AIr pollution forecasting

By: Dr. Jeff Masters , 18. toukokuuta 2006 klo 14:49 (GMT)

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Over the past decade, more state and local agencies have begun air quality forecasting for their communities. Today, about 300 cities nationwide are issuing air quality alerts based on forecast concentrations of known pollutants such as ozone and particle pollution, but have been doing so without the benefit of the kind of high-powered national forecasting technology and guidance that supports local weather forecasts. However, this is changing this year, with the arrival of new NOAA forecasting guidance to improve forecasters� ability to predict the onset, severity, and duration of poor air quality. For communities in most of the country, this will be the first time that comprehensive air quality predictions, with hour-by-hour information for cities, suburbs and rural communities alike will be available.

Figure 1. Ozone pollution forecast for 7pm EDT May 18, 2006, generated by NOAA's new air pollution forecasting system. With a major push of clean Canadian air over the eastern half of the country, the usual pattern of pollution over the Northeast and Midwest is absent today.

NOAA, in partnership with EPA, has implemented the first stages of an air quality forecast (AQF) capability. Now providing ozone forecast guidance for the eastern U.S. (predictions available at, the AQF capability uses the National Weather Service�s most advanced operational computer weather models at NOAA�s National Centers for Environmental Prediction (NCEP) coupled with a community multi-scale air quality (CMAQ) chemical transport model to produce daily forecast guidance for surface ozone. Meteorological information such as current and predicted temperature, humidity, winds, cloudiness, and precipitation, combined with pollutant emissions data supplied by EPA, are input to CMAQ to predict ozone concentrations through the next day. In summer, 2006 an experimental version of the AQF capability will cover the lower 48 states. Currently, the AQF capability covers the eastern US from the Atlantic Seaboard to the Mississippi Valley, with hourly and 8-hourly forecast ozone concentrations out to midnight, next day, at 12 km (about 7 miles) grid resolution. This information, converted to EPA�s health-based Air Quality Index (AQI) is also available on EPA�s AIRNow website.

In the next few years, the operational ozone prediction domain will be expanded still further to include Alaska and Hawaii and the forecast range will be extended out to several days. Also in development are predictions of airborne particulate matter (PM). As a component of the eventual PM forecast capability, a daily smoke forecast tool is being tested experimentally. For this tool, NOAA�s National Environmental Satellite and Data Information Service provides fire locations of active fires from complex satellite-based imaging techniques. Smoke transported from these fires is simulated with a computer transport model called HYSPLIT linked to NWS� operational weather forecast models. Predictions of the smoke are updated each morning and provided on a web site at State and local air quality forecasters will be able to use the expanding guidance when they prepare their forecasts or issue local alerts for their communities. The public, especially those with greater sensitivity to poor air quality, will be able to see hour-by-hour trends for the entire Nation and take appropriate actions.

I'll conclude my series on air pollution tomorrow, with a look at why one of NOAA's P-3 weather research aircraft will be flying an air pollution research project this summer in Texas instead of chasing hurricanes.

Jeff Masters

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180. ScienceCop
21. toukokuuta 2006 klo 00:47 (GMT)
Posted By: swlaaggie at 8:49 AM CST on May 19, 2006.
At 32 feet deep the water pressure is 16 pounds per inch, which is roughly equal to surface air pressure.


I agree with your post in general. However, you were way off with this comment. The pressure at 32 feet is roughly 16 psig. You have to also add atmospheric pressure of 15 psi(at sea level) for a total of 31 psia.

Picky point considering the rest of the post is essentially correct. No offense intended.

Not in an open system with a pipe or tube axially oriented up-down with both ends open. The air pressure of the atmosphere is pressing on the whole ocean so that any pressure applied to the top of the tube by air pressure is countered by air pressure applied everywhere else other than the tube top and is transferred down to the depths to exert an equal pressure underneath the bottom of the tube, effectively cancelling the air pressure at the tube top.

