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Why is IMD’s monsoon forecast often inaccurate? Indian Ocean Dipole and Madden Julian Oscillation

Why is IMD’s monsoon forecast often inaccurate? Indian Ocean Dipole and Madden Julian Oscillation


  •  GS 1 || Geography || Oceanography || El Nino & La Nina

Why in news?

In recent years, the Indian Meteorological Department’s monsoon projections have been inaccurate.

Previous Years’ Analysis:

  • The 2020 monsoon, like the 2019 monsoon, was exceptional in that it was just the third time in a century that India saw back-to-back years of above-average rainfall.
  • The monsoons of both years, notably the 2019 monsoon, were at a 25-year high.
  • The IMD was unable to predict the extent of the surplus, only stating that the monsoon will be “above average.”

Monsoon forecast:

  • Forecasting monsoons is a difficult challenge on the Indian subcontinent, where monsoons are a major weather system that affects a big population.
  • Short and medium-range predictions, as well as seasonal predictions, are required for a variety of weather-sensitive activities such as farming, flood forecasting, water resource management, sports, and transportation.
  • Due to the intricate interconnections involved, forecasting the monsoon weather system and related rainfall is one of the most challenging topics in Numerical Weather Prediction (NWP).
  • These include topographic effects, synoptic scale system treatment, mesoscale convective systems, and the lack of excellent quality high resolution data across land and water.
  • This year, the India Meteorological Department (IMD) may adopt new monsoon models to better anticipate rainfall variations.
  • Dynamical Model:
    • The Monsoon Mission Coupled Forecast System is another name for it. It uses supercomputers to simulate the physics of the ocean and atmosphere theoretically.
    • This model is better at forecasting the status of the weather a weekor two ahead of time, but meteorologists still don’t trust it to anticipate the monsoon.
  • Benefits of the model:
  1. Rather to long-range predictions that merely provide a hazy picture of the monsoon’s anticipated performance, these shorter forecasts are considerably more dependable and assist farmers in making planting decisions.
  2. These models may also be used to predict heat waves or cold waves, which is beneficial to city planners and government officials.
  3. Climate, as well as technological change, allows new weather variables such as surface temperatures from as remote as the southern Indian Ocean and regular updates from the Pacific Ocean to be mapped.
  • Statistical Model:
  • Traditional statistical models relate correlations of physical characteristics with actual recorded rainfall in the past, such as sea surface temperatures, snowfall, landmass temperature, and so on.
  • For example, it takes into account global meteorological models that show El Nino, a warming of the central equatorial Pacific linked to the drying up of monsoon rain, as a remote possibility. This model is used by the IMD.
  • There is a 33% possibility of a regular monsoon in any given year, which is why there is high confidence that the monsoon in 2020 will be normal.
  • Proposed Models- The three models under consideration are:
    • 12 dynamical global circulation models whose outputs would be integrated into one.
    • In the tropics, a model that calculates rainfall depending on sea surface temperature.
    • Statistical model based on pre-monsoon climatic variables; all of them are ‘ensembles,’ meaning smaller models are merged to arrive at an average value.

Importance of weather forecasting:

  • Weather forecasting is utilized in a variety of scenarios, including severe weather warnings and advisories, cloud behavior prediction for air transportation, waterway prediction in a sea, agricultural development, and forest fire prevention.
  • Severe weather alerts and advisories: Severe weather alerts and advisories, issued by the National Weather Service in advance of severe or dangerous weather, are an important element of contemporary weather forecasting. This is done to ensure the safety of people and property.
  • Predicting the behavior of the cloud for Air transport: The aviation sector is very weather-sensitive, thus precise weather forecasting is critical. Many planes are unable to land or take off due to fog or extremely low ceilings.
  • Prediction of waterways in a sea: Wind direction, speed, wave periodicity, high tides, and precipitation can all hinder commercial and recreational usage of rivers. Each of these elements can have an impact on the safety of sea transportation.
  • Agricultural development: The weather has a significant impact on agricultural productivity. It has a significant impact on crop growth, development, and yields, pest and disease incidence, water needs, and fertilizer requirements in terms of differences in nutrient mobilization due to water stresses, as well as the timeliness and effectiveness of prophylactic and cultural operations on crops.
    • Avoiding Forest fire: Weather forecasting of wind, precipitations and humidity is essential for preventing and controlling wildfires.
    • Military applications: Weather forecasters in the military provide weather updates to the war fighting community. Pilots get pre-flight and in-flight weather briefings from military weather forecasters, as well as real-time resource protection services for military sites. The seas and ship weather forecasts are covered by naval forecasters.
    • Air Force: The Air Force and the Army use Air Force Weather to forecast weather. Aviation Force forecasters offer Army assistance and cover air operations in both war and peacetime.

