Tools for weather forecasting

Tools used in weather forecasting

1. Tools Used In Weather Forecasting Harithalekshmi V. 2018-11-067

2. Basic Inputs For Weather Forecasting Area coverage under the network of meteorological station Collection of meteorological data on cloud cover, sunshine, radiation, rainfall, temperature, wind and pressure Upper air data on wind, humidity and temperature from various heights

3. Pilot Balloons Small balloon filled with Hydrogen or Helium. Measure wind direction and speed at different heights in the atmosphere by using a theodolite Measures temperature, humidity and pressure at different heights using meteorographs Balloons meant to stay at a constant altitude for long periods of time are known as transosondes

4. One of the first people to use weather balloons was L. T. de Bort , a French meteorologist. Starting in 1896 he launched hundreds of weather balloons from his observatory in Trappes , France . These experiments led to his discovery of the tropopause and stratosphere

5. Launch time, location The ascent rate can be controlled by the amount of gas with which the balloon is filled . About 800 locations around the globe do routine releases, twice daily, usually at 0000 UTC and 1200 UTC.

6. Operation B alloon filled with either helium or hydrogen lifts the device up through the atmosphere . The maximum altitude to which the balloon ascends is determined by the diameter and thickness of the balloon . As the balloon ascends through the atmosphere, the pressure decreases, causing the balloon to expand. Eventually , the balloon will expand to the extent that its skin will break, terminating the ascent . After bursting, a small parachute on the instruments carries them to Earth .

7. Theodolite Optical telescope – measures wind direction and speed at different heights in the atmosphere Measures horizontal and vertical angles of ascending balloons at known intervals of time. In an obscured sky balloon is lost and can not trace. This can be overcome by radio – theodolite, where radio signals are used to track the balloons

8. Modern electronic theodolites R eadout of the horizontal and vertical circles is usually done with a rotary encoder This produce signals indicating the altitude and azimuth of the telescope which are fed to a microprocessor

9. Meteorographs Combinations of barographs, thermographs and hygrograph. Once the balloon burst at greater heights, the meteorograph fall in unknown locations Utility is very much limited

10. Radiosonde Transmit weather observations to the ground receiver by radio signals It is carried by means of a balloon Measeres Temperature - +40°C to - 90°C Relative humidity - 15 – 100% Baraometric pressure – 1040 – 40 hPa Data is immediately available and useful in weather forecasting IMD has 39 radiosonde and 62 pilot balloon observatories spread all over the country Radiosondes measuring ozone concentration are known as ozonesondes

11. Radio Detection And Ranging (RADAR) The active technique of remote sensing is used Transmit electromagnetic pulses of given characteristics and also receives them back Modification of transmitted pulses can be interpreted in terms of the characteristics of the reflected surface

12. Doppler weather radar It is capable of measuring the approach (or departing) speed of raindrops. Works based on Doppler effect Detects rain in the atmosphere by emitting pulses of microwave and measuring the reflected signals from the raindrops.

13. The faster the raindrops move towards the radar, the higher will be the frequency of the microwave reflected from raindrops The more intense the reflected signals, the higher will be the rain intensity . The distance of the rain is determined from the time it takes for the microwave to travel to and from the rain.

14. Weather Radar Network Of India M eteorological Department Radar used in IMD for detecting Thunder storms Hail storm Tracking o f Cyclone Rainfall Estimation IMD has replaced conventional radar systems with Doppler Weather Radar(DWR) First DWR was installed at Sriharikota in 2004 Existing DWRs are networked to provide data for numerical weather prediction model for nowcasting

15. Sonic Detection And Ranging ( SODAR) U sed as wind profiler - M easure wind speed at various heights above the ground. Calculate the wind speed by measuring the scattering of sound waves by atmospheric turbulence

16. Satellite For viewing large weather systems on a world wide scale Geostationary Satellites are being used for weather forecasting They are orbiting at a height of 3600 KM Orbital period is synchronous to that of earth. Geostationary satellites appear to be fixed over one spot

17. The first weather satellite, Vanguard 2 l aunched on February 17, 1959 . Designed to measure cloud cover First weather satellite considered to be successful is TIROS I L aunched by NASA on April 1, 1960

18. Indian National Satellite System S eries of multipurpose geo-stationary satellites launched by ISRO to satisfy the telecommunications, broadcasting, meteorology, and search and rescue operations Gives information on cloud spread and temperature Used in Short and medium range weather forecasting INSAT 1B – 1983 –First in the series VHRR (Very High resolution Radiometer) – Measures Radiation in 2 narrow spectral windows.

19. Insat 2E – Resolution of VHRR was increased – Added water vapour channel 1996 – Satellite Image was opened for public through IMD website. INSAT-3A - Data Relay Transponder (DRT ) to receive data from automatic weather stations of different institutions from all over the India INSAT-3D - Launched in July 2013 INSAT-3DR - Weather satellite meant to provide meteorological services to India. Launched on 9 September 2016

20. KALPANA-1 E xclusive meteorological satellite launched in 12 th September 2002 It was located at 74 degree East longitude Originally known as MetSat-1 On February 5, 2003 it was renamed to Kalpana-1 Its mission is to collect data in layer of clouds, water vapor, and temperature of the atmosphere Kalpana-1 went out of service in mid 2018

21. Working Principle There are two types of sensors Visible light sensor – Imager – Works like a camera – Gather information Used only during daylight hours Images are created based on the reflected light Infrared sensor – Sounder- Measures temperature The higher the temperature of the object the more energy it emits Sensors measures the amount of energy radiates from earth It can be used in night In addition to providing visual images, satellites can also provide data that allow calculation of atmospheric temperature,moisture profiles etc.

22. At present only 2 meteorological satellites are under operation They are INSAT 3D and INSAT 3DR For Every 15 minutes a new set of images are available for forecasters Temperature and humidity profile are available in every 3 hour The earth stations in Hassan and Bhopal receive data from INSAT The satellite data is processed and out puts are generated. The out puts like OLR(Out going long wave Radiation ), Wind speed over sea can be used in the prediction of onset of monsoon.

23. Detect genesis, growth, intensity and location of tropical cyclone Cyclone Phailin the strongest tropical cyclone ever recorded in india,2013

24. Thank You.