National Monsoon Mission (NMM)

The upcoming new mission to improve weather forecasting in India, with a budget surpassing Rs 10,000 crore, builds on the success of the existing National Monsoon Mission (NMM). This enhanced mission is designed to leverage advanced technologies, including artificial intelligence (AI), machine learning (ML), and cutting-edge weather forecasting tools, to provide more precise and hyperlocal predictions.

Key Features of the New Weather Mission:

• Advanced Simulation Models: Developing specialized models tailored to India's unique climate, improving accuracy in predicting weather events, especially the monsoon.
• Enhanced Instruments: Deployment of Doppler radars, new weather satellites, and more advanced observation tools will expand India's weather monitoring capabilities.
• AI/ML Integration: AI and ML are set to revolutionize hyperlocal forecasting, with successful trials already underway in cities like Mumbai, potentially offering real-time, highly accurate predictions.

Achievements of the National Monsoon Mission (NMM):

• Reliable Forecasts: The NMM has improved the accuracy of weather predictions, which are critical for sectors like disaster management, agriculture, and energy production. Reliable monsoon forecasts aid in preparing for floods, droughts, and planning agricultural activities.
• Disaster Management: Early warning systems have enabled better preparedness for extreme weather events, potentially reducing the loss of life and property.

Challenges Faced by the National Monsoon Mission (NMM):

• Complex Monsoon Dynamics:
• The Indian monsoon is influenced by a combination of oceanic conditions, land processes, and atmospheric circulations. The interactions among these factors make accurate prediction of monsoon patterns difficult.
• Data Limitations:
• Accurate forecasting relies on comprehensive data, but the availability and quality of data, especially in rural and remote areas, remain inconsistent. This results in gaps and potential inaccuracies in predictions.
• International Collaboration:
• Collaborating with foreign institutes is a key goal of the NMM, but aligning different methodologies, standards, and data-sharing protocols poses challenges. Effective international collaboration requires sustained technical and diplomatic efforts.
• Adapting to Climate Change:
• The Indian monsoon is increasingly affected by climate change. Adapting the NMM to account for these shifts and ensuring resilience to climate variability is a critical challenge. Models need to be updated continuously to reflect changing patterns.
• Regional Disparities:
• Not all regions in India benefit equally from NMM forecasts. Some areas, particularly the most vulnerable regions, face challenges in accessing timely and accurate weather information. Ensuring equitable benefits across all regions remains an ongoing issue.

The National Monsoon Mission (NMM), launched by the Ministry of Earth Sciences (MoES) in 2012, is a pioneering initiative aimed at improving the accuracy and reliability of monsoon forecasts in India. Given the vital role that the monsoon plays in India’s agriculture, water resources, and disaster management, the NMM focuses on enhancing the country’s ability to predict the onset, intensity, and progression of the monsoon season.

Objectives of the National Monsoon Mission:

• Development of Monsoon Forecast Models: The mission aims to improve both short-term (up to 10 days) and long-term (up to a season) forecasting through the development of state-of-the-art dynamical prediction systems.
• Short-term weather forecasting provides real-time predictions of weather events like rain, storms, or drought conditions.
• Seasonal forecasting predicts the broader trends of the monsoon across the country.
• Operationalizing Forecast Models: The NMM focuses on implementing high-resolution, dynamic models into India’s weather forecasting operations. These models aim to capture the complex interactions between the land, ocean, and atmosphere that influence monsoons.
• Integration of Global Models: The mission integrates models developed by the United States, United Kingdom, and Japan, adapting them to suit India’s climatic conditions.
• Data Assimilation: Improving observational data collection and processing, such as using satellites, ocean buoys, and Doppler radars, to enhance the predictive power of these models.

