November 30, 2007

Special Feature: Some dust in Cape Town and Farewell

As the GEO IV Plenary Meeting wraps up, we make our final special post on air quality in South Africa for Friday.

All the air quality activity is on the western coast of South Africa near Cape Town, so we'll start with a true color image of that area from the NASA MODIS sensor on the Terra satellite (left image). Look closely near the coast just north of Cape Town to see a small yellowish plume of dust over the Atlantic Ocean. On the right is a zoomed in version with the plume circled in red. This is confirmed with the EUMETSAT algorithm that can detect dust, shown in pink/magenta in this dust image of southwest sector of the full disc.

The ground-based monitors from the City of CapeTown show a huge increase in PM10 levels from one of the monitors during the middle of the day, including the time as the MODIS image. This partially confirms the potential of dust or other coarse pollution seen by MODIS. (Recall that PM10 is a measure of particles in the air that are less than 10 microns in diameter and the 24-hour average health standard for PM10 is 50 micrograms per cubic meter (ug/m3).)

(Please note that these data are preliminary "live data" that have not been validated and that the standard is an average of these points, not any single value).

The SCIAMACHY UV index was 11 again Friday in Cape Town, an indicator of extreme risk of harm from unprotected sun exposure. The Cape Town web cam has beautiful sunny, slightly hazy skies.

We enjoyed our virtual week in Cape Town and wish the attendees of the GEO Plenary meeting safe travels in clear skies!

Posted by Jill Engel-Cox at 6:45 PM | Comments (0)

Good Air Quality in the East, Moderate in the Gulf Coast

The eastern half of the continental US continues to enjoy good air quality, with the exception of the gulf coast. The mid-atlantic looks nice and clear in this MODIS Terra image (right) but some haziness can be found over Louisiana and Mississippi. Central California is in the orange range (unhealthy for sensitive groups) and cloudy, so not much in terms of satellite imagery today.

Posted by Ana Prados at 6:30 PM | Comments (0)

November 29, 2007

Special Feature: Air pollutants in South Africa and the need for more 'eyes'

The more than 70 government delegations at the GEO IV Plenary Meeting are preparing for Friday's Ministerial summit, but we here at the "Smog Blog" hope they have a chance to enjoy the atmosphere of Cape Town, which looks beautiful from all the Earth observing sensors. Our special coverage of South Africa continues today with a multi-sensor review of Thursday's air quality in South Africa and Cape Town, and the need to develop the capacity for many more 'eyes' to observe the air we breathe.

The NASA MODIS sensor on the Terra satellite showed a few clouds Thursday morning over western South Africa (left image). By afternoon, when the MODIS sensor on the Aqua satellite flew over, the clouds had turned to storms in the north-central part of the country (right image). All day though, it continued clear and sunny over Cape Town. The SCIAMACHY UV index was 11 again Thursday in Cape Town, an indicator of extreme risk of harm from unprotected sun exposure. (The UV index was 12.3 in Durban, South Africa, and 15 in some of the other southern African countries.)

For Cape Town, we can look at a couple of on-the-ground sensors. Sometimes a sensor as simple as a webcam can tell us about visibility. On the left is an image from the Cape Town web cam, showing those sunny skies with a little light haze. More quantitatively, the City of Cape Town again kindly shared their PM10 monitoring data with us for Thursday. (PM10 is a measure of particles in the air that are less than 10 microns in diameter; the 24-hour average health standard for PM10 is 50 micrograms per cubic meter (ug/m3).) The time series graph from the Waterfront and Khayelitsha monitors again shows significant peaks (right), likely due to cars, shipping, road dust, and local emissions.

(Please note that these data are preliminary "live data" that have not been validated and that the standard is an average of these points, not any single value).

EUMETSAT is a weather satellite, but it does have an algorithm that can detect dust. The dust image of southwest South Africa is a little hard to interpret, but the pink/majenta color indicates dust. It does show higher levels off the coast of Cape Town, so perhaps some of the increased PM10 is dust, as well as industrial and roadway pollution.