Why it is difficult to forecast accuracy of monsoon in India?

  • El Nino Southern Oscillation (ENSO): A climatic event linked to the warming of the eastern Pacific Ocean. Other variables, such as the Indian Ocean Dipole (IOD), which is the difference in Sea Surface Temperature between the western Indian Ocean in the Arabian Sea and the eastern Indian Ocean in the Bay of Bengal, moderate or increase El Nino’s influence. A positive IOD is caused by a warmer western pole, which can operate as a counter-cyclone to El Nino and result in normal rainfall. Equatorial Indian Ocean Oscillation (EQUINOO), Madden Julian Oscillation, and others are among the other contributors. Furthermore, they have complicated relationships with one another, thus complicating the situation.
  • Anthropogenic Emissions affect rain patterns: More variability in the monsoon is directly proportional to a warmer atmosphere.
  • Air Pollution: As aerosols such as black carbon interact with sunlight, they scatter or absorb light, which complicates rainfall unpredictability. Scattering prevents light from warming the earth’s surface, but absorption allows the particles to warm the air surrounding them, altering the atmosphere’s heating pattern and the warming of the land in relation to the ocean.
  • Forest Cover: Around a quarter of the precipitation in the broad basin of eastern India originates from the land surface in August and September, primarily through evapotranspiration in the forests. Deforestation on a large scale throughout the world has the potential to reduce the Indian Monsoon by 18%.
  • Other factors: For instance dust over in North Africa and the Arabian Peninsula absorbs sunlight, heats the air, and intensifies the wind, which carries moisture eastward and causes heavy rain in India. Similarly, climate change adds to the complication.

Missions to forecast monsoons:

  • Monsoon Mission of India: This Ministry of Earth Sciences program, which began in 2012, has used novel methodologies (high resolution, super parameterizations, data assimilation, and so on) to increase prediction skill quantitatively for India Meteorological Department forecasting services (IMD).
    • The goal was to create a cutting-edge dynamical forecast system for monsoon rainfall on various time scales.
    • The Indian Institute of Tropical Meteorology (IITM) in Pune is in charge of the mission’s implementation and coordination.
    • The Climate Forecast System (CFS) of the United States has been chosen as the primary modeling system for the following purposes since it is one of the finest.
  • The IMD’s monsoon model, the Coupled Anticipate Model (CFS), which is part of the National Monsoon Mission (NMM), failed to forecast the excessive rainfall that occurred in August and September 2019.
  • National Monsoon Mission are:
  • Objective:-
  1. Create more accurate mathematical and simulation models.
  2. Improve collaboration between research and operational entities.
  3. To increase the efficiency of organizations, infrastructure and skilled staff must be developed.
  • Steps taken:-
  1. New designs CFS are used to forecast short, medium, and long-term outcomes.
  2. Flood forecasting is available for many river basins.
  3. In Delhi, an air pollution monitoring and forecasting system has been established.
  • Achievements: –Several natural disasters struck India in 2013-14, including Phailin, Helen, Lehar, Mahasen, Madi, and others. The government was able to take timely actions because to improvements in data assimilation methods and climate models, which were well welcomed.


India’s monsoon has a long history of unpredictability and uncertainty. Given that agriculture employs about 70% of the population, even a minor shift in the Monsoon pattern would have a significant impact on the economy. More than 50% of cultivated area in India depends on Monsoon, hence an early warning system becomes necessary. Proper prediction of monsoon is very much necessary for proper cultivation and bigger infrastructure project, tourism and many more.

Mains oriented question:

For better assessment of life and property accurate prediction of weather is very important, what important role does proper monsoon plays in climatic condition of India? (200 words)