Seawifs continues to show (on 18 April) heavy dust flows emerging from China and extending over the North Pacific. From Doug Westphal's web site, the "western Pacific" Seawifs image:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/westpac/200104/2001041800_westpac.jpg
An especially heavy stream of dust crosses the Asian coast over Russian territory north of Vladivostok. The heavy cloud passes north of Hokaido and swirling bands of dust are seen east of Hokaido over the western North Pacific.

Norman Kuring (norman@tursiops.gsfc.nasa.gov) provides links to Seawifs full resolution images that show very clearly the huge dust clouds. Note also the heavy dust over Mongolia on the image of April 18 (note that the images use Julian dates with April 18 being 2001108). Note that these are huge images, about 17Mb each.
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/NorthEastAsia/S2001107.L1A_HJMS_ROC.AsianDust.ppm
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/NorthEastAsia/S2001108025013.L1A_HJMS.SakhalinDust.ppm

Meanwhile, Asian dust continues to be reported over the western United States and dust (as of 18 April) moved over the central and eastern United States. Norman Kuring (norman@tursiops.gsfc.nasa.gov) provides links to Seawifs full resolution images that show that show dust over the Great Lakes:
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/USA/S2001107183639.L1A_HNSG.SuperiorDust.SwollenMississippi.ppm
He states:

Yesterday's SeaWiFS image of the Midwest shows

Asian aerosols over lakes Superior and Michigan

(note the brownish tinge over the normally dark

blue water). Also note the flood-swollen Mississippi River

to the west of Lake Michigan.

 

Doug also presents a link to the NAAPS model forecast for the US which shows that Asian dust has covered the US for the past several days.
http://www.nrlmry.navy.mil/aerosol_web/globaer_noramer_loop.html
He shows for example that dust was over South Florida yesterday. Indeed, I noted last night as I drove home at 7PM that there was a very large neutral extinction aureal around the sun and that the sky had a very diffuse gray appearance over very large angles from the sun. (I noted this before seeing Doug's model prediction and had commented on this in some emails - so this is an unbiased observation.)
 

Personal Observations of Chinese Dust Event:
Zev Levin reports on his observations during his visit to China during the huge event on 7 April 2001:

On April 7 I visited Baichen, Jilin Province, China. It is about one hour away from Ulan Hot, Inner Mongolia. We woke up at about 7:00 AM to witness the most amazing storm I have ever seen. The sky was dark as if it was midnight. The lights from the few cars that dare travel in the streets was yellowish. This is in contrast to the case in Israel in March 1998 when the color of the head lights was light blue. The difference is probably due to the difference in the size of the dust particles and  the different chemical composition. In Israel it must have been absorption of the red by the particles. In China it may have been less absorbing.

 

The wind was fairly strong (I had no way of measuring it) and may have been stronger at night before we woke up.

The visibility at this point was close to 20 m. About two hours later the visibility increased about 50 m and stayed so until about 10:00 AM. At that point we decided to drive to Ulan Hot. A drive that normally takes about 1 hour, took us close to 2 hours. The dust lifted a little and by the time we reached Ulan Hot the visibility was about 200 m. At a number of points along the way, the wind picked up and the visibility on occasions decreased to 20-50 m, making it very dangerous to drive.

 

According the Director of the weather service in Ulan Hot the pressure at the center of the LOW reached 977 mb. This explains the strong winds we encountered on the way. The dust remained in the air until the late afternoon when it slight lifted, increasing the visibility to 300 m. I would like to point out that the dust remained in the air for about two more days. On the second day a short period of rain occurred  as the cold front passed the region.

 

[The Observatory uses a] GOES split-window (band 4 - 5 brightness temperature difference) data to detect eruptions. [The algorithm triggers an alarm.] We first detected an unusual layer moving through the North Pacific from the west on April 12. This layer had split-window values as low as -4 C, which is quite unusual for meteorological clouds, and is more  typical of ash (or silicate) clouds. Please see the attached images. This cloud rang our alarm for more than 12 hours. Subsequent investigation of TOMS data reveled the source as a large dust storm.

