尼泊尔Andhi Khola河研究参照点的识别及确认

参照条件是开展河流生态学研究的基础,这些条件不受或很少受到人为干扰。为研究尼泊尔Andhi Khola河上一处河坝的生态影响,采用野外快速生物筛分（RFB）法预先划分出2个研究参照点或最少干扰参照点,于2013年1月和2月采集了生物学样品（大型脊椎动物）和物理-化学样品。对大型无脊椎动物区系使用多栖息地采样（MHS）法。通过一些指标对预选的研究点进行了确认,这些指标是：尼泊尔生物评价法（NEPBIOS）、生物监测评价法（BMWP）、兴都库什喜马拉雅生物评价法（HKHBIOS）、Hilsenhoff法（HILSENHOFF）,以及国家卫生基金会水质指标法（NSFWQI）。NEPBIOS、HKHBIOS、HILSENHOFF、RFB以及NSFWQI指标预测2个参照点的河水水质都比较好,达到II级水准。只有BMWP/ASPT水质指标预测2个参照点的河水水质都很好,达到I级水准。如此,预选的这2个水质较好的点（II级）被确认为研究参照点。本研究表明,多度量法适用于即将修建水利工程的河流的监测与评价。     

Evolutionary Features of Marine Atmospheric Boundary Layer (MABL) over the Arabian Sea and the Onset of Monsoon over Kerala during ARMEX-2003

In this study an attempt has been made to examine the evolutionary features of the dynamic and thermodynamic characteristics of the marine atmosphere over the South-East Arabian Sea near 9.22°N, 74.51°E just two to three days prior to the onset of southwest monsoon over Kerala during 2003 and seek the linkages with the large-scale flow in the lower and middle troposphere at that time over the region. The marine meteorological data collected onboard ORV Sagarkanya as part of the experiment ARMEX-2003 for 4–8 June, 2003 are used. The monsoon onset over Kerala occurred on 8 June, 2003. The observed changes in the marine atmospheric boundary layer (MABL) characteristics just two days prior to the onset are discussed. It is observed that the MABL increased in height up to 4 km on 6 June from an initial height 2.8 km on 5 June. The top of the MABL dried up (Relative Humidity RH ~ 30–40%) with weak and variable winds throughout the day on 6 June while the air at 850 hPa is relatively humid (RH ~ 50–80%) but not saturated. A sequential increase in RH is associated with a change in the winds from southwesterly to westerly from 6 June onwards until the onset date. The changes in the lower and middle troposphere flow patterns over the Arabian Sea and Indian region are highlighted.     

Monitoring Horizontal and Vertical Cropping Pattern and Dynamics in Bihar over a Decade (2001–2012) Based on Time-Series Satellite Data

Increasing population and natural disasters like drought, flood, cyclone etc., has impacted global agriculture area and hence continuously modifying cropping pattern and associated statistics. The present study analysed agriculture dynamics over one of the densely populated and disaster prone state (Bihar) in India and derived vital statistics (single, double and triple cropping area, and monthly, seasonal, annual and long term status at the state and district level) for the years 2001–2012. The study used time-series MODIS vegetation index (EVI; MOD13A2, 1 km, 16 day, 2001–2012), MODIS annual Land Cover product (MCD12Q1, 500 m, 2001–2012) and Global Land Cover map (Scasia_V4, 1 km, 2000; Globcover_V2.2, 300 m, 2005/2006 and V2.3, 2009, 300 m), and extracted horizontal (i.e., area change) and vertical (i.e., cropping intensification) agriculture change pattern. The results were inter-compared, and validated using government reports as well as with high spatial resolution data (IRS-LISS III 23.5 m). From 2001–2006 to 2007–2012, the net horizontal and vertical change in agriculture area is +145.24 and +907.82 km², respectively, and net change in seasonal crop area (winter, summer and monsoon) is +959.21, +1009.84 and ?1061.64 km², respectively. The districts which are located along the eastern part of Ganges experienced maximum positive changes and the districts along Gandak river in the north-western part of the study area experienced maximum negative changes. Overall, the study has quantified and revealed interesting space–time agriculture change patterns over 12 years including impacts caused by droughts and floods in the study area.     