Hydraulics is not a new subject. The entire industrial revolution came about because coal mines flooded and pumps couldn't keep up with it, so stream engines were invented to better pump water out of coal mines, which led to stream locomotives, blah-blah-blah, and so on and so forth, you and me talking on comuters in an pollution thread.

Some of the greatest genius of the human race has been applied to understanding hydraulics. I also fudged the numbers by rounding off 14.7 psi as 15 psi air pressure, and the water pressure is not precisely 0.5 psi per foot of depth, and the real numbers cannot be stated except under specific barometic and temperature conditions, plus there are few slight gravitational anomolies, so you have to specify latitude and longitude as well. "Close enough for government work".

179. ScienceCop
21. toukokuuta 2006 klo 00:28 (GMT)
Posted By: cyclonebuster at 12:16 PM GMT on May 19, 2006.
Along with Pascal working for us at the tunnel entrance at depth it works just fine.

Pascal can't help you. In order to move water out of the mouth of the tube you need lower pressure above. Water passing over the mouth at any leisurely place creates no substantial low pressure. Very little expansion from within the tube can happen to expell any contents out the mouth of the tube. The reduced pressure at the tube mouth, and just below the mouth, cannot draw up a column of water going down a minimum of 500 feet. The inertia of a column of water 500 feet tall is too great to be affected by the piddling reductions in pressure.

The path of least resistance is water from the current will be drawn down into the top part of the tunnel in a shallow layer of turbulence. The water above is under far less pressure, and has far less column weight. You will achieve a shallow layer of turbulence and that is the end of it. Nothing more than that can happen.

Pascal is not here to defend himself, but nothing Pascal ever said or did can undo what Issac Newton accomplished. Bodies at rest remain at rest unless acted upon by an outside force. You have described a weak outside force and a very deep massive body at rest. You postualte a suction force, which we know from well pumps all over the world for generations of experience CANNOT EVER SUCK WATER MORE THAN 30 FEET. You can't break the laws of physics and Pascal can't help you break the laws of physics.

An F5 Tornado cannot suck water more than 30 feet up a tube. There is no force on earth that can suck a column of water more than 30 feet up a tube at sea level air pressures. Pascal, Bernouli and Venturi never sucked water more than 30 feet up a tube. It has never been done in the history of the world, not even once by you or anybody else.

I explained it once. As you suck on the water you reduce the pressure, and as you reduce the pressure you expand the liquid. As the liquid expands to it's limit it changes from liquid to gas. These gas bubbles float upwards and break the suction with an air pocket. That's the end of the process. It never gets better than that. It's over. Finished. Done.

A leisurely current flow over the tops of tubes is not even substantial source of suction pressure. It just creates a barely noticable turbulence zone on the top of the tube area and nothing more. You have designed a dud. You can't take 50 feet of cheap irrigation plastic pipe and draw water up by suction no matter what device you try. You never even tried that simple experiment that costs $10 for plasic pipes. You quit learning too soon about the physical mechanics of the planet you live on and you put out a half-baked theory with no chance of success.
178. louastu
19. toukokuuta 2006 klo 15:17 (GMT)
New blog up.
177. swlaaggie
19. toukokuuta 2006 klo 15:15 (GMT)
Question everyone: No cringing needed, I'm guesing this one will be simple.

I posted the other day regarding some of the terminology that is used in weather discussions from NWS offices. To this lay person at this point in my self-education, it really seems encrypted. Now I see the recent posts about more befuddling terminology.

When a NWS office issues a weather discussion, is the individual forecaster given a great deal of latitude regarding terminology(please, no duh here) and content or are there guidelines that must be followed?

Not a world shifting question, just curious.

Thanks for any reply.
Member Since: 26.04.2006 Posts: 0 Comments: 1032
176. swlaaggie
19. toukokuuta 2006 klo 15:06 (GMT)
At 32 feet deep the water pressure is 16 pounds per inch, which is roughly equal to surface air pressure.


I agree with your post in general. However, you were way off with this comment. The pressure at 32 feet is roughly 16 psig. You have to also add atmospheric pressure of 15 psi(at sea level) for a total of 31 psia.

