Ozone pollution improving in the U.S.

By: Dr. Jeff Masters , 7:03 PM GMT on May 01, 2007

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Air pollution season is here, and the good news is that ozone pollution in 2006 was considerably better than in previous years. Along with pollution due to small particles (particulate matter), ground-level ozone is the most serious pollutant in the U.S. Ozone levels in 2006 showed improvement in 23 out of 35 of the major cities in the U.S. (Figure 1) compared to 2005, and was at or below the 10-year average in all but five cities. Atlanta, Georgia, showed the greatest jump in the number of unhealthy days, from 17 in 2005 to 30 days in 2006; however, this number was still below the 10-year average. Many western cities reached levels at or above the 10-year average, including San Diego, Sacramento, Denver, and Las Vegas. This was in part due to much above average summertime temperatures in the western U.S. (Figure 2). Los Angeles had the worst ozone pollution in the U.S., with 46 unhealthy days. Los Angeles also was the most polluted city overall in 2006, according to the American Lung Association. However, Los Angeles' bad ozone days declined by 16% in 2006 compared to 2005.


Figure 1. The number of days in May through September of 2005 and 2006 in which ground-level ozone reached Unhealthy for Sensitive Groups--an Air Quality Index (AQI) above 100. Corresponding 10-year averages are also shown. Image credit: EPA.

Ozone pollution has improved
Is the improvement seen in ozone levels in 2006 merely due to a lack of meteorological conditions that favor air pollution? To check, I've plotted the difference in surface temperature (degrees C) from May-September 2006, compared to the 10-year average from 1995-2005 (Figure 2). The chemical reactions that form ozone are most efficient at high temperatures, so if the summer of 2006 was cooler than usual, we'd expect a drop in ozone levels. However, the summer of 2006 was the second warmest in U.S. history--but ozone levels still dropped. All of the cities where ozone increased significantly in 2006 over 2005 levels were areas where temperatures were above average. Los Angeles had summer temperatures more than 1 degree C above normal, yet still recorded a drop in ozone, suggesting that strategies to control ozone pollution there are paying dividends. In fact, new rules to limit nitrogen oxide emissions from power plants have been enacted nation-wide in the past few years, and the ozone pollution statistics from 2006 are evidence that these emissions rules are working. Ozone pollution since 1980 has dropped 21% (Figure 3), despite the fact that the average summer temperatures have generally been increasing.


Figure 2. The difference in surface temperature (degrees C) from May-September 2006, compared to the 10-year average from 1995-2005. Temperatures were above the 10-year average across most of the country, except for New Mexico, and portions of the Ohio Valley surrounding Kentucky. Image credit: NCAR/NCEP.


Figure 3. Trends in ozone air pollution in the U.S. (white line) and uncertainty (blue areas, marking the standard deviation). The federal standard of 0.08 ppm is indicated by the dashed line. Since 1980, maximum ozone levels have declined 21%. Since 1990, the decline has been 9%. Note that the lowest ozone levels were recorded in 2004, which was an exceptionally cool summer across most of the U.S. Image credit: U.S. EPA.

Next blog (Thursday): Pollution costs and deaths exceed the impact of a new Hurricane Katrina hitting the U.S. each year.

Jeff Masters

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138. kmanislander
2:23 AM GMT on May 02, 2007
hi pottery

yeah we did have some cover but pics can be deceiving. You would think we had a shower or two but all day hot sun with a little overcast.
At least its a start
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137. Bamatracker
2:24 AM GMT on May 02, 2007
that second "wave" looks impressive...dont they usually die down a bit once they get to sea though?
Member Since: May 17, 2006 Posts: 6 Comments: 1367
136. kmanislander
2:21 AM GMT on May 02, 2007


here comes # 2
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135. weathermanwannabe
10:17 PM EDT on May 01, 2007
Good evening Back....Nice concise article on the BH Cane (I saw this article last year)...This is another piece of the great puzzle; we can have all of the other pieces in place once the Cape Verde season hits, but,this probably plays the greatest role in US vulnerablity (strikes vs. fish storms)..
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134. pottery
10:20 PM AST on May 01, 2007
Hi Kman. How goes it. See you had some cloudcover today ?
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133. Bamatracker
2:21 AM GMT on May 02, 2007
yea first wave but the wind shear is still pretty strong.
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132. kmanislander
2:18 AM GMT on May 02, 2007
bama

slow isn't the word !
I see we have our first wave. Don't know how that compares with other seasons in terms of how soon the first one came off.