Achievements of the National Monsoon Mission:

• Improved Weather and Climate Forecasting:
• The NMM has successfully implemented high-resolution prediction models, improving the accuracy of both short-range (up to 3 days) and seasonal forecasts.
• These models have been integrated into India’s weather forecasting systems, helping the India Meteorological Department (IMD) provide more reliable and timely monsoon predictions.
• Disaster Preparedness:
• The NMM has been instrumental in providing better forecasts for extreme weather events such as cyclones, floods, and droughts, allowing for more effective disaster management and preparedness.
• Agriculture and Water Resource Management:
• Reliable seasonal forecasts have been critical for the agriculture sector, helping farmers plan crop cycles, irrigation, and harvesting.
• Improved forecasts also assist in water resource management, helping authorities plan for water storage and distribution during the monsoon and non-monsoon periods.
• Collaborative International Research:
• The NMM has fostered collaboration with international research organizations, including the UK Met Office, NOAA (National Oceanic and Atmospheric Administration) in the USA, and Japan Meteorological Agency, which has strengthened the scientific understanding of monsoons.
• Reliable Forecasts: The NMM has improved the accuracy of weather predictions, which are critical for sectors like disaster management, agriculture, and energy production. Reliable monsoon forecasts aid in preparing for floods, droughts, and planning agricultural activities.
• Disaster Management: Early warning systems have enabled better preparedness for extreme weather events, potentially reducing the loss of life and property.

Way Forward:

• Technological Upgrades: Investment in more sophisticated weather monitoring technologies and satellite systems will help reduce inaccuracies.
• Capacity Building: Training local communities and strengthening data collection networks can bridge data gaps, especially in rural areas.
• Climate Adaptation: Incorporating climate change scenarios into forecasting models is essential for future resilience and preparedness.
• Strengthening International Partnerships: Continued collaboration with global weather institutions, especially on data sharing and technology transfers, can improve forecast accuracy.

About  Indian Monsoon

The Indian Monsoon is a complex and dynamic weather system that plays a crucial role in determining the climate and agriculture of India and other parts of South Asia. Derived from the Arabic word "Mausim," meaning season, the monsoon refers to the seasonal reversal of winds, which is accompanied by distinct wet and dry periods.

Classical Concept of Indian Monsoon:

The classical or thermal concept of the Indian monsoon, proposed by astronomer Edmund Halley in the 17th century, emphasized the role of differential heating between the land and sea. This concept explains the seasonal reversal of winds based on temperature-induced pressure differences.

Key Features of the Thermal Concept:

• Winter Monsoon (Northeast Monsoon):
• During winter, the landmass of Asia cools rapidly, creating a high-pressure system over the continent.
• The surrounding oceans, which cool more slowly, have relatively low pressure.
• This creates a pressure gradient from the land to the sea, resulting in outflows of dry, cold air from the land towards the oceans. This forms the northeast monsoon, bringing dry conditions to India.
• Summer Monsoon (Southwest Monsoon):
• In summer, the landmass heats up rapidly, creating a low-pressure system over India and Southern Asia.
• The adjacent oceans, which heat more slowly, remain at higher pressure.
• The pressure gradient shifts from the sea to the land, bringing moist air from the Indian Ocean towards the land, which results in the southwest monsoon. This is responsible for the heavy rainfall in India during summer.

Additionally, the Intertropical Convergence Zone (ITCZ) moves northward towards Southern Asia during the summer, reinforcing the low-pressure system and attracting moist air over the Indian subcontinent.

Limitations of the Thermal Concept:

• The thermal concept does not fully explain the complex behavior of the monsoon system, including phenomena like the sudden onset (burst) of the monsoon, breaks in monsoon rainfall, and the spatial and temporal variability of rainfall across different regions.
• The nature of rainfall during the monsoon is not only convectional (rising warm air), but also a mix of orographic (mountain-induced) and cyclonic rain patterns.
• It also fails to account for the movement and shifting nature of the low-pressure systems, which are not stationary.

Recent Concepts of the Indian Monsoon:

Modern understanding of the monsoon system has evolved to include a range of complex factors, such as upper air circulation, geographical features, and global climate phenomena.

1. Role of the Himalayas and Tibetan Plateau:

• The Himalayas and the Tibetan Plateau act as physical barriers that block cold polar air from reaching the Indian subcontinent.
• In summer, the Tibetan Plateau becomes a source of intense heat, creating a strong low-pressure area that attracts moist air from the Indian Ocean.

2. Upper Air Jet Streams:

• The presence of jet streams (narrow bands of fast-moving air in the upper atmosphere) over the Indian subcontinent influences the behavior of the monsoon.
• These jet streams, particularly the subtropical westerly jet and the tropical easterly jet, play a role in the distribution of monsoon rains and the movement of weather systems.