With satellite sensors, we can get some perspective on other air pollutants especially in areas where we don't have ground-based monitors. ESA/KNMI's Tropospheric Emission Monitoring Internet Service (TEMIS) provides some near real-time data from the NASA/ESA Ozone Monitoring Instrument (OMI). The OMI sensor provides SO2 data that works best for high concentrations from volcanos and large industry. So it is interesting that on Thursday there were some increased levels of SO2 in spots near Johannesburg and in the central part of the country (left image). A portion of this region was declared an air pollution hot spot this week by the South Africa Environmental Affairs and Tourism Ministry, due to high levels of pollutants from industry and agriculture. The NO2 levels, also from OMI, were high in the same area (right image). The MODIS true color image of eastern South Africa showed clouds and several small smoke plumes likely from wildfires.

In this assessment, we used 8 satellite and ground-sensors, reviewed about 20 websites, and received and processed data directly from the city, in order to just begin to review the air quality of all of South Africa, over 1.2 million square km. (And there are many other sources of data available retrospectively that have not been included!) It took about 3 hours for this review for just this one location and one day with a subset of information. Obviously, one set of eyes cannot possibly use all the wonderful monitoring resources being launched and deployed, and one person located thousands of miles away cannot know about the local industry, terrain, traffic, weather, and other factors important in understanding air quality. So, we need to develop the capacity of many more human 'eyes' everywhere to use Earth monitoring data to observe our atmosphere and the world. We are working with the SERVIR project to transfer the Smog Blog and the skills to interpret air quality data to Central America. We hope we can take many more small steps to build and connect the global air quality community in order to better understand air pollution, its causes, and the ways to create clean air for everyone.

Posted by Jill Engel-Cox at 8:10 PM | Comments (1)

Haze in California and the Gulf Coast

The main regions of haze today were California and the Gulf coast. See below for MODIS imagery in both regions. Otherwise particulate air quality was good throughout the U.S. Along the Gulf coast, PM2.5 concentrations were in the moderate range.

Posted by Ana Prados at 6:29 PM | Comments (0)

November 28, 2007

Clear day

It was clear today. The hourly PM 2.5 concentrations in the range of 5.2 to 11.9 ug/m3 were recorded at the Oldtown site during ELF’s operation. The aerosol optical depth was ~0.1 in the morning, then increased to ~0.2 in the afternoon from the AERONET site, MD Science Center. There were high clouds at ~11km during ELF’s running and lower clouds at ~6km from 21:00(UTC) to 23:00(UTC), (not shown in the image).

Posted by li at 11:10 PM | Comments (0)

Special Feature: Multiple monitors needed to describe air quality in Cape Town

As our special coverage of South Africa continues during the GEO Summit, we consider that one of the biggest challenges in assessing atmospheric issues using Earth observation data is timely data access. There are a dozen (likely more) satellite sensors that provide global or hemispheric data relevant to air quality and other atmospheric conditions (not even counting weather satellites). There are tens (maybe even hundreds) of ground-based networks around the world consisting of thousands of ground-based monitors for various air pollutant concentrations, visibility, and aerosol optical depth. Yet, much of the data is not available when trying to assess conditions on a near real-time basis for specific countries, such as we do here at the Smog Blog. And much of it is not available at all.

So, as we consider the air quality in South Africa for Wednesday, I'll mention a few potential data sources that were not available to help us today. But I'll also include some new data from ground monitors in Cape Town, that shows that making friends in the global air quality community can give us new data, information, and insights.

Wednesday was stunningly clear over Cape Town and western South Africa. Thanks to the NASA RapidFire site, we have MODIS images over much of the world by early afternoon, including CapeTown. The UV index was 11, so the sunshine was really coming through.

Satellite sensors are great for telling us about regional scale pollution and wildfires. Air quality overall in western South Africa looked pretty good on Wednesday. Yet, conditions on the ground can vary significantly minute by minute, hour by hour, especially in urban areas. The City of Cape Town was generous enough to share their PM10 monitoring data with us for Wednesday. PM10 is a measure of particles in the air that are less than 10 microns in diameter--fine enough to cause health problems when we breath them in. The 24-hour average health standard for PM10 in Cape Town is 50 micrograms per cubic meter (ug/m3) concentration. Below is a time series graph of 1 minute averages from two monitors in Cape Town: one near the Waterfront and one near Khayelitsha, a busy urban area. (Please note that these data are preliminary "live data" that have not been validated and that the standard is an average of these points, not any single value).

