Long range prediction of Indian summer monsoon rainfall

The search for new parameters for predicting the all India summer monsoon rainfall (AISMR) has been an important aspect of long range prediction of AISMR. In recent years NCEP/NCAR reanalysis has improved the geographical coverage and availability of the data and this can be easily updated. In this study using NCEP/NCAR reanalysis data on temperature, zonal and meridional wind at different pressure levels, few predictors are identified and a prediction scheme is developed for predicting AISMR. The regression coefficients are computed by stepwise multiple regression procedure. The final equation explained 87 of the variance with multiple correlation coefficient (MCC), 0.934. The estimated rainfall in the, El-Niño year of 1997 was -1.7 as against actual of 4.4. The estimated rainfall deficiency in both the recent deficient years of 2002 and 2004 were -19.5 and -8.5 as against observed -20.4 and -11.5 respectively

Satellite Coastal and Oceanographic Research Inter-comparison Exercise (SICOME)

INCOIS is coordinating Satellite Coastal and Oceanographic Research (SATCORE) project SATCORE programme since XIth plan with an aim of long-term measurements of bio-optical properties in the Indian coastal waters. The principal aim of these measurements is continuous measurement of in situ bio-optical data for validation of existing ocean color algorithms, improvement, development of new bio-optical algorithms in coastal waters of India. INCOIS had identified 12 time series sampling transects along east and west of India for continuous measurement of bio-optical parameters. Regular in situ sampling and analysis at time series stations are carried out by sub-projects sanctioned under SATCORE program to various Research and Academic &D Institutions: Junagadh Agricultural University (Off Okha), NIO, Goa (Off Goa), Goa University (Off Goa), Mangalore University (Off Mangalore), CIFT, Kochi (Off Kochi), Annamalai University (Off Parangipettai), IIT Madras (Off Chennai), Andhra University (Off Visakhapatnam), CSBoB, Andhra University (Off Visakhapatnam), Berhampur University (Off Gopalpur), Jadavpur University (Off Frazergunj), CARI (ICAR) (A & N Islands). To ensure the accuracy of the parameters measured at vasrious laboratories at different time-series locations, Satellite Coastal and Oceanographic Research-Inter-comparison Exercises (SICOME) were conducted during 2014 and 2015. During SICOME samples of Optically Active Substances i.e chlorophyll-a (chl-a), coloured dissolved organic matter (CDOM) and total suspended matter (TSM) were collected from one location. The master samples were immediately analyzed and duplicate samples were sent to different SATCORE laboratories. All the fluorometers were calibrated with teh standards for chlorophyll-a, Chromophoric Dissolved Organic Matter (CDOM) and Turbidity. All five Radiometers were also operated simultaneously to estimate the instrument bias. The document provides results of the instrument and analytical bias for same samples analyzed at various SATCORE laboratories so as to maintain the data quality for international standard

Classical orbital paramagnetism in non-equilibrium steady state

We report the results of our numerical simulation of classical-dissipative dynamics of a charged particle subjected to a non-markovian stochastic forcing. We find that the system develops a steady-state orbital magnetic moment in the presence of a static magnetic field. Very significantly, the sign of the orbital magnetic moment turns out to be {\it paramagnetic} for our choice of parameters, varied over a wide range. This is shown specifically for the case of classical dynamics driven by a Kubo-Anderson type non-markovian noise. Natural spatial boundary condition was imposed through (1) a soft (harmonic) confining potential, and (2) a hard potential, approximating a reflecting wall. There was no noticeable qualitative difference. What appears to be crucial to the orbital magnetic effect noticed here is the non-markovian property of the driving noise chosen. Experimental realization of this effect on the laboratory scale, and its possible implications are briefly discussed. We would like to emphasize that the above steady-state classical orbital paramagnetic moment complements, rather than contradicts the Bohr-van Leeuwen (BvL) theorem on the absence of classical orbital diamagnetism in thermodynamic equilibrium.Comment: 6 pages, 4 figures, Has appeared in Journal of Astrophysics and Astronomy special issue on 'Physics of Neutron Stars and Related Objects', celebrating the 75th birth-year of G. Srinivasa

Study of spatial-temporal variations in the green Noctiluca scintillans and diatom blooms in the Arabian Sea using MODIS data

Phytoplankton blooms of green Noctiluca scintillans (a dinoflagellate) and diatom, which appear in the Northern and Central Arabian Sea during winter are far-reaching and persistent. Generation of phytoplankton species images revealed a massive winter bloom with huge spatial extent in 2015. In contrast to this, the classified species images for 2013 indicated relatively weaker bloom with respect to its spread. A plot of total number of pixels classified as diatom and Noctiluca scintillans for different years revealed a cyclic pattern of the spread. The report deals with an approach to forecast the bloom / productivity of the oceanic waters in the Northern-Central Arabian Sea in a qualitative way making use of the systematic pattern of its distribution across the year

Cyclone Phailin enhanced the productivity following its passage: Evidence from satellite data