3. Circum-Polar Whirls:

• The existence of upper-air circum-polar whirlwinds over the North and South Poles affects the large-scale circulation of the atmosphere, influencing monsoon patterns.

4. ENSO (El Niño and Southern Oscillation):

• ENSO refers to periodic fluctuations in sea surface temperatures and atmospheric pressure in the South Pacific Ocean.
• El Niño (the warm phase of ENSO) is associated with a weakening of the Indian monsoon, often leading to droughts in India.
• La Niña (the cool phase) typically results in stronger monsoon rains.

5. Walker Circulation and Indian Ocean Dipole (IOD):

• The Walker cell is an atmospheric circulation pattern over the Indian Ocean that impacts wind patterns and rainfall distribution during the monsoon season.
• The Indian Ocean Dipole (IOD) is an oscillation of sea surface temperatures in the Indian Ocean. A positive IOD (warmer waters in the western Indian Ocean) usually strengthens the Indian monsoon, while a negative IOD (warmer waters in the eastern Indian Ocean) can weaken the monsoon.

Importance of the Indian Monsoon:

The Indian monsoon is crucial for:

• Agriculture: As India’s agriculture is heavily dependent on monsoon rains, timely and adequate rainfall is essential for crop production.
• Water Resources: Monsoon rains replenish groundwater and reservoir levels, vital for drinking water and irrigation.
• Energy Production: Hydropower generation is influenced by the amount of water received during the monsoon season.

The Himalayas and the Tibetan Plateau play a pivotal role in shaping the Indian monsoon by acting as both a physical barrier and a heat source that affects atmospheric circulation. Their influence extends across multiple layers of the atmosphere, particularly through the creation of jet streams and the regulation of pressure systems.

Role of the Himalayas and Tibetan Plateau in the Indian Monsoon:

• Thermal Heating of the Tibetan Plateau:
• The Tibetan Plateau is one of the highest and largest plateaus in the world, covering an area of approximately 4.5 million square kilometers with an average altitude of around 4,000 meters.
• Due to its high elevation, the plateau absorbs 2-3°C more solar radiation (insolation) than surrounding areas. This heating leads to the formation of a strong low-pressure zone over the plateau during summer.
• The thermal low over the plateau strengthens the overall monsoonal circulation by attracting moist air from the Indian Ocean towards the Indian subcontinent.
• The heating of the plateau plays a crucial role in generating the Tropical Easterly Jet (TEJ), which influences the timing and intensity of monsoon rains.
• Impact on Jet Streams:
• In winter, the Himalayas and the Tibetan Plateau act as a barrier to the cold polar air masses, helping to maintain a high-pressure zone over northern India and the Tibetan region.
• This barrier effect also leads to the bifurcation of the Subtropical Westerly Jet (STJ), which flows at high altitudes. One branch of the jet flows to the north of the Tibetan Plateau, while the other flows to the south.
• During summer, the Tropical Easterly Jet (TEJ) forms due to the intense heating of the Tibetan Plateau. The TEJ flows from east to west at altitudes between 6-9 km, affecting Peninsular India and Northern Africa. It plays a key role in triggering the onset of the southwest monsoon by reversing upper-air circulation patterns and creating low-pressure zones over the Indian subcontinent.
• TEJ Formation and Snow Cover: If there is excessive snow cover over the Tibetan Plateau, it prevents the rapid warming necessary for the formation of the TEJ. This leads to weaker monsoon rainfall in India, as the easterly jet does not fully develop.
• Influence on the Somali Jet:
• The Somali Jet is a low-level jet stream that flows from the east coast of Africa, crossing the Arabian Sea towards the Indian subcontinent. Its northward shift in early June is critical for the formation of the TEJ.
• The Somali Jet is part of the low-level winds that contribute to the southwest monsoon over India. After crossing the equator, these winds become southwesterly, bringing moist air from the Indian Ocean into the Indian subcontinent.
• Interaction with the Mascarene High:
• The Mascarene High is a high-pressure cell located over the southern Indian Ocean, near the Mascarene Islands. It acts as a source for the onshore winds that feed the Indian monsoon.
• The winds generated by the Mascarene High flow towards the thermally induced low-pressure system over northern India. As they cross the equator, they become the southwesterly monsoon winds, which bring moisture-laden air towards the Indian landmass.
• The interaction between the TEJ, Somali Jet, and Mascarene High establishes the overall circulation that drives the southwest monsoon.

