatures in the 4.3 and 15µm CO2 bands utilized for atmospheric temperature profile retrievals. A new multi-spectrum retrieval (MSR) method (Kappel et al., 2012, Kappel, in press) provides deep atmosphere CO2 opacity correction parameters, which affect cloud parameter retrievals from short-wavelength emission windows.The main features of retrieved latitude and altitude-dependent temperature fields (zonal averages) are in good quantitative accordance with earlier obtained results. Prominent structures like ‘cold collar’ and ‘hot dipole’ are re-examined. The cold inversion layer is centered at about 62–66km and 55 and 75°N. Below the collar, temperature usually decreases with latitude at the same altitude, while it typically increases toward the pole above 70km. Absolute temperature differences between zonal averages of VIRTIS and PMV results are usually below 3K between 58 and 80km, while a 9K lower VIRTIS temperature is only observed at 75°N near 60km. Both VIRTIS and PMV retrievals reveal a slow decrease of cloud top altitude from about 71km at the equator to about 70km at mid latitudes. Northward of 55°N, it quickly descends down to about 61.5km at polar latitudes in accordance with earlier results. Cloud particle size and total cloud optical depth exhibit a minimum at 50°N and increase towards the equator and the North Pole. The hemispheric average of cloud opacity derived from VIRTIS data is 34.7 at 1µm.

Investigating an annular nozzle on combustion products of hydrocarbon fuels

Full-scale and computational experiments were used to investigate the flows in the jet thrust unit with annular nozzle and deflector in the form of a spherical segment. The used working gas was the combustion products of air mixtures with acetylene, gas-phase aviation kerosene, and natural gas. Experimental studies were carried out in a hot-shot wind tunnel in the range of stagnation pressure from 0.48 to 2.05 MPa. The calculations for the cases of combustion products outflow in terrestrial and high altitude conditions were performed with the original computer program that used the Euler and Navier-Stokes systems supplemented by equations of chemical kinetics. It was found that the thrust of the jet module with an annular nozzle at high altitude almost twice exceeds the sound nozzle thrust, but is lesser (about 25 %) than the thrust of the ideal calculated Laval nozzle; the difference therewith decreases markedly with the decrease of flight altitude and stagnation pressure.

Preliminary evidence for drizzle in the middle cloud layer of Venus

Vertical trajectory data from the VEGA 1 and 2 balloon flights in the atmosphere of Venus is re-analyzed. A previously employed helium leak rate profile invoked to entirely account for the decrease in equilibrium float altitude of VEGA 2 is questioned and deemed ad hoc. As an alternative, it is proposed that both VEGA 1 and 2 experienced in-flight mass increases due to the deposition of cloud particles onto their envelopes, as well as losing helium at a reduced rate consistent with the pre-flight prediction. Particle deposition rates are estimated and found to be compatible with this alternative scenario. Possible evidence for drizzle is also presented. Preliminary experiments to derive aerosol deposition rate on a flat plate and the maximum feasible liquid mass that may be accumulated on a near-spherical envelope are briefly described. Further experimental work is recommended to constrain the deposition efficiency values involved and the maximum feasible drizzle fluxes that could have been encountered by both VEGA 1 and 2.

Evidence of ancient earthquakes in the alluvial deposits of Katun River (Uimon depression, Gorny Altai)

