Transcript ThePerfectStormRept2

The ‘Perfect Gobi Dust Storm’ – April 2001
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The Prospero Dust Reports:
Joe Prospero, [email protected],
April 8 Dust Summary
April 17 Dust Summary
On 6 April, a huge dust storm erupts over much of southern Mongolia and inner Mongolia. An interesting feature of this image is that the dust cloud seams to be derived from a relatively small number of "point" sources.
Just to the right of the center of the image you can see many very long "plumes" which appear to trail from specific sources. The source areas seem to be arrayed roughly along the 100E longitude. (Note the dark roundish
object in the image in the lower center of the image; this is Qinghai Hu, a salt lake, 4300 km2, located at 37.0N, 100.0E.) The northern extent of the dust activity is at about 45N and dust activity extends south to about 36S
(i.e., to the region east of the salt lake). Note that the dust cloud in
the southern end of the dusty area has a rather uniform appearance compared to the area to the dust area to the north where a lot of character can be seen in the distribution. This suggests that the dust cloud on the north is
relatively fresh while that to the south was probably advected from the east and is "old".
On 6 April, there continues to be a tremendous amount of dust activity but the dusty area begins further to the east at about 110E. (You can orient yourself with reference to Lake Baikal, the long white area oriented NE-SW
in the top of the image.) Once again, the dust appears as a series of closely packed long plumes, each well-defined. Note in the upper right of the image the large cyclonic rotation feature in the clouds.
In the following series of images, we look at Seawifs images on the same dates, but here we refer to Doug Westphals "western Pacific" images. On 3 April, we do not see much activity: Some light dust activity can be seen
on the extreme left of the image at about the mid point. On 4 April, you can't see much in the image. On 5 April, heavy dust activity can be seen on the extreme left of the image. On 6 April, the dust storm erupts over
southern Mongolia and Inner Mongolia. Note once again the very clear plume-like character to the dust cloud.
And then 7 April. This is the most remarkable dust storm image that I have ever seen. And I have seen a lot.
The center of the cyclonic circulation is located near Hulun Nur (the white rectangle oriented NE-SW to the west of the center of the circulation center) which is at 49N, 117E. I draw your attention once again to the
clearly-defined dust plumes located to the south of the cyclonic circulation. Using the Yellow Sea as a measure of distance, I judge the plumes to be 600-800 km long!
Rudy Husar has some labeled images on his web site: April 6, April 7. The TOMS Absorbing Aerosol product has captured this massive dust event very nicely. 3 April, 4 April, 5 April, 6 April, 7 April, 8 April.
Dust Transport: NRL Model
D. Wespthal, [email protected]
•
On April 7, The NRL dust model
shows the dust cloud emerging from
the Gobi desert
•
A week later, part of the dust cloud
passes over N.America toward the
Atlantic
See the animation that illustrates the transport dynamics
Satellite Images of the Storm (GMS-5, SeaWiFS)
Click o the images for full resolution
See animation of the April 6 Storm
Gif small (340kB)
Gif med ( 3 mb)
Gif large (11 mb)
AVI large (19 mb)
SeaWiFS Images of THE Dust Storm
SeaWiFS
MODIS
Norman Kuring, [email protected]
SeeHigh
fullresolution
size SeaWiFS
images
offor
dust
transport
SeaWiFS
images
April
7, 10, 13across the Pacific (1.6 mb each) for April 6, 7, 8,
Friday, the 13th
TOMS Absorbing Aerosol Index
See also the daily TOMS animation, April 6 - April 22
Dust Seen over the West Coast of NAM
Dust is recognized by the yellow coloration,
compared to bluish sulfate/organic
haze.
GOES View of the Dust Streak Across N. America,
Friday, April 13
GOES10 (West) view of dust streak
on the morning of Friday 13th
GOES8 (East) view of dust streak
on the evening of Friday 13th
GOES View of the Dust Streak Across N. America,
April 17
GOES10 (West) view of dust streak
on the morning of April 17
GOES8 (East) view of dust streak
on the evening of April 17
.. and on to the Atlantic …
The dust plume location from the GOES8 over the Atlantic is consistent
with the dust location over the Midwest on the day before.
IMPROVE Network, Bret Schichtel, [email protected]
• Transmissometer measures the total light extinction, Bext, while the nephelometer records the light scattering, Bsp,
integrated over all angles except near the direction of the light.
Light Extinction and Scattering During Dust Event
• Nephelometers underestimate coarse particle scattering by as much as 50% due to truncation of the forward scattering lobe.
• The large difference between the Bext and Bsp along with the low RH at Yosemite and the Grand Canyon Nat. Parks is a
good indication that the Asian dust was present during April 14-17.
Asian Dust, April 16-19, 2001
Asian
Dust
April
16
April
16
April
19
April
19
Asian
Dust
Lidar Depolarization by Dust.
Salt Lake City, April 15
K. Sassen, [email protected]
•
•
Preliminary (hurried) lidar images of the 15 April dust layer over Salt Lake City.
The linear depolarization ratios in the surface to 4.5 km MSL dust layer were ~20%,
sometimes ~25%, and up to ~15% aloft. This is quite high for our region.
Dust Optics: The Twilight Zone Toronto April 18
Dust Optics: Layering
.. and so on…
• Insert your slides here or anywhere else…
Stories on the perfect dust storm.
Tom Gill, April 13, [email protected]
Fierce Sandstorms Hit China Western Arid Regions Alternate link
Zev Levin, April 17, [email protected]
The Chinese Dust Storm – A personal Report
Dustfall on Snow at Zhenbeitai, China.
This picture was taken near the ACEAsia sampling station on the afternoon
of 9 April 2001, the day following the
big dust storm.
Photo: Sondra Sage ([email protected])
Submitte: Rich Arimoto
([email protected])
China
Dust
•
Earth Observatory
Dust Optics: Halo