Thursday, February 28, 2013

IMD and Rs/Rw Visit

         We visited the Regional Meteorological Department, RSRW Observatory, Vile Parle on the 14th of February 2013. Our objective in visiting RMD was to understand the weather monitoring system used in the observatory. Prior to this we had also visited the Indian Meteorological Department on 8th February 2013, Colaba, for the very same objective.
         The Regional Meteorological Centre, Mumbai is one of the six Regional Centres of India Meteorological Department. This Centre was established in April 1945 for providing weather related services to the states of Maharashtra, Goa and Gujarat excluding Vidarbha region of Maharashtra State. These centres are under the World Meteorological Organization (WMO), a specialized agency of the United Nations. WMO provides the framework for international cooperation on weather data. WMO promotes cooperation in the establishment of networks for making meteorological, climatological, hydrological and geophysical observations, as well as the exchange, processing and standardization of related data, and assists technology transfer, training and research.

Forecasting Services done by the observatories in India are :   
§  Cyclone Warning Services for Maharashtra, Goa, Gujarat states and Arabian Sea.

§  Services to Aviation.

§  Services for Shipping & Fisheries, and  Ports.

§  Inland Warning Services to District revenue, Irrigation, Railway.

§  Services to Public by issue of weather bulletins and warnings.

§  Services to Agriculture and Farmers.

§  Hydrometeorological and Flood Forecasting Services.

§  Supply of Meteorological data to members of public, Government Agencies and Industries for research and planning.

        The setups at both the places were similar. They used both primitive and modern techniques for measurement and compared the readings obtained. The modern equipments were good but the primitive techniques of weather monitoring and data acquisition were mind-blowing. We were amazed to see how highly efficient the ancient techniques were inspite of having less resources and technology in those days.

       The weather data from IMD and Rs/Rw is given to a geostationary meteorological satellite (METSAT) system devoted totally to meteorology which was launched in 2002. It has been renamed as Kalpana-1 and is currently the operational satellite system being used by IMD.

       We saw the live recording of an earthquake on ritcher scale at IMD Colaba. The earthquake occurred at Santa Cruz Islands, USA, magnitude 6.9 (which is quite high), at the same time. It also has a Doppler radar imaging setup.
 Following  equipments  are currently in use at the Rs/Rw observatory: 

1.      Stevenson’s Screen – Used for temp Measurement. Four types : 
       i. Dry Valve – Used for Humidity and Dew point measurement.
 ii. Wet Valve – Used for Humidity and Dew point Measurement.
 iii. Max Valve – Similar to Doctors thermometer. It doesnot allow back flow of mercury.
 iv. Min Valve – It is permanently calibrated once in a day. The dumbles within it falls back as per the temperature.The first 3 thermometers are mercury thermometers and the last one is an alcohol thermometer 
as its freezing point is below mercury and thus becomes useful in colder regions.
  2.  Self-Recording Rain Guage – Measures average rainfall without   manual help...... and hence known as self recording. It consists of a funnel of fixed diameter depending on  the scale used. Once the funnel is filled with water upto 10 mm the water gets drained from the funnel and is collected in a jar. Its accuracy is around 98 %.
        3.   Ordinary Rain Guage – Measurements here are done manually every 3 hours. It is highly accurate with accuracy 100 %.
        4.   Barograph – Used to measure pressure.
Barographs are of 2 types – Direct and Q- pattern. In Direct,
the height should be known and the one being used at Rs/Rw is  the Q  pattern barometer. Readings are taken every 24 hours and the graphs are plotted accordingly.
        5.    Thermograph – Used for temperature measurement. It is based on a simple concept; the bimetallic plate in it expands and contracts proportionally with temperature.
       6.      Hygrograph – Measures humidity. Uses wet horse hair since hair expands on getting wet and contracts drying.
       7.      Sunshine recorder – It uses a convex lens. Rays are focused at a particular point after they pass through the lens and is focused on a curved metallic strip. The strip length is long, short and straight for different seasons depending on the length of the day.
       8.      Wind Vane- It is used to measure wind direction. It consists of  three Anometers which are circular in shape. The wind speed measurement is done manually.

       They also have a fully automated weather station which is very much similar to the one installed by Atharva Satellite Ground Station in our college. The data from their automated weather station is transmitted to Kalpana using a stationary crossed Yagi Antenna of 401MHz.

       These equipments were well maintained. We were lucky to see a live demonstration of all these equipments.

  1. The observatory launches 4 hydrogen balloon of 70gm at different time intervals to measure height(12km-14km), wind speed and direction.
  2. It also ascends two hydrogen balloon of 800gm with a payload to measure overall weather data at different atmospheric levels upto a range of 30km.
  3. The hydrogen filled in the balloon is prepared in the hydrogen shed. The chemicals used are ferrisilicon, caustic soda and water which is mixed in  large cylinders kept under 100 atm pressure.
  4. The payload used for 800gm balloon consists of a thermistor, humidity sensor(hygristor) , transmitter, a capsule filled with vacuum which expands as pressure increases and a  battery.
  5. The battery, aquasonde is a 22V, water activated battery which has to be immersed in water for 5 minutes before use. Its advantage over other batteries is that it is cost effective and comparatively lighter in weight.
  6. The total weight of the payload of the balloon is about 1kg.
  7. The antennas used for tracking the balloon were helical antenna, 2 and 5 beam-width radar.
     Overall it was a very good learning experience for us. Sorry for not sharing the pictures of these instruments as they are very confidential. We look forward for interactive inputs and queries from readers…

1 comment:

  1. very useful really good information thanks for posting such a good information it will hepls the people a lot keep it up , Regards, obiee training in hyderabad informatica training in hyderabad,