M5 model tree based modelling of reference evapotranspiration

This paper investigates the potential of M5 model tree based regression approach to model daily reference evapotranspiration using climatic data of Davis station maintained by California irrigation Management Information System (CIMIS). Four inputs including solar radiation, average air temperature, average relative humidity, and average wind speed whereas reference evapotranspiration calculated using a relation provided by the CIMIS was used as output. To compare the performance of M5 model tree in predicting the reference evapotranspiration, FAO–56 Penman–Monteith equation and calibrated Hargreaves–Samani relation was used. A comparison of results suggests that M5 model tree approach works well in comparison to both FAO–56 and calibrated Hargreaves–Samani relations. To judge the generalization capability of M5 model tree approach, model created by using the Davis data set was tested with the datasets of four different sites. Results from this part of the study suggest that M5 model tree could successfully be employed in modeling the reference evapotranspiration. Further, sensitivity analysis with M5 model tree approach suggests the suitability of solar radiation, average air temperature, average relative humidity, and average wind speed as input parameters to model the reference evapotranspiration Copyright © 2009 John Wiley & Sons, Ltd.     

A Technique of Rainfall Assimilation for Dynamic Extended Range Monsoon Prediction

Summary ?A methodology has been developed to assimilate satellite-measured rainfall during the initial phase of model integration for extended range monsoon prediction. The vertical profiles of latent heating corresponding to different rain rates have been derived from the model statistics. These heating rates have been assimilated through nudging in the thermodynamics equation of the model. This procedure of assimilating observed heating has corrected the simulation of heating location in the model and consequently removed the anomalous sinking motion over Indian landmass. With the correction of vertical circulation, both mean July rainfall over India and the distribution have improved. Interannual variability has been brought out for the years 1987 and 1988. In view of the availability of rainfall profile from Tropical Rain Measuring Mission (TRMM) there is a scope of adopting this method of assimilating observed rainfall, for extended range monsoon prediction. Received February 12, 1999/Revised May 4, 1999     

Petrology and geochemistry of mafic dykes of Sylhet traps,Northeastern India,and their Kerguelen plume linkage

Mineralogy and Petrology - We present here a new set of mineralogical and geochemical data from a cluster of east southeast-trending mafic dykes that intrude a lava flow of Sylhet traps. These...     

Analysis of plasma and field conditions during some intensely geo-effective transient solar/interplanetary disturbances of solar cycle 23

The problem of solar wind-magnetosphere coupling is investigated for intense geomagnetic storms (Dst < -100nT) that occurred during solar cycle 23. For this purpose interplanetary plasma and field data during some intensely geo-effective transient solar/interplanetary disturbances have been analysed. A geomagnetic index that represents the intensity of planetary magnetic activity at subauroral latitude and the other that measures the ring current magnetic field, together with solar plasma and field parameters (V, B, Bz, σB, N, and T) and their various derivatives (BV,-BVz, BV², -BzV², B²V, Bz²V, NV²) have been analysed in an attempt to study mechanism and the cause of geo-effectiveness of interplanetary manifestations of transient solar events. Several functions of solar wind plasma and field parameters are tested for their ability to predict the magnitude of geomagnetic storm.     

Indices based assessment of built-up density and urban expansion of fast growing Surat city using multi-temporal Landsat data sets

GeoJournal - The population growth in urban areas leads to the expansion of built-up area which leads to a number of serious problems like environmental pollution, destruction of urban ecology,...     

The Gyldén‐type problem revisited: More refined analytical solutions

We resume and consistently extend our previous researches concerning the Gyldén‐type problem (a two‐body problem with time‐dependent equivalent gravitational parameter). To approach most of the concrete astronomical situations to be modelled in this way, we consider a periodic small perturbation. For the nonresonant case, we present a second‐order analytical solution. For the resonant case, we adopt the most realistic astronomical situation: only one dominant term of the Hamiltonian. In this case we point out a fundamental model of resonance, common to every resonant situation, and, moreover, identical to the first fundamental model of resonance . Considering the simplest model of periodic change of the equivalent gravitational parameter, we .nd that all possible resonances are con.ned to the first fundamental model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)