Response spectrum of incompatible acceleration,velocity and displacement histories

The ground motions induced by an earthquake are expressed by the histories of acceleration, velocity and displacement. It is generally assumed that the acceleration, velocity and displacement histories contain identical information, i.e. the velocity history is obtained by integration of the acceleration history, and the displacement history is obtained by integration of the velocity history. However, this is not always true. In conventional processing of ground motion histories, additional corrections are applied to the velocity and displacement histories, which are not reflected in the acceleration history. As a result, the three ground motion histories contain slightly different information, or they are not fully compatible with one another. The structural response computed from the acceleration history, therefore, does not correspond to the processed velocity and displacement histories. The purpose of this paper is to underscore the engineering difficulties associated with incompatible histories and to provide a method of computing the response spectrum, which is compatible with the acceleration, velocity and displacement histories. Copyright © 2001 John Wiley & Sons, Ltd.     

TropFlux: air-sea fluxes for the global tropical oceans—description and evaluation

In this paper, we evaluate several timely, daily air-sea heat flux products (NCEP, NCEP2, ERA-Interim and OAFlux/ISCCP) against observations and present the newly developed TropFlux product. This new product uses bias-corrected ERA-interim and ISCCP data as input parameters to compute air-sea fluxes from the COARE v3.0 algorithm. Wind speed is corrected for mesoscale gustiness. Surface net shortwave radiation is based on corrected ISCCP data. We extend the shortwave radiation time series by using “near real-time” SWR estimated from outgoing longwave radiation. All products reproduce consistent intraseasonal surface net heat flux variations associated with the Madden-Julian Oscillation in the Indian Ocean, but display more disparate interannual heat flux variations associated with El Ni?o in the eastern Pacific. They also exhibit marked differences in mean values and seasonal cycle. Comparison with global tropical moored buoy array data, I-COADS and fully independent mooring data sets shows that the two NCEP products display lowest correlation to mooring turbulent fluxes and significant biases. ERA-interim data captures well temporal variability, but with significant biases. OAFlux and TropFlux perform best. All products have issues in reproducing observed longwave radiation. Shortwave flux is much better captured by ISCCP data than by any of the re-analyses. Our “near real-time” shortwave radiation performs better than most re-analyses, but tends to underestimate variability over the cold tongues of the Atlantic and Pacific. Compared to independent mooring data, NCEP and NCEP2 net heat fluxes display ~0.78 correlation and >65?W?m^?2 rms-difference, ERA-I performs better (~0.86 correlation and ~48?W?m^?2) while OAFlux and TropFlux perform best (~0.9 correlation and ~43?W?m^?2). TropFlux hence provides a useful option for studying flux variability associated with ocean–atmosphere interactions, oceanic heat budgets and climate fluctuations in the tropics.     

Long-term ultraviolet variability of Seyfert galaxies

Flux variability is one of the defining characteristics of Seyfert galaxies, a class of active galactic nuclei (AGN). Although these variations are observed over a wide range of wavelengths, results on their flux variability characteristics in the ultraviolet (UV) band are very limited. We present here the long-term UV flux variability characteristics of a sample of fourteen Seyfert galaxies using data from the International Ultraviolet Explorer acquired between 1978 and 1995. We found that all the sources showed flux variations with no statistically significant differences in the amplitude of UV flux variation between shorter and longer wavelengths. Also, the flux variations between different near-UV (NUV, \(1850{-}3300\) Å) and far-UV (FUV, \(1150{-}2000\) Å) passbands in the rest frames of the objects are correlated with no time lag. The data show indications of (i) a mild negative correlation of UV variability with bolometric luminosity and (ii) weak positive correlation between UV variability and black hole mass. At FUV, about 50% of the sources show a strong correlation between spectral indices and flux variations with a hardening when brightening behaviour, while for the remaining sources the correlation is moderate. In NUV, the sources do show a harder spectrum when brighter, but the correlation is either weak or moderate.     

