Standardised Precipitation Index

About Standardised Precipitation Index:

• It estimates wet or dry conditions based on precipitation variables. 
• The SPI calculation is based on the long-term precipitation record for a particular location and long-term period (longer than 30 years is desirable).
• This index is negative for drought and positive for wet conditions. As the dry or wet conditions become more severe, the index becomes more negative or positive respectively.
• Time scale: It includes timescales of 1, 2, 3, 6, 9, 12, 24, 36, 48, 60 and 72 months. 

Key points about India Meteorological Department

• It was established in 1875. It is the country's National Meteorological Service and the principal government agency in all matters relating to meteorology and allied subjects.  
• There are 6 Regional Meteorological Centres, each under a Deputy Director General with headquarters at Mumbai, Chennai, New Delhi, Calcutta, Nagpur and Guwahati.
• Mandate:

• To take meteorological observations and to provide current and forecast meteorological information for optimum operation of weather-sensitive activities like agriculture, irrigation, shipping, aviation, offshore oil explorations, etc.
• To warn against severe weather phenomena like tropical cyclones, norwesters, duststorms, heavy rains and snow, cold and heat waves, etc., which destroy life and property.
• To provide meteorological statistics required for agriculture, water resource management, industries, oil exploration and other nation-building activities.
• To conduct and promote research in meteorology and allied disciplines.

• Nodal ministry: Ministry of Earth Sciences (MoES)
• Headquarters: New Delhi.