I am sure someone lurking knows the answer LOL
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131. Bamatracker
2:16 AM GMT on May 02, 2007
what up kman!!! slow night
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130. kmanislander
2:09 AM GMT on May 02, 2007
good evening all
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129. TheCaneWhisperer
2:05 AM GMT on May 02, 2007
For those curious! HERE is a good explination of the Bermuda High!
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128. chessrascal
1:28 AM GMT on May 02, 2007
lol

heres the water vapour
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127. pottery
9:21 PM AST on May 01, 2007
......the Mid-Level water vapour map, from meteostat8 is interesting too................
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126. chessrascal
1:23 AM GMT on May 02, 2007
come over to my blog
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125. StormJunkie
1:20 AM GMT on May 02, 2007
Yep BT, nothing is going to charge through 40kts of shear.

Alright I am out. Catch y'all later!
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124. pottery
9:17 PM AST on May 01, 2007
Ah !
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123. chessrascal
1:13 AM GMT on May 02, 2007
wow look at that huge blob of convection still over land:

lol
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122. pottery
9:10 PM AST on May 01, 2007
That last image of the wave that Rascal posted, shows the heavy rainfall I referred too, still onshore Africa.
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121. Tazmanian
6:08 PM PDT on May 01, 2007
DWR Survey Shows Sierra Snow Level At 29% Of Normal
Tuesday, May 01, 2007 - 06:00 PM

BJ Hansen
MML News Reporter
Sacramento, Ca -- The California Department of Water Resources has conducted its fifth and final snow survey for the 2006-07 season.

Statewide, snowfall is at 29% of normal for this time of year. The Northern Sierra is at 27%, the Central Sierra is 33% and the Southern Sierra is 29%.

“Now more than ever, we need to support the Governor's Strategic Growth Plan,” says DWR Director Lester Snow. “It will allow us to address this critical need for additional surface and groundwater storage, conservation and Delta preservation to cope with California's population growth.”

Recently, water districts in Tuolumne County, Calaveras County and Groveland began implementing voluntary water restrictions for the coming months.
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120. 882MB
1:09 AM GMT on May 02, 2007
Hey everybody, I just heard of the first tropical wave, but have you seen THE SATELLITE OF AFRICA IT SHOWS THE SECOND WAVE SURE HAS ALOT OF CONVECTION BUT NOTHING EVER FORMS OFF THE COAST OF AFRICA TO EARLY IN THE SEASON!
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119. Bamatracker
1:08 AM GMT on May 02, 2007
evening all!!! I like that shield of orange protecting the US! (on the shear map)
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118. Tazmanian
6:07 PM PDT on May 01, 2007
and 23?
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117. chessrascal
1:07 AM GMT on May 02, 2007
lol

heres a cool pic of the wave
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116. hurricaneman23
1:06 AM GMT on May 02, 2007
is there a lot of shear to prevent development?
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115. hurricane23
9:05 PM EDT on May 01, 2007
A bit long range but look at the shear forcasted along the easter atlantic in the next 2 weeks.

ggg
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114. hurricaneman23
1:03 AM GMT on May 02, 2007
there is no chance of development off the coast of africa at this time of year, am i correct?
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113. Tazmanian
6:00 PM PDT on May 01, 2007
but no 90L
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112. pottery
8:58 PM AST on May 01, 2007
....there is also a large area of rainfall, 10 hrs. or so, behind that wave. We should keep an eye on that one too.
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111. franck
12:56 AM GMT on May 02, 2007
...and little convection.
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110. StormJunkie
12:56 AM GMT on May 02, 2007
Good point K8E, but a little is an understatement! It is around what 2N?
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109. StormJunkie
12:54 AM GMT on May 02, 2007
Well K8E, that all depends on the storms and the timing! Forbide one should make landfall, if it is close enough and I can get the time off work, then yes.
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108. K8eCane
12:54 AM GMT on May 02, 2007
yes it is clearly defined but is it a little south?
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107. chessrascal
12:53 AM GMT on May 02, 2007
wave