NEOTECTONIC STRUCTURE AND SEISMICITY OF THE STUDY AREAInstrumental observations show that the GornyAltai is a seismoactive territory. For solving problemsconcerning the evolution of its seismicity, analysis ofdifferent type deformations, which disturb the primarystructures of sedimentary complexes and can be foundin natural outcrops and artificial sections, have gainedincreasing importance recently. Examples of suchstudies are for the Neopleistocene interval are publications [1, 2] and [7] for the upper Holocene. Paleoseismogeological studies have been mostly concentratedin the southeastern part of the Gorny Altai, where thetwo largest basins (Chuya and Kurai) are located andwithin the limits of major river valleys (Chuya andKatun). However, specialized paleoseismogeologicalstudies in the central part of the Gorny Altai, wherethe Uimon basin, which is third in size, is located(Fig. 1), may also be promising.To the north, the Uimon basin is framed by theTerekta and Kamza ridges (see Fig. 1) of 2000 to 2900m high. Their block structure and general decrease inaltitude towards the depression is determined by acombination of three fault systems of different orientations: northwestern, northeastern, and sublatitudinal [3]. The geological and geophysical data indicatethe thrust of the northern mountain framing onto theCenozoic deposits of the Uimon depression along theSouth Terekta fault zone; the deposits are involved inthe tectonic motion and a series of tectonic scarps isformed [3, 10]. To the south, the intermontane is confined by the branches of Katun Ridge of 2000 to3000 m high and higher. Their neotectonic structure isdetermined by a combination of submeridional andarcshaped faults [3].In the mountain framing of the basin and in theadjacent areas (including Rudny Altai), earthquakesof up to the 12th energy class are recorded by a regularseismic network (see Fig. 1). An example of a relativelystrong events is the Tyngur earthquake of September18, 1997, whose magnitude was 4.0 to 5.2 based on thedata of various agencies. The regional value of magnitude was

Effect of seasonal freeze–thaw cycle on net nitrogen mineralization of soil organic layer in the subalpine/alpine forests of western Sichuan, China

Nitrogen mineralization, a main way that soil organic nitrogen converts to mineral nitrogen, is one of the key processes in soil nitrogen cycle. The mineral nitrogen has an important role in plant growth in the growing season. It has been widely accepted that soil freezing in winter can kill a number of microorganisms, weakening soil nitrogen mineralization. However, more and more recent studies have documented that soil microorganisms still have high activity during the deep freezing period, and obvious nitrogen mineralization in winter. Seasonal freeze–thaw cycle is a common phenomenon in the subalpine/alpine forest region, which may have a strong effect on soil ecological processes. Furthermore, the changing pattern of seasonal freeze–thaw cycles might have a significant influence on soil nitrogen mineralization in this region in the scenarios of global warming. As yet, little attention has been given to nitrogen mineralization of soil organic layer as affected by changed seasonal freeze–thaw pattern, although the increasing studies have demonstrated that winter warming might give strong effects on the litter decomposition and microbial activity in the subalpine/alpine forest regions. Therefore, a method of intact soil core incubation in combination with natural environmental gradient was employed by transferring forest soils from 3582m (A1) of altitude to 3298m (A2) of altitude and 3023m (A3) of altitude in the subalpine/alpine forests of western Sichuan, respectively. The amounts and rates of net nitrogen mineralization in soil organic layer were measured. The incubation period included the growing season and the freeze–thaw season from May 24, 2010 to April 19, 2011. The results suggested that significant net nitrogen mineralization was only observed in soil organic layer at low altitude (A3) during the whole incubation period. Forest soils at higher altitudes (A1 and A2) showed obvious soil nitrogen immobilization. In comparison with the growing season which showed remarkable nitrogen immobilization characteristic, the freeze–thaw season showed obvious nitrogen mineralization at lower altitudes (A2 and A3). In contrast, the nitrogen immobilization amounts at high altitude (A1) in freeze–thaw period were less than those in the growing season. Besides, the maximum of net nitrogen mineralization amounts and rates at high altitude (A1) in soil organic layer mainly occurred in the late stage of growing season and the onset of freezing, soil nitrogen mineralization at the middle altitude (A2) mainly occurred in the onset of freezing and the deep freezing period, while the highest amount and rate of net nitrogen mineralization at low altitude (A3) occurred in the early stage of thawing and the late stage of growing season. Furthermore, the amount and rate of soil net nitrogen mineralization during the freeze–thaw season were increasing with the decrease of altitude, which correlated with soil freeze–thaw cycle and freezing process at different altitudes. These results indicated that increasing soil temperature in the future could not only significantly enhance soil nitrogen mineralization in the freeze–thaw season, but also improve soil nitrogen mineralization by increasing freeze–thaw cycle times and shortening freeze–thaw period. However, the processes were significantly influenced by soil micro-environment of subalpine/alpine forest regions.

