Weather Prediction in India

CONTEXT

With the Indian Meterological department getting it’s monsoon forecast wrong this year, it’s modelling has necessarily come under scanner. In April this year, IMD had predicted “near normal “or  96% rains and upgraded it later to 98% but the country later ended up with” below normal “ rains.

IMD AND IT’S FUNCTIONING

Indian meteorological department also referred to as MET department is an agency of the Ministry of Earth Sciences of the Government of India.

It is the principal agency responsible for meteorological observations, weather forecasting and seismology.

It is headquartered at Pune and operates observation centres at various other places.

INDIAN SATELLITES INVOLVED IN WEATHER FORECAST

Weather satellites:

There are two basic types of weather satellites: those in geostationary orbits and those in polar orbits.

Geostationary satellites: these satellites orbit very high above the earth at an altitude of 35,800 km and take the same time to orbit the earth as the earth takes to revolve once. From earth, therefore, the satellite appears to stay still always above the same region all the time.

These satellites give ‘real-time’ images and hence, a series of photographs from these satellites can be displayed in a sequence to show cloud movement.

Polar orbit satellites: This type of satellite orbits in a path that closely follows the Earth’s meridian lines, passing over the north and south poles once each revolution. These circle at a much lower altitude at about 850 km. This means that they can photograph clouds from a much closer level and provide more detailed information about violent storms and cloud systems.

Uses:

• Radiation measurement from earth surface
• Fishermen can find out valuable information about the temperature of the sea from measurements of these satellites.
• Infrared sensors on satellites can monitor crop conditions, areas of deforestation and regions of drought.
• Satellites can detect volcanic eruptions and the motion of ash clouds.
• Ice-mapping, snow storms in the Arctic and Antarctica and the mountain chains-Monitoring of Global Warming
• Observation of Auroras
• Water and air pollution can be pinpointed
• Oil spills can be detected.

Weather Satellites in India(those in service):

• INSAT system: the Indian National Satellite system was commissioned with the launch of INSAT-1B in 1983 and ushered in a revolution in India’s television, radio and meterological broadcasting. Of the 24 satellites so far launched, 11 are still in operation.
• INSAT-3C
• INSAT-3D
• INSAT-3E
• KALPANA-1
• MEGHA-TROPIQUE

SYSTEMS INTERFERING WIH THE INDIAN MONSOON

El-nino: El-Nino is the warm phase of the El-nino Southern Oscillation or ENSO and is associated with a band of warm water that developes in the  central and east-central equatorial Pacific. It is accompanied by high pressure in the western pacific and low pressure in the eastern pacific.

El-nino modoki: It is a coupled ocean-atmosphere phenomenon in the tropical pacific. Conventional El-Nino is associated with strong anomalous warming in the eastern equatorial pacific while El Nino Modoki is associated with strong anomalous warming in the central tropical pacific and cooling in the eastern and western tropical pacific.

Indian ocean dipole: The Indian Ocean Dipole or the Indian nino is an irregular oscillation of the sea-surface temperatures in which the western Indian Ocean becomes alternately warmer and colder than the eastern part of the ocean. Monsoon in India is generally affected by the temperatures between the Bay of Bengal in the east and the Arabian sea in the west.

PROBLEMS OF WRONG FORECAST:

• Crop sowing and harvesting patterns are affected adding to the vows of the farmers.
• Drought management measures are affected
• Any rainfall in excess of what is predicted, causes the administration to be caught unawares and unprepared.
• Inaccurate policy formulation due to the expectation of a normal monsoon and hence, a good agricultural year.
• Effects on stock markets and investment environment.

WAY FORWARD

Although it is difficult to predict accurately the rainfall patterns and weather phenomenon in tropical countries, yet the IMD could do better than just get these blanket 4 month predictions and reducing the task to a numerical jugglery. The IMD is increasingly relying on supercomputers and sophisticated models to warn of weather changes at district level. Such local estimate practise should be strengthened and more accuracy vouched for.