The word Monsoon has been derived from the Arabic Word ‘Mawsim’ which means season.
Monsoon refers to seasonal change in the direction of prevailing winds of the Indian subcontinent region. These are seasonal winds which start to blow in the reverse direction with the change of season.
Although the exact cause of monsoon yet to be found, the most relevant reason has been the temperature difference between the landmass and the Indian Ocean adjacent to it.
Countries like India, Indonesia, Bangladesh, Myanmar etc. receive most of the rainfall due to these winds and the onset of these winds is influenced by Subtropical Jet Streams, Tropical Easterlies and Inter-tropical Convergence Zone (ITCZ).
Indian Meteorological Department
Meteorology is the branch of science that deals with atmosphere and its various phenomenon, along with weather and weather forecasting.
Indian Meteorological Department was constituted in 1875 and it’s the topmost government agency dealing with national meteorological services including seismology and associated subjects.
The functions of IMD include weather forecasting, issuing warnings against severe weather phenomenon (hurricanes, cyclones, heavy rains etc.), providing weather statistics, research and development in meteorology, detection of earthquakes etc.
The IMD data is extremely helpful to the weather-dependent economic activities like shipping, agriculture, aviation, defence services etc.
IMD’s Division of Agricultural Meteorology provides agriculture specific data to the agriculturist community of India as Agriculture is a major part of Indian Economy.
National Monsoon Mission (NMM)
NMM was launched by the Ministry of Earth Sciences in 2012 as a reformative step towards developing a more refined, efficient and state-of-the-art prediction system for monsoon, rainfall due to these winds and weather in general.
The execution and coordination of the mission were done by Indian Institute of Tropical Meteorology (IITM), Pune.
To improve prediction of monsoon rainfall on the extended range to the seasonal time scale of up to 16 days to about one season.
To give out an improved prediction of temperature, rainfall and severe weather events on short to medium range time scale up to 16 days.
Ministry of Earth Sciences decided to deploy the Coupled Forecast Model (CFS) to refine the weather prediction services in India.
Coupled Forecast Model
Coupled Forecast Model is a coupled ocean-atmosphere modelling system that combines data from ocean, atmosphere and land for providing long-range forecasting.
The Coupled Forecast Model is based on the Climate Forecast System (CFS) developed by the National Centre for Environmental Prediction (NCEP), USA.
On the implementation part, it has been implemented on Prithvi High-Performance Computers at Indian Institute of Tropical Meteorology (IITM), Pune.
This system captures the interaction between landmass, oceans and atmosphere, mathematically simulates on the Prithvi HPCs and gives its long-range predictions accordingly.
IMD’s performance after implementation of NMM
Data available from 2019 to 2020 shows that IMD’s monsoon and weather predictions, even after adopting the Coupled Forecast model, hasn’t improved much.
In 2019, IMD’s CFS had predicted 97% of the normal monsoon rainfall but the actual rainfall exceeded 110%.
From 2012 to 2019, IMD’s CFS has mostly been wrong in the prediction apart from one instance in 2015.
In 2012, actual annual rainfall was 93% of the normal but the system estimated it to be 104%. In a similar instance in 2016, the predicted rainfall was 112% against the actual figure of 96%.
Reason for prediction failure of IMD
The IMD scientists have admitted that dynamic models aren’t yet capable of factoring in changes in Indian Ocean one or two months prior.
The prime reason behind such variation in predicted data and the actual data is the unusual weather phenomenon and the rapid rise of anomalies in the Indian Ocean.
The weather systems like El Nino have a fixed cycle of 18 months and that’s the reason its predictions come out to be near accurate but the weather systems in Indian Oceans are unpredictable.
The meteorological data plays a major role in the lives of Indians.
Economically, the sectors like agricultural, shipping, aviation etc. depend directly on the forecasts.
The Peninsular areas and North-Indian Plains experience a massive flood every year that cause large scale damage to life and property.
Other than that, people living in coastal regions of peninsular India need to know the information about hurricanes and cyclones so that they can get prepared for it in the advance.
A more efficient weather prediction system will be beneficial for the people of the country and even help the administration to make preparations for rescue operations, in case a severe weather activity is on the cards.