A distinct sulphurous #scent dimethyl disulfide and phenol, like an extinguished match, combines with the toasty bready #aroma of acetyl pyrazine, to produce the impression of burnt toast and roasting coffee, with a powdery feel in the nose and throat.

This warm afternoon #air has a light but palpable dusty texture that dries skin and seems to leave a thin residue. Soft erratic breezes swirl over the balcony.

Unsurprisingly, this mirrors the move toward what we'd consider typical fall food flavours (in North America): apple, cinnamon, clove, nuts, baked foods.

represents a move in olfactory perceptual space from the upper periphery (the citrus and terpenic poles) toward centre (the sweet vanillin pole) and the lower pyrogenic zone (the acetylpyrazine pole).

Perceptually, coumarin is located near the centre of olfactory space, adjacent to vanillin and cinnamaldehyde. So this shift in the #scentscape from the lighter, brighter, fresher terpenic aromas (e.g. pine, linalool, bergamot) to the sweeter, heavier coumarin and the pyrogenic isobutyl quinoline,

The coumarin molecule, first isolated in 1820, is emitted by many plants (notably drying hay). Its #fragrance is associated with fig leaves, grasses, many leafy herbs, and is a component of fougère perfumes. As a flavour it appears in many desserts. It's also found in the scent of cleaning products.

This is the purest coumarin smell I've ever encountered in Vancouver. (It was also prevalent at higher elevations in Garibaldi Park last weekend, so it's not just a local phenomenon.) Sometimes it's appearing in an accord with isobutyl quinoline (notes of rubber, tomato vine/stem, leather).

The turpenic, pine, cedar, and floral tones (alpha-pinene, vetiveryl acetate, 2-phenylethanol) of early- and mid-summer have disappeared or mostly faded into the background, replaced by an increasingly strong coumarin ( #scent notes of hay, ripe apples, and cinnamon).

Southwestern crater edge, 13:50.
A warm southerly updraft from the valley carries honeyed herbaceous floral accord of phenyl ethanol, ethyl phenyl acetate, thymol, faint methyl salicylate, and a subtle resinous woody note of vetiveryl acetate.

Walking Northwest along crater rim, 13:30.
The cross flow of cold mist is churned by warm sulphurous updrafts rising from within the crater and from beyond the crater rim, infused with dimethyl disulfide and phenol aromas recalling industrial activity or a distant forest fire.

Occassionally bright whiffs of resinous pine terpinyl acetate and grassy hexenol. In the background: deeper woody flavour of vetiveryl acetate and soft earthy geosmin.

The most prominent aroma is a strong accord of coumarin with subtle eugenol, suggesting over-ripe apples, cinnamon, and cloves. A milder fragrance of methyl atratate, acetyl pyrazine, and ethyl maltol evokes toasted tobacco and dry tea with hints of caramel.

The arched underside of the bridge seems to channel a steady eastward breeze flavored with a warm watery swampy earthy and mildly sulphurous accord: geosmin, MBD, methyl atratate, dimethyl disulfide, nonanal, methional, and skatole. A faint taste of pinene appears in the background.

At the north side of the bridge, a westerly breeze carries distinct turpenic conifer wafts of pinene and vetiveryl acetate, with sweet toasted notes of ethyl maltol and acetyl pyrazine, and an herbaceous hint of thymol.

From the southwest, a fresh light conifer aroma of pinene, methyl atratate, benzodioxepinone, and vetiveryl acetate.
Finally, a slightly-sweet warm-concrete minerality: nonanal and faint geosmin with a muted marine flavor of isobutylamine and MBD.

3 understated flavors meet at the top of the bridge:
From the east, a mild floral fruity #scent of phenylethanol, weak undecalactone, and faint cyclopentanone.

At the southern end of the stone footbridge the scentscape opens with a sweet rubbery herby tobacco accord of isobutyl quinoline and phenol with lighter notes of methyl atratate, skatole, acetyl pyrazine, and ethyl maltol.