Migration behaviour of river ganga between Allahabad and Buxar using remotely sensed data

Channel migration includes any change of river channel geometry within the context of the cross-section, pattern or network in a drainage basin. To study the dynamic behaviour of a river, measurements taken with conventional ground-based instruments are time-consuming and expensive. Remote sensing techniques are capable of providing a measure of surface variability including dynamic behaviour of channels, reasonably quickly due to availability of the repetitive remotely-sensed data. These data are well suited for the assessment and monitoring of dynamic changes on the surface of the earth. In the present study Landsat MSS and TM data of winter season in the form of false colour composites (FCC) of years 1982 and 1987 were used for the delineation of river Ganga course lying between Allahabad and Buxar. The interpretation of satellite data was carried out using visual interpretation technique for the assessment of channel migration. The shift in river banks delineated from satellite data were measured with respect to river banks identified from topographical base map. The maximum shift observed in mid channel is 4. 55 km while maximum left and right banks shifts are 4.6 and 4.8 km, respectively.     

The effectiveness of measures to reduce the man-made greenhouse effect. The application of a Climate-policy Model

Summary In this paper we briefly describe the characteristics and the performance of our 1-D Muenster Climate Model. The model system consists of coupled models including gas cycle models, an energy balance model and a sea level rise model. The chemical feedback mechanisms among greenhouse gases are not included. This model, which is a scientifically-based parameterized simulation model, is used here primarily to help assess the effectiveness of various plausible policy options in mitigating the additional man-made greenhouse warming and the resulting sea level rise.For setting priorities it is important to assess the effectiveness of the various measures by which the greenhouse effect can be reduced. To this end we take a Scenario Business-as-Usual as a reference case (Leggett et al., 1992) and study the mitigating effects of the following four packages of measures: The Copenhagen Agreements on CFC, HCFC, and halon reduction (GECR, 1992), the Tropical Forest Preservation Plan of the Climate Enquete-Commission of the German Parliament on CO₂ reduction (ECGP, 1990), a detailed reduction scheme for energy-related CO₂ (ECGP, 1990), and a preliminary scheme for CH₄, CO, and N₂O reduction (Bach and Jain, 1992–1993).The required reduction depends, among others, on the desired climate and ecosystem protection. This is defined by the Enquete-Commission and others as a mean global rate of surface temperature change of ca. 0.1 °C per decade — assumed to be critical to many ecosystems — and a mean global warming ceiling of ca. 2 °C in 2100 relative to 1860.Our results show that the Copenhagen Agreements, the Tropical Forest Preservation Plan, the energy-related CO₂ reduction scheme, and the CH₄ and N₂O reduction schemes could mitigate the anthropogenic greenhouse warming by ca. 12%, 6%, 35%, and 9% respectively. Taken together, all four packages of measures could reduce the man-made greenhouse effect by more than 60% until 2100; i.e. over the climate sensitivity range 2.5 °C (1.5 to 4.5) for 2 × CO₂, the warming could be reduced from 3.5 °C (2.4 to 5.0) without specific measures to 1.3 °C (0.9 to 2.0) with the above packages of measures; and likewise, the mean global sea level rise could be reduced from 65 cm (46 to 88) without specific measures to 32 cm (22 to 47) with the above measures.Finally, the model results also emphasize the importance of trace gases other than CO₂ in mitigating additional man-made greenhouse warming. According to our preliminary estimates, CH₄ could in the short term make a sizable contribution to the reduction of the greenhouse effect (because of its relatively short lifetime of 10 yr), as could N₂O in the medium and long term (with a relatively long lifetime of 150 yr).With 7 Figures     

Snow cover area variability assessment in the upper part of the Satluj river basin in India

In high-altitude areas, snow cover plays a significant role in mountainous hydrology. Satluj, which is a snow-fed river, is a part of the Indus River system in the western Himalayas. Snow cover area (SCA) variability in this river basin affects the spatio-temporal flow availability and avalanche events. Keeping this in mind, the present study focuses on SCA variability and its relationship with various topographical features such as elevation, slope and aspect. The study has been carried out in the upper part of the Satluj River Basin on the basis of MODIS Terra (MOD10A2) data from 2001 to 2014. It has been noticed that the average annual SCA in this part of the Satluj River Basin varies from 44 to 56% with an average of about 48% of the total basin area of 16, 650 km². Further, snow accumulation and depletion curves have been suggested for assessing the SCA in the study area.     