I would say this wave is very clearly defined for being the first wave!
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106. pottery
8:46 PM AST on May 01, 2007
Good evening. How is everybody tonight? The SAL shows distinct signs of dissipating. Thats a good sign for storms, may be a bad sign for coastal dwellers and Island people.
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105. K8eCane
12:51 AM GMT on May 02, 2007
RAH RAH RAH
long as no one gets hurt!
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104. chessrascal
12:50 AM GMT on May 02, 2007
there is no chance for survival but its still fun to watch an actual wave!
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103. K8eCane
12:50 AM GMT on May 02, 2007
you too SJ
are you going to chase this year?
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102. chessrascal
12:49 AM GMT on May 02, 2007
three chears for the first wave!
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101. StormJunkie
12:49 AM GMT on May 02, 2007
Well only kinda K8. NOt much chance of anything off of Africa being of any importance until mid to late July.

Good to see you!
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100. chessrascal
12:49 AM GMT on May 02, 2007
PA radarradar
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99. K8eCane
12:48 AM GMT on May 02, 2007
sorry for the caps
i got excited i guess lol
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98. K8eCane
12:47 AM GMT on May 02, 2007
omg WE ACTUALLY HAVE THE FIRST WAVE WE CAN WATCH???
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97. hurricaneman23
12:29 AM GMT on May 02, 2007
so is this the first wave of the year?
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96. weatherboykris
12:25 AM GMT on May 02, 2007
hello
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95. hurricane23
8:19 PM EDT on May 01, 2007
Hey guys....
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94. weatherboykris
12:16 AM GMT on May 02, 2007
Latest Quikscat clearly shows the wave:

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93. weatherboykris
12:15 AM GMT on May 02, 2007
Can you feel the season approaching?
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92. weatherboykris
12:12 AM GMT on May 02, 2007
The wave is on the map,but ok.


From 00Z NHC discussion:

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N12W 4N20W 3N30W CROSSING THE
EQUATOR AT 40W INTO NE BRAZIL NEAR 2N47W. THE LARGEST
CONCENTRATION OF CONVECTION NEAR THE ITCZ IS ASSOCIATED WITH A
TROUGH THAT IS ALONG 23/24W ON THE 18Z SURFACE MAP. DURING THE
LAST FEW HOURS...THE STRONG CONVECTION ASSOCIATED WITH THIS
TROUGH HAS DIMINISHED A BIT. THIS AREA OF CONVECTION CAME OFF
THE AFRICAN COAST TWO DAYS AGO AND HAS BEEN MOVING WWD SHOWING
SOME TROPICAL WAVE-LIKE CHARACTERISTICS.
AS THE DAY WORE ON...A
DRIFTING BUOY LOCATED NEAR 23W SHOWED A WIND SHIFT FROM NE TO SE
WITH THE TROUGH PASSAGE.
SCATTERED MODERATE CONVECTION IS FOUND
AHEAD OF THE TROUGH AXIS FROM EQ-5N BETWEEN 25W-32W. ANOTHER
CLUSTER OF STRONG CONVECTION IS INLAND OVER AFRICA APPROACHING
THE PRIME MERIDIAN.



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91. StormJunkie
12:09 AM GMT on May 02, 2007
Thanks kris, I often have a hard time finding stuff at the NHC and NWS due to information overload and my impatience to wade through it! Thanks for letting me know where it is!

Post the discussion if you don't mind!

duh, no discussions, surface map...I think that is the map I posted a link to earlier.

The Navy Met Ocean Center also has some good analysis maps.

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90. weatherboykris
12:08 AM GMT on May 02, 2007
BTW..we have our first,NHC recognized,African wave of the year!

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89. weatherboykris
12:05 AM GMT on May 02, 2007
SJ...the NHC has surface analysis maps in their "marine" section.
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88. StormJunkie
11:52 PM GMT on May 01, 2007
Don't worry xyz, I have trouble with lots of stuff and need it explained to me several times before I get it. I did not really get the high either until some one threw out the mountain and valley analogy ☺
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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.