NOPR Collection:

Use of ERS-1 scatterometer and Topex altimeter data in a nonlinear reduced gravity model of the northwestern Indian Ocean

Wed, 01 Mar 2000 00:00:00 GMT

Title: Use of ERS-1 scatterometer and Topex altimeter data in a nonlinear reduced gravity model of the northwestern Indian Ocean Authors: Tewari, Kalpana; Kumar, Raj; Gohil, B S; Basu, Sujit Abstract: This paper describes the use of ERS-1 scatterometer winds and sea level from Topex altimeter in the simulations of oceanic circulation during the monsoon season by a nonlinear reduced gravity model of the northwestern Indian Ocean. Results have been presented for June and July 1993. In the first case, monthly means of ERS -1 scatterometer winds have been used for model forcing while in the second case the analysed winds provided by Florida State University (FSU) have been used. For both the cases, sea level provided by Topex altimeter has been used to initialise the model. The model generated sea level variability has been compared with altimeter sea level variability for the months of June and July. The model results with scatterometer wind forcing are in better agreement with altimeter data of the same month and produce additional eddy near Socotra island which is not observed in the case of FSU wind forcing. Thus satellite data have significant use in the simulation oceanic circulation. Page(s): 1-6

Recent trends in summer temperatures over the North Indian Ocean

Wed, 01 Mar 2000 00:00:00 GMT

Title: Recent trends in summer temperatures over the North Indian Ocean Authors: Singh, O P Abstract: Trends in sea and air temperatures over the North Indian Ocean (Equator to 20^oN) during summer (May) have been examined. The trend analysis reveals that both sea surface temperature (SST) and air temperature have registered significant increasing trends during the period 1961-86. The trend in SST during 26 years' period ranges from 0.4°C to 0.8 °C and that in air temperature ranges from 0.6°C to 0.7°C. Power spectrum analysis shows a significant EI-Nino / Southern Oscillation (ENSO) scale cycle (2-5 years) in SST and air temperature variations. The frequency of cyclonic disturbances (depressions and cyclones) has shown a significant decreasing tendency during 1961-86. Page(s): 7-11

Oxygen consumption, ammonia excretion and total ninhydrin positive substances in black clam Villorita cyprinoides (pelecypoda) exposed to various salinities

Wed, 01 Mar 2000 00:00:00 GMT

Title: Oxygen consumption, ammonia excretion and total ninhydrin positive substances in black clam Villorita cyprinoides (pelecypoda) exposed to various salinities Authors: Chandran, R Vinu; Damodaran, R Abstract: Changes in the rate of oxygen consumption, ammonia excretion and the tissue content of total ninhydrin positive substances in the black clam, Villorita cyprinoides, were studied during the exposure of the animal to salinities 0, 5, 10, 15 and 20 ppt. The content of total ninhydrin positive substances was found to increase with an increase in ambient salinity, maximum concentration was found at 15 ppt. Rate of oxygen consumption also showed an increase with increase in salinity. Rate of excretion of ammonia nitrogen decreased with an increase in ambient salinity. The role of ninhydrin positive substances in the osmoregulation is depicted and the existence of a degradation-synthesis balance for the regulation of osmotic effector pool is suggested. Page(s): 80-82

Seasonal variation in the growth of marine red alga Asparagopsis delilei (Rhodophyta/ Bonnemaisoniales) from the Mandapam region, southeast coast of India

Wed, 01 Mar 2000 00:00:00 GMT

Title: Seasonal variation in the growth of marine red alga Asparagopsis delilei (Rhodophyta/ Bonnemaisoniales) from the Mandapam region, southeast coast of India Authors: Vasuki, S; Ganesan, M; Rao, P V Subba; Mairh, O P Abstract: The growth of Asparagopsis delilei and other seaweeds have been described from Putty and Valai Islands of Mandapam region from August 1993 to March 1995. At both the islands, plants started appearing on the reef from August, attained maximum growth during November - March and subsequently disappeared gradually from the reef. Antheridial and cystqcarpic plants and tetrasporic phase (Falkenbergia) of Asparagopsis delilei were recognised. A positive correlation was observed between length and fresh weight, whereas, negative correlation was observed between algal biomass and the environmental parameters such as salinity and temperature of seawater. Thirty-two taxa were found in association with A. delilei at both the islands. Of these, Sargassum wightii and Chondrococcus hornemanii were occurring throughout the study period. The results indicated good biomass of A. delilei can be harvested from these islands during its peak growth period December and January to meet our iodine requirements partially. Page(s): 61-64