A high-altitude mass of volcanic ash and fumes from the Sunday morning eruption of the Hayli Gubbi volcano in northern Ethiopia is moving east - at speeds up to 120 km/hour - and reached Delhi this morning, affecting flight operations in the city and, as a result, at airports across India.
The volcano in Ethiopia's Afar region erupted for the first time in nearly 12,000 years and spewed clouds of toxic gases, gravel, and fine ash, which satellites tracked across the Red Sea region and the Arabian Peninsula, and over Pakistan, before crossing over into Indian skies.
The cloud formed a continuous belt from the Oman-Arabian Sea sector into north and northwest India, but it is gradually thinning and dispersing the further it travels from the source.
That said, pockets of higher concentration can still affect flights or lead to hazy skies.
The cloud should move from India (and towards China) by 7.30 pm.
What is in the ash cloud?
It consists mostly of volcanic ash, which is pulverised rock and glass, and high concentrations of sulphur di-oxide, as well as quantities of gravel. Scientists said an initial analysis indicated lower ash concentration than in Europe in 2010, after Iceland's Eyjafjallajokull volcano erupted.
RECAP | Eyjafjallajokull Volcano Erupts In Iceland, Ash Cloud Over Europe
On that occasion flights were massively disrupted.
In this case, the high levels of sulphur (and the high altitude) have been flagged as possibly affecting aviation traffic in its path, but the overall density of the cloud is lower, leading to route adjustments and altitude warnings, rather than a regional shutdown of flight operations.
Will Delhi AQI be affected?
In a word, no.
Volcanic plumes can be fatal to human beings if inhaled.
But because the cloud is at a high altitude - between 25,000 and 45,000 feet - the air quality index in and around Delhi, which is already battling a toxic air crisis, is unlikely to be affected.
READ | Ethiopian Volcanic Ash Enters Delhi Amid Toxic Air Crisis, Flights Affected
Even if it does alter surface-level AQI in Delhi, the changes are expected to be minimal.
Where is this volcano?
In Ethiopia's Afar region, which is part of the tectonically active East African Rift.
The location of the volcano - north of the equator and west of the Arabian Peninsula - meant the eruption and the consequent ash cloud was directly in the path of subtropical westerly winds.
These winds carried the toxic materials across the Red Sea and over India.
A preliminary analysis of the eruption indicates the ash was initially ejected a staggering 10 to 15 kilometres into the atmosphere before it settled at a maximum ceiling of 45,000 feet.
This is near the lower stratosphere layer of Earth's atmosphere and relatively fast-flowing west-to-east winds aided dispersal thousands of kilometres eastwards. Since the eruption the cloud has drifted over Yemen, Oman, and Pakistan, before entering India via Gujarat and Rajasthan.
What is the risk factor for India?
Primarily aviation safety.
The national regulator, the Directorate-General of Civil Aviation, put out warnings Monday after it became apparent the ash cloud was drifting towards India. As a result, several flights were either delayed or cancelled. These included flights from the Gulf region to India.
Some flights from India to neighbouring Asian countries have also been impacted.
The DGCA warning asked all airlines to avoid confirmed volcanic ash-affected areas and flight levels. and adjust planning, routing, and fuel considerations based on the latest advisories.
Air India, IndiGo and SpiceJet were among the affected airlines.
As explained above, the impact on AQI on India will be negligible.
But an independent weather expert told NDTV high SO2 levels could affect higher altitude countries, like Nepal, parts of the Himalayas, and the adjoining Terai belt of Uttar Pradesh.
What could be the global effect?
The high-concentration of SO2 and the fine particulate matter in the cloud require monitoring for possible impact on regional radiation, cloud microphysics, and future flight routes.
READ | "It Felt Like A Sudden Bomb": Eyewitness On Ethiopian Volcanic Eruption
The current disruption - to flights - could evolve into major climatic changes or even affect monsoon patterns for the Indian subcontinent, though that too is unlikely given its altitude.
However, large volcanic eruptions can influence monsoonal rainfall by injecting aerosols into the stratosphere. These can partially block sunlight, cool the surface, and alter atmospheric circulation patterns, potentially affecting rainfall distribution in subsequent monsoon seasons.