Ecosystem services of coastal sand dunes saw from the aspect of Sake breweries in Chiba Prefecture, Japan: A comparison of coastal and inland areas

In this report, we reviewed the differences in the ecosystem services of coastal and inland areas surrounding 39 Sake breweries in Chiba Prefecture by investigating environmental variables (e.g., location, altitude, soil, and hardness of preparation water). The Sake breweries were located in three distinct environments: the coastal vicinity, the river plains region, and the plateau/ mountainous region. The hardness of the preparation water and the soil types in the coastal vicinity were compared with those of the river plains and the plateau/mountainous region. Strong hard and hard water sources were observed in 70% or more of the breweries in the coastal vicinity, and sand dune regosol, coarse particle brown lowland soil, and coarse particle grey soil were more prevalent along the coast than inland. Most of the Sake brewery wells in the coastal vicinity were approximately 5 - 10 munderground, and there were no great differences in the number of Sake breweries in each well depth class in the river plains and the plateau/mountains region. We analysed environmental factors (distance from the sea, soil type, water hardness and preparation water collection depth) using a principal component analysis. This analysis revealed the existence of three main environments: the coastal vicinity, the river plains and the plateau/mountainous region. We conclude that the decrease in altitude between the inland Sake breweries and those along the coast is accompanied by a corresponding increase in the hardness of preparation water (from soft water to strong hard or hard water) and shifts in soil composition from gley soil, grey lowland soil, brown forest soil, and andosol to sand dune regosol, coarse particle brown lowland soil, and coarse particle grey soil.

In Situ Aircraft Measurements of the Vertical Distribution of Liquid and Ice Water Content in Midlatitude Mixed-Phase Clouds

AbstractThe vertical distribution of liquid and ice water content and their partitioning is studied using 34 cases of in situ measured microphysical properties in midlatitude mixed-phase clouds, with liquid water path ranging from near zero to ~248 g m−2, total water path ranging from near zero to ~562 g m−2, and cloud-top temperature ranging from −2° to −38°C. The 34 profiles were further divided into three cloud types depending on their vertical extents and altitudes. It is found that both the vertical distribution of liquid water within a cloud and the liquid water fraction (of total condensed water) as a function of temperature or relative position in a cloud layer are cloud-type dependent. In particular, it is found that the partitioning between liquid and ice water for midlevel shallow clouds is relatively independent on the vertical position within the cloud while it clearly depends on cloud mean temperature. For synoptic snow clouds, however, liquid water fraction increases with the decrease of altitude within the cloud. While the liquid water fraction in synoptic clouds also decreases with lowering temperature, its magnitude is only about 50% near 0°C.

Geochemical characterization of surface water and spring water in SE Kashmir Valley, western Himalaya: Implications to water–rock interaction

Water samples from precipitation, glacier melt, snow melt, glacial lake, streams and karst springs were collected across SE of Kashmir Valley, to understand the hydrogeochemical processes governing the evolution of the water in a natural and non-industrial area of western Himalayas. The time series data on solute chemistry suggest that the hydrochemical processes controlling the chemistry of spring waters is more complex than the surface water. This is attributed to more time available for infiltrating water to interact with the diverse host lithology. Total dissolved solids (TDS), in general, increases with decrease in altitude. However, high TDS of some streams at higher altitudes and low TDS of some springs at lower altitudes indicated contribution of high TDS waters from glacial lakes and low TDS waters from streams, respectively. The results show that some karst springs are recharged by surface water; Achabalnag by the Bringi stream and Andernag and Martandnag by the Liddar stream. Calcite dissolution, dedolomitization and silicate weathering were found to be the main processes controlling the chemistry of the spring waters and calcite dissolution as the dominant process in controlling the chemistry of the surface waters. The spring waters were undersaturated with respect to calcite and dolomite in most of the seasons except in November, which is attributed to the replenishment of the CO2 by recharging waters during most of the seasons.