NISCAIR Online Periodicals Repository Collection: IJMS Vol.37(1) [March 2008]

Size distributions of aerosols over the Indian Ocean

Wed, 27 Feb 2008 22:58:59 GMT

Title: Size distributions of aerosols over the Indian Ocean

Authors: Pant, Vimlesh; Deshpande, C G; Kamra, A K

Abstract: Concentration and size distribution of aerosol particles in the size range of 0.5 to 20.0 µm were measured over the Indian Ocean during January 23 to March 31, 2004. Total aerosol concentration showed the North-to-South positive gradient with latitude over the Indian Ocean North of the Inter Tropical Convergence Zone (ITCZ). Minimum concentration of aerosols was observed immediately South of the ITCZ and it increased on either side of the ITCZ. Contrary to being monomodal in shape in this size range as is generally expected over open ocean, the aerosol size distributions followed the Junge’s power law and show the transport of aerosols from the Indian subcontinent to North of the ITCZ, even though several hundreds of kilometers away from the Indian coastline. Aerosols South of the ITCZ exhibited monomodal size distributions which were typical of marine aerosols in the pristine environments. Aerosol size distributions in the roaring forties clearly showed the generation of sea-salt particles due to the wave breaking activity in this region of high winds. Abundance of particles of < 1.0 µm diameter dominated over the Indian Ocean North of the ITCZ.

Page(s): 104-108

Measurement of column ozone, water vapour over Indian Ocean

Wed, 27 Feb 2008 22:58:59 GMT

Title: Measurement of column ozone, water vapour over Indian Ocean

Authors: Jain, S. L.

Abstract: The study of various minor constituents in the atmosphere plays an important role in the understanding of physics, chemistry, dynamics and radiation budget of the atmosphere. These trace species have temporal as well as spatial variation and therefore the knowledge of latitudinal distribution of these species is of great significance. Keeping this in view a highly sophisticated and microprocessor based compact sun photometer consisting of five filter channels at 300, 305, 312, 940 and 1020 nm was used to measure column ozone, water vapour in addition to various other parameters such as UV-B radiation, near IR radiation, aerosol optical depth etc. The measurements were made from Goa, India (15° 24´ N, 73° 42´ E) to Maitri, Antarctica ( 70° 46´ S, 11° 45´ E) over Indian Ocean during 16th Indian Scientific Expedition to Antarctica (December 1996-March 1997). It was found that water vapour decreased while total ozone increased as the ship moved towards the coldest, the windiest and the largest icy continent i.e. Antarctica.

Page(s): 99-103

Meteorology of Southern Ocean in Lazarev Sea area as revealed from observations obtained from Indian Antarctic Expeditions

Wed, 27 Feb 2008 22:58:59 GMT

Title: Meteorology of Southern Ocean in Lazarev Sea area as revealed from observations obtained from Indian Antarctic Expeditions

Authors: Lal, R. P.

Abstract: Ship observations taken during voyage through Southern Ocean and observations recorded at Indian Antarctic Station Dakshin Gangotri (DG), have been used to study the latitudinal and diurnal variations of air temperature and sea surface temperature (SST) and climatology of Lazarev Sea area. Air temperature and SST are highly correlated and the SST lags by 1.5 °C during summer and the degree of lag reduces as winter approaches. The meteorological surface observations show an annual mean surface pressure of about 985 hPa. Surface wind is mainly easterly with annual average mean wind speed of 17 Kn. The annual average air temperature is –16.6 °C with a highest average air temperature of –2.5 °C during January and lowest average air temperature of –28.1 °C during August. Highest maximum temperature of 9.9 °C and lowest minimum temperature of –52.0 °C has been reported from coastal station. Diurnal variations of SST and air temperature have been observed in Lazarev sea area. It was not feasible to visualize these variations on moving ship.

Page(s): 93-98

In-situ data and NCEP reanalysis: A comparative study in the Southern Ocean and Antarctic Ocean

Wed, 27 Feb 2008 22:58:59 GMT

Title: In-situ data and NCEP reanalysis: A comparative study in the Southern Ocean and Antarctic Ocean

Authors: Das, I. M. L.; Mitra, Amitabh

Abstract: A special expedition was launched by the National Center for Antarctic and Ocean Research (NCAOR), India on board R/V Akademik Boris Petrov during 25 January to 1 April 2006 passing the Southern Ocean and reaching the Larsemann Hills area of East Antarctica. The surface layer in-situ data generated from the cruise are compared with that obtained from the NCEP reanalysis during the same period along the track of the vessel. It is concluded that the NCEP reanalysis sea surface temperature and air temperature have some discrepancies as the vessel enters the sea ice zone near the Antarctic coast. The air pressure is well modeled but the relative humidity shows high variability throughout the period of the study. The wind speed is poorly correlated with that obtained from the NCEP due to the use of “Course over the ground” in place of ship “heading” while calculating the true wind.

Page(s): 86-92