 

Tom Gill forwards a link to a spectacular B&W global image of the Perfect Storm:

This is forwarded to me by Richard Peterson, Chairman of the Geosciences Dept. at Texas Tech University. This is a B/W satellite image that shows half the globe, from the satellite image page of Dundee University in Britain.  Its impact is dramatic because the storm over China clearly stands out on a truly global picture here! >

http://www.sat.dundee.ac.uk/pdus/JV/200104070000JV1_g.jpg

 

Asian dust is measured from several sites in the western US ranging from 0.5 at San Nicholas Island, to .15 near Phoenix, to 0.3 in Idaho to 0.4 on coastal British Columbia.  The peak was on the 14 and 15th and gradually decreased to baseline levels since.  Evidence of dust was traceable to Oklahoma and Kansas, Bondville Ill., and Howland Maine.

 

Our MPL instrument here at Goddard has been seeing what we think are

asian dust layers overhead for most of the afternoon (up to around 7

km).  I'm planning to have a prelim image ready by tomorrow (my time).

It will be available thru our MPL-Net website:

http://virl.gsfc.nasa.gov/mpl-net/

 

The MPL-Net project has found itself in the unique position of having

possibly tracked this plume periodically throughout its journey from

China to the east coast of the US. MPL-Net has the following MPL sites

in operation now (includes ARM MPL project which is joint with ours): [He lists sites.]

 

http://capita.wustl.edu/AsiaDust0104

 

AFRICAN DUST OVER THE MEDITERRANEAN
The huge and continuing Chinese dust events have not diverted my attention from other aerosol events. But I did not want to overburden your mailbox. But there has been a very impressive African dust event over the past few days.

The storm began on 16 April. The major source is visible in eastern Algeria and southern Tunisia:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041612_sahara.jpg
The source is the hazy area to the right of the orbital blank and SE of the cloud band. Compare this same area on this image 2 days prior on 14 April:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041412_sahara.jpg
Note how clear and sharp the source region looks on 14 April.

On 17 April there is heavy dust streaming over the coast of Libya.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041712_sahara.jpg
Note also the heavy dust along the west coast of North Africa and over the Canary Islands.

On 18 April heavy dust blankets the eastern Mediterranean but, unfortunately, so does the orbital cutout.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041812_sahara.jpg
Norman Kuring <norman@tursiops.gsfc.nasa.gov> provides a high resolution Seawifs image link (17Mb!) that shows the very heavy dust plume over the Eastern Mediterranean in its entirety.
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/Africa/S2001108.L1A_HBHR_ROM.MediterraneanDust.ppm
This shows the dust spanning the Mediterranean from the coast of Egypt to Turkey.

Both Westphal's NAAPS model and the Dream model caught this storm nicely:
http://www.nrlmry.navy.mil/aerosol_web/dream_globaer_toms_noaa_loop.html
(Although there are some glitches with this loop)
Westphal's NAAPS model shows this dust event moving into central Asia:
http://www.nrlmry.navy.mil/aerosol_web/globaer_world_loop.html

The TOMS absorbing aerosol product shows this event very nicely. Thumbnails are attached.
Note that there is now much activity in Africa. Also note the new activity in China.
 

CONCLUSION:
These are great days for dust enthusiasts!