An Information fusion approach for PALSAR data to retrieve soil moisture

Estimation of vegetation covered soil moisture with satellite images is still a challenging task. Several models are available for soil moisture retrieval in which water cloud model (WCM) is most common. But, it requires an estimation of accurate vegetation parameterization. Thus, there is a need to develop such an approach for soil moisture retrieval which minimize these limitations. Therefore, this paper deals with the soil moisture retrieval using fully polarimetric SAR data by fusing the information from different bands. Various polarimetric indices and observables were critically analysed, and found that the index; SPAN (total scattered power) gives better information of vegetation cover as compared to other indices/observables. Based on this, WCM model has been modified using SPAN as parameter and soil moisture content were retrieved.     

An artificial neural network based approach for urban growth zonation in Dehradun city,India

For regulating urban growth, it is imperative to produce urban growth zonation maps, in which future urbanizable areas along with their urban growth potential are delineated. As, these maps provide a rational and scientific basis for taking future decisions regarding the growth of the city. The conventional approach for generating urban growth zonation maps is subjective in nature. To reduce this subjectivity, an artificial neural network (ANN) approach has been proposed for generating urban growth zonation maps. The database required for ANN-based urban growth zonation has been compiled from remote sensing data and other existing maps. GIS is used for handling of this spatial data. A comparison of the ANN- and conventional approach-derived zonation maps was also done. The study demonstrated the potential of ANN for urban growth zonation of an area, which may provide a valuable input to the urban planning authorities for regulating urban growth     

Glacier changes using satellite data and effect of climate in Tirungkhad basin located in western Himalaya

Glaciers are widely recognized as key indicators of climate change, and melt water obtained from them is an important source of fresh water and for hydropower generation. Regular monitoring of a large number of Himalayan glaciers is important for improving our knowledge of glacier response to climate change. In the present study, Survey of India topographical maps (1966) and Landsat datasets as ETM+ (2000, 2006) and TM (2011) have been used to study glacier fluctuations in Tirungkhad basin. A deglaciation of 26.1% (29.1?km²) in terms of area from 1966 to 2011 was observed. Lower altitude small glaciers (area?<?1?km²) lost more ice (34%), while glaciers with an area <10?km² lost less (20%). The percentage of change in glacier length was 26% (31.9?km) from 1966 to 2011. The south-facing glaciers showed high percentages of loss. From 2000 to 2011, debris cover has increased by 1.34%. The analysis of the trend in meteorological data collected from Kalpa and Purbani stations was carried out by Mann Kendall non-parametric method. During the last two decades, the mean annual temperature (T_max and T_min) has increased significantly, accompanied with a fall in snow water equivalent (SWE) and rainfall. The increasing trend in temperature and decreasing trend in SWE were significant at 95% confidence level. This observation shows that the warming of the climate is probably one of the major reasons for the glacier change in the basin.     

A circular statistical method for extracting rotation measures

We propose a new method for the extraction of rotation measures from spectral polarization data. The method is based on maximum likelihood analysis and takes into account the circular nature of the polarization data. The method is unbiased and statistically more efficient than the standard χ ² procedure. We also find that the method is computationally much more convenient than the standard χ ² procedure if the number of data points is very large. We find that for most sources the method gives results very close to the standard χ ² minimization procedure. We give results for all the cases for which the method gives significantly different results from χ ² minimization. We also make a λ ³ fit to the data in order to extract non-Faraday rotation behaviour for those sources for which a large number of data points are available.     

Energetics and Dynamics of an Impulsive Flare on March 10, 2001

We present Hα observations from ARIES (Nainital) of a compact and impulsive solar flare that occurred on March 10, 2001 and which was associated with a CME. We have also analyzed HXT, SXT/Yohkoh observations as well as radio observations from the Nobeyama Radio Observatory to derive the energetics and dynamics of this impulsive flare. We coalign the Hα, SXR, HXR, MW, and magnetogram images within the instrumental spatial-resolution limit. We detect a single HXR source in this flare, which is found spatially associated with one of the Hα bright kernels. The unusual feature of HXR and Hα sources, observed for the first time, is the rotation during the impulsive phase in a clockwise direction. We propose that the rotation may be due to asymmetric progress of the magnetic reconnection site or may be due to the change of the peak point of the electric field. In MW emission we found two sources. The main source is at the main flare site and another is in the southwest direction. It appears that the remote source is formed by the impact of accelerated energetic electrons from the main flare site. From the spatial correlation of multiwavelength images of the different sources, we conclude that this flare has a three-legged structure.     

How Good are the Predictions for Oscillation Frequencies

We have used available intermediate degree p-mode frequencies for solar cycle 23 to check the validity of previously derived empirical relations for frequency shifts (Jain et al., 2000). We find that the calculated and observed frequency shifts during the rising phase of cycle 23 are in good agreement. The observed frequency shift from minimum to maximum of this cycle as calculated from MDI frequency data sets is 251±7 nHz and from GONG data is 238±11 nHz. These values are in close agreement with the empirically predicted value of 271±22 nHz.