Long-period average (LPA)
( UPSC Prelims)
News Context
The India Meteorological Department (IMD) predicts that the southwest monsoon season from June to September will experience 'above normal' rainfall, amounting to 105% of the long-period average (LPA) of 87 cm for the years 1971-2020.
About Long-period average (LPA)
● Concept: This term denotes the average rainfall measured in a particular area over a specified time frame.
● Period: The calculation is done over an extended duration, typically spanning 30-50 years.
○ In India, the IMD currently utilizes the LPA derived from rainfall data between 1971 and 2020.
● Purpose: The LPA acts as a reference point to evaluate current or predicted rainfall, aiding in classifying it as normal, above normal, or deficient.
| Category | Range of LPA | Meaning |
|---|---|---|
| Deficient | < 90% | Drought-like conditions |
| Below Normal | 90% – 95% | Slightly less rain than usual |
| Normal | 96% – 104% | Ideal, expected rainfall |
| Above Normal | 105% – 110% | Slightly more rain than usual |
| Excess | > 110% | Risk of flooding |