[NOTE (29 Nov 07): Figure revised from original post to include 24 hours of data and correct graphing error.]

Clearly, on the ground conditions are more dynamic than we can see from orbit with the satellite sensor! However, by having both the regional view from the satellite and the concentrations right on the ground, we now know that the air pollution is very local and much higher during the times when people are commuting to work--thus it is likely from urban sources, such as cars, road dust, and industry, instead of large wildfires or dust storms.

Although the true color image is available from MODIS, we do not have any near real-time aerosol optical depth data (a unitless measure related to particle air pollution) for this region from MODIS, POLDER, MISR, OMI, CALIPSO, AERONET, or other aerosol measuring instruments. To the credit of ESA/KNMI's Tropospheric Emission Monitoring Internet Service (TEMIS), we do have OMI instrument NO2 concentrations (averaged over the bottom layer of the atmosphere) and SO2 concentrations (over the total atmosphere), as well as global UV index from the SCIAMACHY instrument. Of those, only the UV index values are of significant concern.

So, what is the conclusion for Cape Town and South Africa on Wednesday? Sunny with high UV, good air quality regionally, but higher levels of pollutants during the day in the busy city areas. And that there is tremendous value in using multiple sensors to learn about our air every day.

Posted by Jill Engel-Cox at 8:30 PM | Comments (0)


The air quality in California has not changed much from yesterday. The AQI remains high (reached "unhealthy" ~ code red) and smoke/haze lingers (refer toTERRA MODIS below, source: MODIS Rapid Response System). A smoke plume, currently not impacting the local AQ, was also visible in South Carolina. Lastly, several fires (in between the clouds, look carefully) are in Louisiana.

Posted by Nikisa Jordan at 5:11 PM | Comments (0)

November 27, 2007

Special Feature: High UV levels and good air quality in South Africa

It is a good thing the delegations at the GEOSS conference will be in those conference rooms all day, since the ultraviolet radiation index is predicted to be high. But first, a little on the air quality in South Africa on Tuesday as part of our special series this week.

Tuesday was clear over Cape Town and western South Africa, as seen in the MODIS image on the left. The eastern part of the country was also clear, except for dense cloud cover over the coastal regions (MODIS image on the right). There were some increased concentrations of NO2 near Johannesburg according to the Ozone Monitoring Instrument (OMI is a joint ESA/NASA and
Netherlands/KNMI sensor on the Aura satellite), which I expect will continue.

All that sunshine comes at a cost -- increased ultraviolet (UV) radiation. In addition to air quality data, satellite and ground-based Earth monitoring instruments can also measure UV radiation levels. The UV index is a measure related to how harmful the UV levels are to humans and other life. UV index values over 8 are considered to present a "very high" risk of harm; values over 11 are "extremely high" risk. The TEMIS site provided a global UV index map (below) from the SCIAMACHY instrument (run by KNMI and ESA) that showed UV index in South Africa on Tuesday to be well over 11. The UV forecast is for those high levels of UV to continue all week.

So, while the air quality may be good, be careful of the sun! Clear skies and good air quality expected to continue over much of the country tomorrow.

Posted by Jill Engel-Cox at 11:51 PM | Comments (0)

Poor AQ in CA

CA haze/smoke visible in today's AQUA MODIS image (source: UW MODIS Direct):

Air quality conditions have not improved in California; EPA AIRNow reports mostly code orange (15.5< PM2.5 (ug/m3) < 52.0) AQI. Smoke from local fires is primarily contributing to the poor conditions. The rest of the nation has good AQ.

Posted by Nikisa Jordan at 6:53 PM | Comments (0)

November 26, 2007

Special Feature: Continued good air quality in most of South Africa, with some light haze off east coast

Continuing our coverage of South Africa air quality as part of the GEO Summit, Monday had cloudy rainy conditions in the southwest part of South Africa, including Cape Town. The fire count product of MODIS identified one fire (shown as a red square on the image) near the city of Saldanha, but there was no smoke plume so it was likely not significant.

On the eastern half of South Africa on Monday, conditions were cloudy in the north but the air quality looked good throughout the rest of the region. NASA MODIS (below left) identified a few "hot spots" without significant smoke (shown as red squares on the image). Also in the MODIS image, some very light haze can be seen off the northeast coast near Durban and Richards Bay, where it is more visible over the Indian Ocean (pointed out by the yellow arrows). This is confirmed in the OMI NO2 real-time data (below right), which shows increased concentrations of tropospheric (bottom layers of the atmosphere) NO2 levels in the same location.