GIS-based evaluation of micro-watersheds to ascertain site suitability for water conservation structures

The planning of conservation measures to conserve water and soil resources taking hydrological planning unit as micro-watershed is considered to be effective. The automated watershed delineation technique using the spline interpolated filled digital elevation model (DEM) is effective in converging slopes of the area in which the stream patterns match with the manually digitized stream patterns of the topographical map. The various vector spatial layers like the slope/aspect, land-use/land-cover, runoff potential, soil erosion potential and the associated attribute information governing the criteria for different conservation structures can act as input layers in integrated spatial analysis module in GIS environment to evolve derived layers indicating the locations of conservation sites meeting the requisite criteria. The reliability of suitable conservation sites suggested out of integrated spatial GIS analysis could be ascertained using the multi criteria analysis incorporating the various factors controlling soil erosion process in the micro-watershed groups. The details of the above work are discussed in the paper.     

Thermodynamic structure of the boundary layer in relation to a monsoon depression over the Bay of Bengal — A case study

Aerological observations carried out on board ORV Sagarkanya at a stationary location (20° N, 89° E) over the Head Bay of Bengal during August 18–21, 1990 were analysed to study the thermodynamic structure of the marine boundary layer in relation to a monsoon depression which formedin situ with its centre at 20° N, 88° E. The q(mixing ratio) reversal observed at 850 hPa prior to formation of the low pressure area shifted to a higher level (h<700 hPa) with the formtion of the low. Positive buoyancy below 850 hPa prior to the formation of the low indicated conditions favourable for deep convection. When the low pressure area intensified into a depression, negative buoyancy was observed at lower levels.     

Impact of Climate Change on Runoff of the Major River Basins of India Using Global Circulation Model (HadCM3) Projected Data

The effects of climate change on hydrological regimes have become a priority area for water and catchment management strategies. The terrestrial hydrology driven by monsoon rainfall plays a crucial role in shaping the agriculture, surface and ground water scenario in India. Thus, it is imperative to assess the impact of the changing climatic scenario projected under various climate change scenario towards the hydrological aspects for India. Runoff is one of the key parameters used as an indicator of hydrological process. A study was taken up to analyse the climate change impact on the runoff of river basins of India. The global circulation model output of Hadley centre (HADCM3) projected climate change data was used. Scenario for 2080 (A2 scenario indicating more industrial growth) was selected. The runoff was modeled using the curve number method in spatial domain using satellite derived current landuse/cover map. The derived runoff was compared with the runoff using normal climatic data (1951–1980). The results showed that there is a decline in the future climatic runoff in most of the river basins of India compared to normal climatic runoff. However, significant reduction was observed for the river basins in the eastern region viz: lower part of Ganga, Bahamani-Baitrani, Subarnrekha and upper parts of the Mahanadi. The mean projected runoff reduction during monsoon season (June–September) were 18 Billion Cubic Meter (BCM), 3.2 BCM, 3.5 BCM and 5.9 BCM for Brahmaputra-Barak Subarnrekha, Subarnarekha and Brahmini-Baitrani basin, respectively in comparison to normal climatic runoff. Overall reduction in seasonal runoff was high for Subarnrekha basin (54.1%). Rainfall to runoff conversion was high for Brahmaputra-Barak basin (72%), whereas coefficient of variation for runoff was more for Mahanadi basin (1.88) considering the monsoon season. Study indicates that eastern India agriculture may be affected due to shortage of surface water availability.     

Snow Cover Area Mapping Using Synthetic Aperture Radar in Manali Watershed of Beas River in the Northwest Himalayas

The current study has used Synthetic Aperture Radar (SAR) satellite data to estimate the Snow Cover Area (SCA) in Manali watershed of Beas River in Northwest Himalayas of Himachal Pradesh, India. SAR data used in this study is of Radarsat-2 (RS2) and Environmental Satellite (ENVISAT), Advanced Synthetic Aperture Radar (ASAR). The SAR preprocessing was done with SAR image processing tools for converting raw SAR images into calibrated geo-coded backscatter images. Maps for forest, built area, layover and shadow were created and used for masking snow cover in these areas. The backscattering ratio of wet snow to reference image threshold method with value range from ?2 to ?3 db was used to estimate wet SCA for study area. In this technique, if the threshold is too high (≥-2 db) wet SCA is overestimated and if it is too low (≤-3db), this method underestimates the SCA. The wet SCA is under/over estimated (+6 % to?8 % on average) in late spring season due to the inherent terrain and SAR imaging effects of layover/foreshortening and shadow and also due to the masking of forest areas. Overall, the SCA derived from SAR data matches well when compared with total SCA derived from cloud free optical remote sensing data products, especially during wet season.