R. K. Giri ¹, R. K. Sharma ²

Affiliations
1 India Meteorological Department, Lodi Road, New Delhi-110003, IN
2 N.A.S. Degree College, Meerut, UP-250004, IN

Abstract

In the determination of atmospheric motion vectors (AMVs) from sequential images obtained from geostationary satellites, registration of the images play a primary and important role. Image registration is an essential and fundamental component in the retrieval of AMVs from triplet consecutive images of Kalpana -1 satellite is done by suitable matching of valid tracers in back and forth from middle image. If the triplet is not properly registered than it may lead to errors in wind speed and direction. The inaccuracy of registration (N-S or E -W shift) in one set of triplet images will generate the errors in wind speed and direction this will affect in other images if available in sequence also. Image registration maintains the spatial relationship between the pixels within images and between images. Improper registration results due to the deviation in orbital parameters, spacecraft attitude, thermal distortions and earth sensor biases. If we need continuous train of images like, sometimes we need morphing in images to get continuous AMVs which can be a potential source of errors for the input of Numerical Weather Prediction (NWP). But in this framework the other issues will also need further investigation like cloud evolution, height assignment and thickness biases, etc. in AMVs. In this paper, authors will deal only the registration issue. It has been shown from daily registration shift in Kalpana -1 satellite images during the year 2008 between 0000UTC to 0200 UTC in Northern Hemisphere that, the errors introduced in wind speed varies from 10 m/sec to 45 m/sec at nadir due to registration only. Few cases have been shown appreciable improvement after applying the interactive correction of registration errors.

Keywords

AMV, Image Registration, NWP, Weather

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R. K. Giri ¹, R. K. Sharma ²

Affiliations
1 India Meteorological Department, Lodi Road, New Delhi-110 003, IN
2 Department, D.A.S. Degree College, Meerut- 250004 UP, IN

Abstract

Currently, atmospheric motion vectors (AMVs) are hourly generated satellite derived product on operational basis at India Meteorological Department (IMD), New Delhi. These wind vectors are associated with errors and difficult to use in mesoscale models without considering the quality issues. Quality control is an integral part of the AMVs retrieval from geo-stationary satellites. Present paper deals with various quality indicator or flags used in Automatic Quality Control (AQC) scheme of European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) with new coefficients and Auto Editor (AE) criterion at Cooperative Institute for Meteorological Satellite Studies (CIMSS) on Kalpana -1 satellite data. The results obtained from the new parameters in AQC and with height adjustment made with AE are more realistic and free from spurious winds in both Infrared (IR) and Water Vapour (WV) channels. Collocation with radiosonde during one month period shows an average decrease (decrease) of RMSE in CMVs (WVWs) is of the order of 4 % (3 %) and increase (decrease) in mean bias is of the order of 3 % (10 %).

Keywords

Automatic Quality Control (AQC), Atmosphere Motion Vector (AMV), IR, Meteorology, Wind Vapour,india

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R. K. Giri ¹, R. K. Sharma ²

Affiliations
1 India Meteorological Department, Lodi Road, New Delhi-110003, IN
2 N.A.S. Degree College Meerut-UP-250001, IN

Abstract

The atmospheric motion vectors (AMV's) derived from geostationary satellites are valuable tool in weather forecasting especially in data sparse region. This paper presents the results of an inter-comparison of AMVs assigned heights derived from Meteosat -7&Kalpana -1, geostationary satellite data for both lower and upper levels by Infrared Window (IRW) and Water Vapour (H₂O or IR/WV) intercept methods. The Kalpana -1 satellite data (different sensor and resolution than Meteosat -7) is being processed by similar algorithm as Cooperative Institute of Meteorological Science (CIMSS), USA. In this short study of inter-comparison, the utility of the IR/WV intercept method in assigning the height of derived wind vectors especially at upper level winds is shown graphically. It is observed that actual wind speed direction from radiosonde data at upper levels (300-150 hPa) is higher up to the order of 8-12 m/sec and 5-8 degree for Kalpana - 1 data after applying the semi-transparency correction.