Update: The data from the ground-based air quality monitors on Monday in Cape Town from the City of Cape Town Air Quality Monitoring Network all indicate good ('green') air quality.

Posted by Jill Engel-Cox at 11:18 PM | Comments (0)

Moderate AQ in CA

The haze in CA and MN was observed by Terra. The unhealthy for sensitive groups air quality in CA was still recorded by AIRNow. Moderate air quality was also observed in the Northeast and Northwest US.

Posted by li at 5:23 PM | Comments (0)

November 25, 2007

Special Feature: GEOSS Summit in South Africa

This week, the Group on Earth Observations (GEO) holds its Ministerial Summit in Cape Town, South Africa. GEO manages the development of the Global Earth Observation System of Systems (GEOSS), an international distributed network of space- and ground-based monitors to observe the Earth's land, water, and air. Many of the sensors that we use here at the Smog Blog are becoming part of GEOSS and we believe such an international effort will increase the monitoring and understanding of air quality throughout the world.

During the week of the GEO Summit, we'll be making special daily posts on the air quality in South Africa. We'll start today with a NASA MODIS image of the west coast of South Africa, including Cape Town, and a map to orient our images throughout the week. A few small clouds and good air quality for the South Africa today. NO2 values from OMI are slightly elevated near Johannesburg, but otherwise the air quality in the country is good at the beginning of the GEO Summit week.

Update: Here (left image) are data from the ground-based air quality monitors in Cape Town from the City of Cape Town Air Quality Monitoring Network. All the monitors are 'green' indicating good air quality. Aerosol optical thickness from the PARASOL satellite instrument (right) was also very low, less than 0.05, indicating very low fine particle concentrations (click on the image to see it at full size).

Posted by Jill Engel-Cox at 10:35 PM | Comments (2)

Your comments now welcome!

We have at last turned on the comment feature of the Smog Blog, so you can now make comments on recent posts. We encourage everyone to add their input and observations to our daily posts and special features by leaving a comment. Tell us about new sources of images, add links to your air quality-related sites, or just let us know when you find the Smog Blog interesting or useful.

We also made a few other improvements to the site, including an easier to use monthly archive. Let us know what you think!

Posted by Jill Engel-Cox at 9:14 PM | Comments (0)

Fires in the Northwest, improving conditions elsewhere

Most of the eastern and southern U.S. was under dense cloud cover today. Southern and central California and parts of the west were cloudy as well, which improved air quality conditions and obscured smoke from the Malibu fire. The Oregon and Washington coast had several fires producing long smoke plumes over the Pacific, as seen in the MODIS image below.

Posted by Jill Engel-Cox at 6:25 PM | Comments (2)

November 24, 2007

"Almost paradise, almost" - Another Santa Ana and more Malibu fires

The quote above was from a resident of Malibu on the NBC Nightly news. A short Santa Ana has high canyon winds above Malibu and another 34 houses were reported burned. Forecast is for the winds to die down tomorrow. GASP West has a nice animation of the smoke from the fire today.

Unhealthy particulate air quality can be found in the Northwest on the AIRNow site. We can't see what's going on through the clouds.

Posted by Ray Hoff at 6:55 PM | Comments (0)

November 23, 2007

Moderate AQ in California and Washington State

The U.S air quality picture remains mostly unchanged from yesterday with the exception of continued improvement in the northeast where the particulate air quality was good. Much of the same over southern California and Washington state, with some monitors into the moderate range.

There is also some fire activity over the northwest and I believe I see a smoke plume in the southwestern corner of Oregon (left), which was also detected in the HMS analysis. Today's OMI NO2 (right) shows highest tropospheric column amounts over California and in the eastern half of the U.S. The two red spots over California are the cities of San Diego and Los Angeles. Cars and other vehicles are a major source of NO2 so we'd expect to see high values over large urban areas.

Posted by Ana Prados at 7:00 PM | Comments (0)

November 22, 2007

Improved Air Quality in the East

Thanksgiving Day in the D.C area began with late September like weather, but the cold front and brisk winds sweeping through this evening has brought good air quality to much of the eastern U.S. compared to yesterday. Eastern Pennsylvania and New York and Connecticut were still in the yellow range though.