Role of ENSO (El Niño Southern Oscillation)

The Indian monsoon is significantly influenced by El Niño, the Southern Oscillation (SO), and the Somali current. These atmospheric and oceanic phenomena interact to affect the onset, intensity, and distribution of monsoon rainfall across the Indian subcontinent.

1. El Niño:

• El Niño is characterized by the warming of sea surface temperatures in the central and eastern Pacific Ocean. It disrupts normal weather patterns globally and affects the Indian monsoon.
• During El Niño years, the warm waters of the Pacific cause weakening of the monsoon winds, leading to reduced rainfall in India. Historically, some of India's major droughts have coincided with El Niño events.
• However, there is no strict one-to-one correlation between El Niño and poor monsoons. There have been instances when India experienced normal or even above-average monsoons during El Niño years, and some droughts occurred in non-El Niño years.

2. Southern Oscillation (SO):

• Southern Oscillation refers to the see-saw pattern of atmospheric pressure between the eastern (Tahiti) and western (Darwin, Australia) Pacific.
• The Southern Oscillation Index (SOI), which measures the pressure difference between these two points, helps predict the impact of SO on global weather patterns.
• Positive SOI indicates higher pressure over the eastern Pacific and lower pressure over the western Pacific (favorable for good monsoons).
• Negative SOI implies higher pressure over the western Pacific and Indian Ocean, which is generally associated with weaker monsoons and drier conditions.

3. La Niña:

• La Niña is the opposite phase of El Niño, characterized by cooling of sea surface temperatures in the central and eastern Pacific Ocean.
• During La Niña years, the Walker Circulation strengthens, leading to a stronger southwest monsoon in India. This generally results in abundant rainfall and better agricultural productivity.

Role of the Somali Jet

The Somali Jet is a low-level wind current that plays a crucial role in the onset and progression of the Indian southwest monsoon. Its relationship with the monsoon is defined by the following characteristics:

• Flow Direction:
• The Somali Current (associated with the Somali Jet) changes direction every six months.
• During the northeast monsoon (winter), the Somali Current flows from north to south.
• During the southwest monsoon (summer), the Somali Current reverses its flow and moves from south to north. This southwest monsoon current drives moisture-laden winds from the Indian Ocean towards the Indian subcontinent.
• Strength and Intensity:
• The strength of the Somali Jet affects the speed and intensity of the southwest monsoon. Stronger winds in the Somali Jet bring heavier monsoons to India.
• The Somali Jet's origin in the Mauritius-Madagascar region strengthens the Mascarene High, a high-pressure zone crucial for driving the monsoon winds toward the Indian subcontinent.
• Impact on Upwelling:
• The low-level jet drives upwelling off the coast of Somalia, cooling surface waters. This process maintains the high-pressure zone over the Arabian Sea, which facilitates the strong flow of the southwest monsoon winds into India.

Role of Walker Cell

The Walker Cell is an east-west atmospheric circulation over tropical oceanic regions. It has a significant impact on monsoon behavior, and its strength is tied to the Southern Oscillation Index (SOI):

• Normal Conditions:
• Under normal conditions, there is a low-pressure zone over Australia and Indonesia, while high pressure exists over the eastern Pacific. This creates a zonal flow of air (Walker Cell) from the eastern Pacific towards the western Pacific.
• In the Indian Ocean, the Walker Cell aids the formation of the southwest monsoon as rising air over Indonesia and Australia generates westerly winds (monsoon winds) that blow towards the Indian subcontinent.
• La Niña:
• During La Niña, the Walker Cell intensifies, strengthening the Indian Ocean branch of the cell, leading to stronger southwest monsoon winds and more intense rainfall in India.
• El Niño:
• During El Niño, the ascending branch of the Walker Cell shifts from the western Pacific (Australia and Indonesia) towards the central and eastern Pacific.
• This shift weakens the Indian Ocean branch of the Walker Cell, resulting in weaker monsoon winds and below-normal rainfall in India.

Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD), also known as the Indian Niño, is a significant ocean-atmosphere phenomenon in the Indian Ocean that has profound effects on the Indian monsoon and global weather patterns. It involves the fluctuation of sea surface temperatures (SSTs) between the western and eastern regions of the Indian Ocean, with three distinct phases: positive, neutral, and negative.

1. Definition and Mechanism

• The IOD is characterized by the temperature difference between the western Indian Ocean (near the Arabian Sea) and the eastern Indian Ocean (south of Indonesia).
• The oscillation between warmer and cooler SSTs creates varying wind patterns and weather conditions, especially over the Indian subcontinent and Southeast Asia.
• It generally develops between April and May, and peaks around October.

2. Phases of IOD

• Positive IOD:
• During a positive phase, warmer sea surface temperatures occur in the western Indian Ocean, while the eastern Indian Ocean (near Indonesia) experiences cooler waters.
• This phase is typically associated with enhanced rainfall over the Indian subcontinent due to increased evaporation from warmer waters in the Arabian Sea.
• Drier conditions prevail over Indonesia, causing reduced rainfall and sometimes drought in Southeast Asia.
• The winds blow from east to west in the equatorial Indian Ocean, further reinforcing the rainfall in India.
• Negative IOD:
• In a negative phase, the SST pattern is reversed, with cooler waters in the western Indian Ocean and warmer conditions in the east.
• This leads to reduced rainfall in India and wetter conditions over Indonesia.
• It weakens the Indian monsoon, often causing below-average rainfall in India.
• Neutral IOD:
• In the neutral phase, SSTs remain near the long-term average, and there is no significant impact on the monsoon patterns.

3. Interaction with Equatorial Indian Ocean Oscillation (EQUINOO)

• The atmospheric counterpart of the IOD is referred to as the Equatorial Indian Ocean Oscillation (EQUINOO), which involves the oscillation of pressure cells between the Bay of Bengal and the Arabian Sea.
• During positive EQUINOO phases, enhanced cloud formation and rainfall occur over the western equatorial Indian Ocean, near Africa, while cloud activity is suppressed near Sumatra.
• EQUINOO can either amplify or weaken the effects of the IOD, but their synchronization is not always consistent. Sometimes, positive IOD events occur without strong EQUINOO phases and vice versa.

4. Impact on Indian Monsoon

• A positive IOD is favorable for the Indian monsoon, as it leads to warmer sea surface temperatures in the western Indian Ocean, enhancing the moisture availability and driving stronger monsoon winds towards India.
• A negative IOD generally results in weaker monsoon and below-normal rainfall, which can cause drought conditions in various parts of India.

5. IOD and ENSO

• The IOD operates somewhat independently from the El Niño-Southern Oscillation (ENSO), although interactions can occur.
• In some cases, a positive IOD can counteract the drying effects of El Niño, bringing normal or above-normal monsoons to India despite El Niño conditions in the Pacific.
• There is no consistent correlation between IOD and ENSO, as positive and negative IOD phases can both occur during La Niña events.

Nature of the Indian Monsoon

Systematic studies of the Indian monsoon reveal several important aspects, including:

1. Onset and Advance of Monsoon

• The differential heating of land and sea remains a primary factor in driving the monsoon. As land heats up more quickly than the ocean during the summer, it creates a low-pressure zone over India.
• This low pressure pulls moist southeast trade winds from the southern hemisphere, which cross the equator and become the southwest monsoon winds. These winds bring moisture-laden air from the Indian Ocean to the Indian subcontinent.
• The monsoon usually reaches the Andaman and Nicobar Islands by May 15 and the Kerala coast by June 1. It progresses northward, reaching Mumbai and Kolkata by June 10-13 and covering the entire country by mid-July.

2. Break in Monsoon

• The monsoon does not bring continuous rainfall but goes through active and break phases. A break in the monsoon refers to periods of reduced rainfall, typically lasting a few days to a week.
• These breaks are linked to shifts in the low-pressure zones and the movement of the Intertropical Convergence Zone (ITCZ), which influences the monsoon's activity.

3. Retreat of Monsoon

• The monsoon retreats as the low-pressure system over India weakens towards the end of the summer. By September, the winds shift, marking the beginning of the northeast monsoon or post-monsoon season. The retreat begins from the northwest and gradually moves southward, finally withdrawing completely by early October.