Over the past decade (2002–2013) the Bay of Bengal has experienced 12 cyclones and 27 tropical storms. The recent one was the cyclone Phailin which was equivalent to a category-5 hurricane on the Saffir–Simpson hurricane wind scale(SSHWS). The cyclonic storm developed over the north of Andaman and Nicobar Islands on 9 October 2013. Subsequen tly,it propagated towards north-northwest and made a landfall at the Gopalpur coast of south Odisha on 12 October

Distribution of hydro-biological parameters in coastal waters off Rushikulya Estuary, East Coast of India: A premonsoon case study

The hydro-biological parameters of coastal waters off Rushikulya estuary was investigated during premonsoon 2011. Important hydro-biological parameters such as water temperature, salinity, pH, DO, NO2, NO3, NH4, PO4, SiO4, TSM, Chl-α, phytoplankton and zooplankton were measured during the present study. Temperature established a strong positive correlation with salinity and pH during the present study. Chl-α found in positive relation with NO3, SiO4 and TSM. Analysis of variance revealed significant monthly variation in pH, salinity and TSM. Significant station wise variation was observed in DO and most of the nutrients i.e., NO3, NH4, PO4, SiO4. A total of 119 species of phytoplankton were identified of which 84 species are of diatoms, 22 species of dinoflagellates, 7 species of green algae, 5 species of cyanobacteria (blue green algae) and 1 species of cocolithophore. Phytoplankton abundance varied between 25543 (Nos. L-1) and 36309 (Nos. L-1). Diatoms dominated the phytoplankton community followed by dinoflagellates in all the months. Diatoms contributed to 82-89 of the total phytoplankton population density whereas dinoflagellates contributed to 6-12. The regression between Chl-α and phytoplankton abundance resulted with weak relation (R2 = 0.042). Zooplankton fauna composed of 134 species of holoplankton and 20 types of meroplankton were encountered during the study period. Zooplankton population dominated by copepod during all months and accounted for 74 to 85 to the total zooplankton. The population density ranged from 6959 to 35869 Nos./10 m3. Analysis of variance explained no significant variation in total zooplankton abundance and also for different groups of zooplankton

On forecasting the Indian summer monsoon: The intriguing season of 2002

This year, the rainfall over India during the first half of the summer monsoon season was 30 below normal. This has naturally led to a lot of concern and speculation about the causes. We have shown that the deficit in rainfall is a part of the natural variability. Analysis of the past data suggests that there is a 78 chance that seasonal mean rainfall this year will be 10 or more below the long-term average value. We discuss briefly how forecasts for seasonal rainfall are generated, whether this event could have been foreseen, and share our perspective on the problems and prospects of forecasting the summer monsoon rainfall over the Indian region

IACT observations of gamma-ray bursts: prospects for the Cherenkov Telescope Array

Gamma rays at rest frame energies as high as 90 GeV have been reported from gamma-ray bursts (GRBs) by the Fermi Large Area Telescope (LAT). There is considerable hope that a confirmed GRB detection will be possible with the upcoming Cherenkov Telescope Array (CTA), which will have a larger effective area and better low-energy sensitivity than current-generation imaging atmospheric Cherenkov telescopes (IACTs). To estimate the likelihood of such a detection, we have developed a phenomenological model for GRB emission between 1 GeV and 1 TeV that is motivated by the high-energy GRB detections of Fermi-LAT, and allows us to extrapolate the statistics of GRBs seen by lower energy instruments such as the Swift-BAT and BATSE on the Compton Gamma-ray Observatory. We show a number of statistics for detected GRBs, and describe how the detectability of GRBs with CTA could vary based on a number of parameters, such as the typical observation delay between the burst onset and the start of ground observations. We also consider the possibility of using GBM on Fermi as a finder of GRBs for rapid ground follow-up. While the uncertainty of GBM localization is problematic, the small field-of-view for IACTs can potentially be overcome by scanning over the GBM error region. Overall, our results indicate that CTA should be able to detect one GRB every 20 to 30 months with our baseline instrument model, assuming consistently rapid pursuit of GRB alerts, and provided that spectral breaks below 100 GeV are not a common feature of the bright GRB population. With a more optimistic instrument model, the detection rate can be as high as 1 to 2 GRBs per year.Comment: 28 pages, 24 figures, 4 tables, submitted to Experimental Astronom

Empirical algorithm to estimate the average cosine of underwater light field at 490 nm

The average cosine of the underwater light field μ(λ), where λ is the wavelength, is an apparent optical property (AOP) that describes the angular distribution of radiance at a given point in water. Here, we present a simple algorithm to determine the average cosine at 490 nm, μ(490), which was developed using the measured optical parameters from the eastern Arabian Sea and coastal waters off Goa. The algorithm is validated using measured optical parameters. This algorithm, based on a single optical parameter, performed better compared with other empirical algorithms in determining the average cosine of underwater light field. The absorption coefficient at 490 nm, derived as an application of μ(490), compared well with the synthetic optical data and optical data measured from other regions