Southern California and Washington State were also in the moderate range. California monitor data over the central valley are not available right now, but the modis AQUA imagery (left) reveals moderate haze. The MODIS Terra imagery over the northwest does not reveal much haze, but I couldn't help posting the image, notice all the snow cover over British Columbia (Canada) including Vancouver, and Washington State.

Posted by Ana Prados at 10:20 PM | Comments (0)

November 21, 2007

New Mexico Fire

MODIS captured a large fire event in New Mexico today (right image). The smoke plume (AOD~ 0.4, source: IDEA) extends into Texas. Officials at the US Forest service refer to this event as the “Ojo Fire”. It stared earlier in the week (11/19/07) and has since intensified. The fire has consumed 7000 acres and an expected containment date has not yet been released. The U.S. Forest Service (.pdf also archived on the smog blog) provides more details on this event. The HMS team also identifies the hotspot (smoke plume shown in gray) along with other fire events in the South (left image).

This fire is currently not having an affect on surface air quality, which is expected since it first started in the mountains at 10,000 ft (~3km), above the PBL. However, this might change as the fire moves and intensifies. Stay linked to the blog for updates!

Air quality elsewhere…

Moderate and few instances of “unhealthy for sensitive groups” AQI was reported in California, Northwest, and the Northeast ( 15.5< PM2.5 (ug/m3) < 65.0). The rest of the country had “good” air quality. Elevated AQI in CA is due to haze [visible in the MODIS Rapidfire image (Terra, 19:30 UTC, 1km res)] from local sources. Haze is also visible over the NE, which is specifically clear over the Atlantic.

And here are the clouds…

Most of the country, particularly the eastern half of the nation, is still covered with clouds. Please refer to yesterday’s post that links to the CIMSS website. They have an interesting post on the “Wave structure on top of a stratus cloud deck”.

Lastly, in case you missed it, EO (Earth Observatory) posted a story on the likely sources of pollution in the United States. Apparently, emissions from local sources are the primary cause for poor AQ in the Nation. For more information regarding this research please refer to ->

Posted by Nikisa Jordan at 5:00 PM

November 20, 2007

Summaries of summer air quality events and the California fires

Check out two new blog entries (post-dated) summarizing the California fires and some of the haze and smoke events this past summer.

Posted by Jill Engel-Cox at 8:46 PM

Smoke plumes, haze, clouds...

Smoke plumes are visible in the Southeast along with some light haze, which as the day progressed, reached over the Atlantic. Air quality conditions are mostly moderate in California and the Midwest. Lastly, skies were primarily cloudy across most of the nation.

Note: CIMSS has an interesting post on the “Wave structure on top of a stratus cloud deck”.

Posted by Nikisa Jordan at 5:51 PM | Comments (0)

November 19, 2007

Haze continued in CA

It was cloudy in most of the US today as observed by MODIS. AIRNow showed that the haze in CA continued and the haze in IL was spreading. The foggy weather around IL was also shown from

Posted by li at 4:40 PM | Comments (0)

November 18, 2007

Intense haze continued in California

The intense haze continued in central and southern California. The MODIS Aqua image on the left shows the haze quite clearly, and the aerosol optical depth values were over 0.5 in several parts of the state. The AIRNow site was down, but the California Air Resources Board indicated PM2.5 levels were peaking over 100 ug/m3 in the Los Angeles area with daily averages (thus far) in the south and central regions as high as 60-80 ug/m3 at many monitors (California ARB map of the state and a graph with data from a few representative sites below).

The south is mostly cloud covered today, but there is some lingering smoky haze and streaky/smoky clouds in the southeast and off the coast of Florida

Posted by Jill Engel-Cox at 10:39 PM

November 17, 2007

California again has haze problems

The AIRNow particles page shows that the only PM unhealthy readings are still in Illinois, southern California and the San Joaquin valley. The haze shows up in the eastern SJ valley in today's Terra MODIS image. Since the image is from the western edge of the Rapidfire playback, it has not yet been image rectified so it shows up as being slightly distorted with overlapping swaths on the west end.

