Pollution and Cyclones...

[Ikester]

I posted this in another thread but it got lost. So I decided to start a thread about it. Interesting topic here...

Here's a question for you guys. I'm a new 'pro' met (been in the business 2 years and avid followers since I was in the womb) and a question was proposed to me and was curious to get others opinions. When hurricanes or TS's approach the coast with dense industries, i.e. Houston, Beaumont, New Orleans, et. el, does the partiulate matter in the sky (aka, pollution) produce stronger cyclones or induce heavier rainfall due to the suspended nuclei in the sky? It's interesting that Tropical Storm Claudette in 1979 produced the all-time 24 hour rainfall totals in Alvin, TX near a highly industrialized area. Tropical Storm Allison dropped 40" of rain on the east side of Houston literally mirroring what New Orleans looked like after Katrina. Is this coincidental or is there more to it? Discuss away.

[HURAKAN]

I think it's more related to movement than anything else. Cyclones like Claudette, Allison, Mitch, Flora, etc, all have that in common, very slow motion producing copious amounts of rain.

[Ikester]

I think it's more related to movement than anything else. Cyclones like Claudette, Allison, Mitch, Flora, etc, all have that in common, very slow motion producing copious amounts of rain.

Perhaps, but Flora and Mitch were 'milked' so-to-speak by topography (mountains). I guess I'm speaking in terms of landfalling U.S. systems where the terrain is relatively uniform.

[HURAKAN]

I think that you would need to measure the levels of pollution before a storm and after. If after the storm, the levels of pollution are significantly less than before, then you may conclude that particulate in the pollution was helping to increase the precipitation and now they have been washed out.

[somethingfunny]

I posted this in another thread but it got lost. So I decided to start a thread about it. Interesting topic here...

Here's a question for you guys. I'm a new 'pro' met (been in the business 2 years and avid followers since I was in the womb) and a question was proposed to me and was curious to get others opinions. When hurricanes or TS's approach the coast with dense industries, i.e. Houston, Beaumont, New Orleans, et. el, does the partiulate matter in the sky (aka, pollution) produce stronger cyclones or induce heavier rainfall due to the suspended nuclei in the sky? It's interesting that Tropical Storm Claudette in 1979 produced the all-time 24 hour rainfall totals in Alvin, TX near a highly industrialized area. Tropical Storm Allison dropped 40" of rain on the east side of Houston literally mirroring what New Orleans looked like after Katrina. Is this coincidental or is there more to it? Discuss away.

I'm definitely no expert but I do have a counter-example: Hurricane Danny in 1997 dropped over 40" of rain on Dauphin Island Alabama, which isn't very industrialized by any stretch.

Though like I said I don't know the answer and I'm looking forward to seeing a promet's answer on this one. Excellent question!

[thetruesms]

This is an intriguing question - I've never thought about it, but it seems quite obvious in retrospect.

I certainly have nothing off hand to answer the question, but my hunch would be that it may indeed serve as an additional pool of condensation nuclei. However, I don't know that it would be enough to make enough of an impact on total rainfall amounts to distinguish itself from things such as storm motion. It would be good to have baseline measurements and post-storm pollutant measurements as Hurakan noted, though you'd probably have to take into account reduced amounts from pollution sources likely being shut down. I suppose you could look at rainfall totals in a polluted area and immediately downstream compared to an area immediately upstream of the pollution as a proxy - however, you'd have to make sure that the convection did not significantly change, or it would ruin the analysis.

As far as making a storm stronger, I think I could answer pretty confidently that it would not, though again, I don't have any kind of quantitative information to back it up. But the area of pollution would likely be so small as to be negligible to the entire energy draw of the storm.

[Ikester]

In terms of making a storm stronger or weaker, I suppose it doesn't matter really. When somebody mentions 'stronger,' it certainly is relative to many other variables. My key argument, backed by Dr. Landsea, is that while global warming may indeed make hurricanes stronger, the increase in accumulated energy or strength of wind would be negligible. Sure hurricanes could be growing stronger, but what is a ~2 or ~3% increase in wind on a 150 mph hurricane? The data could not be measured. It's too small of an increase and would be lost in translation so-to-speak and mistaken for a gust. So IF** pollutants are indeed making hurricanes stronger or inducing more rainfall in industrialized areas over non industry areas, I suppose the data would be returned as 'inconclusive.'

[abajan]

I don’t know about the effects on cyclones but there seems to be a relationship between pollution and rainfall. There was something on TV (on NatGeo, I think) some time back about pollution in cities during the week causing rainfall just when it’s not wanted: During the weekend!
Also, Googling pollution "increased rainfall" brought up some interesting results.

One thing is clear - rain removes airborne pollutants. As the raindrops fall, they grab onto the particles and bring them to the ground.