Picky point considering the rest of the post is essentially correct. No offense intended.

Member Since: 26.04.2006 Posts: 0 Comments: 1032
175. franck
19. toukokuuta 2006 klo 14:52 (GMT)
It is an obscure meteorolgical term?
Member Since: 30.08.2005 Posts: 0 Comments: 1150
174. franck
19. toukokuuta 2006 klo 14:51 (GMT)
That is 'New England'. And here is gihemous:
Member Since: 30.08.2005 Posts: 0 Comments: 1150
173. franck
19. toukokuuta 2006 klo 14:49 (GMT)
Don't know nutt'n about dat word 'gihemous' needer.
If you Yahoo search the word you'll see the same forecaster has used it before.
Member Since: 30.08.2005 Posts: 0 Comments: 1150
172. franck
19. toukokuuta 2006 klo 14:45 (GMT)
That low which was setting up in earnest over the Great Lakes again yesterday is pretty impressive, 1000 milibars in several locations.
It is hauling Atlantic moisture into Mew England again. Wonder if it's going to be moving out as fast as forecast.
Member Since: 30.08.2005 Posts: 0 Comments: 1150
171. louastu
19. toukokuuta 2006 klo 14:40 (GMT)
Anyway, I have posted my first blog. I would really appreciate it if people would drop by, and tell me what they think. It took me about 2 weeks to gather information, sort the information, and decide what information should be included, so hopefully it is good.
170. louastu
19. toukokuuta 2006 klo 14:26 (GMT)
Just speculation.
169. louastu
19. toukokuuta 2006 klo 14:26 (GMT)
Ok, I have done a little research, and this is what I have come up with. It is possible that "gi" means ginormous (big), and that "hemous" is a shortened version of hemionus (ass). Therefore, a "gihemous ridge" may simply mean "big ass ridge".
165. louastu
19. toukokuuta 2006 klo 14:11 (GMT)
I have no idea what gihemous means. I can't find it at, and I can't find it's meaning doing a Google search either.
163. lightning10
19. toukokuuta 2006 klo 13:16 (GMT)
So Cal people take note...

An unusually late season storm may bring heavy rain to
southwestern California late this weekend...

An unseasonably strong and cold upper low was taking shape in the
eastern Pacific this morning. This storm system is forecast to
continue to gather strength and moisture as it slowly drops
southward to a position several hundred miles west of San Francisco
by late tonight. The upper low is forecast to remain nearly
stationary Saturday and Saturday night... with an increasingly
moist and organized surface front developing off the West Coast.

This frontal system is expected to push into southwestern California
on Sunday... causing rain to become likely across the area. A few
computer weather models are indicating that the front will enhance
quite a bit as it moves across the area late Sunday and Sunday
night... possibly bringing heavy rain and even some thunderstorms to
the region. Strong low level southerly flow ahead of the front will
cause wind gusts over 40 mph in the mountains... with gusty winds
likely in many coastal and valley areas Sunday into Sunday night. In
addition... the southerly flow will further enhance rainfall in and
below terrain with a south or southwest exposure to the ocean.

Rain should turn to showers across the area fairly early Monday
morning as the front moves eastward. Since the system has not yet
completely developed... its evolution and its eventual effects on the
weather in southwestern California are still somewhat in question.
However... the potential exists for a fairly good late season soaking
across the area Sunday into early Monday. Very preliminary estimates
of rainfall with this storm are for one half to one inch in coastal
and valley areas... with one to three inches in the foothills and
mountains. Higher amounts are possible in orographically favored
locations. Snow levels will likely be above 7500 feet through
Sunday... then could lower to 6000 feet Sunday night... with several
inches of snow possible above this level.

Residents of southwestern California are urged to stay tuned to
later forecasts and statements concerning this late season storm
system. Stay tuned to NOAA Weather Radio or your favorite media
outlet through the weekend.
Member Since: 24.11.2005 Posts: 41 Comments: 630
161. FlaRob
19. toukokuuta 2006 klo 12:12 (GMT)
Hey SJ, I couldn't find the SSTs on your site, where are they?
160. StormJunkie
19. toukokuuta 2006 klo 11:32 (GMT)
Good morning all.