The OMI data for today is not posted at this time, but comparing to Ana's post of yesterday, the OMI NO2 shows high values in southern California and in a line from Houston northward along the Mississippi up into Iowa. Today, we see some high haze concentrations in Illinois which may be related.

Posted by Ray Hoff at 3:28 PM | Comments (0)

November 16, 2007

Good AQ in the East, smoke plumes off the Gulf Coast

The eastern half of the U.S enjoyed good air quality today with all monitors in the green at 5 pm EDT. See also today's MODIS RGB (right). No haze to be seen in the increasingly brown imagery, as leaves continue to fall and change color.

Central California is still experiencing poor air quality as you can see in the AQI image above. Clouds over California today made the haze hard to see in the MODIS true color imagery. There are also lots of small fires in the eastern half of the U.S although according to the HMS analysis (left) they are not causing significant smoke. The exception are fires along the Louisiana coast leading to some interesting long thin plumes blowing over the Gulf of Mexico. You can see one of them pretty clearly in the MODIS true color imagery (right).

Posted by Ana Prados at 8:00 PM | Comments (0)

November 15, 2007

Unhealthy Air Quality in Central California

Haze remains over California. In the San Joaquin valley the AQI for fine particles was orange to red. You can also see some of the haze in today's MODIS Aqua image (right). Except for a few scattered monitors, AQ was good in the rest of the country.

Posted by Ana Prados at 11:14 PM | Comments (0)

November 14, 2007

Hazy in California…

Skies remain hazy in California (left image- Terra MODIS, pass: 19:25 UTC, pixel size 1km); “unhealthy for sensitive groups” AQI was reported for Bakersfield, Hanford, and Visalia.

Lingering haze is also apparent over parts of the South. Refer to the MODIS AOD (~0.4) image for a measure of the aerosol load (source: IDEA).

Posted by Nikisa Jordan at 7:04 PM

November 13, 2007

Elevated AQ over the East

The air quality is generally moderate (code yellow) over the Eastern half of the nation. Also, the AQ has improved in California; only few reports of moderate air quality conditions. The true color image from AQUA MODIS show haze mixed with clouds over the Southeast. The AOD was, on average, ~ 0.4 (right – source: IDEA) in this region. The AOD was also elevated in California, which is likely due to haze from local sources.

Posted by Nikisa Jordan at 4:05 PM

November 12, 2007

Cloudy over the U.S.

It was cloudy over the US today as observed by MODIS. The moderate air quality was seen over the eastern US and the west coast from AIRNow.

There were rain showers over Baltimore, so we did not run ELF.

Posted by li at 11:58 PM | Comments (0)

November 11, 2007

Moderate air quality across eastern half of the U.S.

Areas of light haze across much of the eastern half of the U.S., especially the midAtlantic (Virginia, North Carolina, South Carolina) and midwest (Kansas, Nebraska, Iowa, Missouri, Wisconsin). Ground-based air quality particle concentrations were generally moderate (code yellow). NO2 values from the NASA OMI instrument were elevated particularly in the midAtlantic.

Posted by Jill Engel-Cox at 7:46 PM | Comments (0)

On Remembrance Day, we remember

Photo Sharing and Video Hosting at Photobucket
Photo credit squeegie162,

Posted by Ray Hoff at 11:11 AM

November 10, 2007

Tough viewing through high clouds

High clouds cover much of the US today and while the PM2.5 levels at the surface are moderate in spotty areas of much of the east (left) and the OMI NO2 column shows very high levels in the east (right), the red-green-blue true color images don't reveal much about sources.

There is underlying haze through much of the south from west Texas (which had an exceedence in El Paso this morning) all the way through to Florida. The haze can be seen in the Texas (left) and mid-Atlantic (images) below:

Finally, there is one lonely fire in the Four Corners area of Arizona (south of the Grand Canyon). It looks like the source of the haze in the southeast, though, is pretty apparent from the O3 forecast from NOAA. It is hot in Houston.

We at USAQ would like to remember those who have fallen in our nation's wars and hope you will take a moment tomorrow to do the same.

Posted by Ray Hoff at 11:38 PM

November 9, 2007

Moderate AQ in the Central U.S

Particulate Air Quality (left) worsened today over the mid-west, south central U.S and parts of the northeast with many monitors recording pm2.5 concentrations in the moderate range. In this MODIS RGB (left) you can see a bit of haze south of the Great Lakes over Ohio and Illinois, as well as over Tennessee and Kentucky. The clouds make it difficult to discern any haze in the northeast.

