MONSOON CORE ZONE

MONSOON CORE ZONE

Subject : Geography

Context : IMD has also been making efforts to develop a separate forecast for the Monsoon Core Zone (MCZ), which represents most of the rainfed agriculture region in the country. A separate forecast will be more useful for agricultural planning and crop yield estimation, etc.

Concept :

• Sub-seasonal rainfall fluctuations, characterized as active and weak spells during the Indian monsoon season (June to September) is an important component of the variability of the Indian monsoon rainfall.
• A new criteria for identification of active and break events of the Indian summer monsoon have been recommended on the basis of the high resolution daily gridded rainfall data set over India (1951-2007) .
• Based on this criteria, the active and break events were identified from the average rainfall data over a critical area, called the core monsoon zone within which the monsoon trough/ Continental Tropical Convergence Zone (CTCZ) normally fluctuates.
• The active and break spells for the period 1901-2015 were derived using IMDs new high resolution (0.25 x 0.25 degree) daily gridded rainfall data set .
• Active and break events are defined as periods in which the normalized anomaly of the rainfall over the monsoon zone exceeds 1 or is less than -1.0 respectively, provided the criterion is satisfied for at least three consecutive days.