I have posted 4 detailed SST maps for the past four years in my blog. Ya'll check it out. It is pretty interesting.

Also stop by Then let me know hat you think in my blog.

Thanks all.
Member Since: 17.08.2005 Posts: 26 Comments: 15472
159. Abaco
19. toukokuuta 2006 klo 11:26 (GMT)
Can anyone explain the orange north south line est of the Florida Keys in the Ozone Map?
158. louastu
19. toukokuuta 2006 klo 10:45 (GMT)
I have posted my first blog. Please take a look and tell me what you think.

I will be back later.
157. aquak9
19. toukokuuta 2006 klo 09:10 (GMT)
Posted By: snowboy at 2:05 AM EDT on May 19, 2006.
If a tunnel a day keeps the hurricanes away, then what keeps the comets away???

Hmmmm....a snowcone?
Member Since: 13.08.2005 Posts: 163 Comments: 25516
156. ScienceCop
19. toukokuuta 2006 klo 09:03 (GMT)
Posted By: cyclonebuster at 5:24 AM GMT on May 19, 2006.
Just build my hydroelectric tunnels and be done with it!


I looked up your "tunnels", which you neglected to draw any pictures of and post on any free webhost or anywhere. If I understand your word-descriptions, you have submerged tubes vertically oriented up-down in the long dimension. You count on water movement over the open tops to be a sucking, drawing, force to raise cold water from the depths up to cool off the surface waters.

Is that a fair summation, so far?

If that is what you are calling "tunnels", it will not function as you describe. The "Bernouli" principle or the "Venturi" principle cannot cancel Newtons prime laws of physics.

Cold water is heavier than warm water. It has less vibrational energy, less heat-kinetic energy, so it does not occupy as large a volume in vibrating. More cold water molecules pack into denser space. Cold water sinks. Warm water molecules are loaded with more heat energy -- they vibrate more and occupy more territory, thus less of them fill a given volume.

Warm water floats on cooler water and the warm water wants to rise, by Archimedes bouyancy principle, while the cold water sinks by the same principle. Actually Archimedes Bouyancy Principle is an example of Newton's general laws of physics.

Raising cooler water is work. It requires expendature of energy. There is an equal and opposite effect of the application of any force. Gravity and Archimedes principle opposes suction drawing up any water. If water attempted to rise upwards it would create a partial vacuum or reduction in pressure, opposing that rise of water.

As a general rule of thumb, water has a pressure of half a pound (0.5) per square inch of surface per foot of depth. At two feet there is one pound of pressure per square inch. At 2000 feet there is 1000 psi. There is no suction you can do which can fight such power pressure.

At 32 feet deep the water pressure is 16 pounds per inch, which is roughly equal to surface air pressure. A suction drawing water up a column of water 32 feet creates an opposite pressure to the air above. This zero pressure point causes a drastic lowering in the vapor point of water, causing in essence "low temperature boiling". If you ever travel up mountains you will notice that decreases in boiling temperature accompanies high altitude -- that doesn't mean boiling water is as hot at high altitudes as boiling water is at sea level. Water can "boil" at below freezing temperatures in vacuums, and that is how "freeze drying" works to make "Astronaut Ice Cream".

The vaporization turns the water to gas, the gas bubbles move up the column (Archimedes bouyancy principle again), and the suction is broken. No suction-type pump can operate more than 30 feet deep on Earth Surface. Sorry. That's physics laws at work.

Deep pumps require submerging the pump down the well to push water upwards. Any well pump in a well more than 30 feet deep is of the pusher-type, not the suction-type. You can push water much higher than you can suck water, but trhe workload increases as the weight of the water increases. Water weighs one gram per CC, or "a pint's a pound the world around". One gallon of water weighs eight pounds. To push a gallon uphill takes energy, work. Carry a five gallon bucket of water up a flight of stairs if you want to experience how much work it takes.