In California PM2.5 concentrations were lower than in previous days, but the haze is all but gone over central California in this MODIS AQUA image (left). Fire activity continues over the southeast and northwest. Notice the plumes over Oregon in this MODIS image (right)

Posted by Ana Prados at 6:40 PM

November 8, 2007

Poor AQ in California continues, Fires in Southeast

Poor Air Quality in California (left) continued today, particularly in the San Joaquin Valley and in coastal urban areas in the south of the state. More on CA later as the MODIS RGBs are not available right now for the west coast. In the southeast air quality has improved, although there is still fire activity, and you can see a few small smoke plumes over Georgia and Alabama (right). Here is today's HMS analysis.

Posted by Ana Prados at 6:20 PM

November 7, 2007

Cloud Capped Boundary Layer

A cloud (dark red counts) capped boundary layer prevailed during today's observations. The colorbar has been reduced by a factor of 3, from the last lidar posting, to highlight today's boundary layer. Hourly PM 2.5 concentrations in the range of 6.3 to 7.6 ug/m3 [AQI Level: Good]were recorded at Maryland's Department of the Enviroment Oldtown site in Baltimore during ELF's operation.

Posted by Ruben Delgado at 11:10 PM | Comments (0)

Western AQ

Air quality conditions remain poor (code yellow-red; 16<PM2.5 –ug/m3<150) in California and other parts of the West (entire AQ map- EPA AIRNow). Light haze mixed with clouds is also present over the Western portion of the Gulf. The HMS analysis suggests that smoke may be a contributing factor. Also, several fires remain in the Southeast.

left: CA AQI from EPA AIRNow
right: MODIS AOD from IDEA

Posted by Nikisa Jordan at 6:48 PM

November 6, 2007

Fire and air pollution story recap

EPA's AIRNow Program and NASA's Applied Sciences Program issued another news story recapping some of the air pollution and smoke events this past summer and fall. We helped with the image (below); the full story is available at AIRNow Status.

Posted by Jill Engel-Cox at 11:24 PM

Hazy South

Skies are relatively clear in the Central U.S. and parts of the East as a cold high-pressure system moves in. This system is likely responsible for pushing most of the haze, visible yesterday in the South-central U.S., over the Southeast. MODIS RGB (UW MODIS Direct-right) and AOD (IDEA –left) images display the band of haze across most of the South and East.


Few fires, specifically located in the Southeast, are also visible. Today’s HMS analysis suggests that fires are also out West. Please refer to the product and accompanied text.

Today's PM2.5 map sourced from EPA AIRNow shows mostly “unhealthy for sensitive groups” air quality in California. Moderate conditions are reported for the Northwest and Southeast (where haze was visible in the AOD image – see above)

Posted by Nikisa Jordan at 4:05 PM

November 5, 2007

Clear day

It was clear today and cloudy in the afternoon. The aerosol optical depth was ~0.2 from the AERONET site, MD Science Center. There were some very thin aloft layers at ~2km, which might be smoke from the west of UMBC from HYSPLIT.

Posted by li at 7:29 PM

haze continues in south-central

The haze in the south-central US continued today from MODIS.

The air quality continued to be unhealthy and moderate in CA. The moderate air quality in the south-central US can also be seen in the AIRNow and the IDEA.

Posted by li at 6:32 PM

November 4, 2007

Haze in south-central continues

Many fires and regions of haze in the U.S. today, similar to the last few days. Dense haze could be seen by MODIS is the south-central region, including Texas, Oklahoma, Arkansas, and Louisiana. Aerosol optical depth levels were about 0.5.

In the Northeast, haze levels were high off the coast of Delaware, Maryland, and Virginia. Southern California was improved, although their air quality levels were code orange and yellow, and there was a general haziness to several areas along the west coast. Florida had code yellow conditions, but no obvious sources of pollution looking at the satellites.