======================================================

RESOURCES
Doug Westphal's NRL/Monterey Aerosol Page shows his daily global aerosol NAAPS model along with various meteorological and satellite products, case studies, links, etc.:
http://www.nrlmry.navy.mil/aerosol_web/
A particularly useful display shows the current NAAPS model product along with the concurrent TOMS absorbing aerosol product and the AVHRR aerosol optical depth:
www.nrlmry.navy.mil/aerosol_web/globaer/ops_01/toms_noaa_globaer_gmt/latest.html
It is useful to click on his display that shows the five-day loop of this composite product:
http://www.nrlmry.navy.mil/aerosol_web/toms_noaa_globaer_gmt_loop.html
The top of the page shows a listing for case studies. For example February 2000:
http://www.nrlmry.navy.mil/aerosol_web/Case_studies/20000226_sahara/
Westphal has recently introduced an experimental product: 72 hour aerosol predictions:
http://www.nrlmry.navy.mil/aerosol_web/globaer/ops_01/world/latest.gif
In addition, he has a forecast loop that shows NAAPS 6 hour iterations out to 72 hours.
http://www.nrlmry.navy.mil/aerosol_web/globaer_world_loop.html

The SeaWiFS interactive browser site (which is zoomable) is at:
http://seawifs.gsfc.nasa.gov/cgibrs/seawifs_subreg.pl?N=0
Note that the SeaWiFS product is updated at (apparently) 12 hour intervals; thus there are two global products presented for each day. I find it convenient to browse at the 12x zoom factor and a 1 by 1 box; this allows you to look at the entire width of the image. The SeaWiFS complete browse utility is at:
http://seawifs.gsfc.nasa.gov/cgibrs/seawifs_browse.pl
This is not as convenient as the zoomable version but it has a large archive.
The home page is at:
http://seawifs.gsfc.nasa.gov/SEAWIFS.html
They have a very nice web page devoted to the huge African dust storms of early March 2000.
SeaWiFS Project - Saharan Dust Storm
Westphal?s aerosol web site has a very nice series of daily high resolution SeaWiFS composites for the entire earth and also for specific subregions:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/world/latest.jpg
He offers a five-day loop of the same SeaWiFS regions.

For an excellent archive of satellite imagery (with lots of SeaWiFS), try NASA's Visible Earth database.
http://visibleearth.nasa.gov/
This searchable archive contains a truly spectacular collection of images (including lots of dust storms, biomass fires, pollution hazes, etc). Click on Atmosphere/Aerosols/. They are usually presented in two versions, one (relatively small files) at low resolution and one at high resolution (with some files in the many-megabytes range). Some images are breathtaking. This is an excellent collection for earth-science teaching purposes.

The TOMS absorbing aerosol product is at:
http://jwocky.gsfc.nasa.gov/aerosols/aerosols.html
The aerosol image set for "today" is found at:
http://jwocky.gsfc.nasa.gov/aerosols/today_aero.html

NOAA NESDIS produces a global product of AVHRR aerosol optical depth:
http://psbsgi1.nesdis.noaa.gov:8080/PSB/EPS/Aerosol/Aerosol.html
The Westphal NRL aerosol site shows the daily AVHRR optical depth product. Note that the AVHRR product carries over ?old? pixels if the current pixel is clouded over. Some images can have pixels that are many days old! It is convenient to look at the AVHRR product on Westphal?s five-day loop page; in this way you can click back-and-forth to see how the image changes from one day to the next so as to identify old pixels.

Rudy Husar (Capita, Washington University, St. Louis) has a web site dedicated to aerosols in general and African dust events in particular, including a "chat" section.
http://capita.wustl.edu/saharadust2000/resources/SeaWiFSGAC/
You can access this site from a link on Doug Westphal's case study page.

The NOAA Operationally Significant Event Imagery web site often has interesting images. They also have an archive of dust events:
http://www.osei.noaa.gov/
-----------------------------------------------------------------------

Joseph M. Prospero
Professor and Director
Cooperative Institute of Marine and Atmospheric Studies (CIMAS)
Rosenstiel School of Marine and Atmospheric Science
University of Miami
4600 Rickenbacker Causeway
Miami, FL
33149
tel: 305-361-4159
fax: 305-361-4457
cel: 786-512-4159
jprospero@rsmas.miami.edu