Hurricanes require water to be hot down to about 50 meters depth, or at least about 150 feet deep. The Loop Current last summer was measured hot down past 500 feet deep. Suction-type devices can never affect those depths. The laws of physics prevent that.

You have misunderstood the Bernouli and Venturi principles and given them unwarranted magical powers that they do not possess. Newton's laws cannot be set aside. There is an equal and opposite effect from every application of force.

Molecules of water in a current will obey Newton's Law of inertia -- a body in motion tends to remain in motion unless acted upon by an external force. Your tunnels will present a blockage in forward motion to those water molecules moving horizontally below the top of your submerged tunnel - these will merely slide around it. Those molecules above your tunnel will slide right over it as if it didn't exist. Only a very thin layer of molecules would actually slide over the horizontal mouth of your tunnel. There is no particular reason that their passage will exert any substantial suction against cooler water at depth pressures measured in at least 75 psi or greater. Because of the molecular nature of water some molecules would press down as well as some deflect upwards. The net sum of activity would be essentially zero. A thermocline would develop inside the tunnel tube of roughly equilibrium temperatures as outside of it. You still have the fundamental bouyancy problem that the warmer waters and cooler waters don't mix.

All that can happen is some warm water in the tunnel tops gets replaced by some warm water in the current at the topmost level of the tunnels, and that is the end of the process -- it never proceeds any further than that. Nothing is changed and the world is not saved. Eventually barnacles, algae scum and corals will colonize the tunnel tubes and choke it closed.

155. Inyo
19. toukokuuta 2006 klo 07:14 (GMT)
also the comet is already gone. forget about it. I'm sure in the next 10,000 years some big comet will smack into the earth. this isnt it.
Member Since: 3.09.2002 Posts: 42 Comments: 867
154. Inyo
19. toukokuuta 2006 klo 07:13 (GMT)
this is impossible to bash into the heads of the neocons but


at most it would supply 6 months of our oil needs.


a few people (oil ceos, etc) would beneifit from the drilling. the effect on gas prices would be BARELY NOTICIBLE if at all.

it's best to give up whining about this because even if you get what you want, it won't do any good.

and yes twc, etc are heavily biased towards the east... if you notice, the 'meteoroligists' almsot always stand right over California... blocking the view to the weather affecting over 30 million people. In the summer, it is true that 'california has no weather' (at least on the coast) but in other seasons the weather is quite variable.. in fact we had severe thunderstorms today over the southern San Joaquin Valley... with a radar-visible outflow boundary that would rival anything seen in the midwest.

The cliamte is warming. How much of this is caused by humans? Almost surely a good portion of it, probably not all. Storms seem to be increasing in severity. This week California has had August-style monsoon weather. Is this an indicator of greenhouse warming? probably not. But combine it with the intense hurricanes everywhere and various examples of abnormal weather... sorry repubnicans, but it's changing.

Gas prices are rising exponentially, partially beacuse of supply.. mostly so the oil CEOS can get 400 million dollar bonuses when they retire. I have no problem with paying extra at the pump to account for increased costs associated with production, refining, and technology to reduce harmful pollution. I sure as hell have a problem with paying extra to make a bunch of CEOs massively rich at my beneifit.

so there.
Member Since: 3.09.2002 Posts: 42 Comments: 867
153. louastu
19. toukokuuta 2006 klo 06:18 (GMT)
Depending on the angle at which a comet (or any other space debris) approaches, the atmosphere. If an object approaches Earth at a shallow angle, it will skip back into space (kind of like skipping a stone on a pond).
152. snowboy
19. toukokuuta 2006 klo 06:05 (GMT)
If a tunnel a day keeps the hurricanes away, then what keeps the comets away???
Member Since: 21.09.2005 Posts: 10 Comments: 2547
150. louastu
19. toukokuuta 2006 klo 06:03 (GMT)
I don't really know. The 200-year-ago version of me is no longer alive, and he didn't leave a note.
149. snowboy
19. toukokuuta 2006 klo 05:56 (GMT)
The question of the hour louastu, is how your 200-year-ago version would see things differently from STORMTOP's?
Member Since: 21.09.2005 Posts: 10 Comments: 2547
147. louastu
19. toukokuuta 2006 klo 05:42 (GMT)
Posted By: newt3d at 10:20 PM CDT on May 18, 2006.
(I'm imagining 200-year-ago versions of louastu and STORMTOP ... they could both see the same swirl of clouds out there and have very different opinions about what is happening)