Posted by Jill Engel-Cox at 9:30 PM

November 3, 2007

Air Quality is poor in Ohio and in California

A high pressure ridge running through the Great Lakes has a slow moving line of clouds with haze piled up behind it. In the left Aqua image, the remnants of Hurricane Noel are affecting the eastern seaboard and the haze is seen on the left of the image. In the right image, zooming in on Lake Erie, New York and Southern Ontario shows the fall colors in New York and Pennsylvania ahead of the front and the haze obscuring Ontario behind.

There also is a heavy haze over Houston. Further east, fires in LA and AL are leading to some increased haze in the southeast.

The San Joaquin Valley is into its third day of poor air quality. The AIRNowTech readings for Visalia, Bakersfield, and Fresno all show elevated PM2.5 levels (in the red range) with the first two cities over 100 μg m-3. Aqua image at 500 m resolution is shown in the right panel.

Posted by Ray Hoff at 5:02 PM

November 2, 2007

Poor Air Quality in California and hazy southeast

Haze continues in the southeast including eastern Texas, Arkansas, Louisiana, Tennessee, Alabama, Mississipi and Georgia. See the two MODIS RGB images below. There is also a bit of fire activity in the eastern half of the U.S and western Canada. Click here for today's HMS image. Surface air quality was in the moderate range over much of Texas and the southeast, including the Gulf of Mexico.
Extratropical storm system Noel (downgraded from a hurricane) can also be seen over the Atlantic (right image) along the U.S coast and is expected to impact the northeastern U.S this weekend.

In California air quality worsened today in the San Joaquin Valley (right). In Fresno, Visalia and Bakersfield the AQI was orange (unhealthy for sensitive groups) to red (unhealthy). In southern California the AQI was highly variable. Good (green) air quality in some coastal areas but code orange in Los Angeles. Notice the whitish haze in the MODIS AQUA image (left) where surface monitors were recording the highest pm2.5 concentrations.

Posted by Ana Prados at 4:45 PM

Movable Type 4 has been installed

Please report any problems to Paul or Kevin.

Posted by kmccann at 3:04 PM

November 1, 2007

ELF/CALIPSO Trick or Treat

Clear skies prevailed over the Baltimore-Washington Metro Area on October 31st. A homogeneous boundary layer, at a height of 1km, was observed until 6:00 UTC (Nov. 1). The boundary layer became active (inhomogeneous) after this time with aloft layers reaching up to 2 km. Cloud coverage (dark red counts) was due to the cold front moving thru the Mid-Atlantic states. CALIPSO's trajectory was about 23 and 59 km east of UMBC around 7:16 and 18:20 [UTC], according to the NASA LaRC Overpass Predictor. Hourly PM 2.5 concentrations in the range of 5.3 to 16.2 ug/m3 were recorded at Maryland's Department of the Enviroment Oldtown site in Baltimore during ELF's operation.

Posted by Ruben Delgado at 11:55 PM

Haze over the Southeast

There was moderate haze today over Tennessee, Arkansas, northeastern Texas, and northern Mississippi and Alabama. You can see the haze clearly in the MODIS AQUA imagery (left). The MODIS AOD was also elevated in the same region. Surface monitors where in the moderate range today over much of that area. Although there is a lot of fire activity in the southeast, the HMS analysis did not identifiy the region as smoke. Most likely the haze is a combination of local and/or regional industrial sources, with perhaps some transported smoke from Texas yesterday as well as local fires.

Air quality was was moderate (yellow) to unhealthy for sensitive groups (orange) in southern California (right) mostly in the San Joaquin Valley, as seen in the MODIS RGB (left). The HMS analysis does have a plume in the southern part of the state but I don't see it in the RGB imagery. Haze (from non-fire sources) in the San Joaquin Valley is not unncommon for California at this time of year. Click on our archive links in to the lower right to look at past imagery and air quality maps for California.

Posted by Ana Prados at 11:27 PM

Summary of air quality from California fires

EPA's AIRNow Program and NASA's Applied Sciences Program issued a news story summarizing the fine particle concentrations during the week of the California fires. The left panel is a composite MODIS AOD image. The right panel is a summary of fine particle concentrations from monitors in the region.

Erica Zell from Battelle put together the AOD composite and we put together this summary of each day's AOD. Notice how the smoke plume blows out over the Pacific from Monday through Wednesday, then back on-shore Thursday through Friday (although our AOD data is limited on Thursday and Friday due to cloud cover).

Posted by Jill Engel-Cox at 8:13 PM