Keywords

Meteosat-7, Kalpana-1, Atmospheric Motion Vectors, IRW, H₂O Intercept, Meteorological Data

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Jagabandhu Panda ¹, R. K. Giri ², K. H. Patel ³, A. K. Sharma ², R. K. Sharma ⁴

Affiliations
1 School of Physical and Mathematical Sciences, Nanyang Technological University, SG
2 Satellite Meteorology Division, India Meteorological Department, New Delhi-110003, IN
3 Ericsson India Gloabal Services Pvt Ltd, Noida-201301, U. P, IN
4 N. A. S. Degree College, Meerut-250001, IN

Abstract

The quantitative data such as satellite derived winds are useful for improvement of the numerical prediction of weather events like tropical cyclones. In this study, the satellite derived winds from QuikSCAT surface observations and KALPANA-1 atmospheric motion vectors are used during the cyclone PHYAN in order to update the initial and boundary conditions through three-dimensional variational assimilation technique within the Weather Research Forecasting (WRF) modeling system. The simulated mean sea level pressure and 850 hPa wind fields from eight experiments are presented in this study in order to analyze the observed and simulated features of the tropical cyclone PHYAN that occurred in the month of November, 2009. The model results are also compared with the KALPANA-1 images and the India Meteorological Department (IMD) predicted results. Further, the intensity and track of the cyclonic storm PHYAN, generated from the simulations are also compared with the IMD predictions in order to evaluate the model performance.

Keywords

WRF Modeling System, Variational Assimilation, Satellite Derived Winds, Cloud Motion Vectors, Cyclonic Storm

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Tajinder Singh Arora ¹, R. K. Sharma ²

Affiliations
1 Department of Electronics and Communication Engineering, Maharaja Surjamal Institute of Technology, Janakpuri - 110058, New Delhi, IN
2 Department of Electronics and Communication Engineering, Ambedkar Institute of Advanced Communication Technologies and Research, Geeta Colony, Delhi – 110031, IN

Abstract

The objective of this paper is to present a novel cubic generator circuit using four quadrant analog multiplier and divider based on third generation current conveyor. A well-established approach has been utilized to implement the new fourquadrant analog multiplier and divider using CCIII exhibiting a larger usable bandwidth. Some additional, relevant, nonlinear applications of CCIII-based four-quadrant analog multiplier and divider have also been worked out to demonstrate its usefulness. PSPICE simulations have been carried out to validate the theoretical findings of the proposed novel cubic generator and other presented circuit configurations. Applications of the new CCIII-based multiplier and divider circuits of this paper have been shown to realize amplitude modulation, squarer and finally the novel cubic generator.

Keywords

Non-Linear Circuits, Analog Multiplier, Analog Divider, Third Generation Current Conveyor, Cubic Generator.

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Tajinder Singh Arora ¹, R. K. Sharma ²

Affiliations
1 Department of Electronics and Communication Engineering, Maharaja Surajmal Institute of Technology, Janakpuri, New Delhi - 110058, IN
2 Department of Electronics and Communication Engineering, Ambedkar Institute of Advanced Communication Technologies and Research, Geeta Colony, New Delhi - 110031, IN

Abstract

The classical “Kerwin-Huelsman-Newcomb” (KHN) filter has been a very popular high performance multifunction biquadratic analog filter. Derived from the adjoint signal flow graph of this KHN circuit a new multi-input universal filter has been presented utilising for the first time all third generation current conveyors. This new universal biquadratic filter employs all grounded passive elements, realizes all the standard five filtering functions namely “Low pass”, “High pass”, “Band pass”, “Band reject” and “All pass” and produces all the outputs without requiring any additional active and /or passive component. The workability of the proposed circuit configuration has been verified by PSPICE simulation along with its non-ideal analysis, time domain analysis, sensitivity analysis and Monte-Carlo analysis. The proposed universal filter with explicit current output may be suitably employed in all current-mode application situations of classical KHN filter such as; FM demodulators, phase-locked-loops etc.

Keywords

Active Filters, Analog Processing Circuits, Biquadratic Filters, Biquadratic Functions, Current Conveyors

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