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ASIAN DUST EVENTS
The news media have been filled with accounts of Chinese dust over
North America. Doug Westphal has a case study on his NRL web site. He shows
comparisons with SeaWiFS
for the East Pac and N. America:
http://www.nrlmry.navy.mil/aerosol_web/Case_studies/20010413_epac/
These comparisons show good agreement between the NAAPS model and Seawifs.
He also has at the top of the case study page a number of loops (some quite
large - 4Mb) that follow the progress of the dust cloud over the eastern
Pacific and North America over the time period 10 April - 21 April:
http://www.nrlmry.navy.mil/aerosol_web/Case_studies/20010413_epac/globaer_noramer_loop2.html
He also has Seawifs loops that show the dust events over China and
the western North Pacific
http://www.nrlmry.navy.mil/aerosol_web/Case_studies/20010413_epac/seawifs_westpac_loop.html
and over the eastern North Pacific:
http://www.nrlmry.navy.mil/aerosol_web/Case_studies/20010413_epac/seawifs_eastpac_loop.html
Taken together, these present a vivid picture of the tremendous scope
of this series of huge dust events.
The dust reached at least as far north as Fairbanks, Alaska. Glen Shaw
(Univ Alaska, Fairbanks) reports on 20 April:
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It is very hazy here in central Alaska. It looks "whitish" and "general"
haze. I thought it most certainly was Arctic Haze, but trajectories are
from the North Pacific. Also, the haze has a rather small aureole, very
different than arctic haze. I am measuring the size distribution and we
are taking chemical samples. Glenn was a little skeptical that it was Chinese
dust but Westphal's model results and the Seawifs images should convince
him.
In my end of the continent, here in Miami, we saw the dust on the evening
of 18 April. Driving home in the evening, towards the west, there was a
very deep diffuse light across much of the western sky. It was very similar
to what we see when we have African dust in the region during the summer.
Norman Kuring (NASA, GSFC) provides some very interesting full resolution
Seawifs images (HUGE files).
On 19 April:
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/USA/S2001109.L1A_HNSG_USF.EasternUS.ppm
Norman notes;
-
There is haze over much of the eastern United States and Canada today as
can be seen in today's SeaWiFS image. The aerosols over the Gulf
of St. Lawrence have a tinge of brown. Whether any of this comes
from Asia I cannot say. I will defer to the aerosol experts.
On 20 April, Norman Kuring provides a full resolution Seawifs of Asian
dust over the Atlantic:
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/Canada/S2001110172758.L1A_HNSG.AsianDustOverAtlantic.ppm
The SeaWiFS image shows brownish aerosols around and over Nova Scotia
and the Island of
Newfoundland and points seaward. He points out that "The blue limb
is my own addition to the image, so don't make any inferences about atmospheric
turbidity based on that feature. he rest of the data is real enough, however."
I attach a small jpeg of the same image. Norman points out that many of
his spectacular dust images end up at:
http://visibleearth.nasa.gov/
If you enter "dust AND SeaWiFS" in the search box, you will get a list
of nearly 100 SeaWiFS images of dust around the world.
Meanwhile, back in Asia, dust activity continues.
On 19 April, (on Westphal's "Mongolia" Seawifs extracts) the Tarim
Pendi/Takla Makan is again filled with dust as is the Turpan Pendi. There
is no major activity in Inner Mongolia or Mongolia.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/mongolia/200104/2001041900_mongolia.jpg
More of the same on 20 April.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/mongolia/200104/2001042000_mongolia.jpg
In Westphal's "western Pacific" Seawifs extracts heavy dust is seen
once again over the East Sea/Sea of Japan on 19 April:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/westpac/200104/2001041900_westpac.jpg
The brown tinge to the clouds north of Hokaido suggests that there
is dust at higher altitudes in that region. Also one can see a large area
of moderately heavy dust to the east of the northern end of Hokaido.
On 20 April, Seawifs shows that the dust seen in the image on the 19th
has moved to the extreme right of the image. There is also heavy haze emerging
from the east coast of Japan in the region of Tokyo; this is probably pollution.
Compare the gray color of this haze with that of the dust.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/westpac/200104/2001042000_westpac.jpg
Zev Levin provides me with three truly remarkable images taken in the
midst of the intense dust storm on 7 April when he happened to be visiting
that area of China. If any wants to see them, I wil forward them. The file
is large: 2Mb.
North Africa and the Mediterranean
In my last report I told of extremely intense dust outbreaks over the
Mediterranean. These continue. On 18 April there was very heavy dust over
the extreme eastern end of the Mediterranean:
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041812_sahara.jpg
Much of the eastern Med is blocked out by the orbit in this image.
Norman Kuring (NASA GSFC) presents a full resolution image of this event
(HUGE file, 17Mb):
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/Africa/S2001108.L1A_HBHR_ROM.MediterraneanDust.ppm
I attach a small thumbnail that he provides. This was clearly a very
major event.
On 19 April a new dust outbreak is seen emerging from Tunis and Libya.
Note also the heavy dust over the Red Sea.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001041912_sahara.jpg
On 20 April, there is extremely heavy dust blowing across the coast
of Libya.
http://www.nrlmry.navy.mil/aerosol_web/satellite/seawifs/sahara/200104/2001042012_sahara.jpg
Note the very heavy, sharply-defined plume the emerges from the region
near Benghazi. I have noted a plume in this region on numerous occasions.
The plume emerges from a low-land south of Benghazi. The dark area along
the coast to the east of the plume is Jabal al Akhdar, a low lying mountain
range. The dust plume is probably orographically forced to some extent;
the coastal lowland provide the dust material.
Slobodan Nickovic (University of Malta, Euro-Mediterranean Centre on
Insular Coastal Dynamics(ICoD),MALTA) reports on 20 April:
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Very strong dust storm passes the Central (today) and Eastern Mediterranean
(next 2 days), as predicted by the
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ICoD/DREAM model
-
http://www.icod.org.mt/Modelling/HydDyn_main.htm
-
Public in Greece has been already warned by media on the coming event (communicated
by Dr. Lagouvardos).
-
It will be interesting to compare models, and available satellite and lidar
observations.
-
We redrew some of the ICoD operational dust forecasts using finer contouring
interval to get more details and made some extra graphs:
-
http://www.icod.org.mt/aerosol_web/dust/med/greece/
Norman Kuring provides a full resolution image of the 20 April dust over
the Mediterranean:
http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/Europe/S2001110.L1A_HROM.MediterraneanDust.ppm
I also attach a compact jpeg of the same image
Meanwhile, the TOMS absorbing aerosol product continues to show much
dust activity on the globe. I attach jpegs of the past several days.
Joe Prospero
Joseph M. Prospero
Professor and Director
Cooperative Institute for Marine and Atmospheric Studies
Rosenstiel School of Marine and Atmospheric Science
University of Miami
4600 Rickenbacker Causeway
Miami FL 33149
Tel: 305-361-4159
Fax: 305-361-4457
jprospero@rsmas.miami.edu
