In windiest month of February, hazy conditions could arise from persistent hot spots: Experts
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February marks the dry phase of the north-east monsoon season, which could fuel the fires, and thus, transboundary haze.
PHOTO: LIANHE ZAOBAO
- Singapore faces potential smoke haze in its windiest month (February) due to fires in Malaysia. NEA is monitoring hotspots.
- Dry conditions and winds could worsen haze; showers offer relief. Current PSI is moderate, PM2.5 is normal.
- Fires in northern ASEAN (Cambodia, Vietnam) cause haze due to dry conditions and slash-and-burn farming.
AI generated
SINGAPORE - With Singapore entering its windiest month of the year, some smoke haze from fires north of the country could be blown here if hot spots persist, said weather experts.
But for air quality to worsen, there would need to be a significant increase in intense regional fires, said urban climatology professor Matthias Roth of the National University of Singapore.
“Elevated readings are unlikely as this would require a significant increase in intense regional fires, combined with persistent winds blowing directly towards Singapore,” he said.
February also marks the dry phase of the north-east monsoon season, which could fuel the fires, and thus, transboundary haze.
On Feb 2, the National Environment Agency (NEA) said on its Facebook page that a few persistent hot spots continued to be detected near Singapore in Malaysia and parts of Indonesia, including Bintan.
Dry conditions are expected until Feb 4, when showers are forecast. As at 6pm on Feb 2, the 24-hour Pollutant Standards Index ranged from 51 to 59, within the moderate range.
The one-hour PM2.5 levels across Singapore were in the normal range, with the highest reading of 28 in the central part of the island. PM2.5 refers to fine inhalable particles in the air measuring up to 2.5 micrometres in diameter. Elevated levels start from a reading of 56.
According to updates on the ASEAN Specialised Meteorological Centre’s (ASMC) website on Feb 2, dry weather is expected to continue over parts of Malaysia and the central parts of Sumatra.
“Under these conditions, the hot spots and smoke haze situation could remain escalated, particularly over the fire-prone areas. The expected showers could help to suppress hot spot activity in the rest of the ASEAN region,” stated the centre.
February is typically Singapore’s windiest month.
Intense winter cold over Asia produces high pressure, driving strong winds from the north-east down across the South China Sea towards the equatorial region and Singapore, said Prof Roth.
The average wind speed in February is 2.8m per second, compared with Singapore’s average wind speed across the year of around 2m per second.
This past January was also drier and windier.
“If forest fires develop to the north of Singapore, the prevailing winds could transport smoke haze towards us,” said NEA.
Parts of the Republic experienced some hazy conditions and a burning smell in late January due to vegetation fires in Johor. On Jan 24, NEA said PM2.5 levels were “slightly elevated”
A peatland fire in Pengerang, Johor
Dr Koh Tieh Yong, a member of the Working Group on Asian-Australian Monsoon under the World Climate Research Programme, said the haze outlook depends on how quickly the fires are brought under control, with the drier phase of the monsoon expected over the next four weeks.
As at Jan 30, smaller fires were seen, but not enough smoke was produced to affect air quality too much over Singapore. Occasional afternoon showers would help alleviate Singapore’s air quality in this period, added Dr Koh.
In the first two weeks of February, thundery showers are expected in the afternoon
Within South-east Asia, most of the current hot spots are in the northern region, including Cambodia and Vietnam, which is experiencing its traditional dry season.
ASMC said clusters of scattered hot spots emitting smoke plumes were observed by satellite over various parts of Cambodia. Smoke plumes from western Cambodia had drifted into the central parts of Thailand.
Parts of Thailand, including Bangkok, have been blanketed in severe haze
Dr Koh said that in the northern ASEAN region, the moisture carried by the monsoon winds from the South China Sea is “wrung out” from the atmosphere as air rises over the mountainous backbone of Vietnam. “When the wind descends over Cambodia and Laos, it is relatively dry. Dry, windy conditions make it easier for fires to get out of control once started,” he said.
Prof Roth added: “These conditions facilitate slash-and-burn agriculture. Prevailing winds then carry the resulting smoke, causing widespread transboundary haze.”