Wow, someone mentioned me. I feel important.
146. louastu
19. toukokuuta 2006 klo 05:36 (GMT)
When did it start asking if you are sure you want to mark a post as spam?
143. snowboy
19. toukokuuta 2006 klo 05:30 (GMT)
... a tunnel a day keeps the hurricanes away? Sorry, I couldn't resist.
Member Since: 21.09.2005 Posts: 10 Comments: 2547
139. newt3d
19. toukokuuta 2006 klo 03:45 (GMT)

All I was trying to point out was that records from the past may not be the most precise, and understandably so.

I agree with you on many points ... and want to point out that I really appreciate the thoroughness of your post. You described the historic methods and reasoning very well.

- I agree that the physics of hurricanes hasn't changed too terribly much in the past 200 years.
- I agree that there was a lot of coverage from a LOT of different people across the Atlantic.

I simply question the exact accuracy of a story written by MANY people 100 years ago and interpreted today. The general knowledge of weather among people has changed tremendously in that time, and that could lead to some confusion. Surely there are some contradictory records that exist as well.

(I'm imagining 200-year-ago versions of louastu and STORMTOP ... they could both see the same swirl of clouds out there and have very different opinions about what is happening)

So, yes, the record we have is the best we'll ever get. It's not likely that we missed 15 hurricanes per year for every year before 1900. We probably did miss a couple though, and probably have less data about intensity and duration.

I think that the compilation of various ship reports, newspaper articles and other sources to recreate a record of hurricanes is great. I also think that in any scientific experiment, data collected with different methods needs to be considered with a grain of salt.
Member Since: 6.10.2005 Posts: 0 Comments: 90
138. Alec
19. toukokuuta 2006 klo 03:30 (GMT)
severe weather actually retreats northward as the battle zone moves northward(cold air and warm air collisions retreat north as summer takes shape across the midwest)......
137. atmosweather
19. toukokuuta 2006 klo 03:27 (GMT)
Michael is right, in the summer you don't get the clash between a warm air mass and a cold air mass so there is no instability.
Member Since: 24.09.2005 Posts: 33 Comments: 9265
135. snowboy
19. toukokuuta 2006 klo 03:12 (GMT)
I think that unfortunately we will have lots of Cat4/Cat5 storms, due in part to the atmospheric changes caused by the greenhouse effect. The increasing CO2 levels are exacerbating the effect, leading to a warming of the lower atmosphere and a cooling of the upper atmosphere (which in turn facilitates the explosive intensification of hurricanes and typhoons).
Member Since: 21.09.2005 Posts: 10 Comments: 2547
133. taco2me61
19. toukokuuta 2006 klo 02:37 (GMT)
Super Dave you can send some of that rain this way when you get enough...

Member Since: 7.07.2005 Posts: 6 Comments: 3182
131. cucumberjack
19. toukokuuta 2006 klo 02:28 (GMT)
I question your logic Colby

1 = e^(2k*pi*i) for any integer k

ln(1)=(2*k*pi*i) aside:[ln1=0]
0=(-4*k^2*pi^2) for k=0
please correct me if i am wrong.
130. StormJunkie
19. toukokuuta 2006 klo 02:28 (GMT)
Ga is way over due taco, but I think the nubmers will be higher then 17 taco. If the shear dies, all bets are off. The heat will help the weakest low develop in a decent environment. Remember 10, 12, katrina.

Check out the sst maps in my blog.
Member Since: 17.08.2005 Posts: 26 Comments: 15472

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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