NOTE: The absence of Aerosol Reports over the past week was
NOT because of a dearth of aerosol events. Indeed, one of the most remarkable
dust events in my memory has been taking place. My excuse is that I was on
The huge Chinese dust storms that started early in April
have continued, essentially unabated. Meanwhile the dust generated from these
early storms has crossed the Pacific and has caused widespread haze in the
western states. I will start off my coverage by reviewing the dust activity
that occurred in China over the past week. Then I will focus on the
observations of dust in the western US. My last report was on 11 April. In this
report I will present in-depth coverage because I feel that these series of
dust storms will be studied for years to come.
As stated earlier, dust activity has been almost continuous in China for the past week. In the following section I discuss and present links to Seawifs images on Doug Westphal's NRL site. I first go through the "Mongolia" images and then I review the "west Pacific" images.
Over the period 11 April to 17 April the Tarim Pendi/Takla Makan is continuously filled with dust.
On 11 April, dust is heavy in the Tarim Pendi, especially over the eastern section around Lop Nor (visible as two very small little N-S irregular features to the right of the orbital cutout. (For orientation, the longish white feature at the top of the image is Lake Baikal. The small black feature below and to the right of the center of the image is Qinghai Hu, a salt lake.) There is also very heavy dust in the Turpan Pendi to the north of Lop Nor and also in the depression around Bosten Hu, a large lake just to the right of the cutout. There is also much dust in the Junggar Pendi (partially blocked by the cutout), a large basin to the north of the Tarim Pendi. These basins have been identified as major dust sources in our TOMS paper: Prospero, J.M., P. Ginoux, O. Torres, and S. Nicholson, Environmental Characterization of Global Sources of Atmospheric Soil Dust Derived from the NIMBUS7 TOMS Absorbing Aerosol Product. Geophys. Rev., submitted. Preprints available on request.) Dust extends along the "dust corridor" on the northern flanks of the Himalayan Plateau.
On 12 April heavy dust action continues in much the same areas as on the 11th but dust activity is less in the Tarim Pendi:
On 13 April, dust continues as on the 11th and 12th but now there is heavy dust as far east as the orbital cutout at about 42E; these sources are over a part of the loess plateau. On 14 April, dust activity is mostly confined to the Tarim Pendi: Similarly on 15 April. And 16 April. Note that on 13, 14, 15, 16 April, there is no visible dust activity over Mongolia.
On 17 April, dust continues in the Tarim Pendi. There is also a large area of dust in Inner Mongolia extending from the Loess Plateau and along the western side of the Da Hinggan Ling Mountains. (The small irregular white rectangle visible through the cloud on the extreme right of the image is Hulun Nur Lake.)
SEAWIFS "WEST PACIFIC"
We now switch to the "west Pacific" images which show some really interesting features.
On 11 April, much of the Western Pacific is covered with cloud. But it is clear that there is a lot of dust in the latitude band Hokaido-Kamchatka; the yellow appearance of the cloud in some regions tells us that the dust is above the cloud.
On 12 April there is again much cloud in the region but there are indications of heavy dust, including the presence of yellow cloud.
On 13 April we can see to the extreme bottom left the dust over the Loess Plateau. There is heavy dust over the Yellow Sea, the East Sea/Sea of Japan, over Hokaido and to somewhat to the east; finally, at the extreme right of the image, on the latitudes of the southern Kamchatka Peninsula, is a large area of dust, some of which lies over cloud. As we will see later, there were many observations of dust in Japan and Korea at this time; lidar data gives altitudes of the dust.
On 14 April, there is heavy dust over the Yellow Sea and along the length of Japan.
On 15 April patches of dust can be seen over large areas of the western North Pacific:
On 16 April there is heavy dust/pollution over the Yellow Sea and a large outbreak of dust along the coast of China north of the Koreas and over Russia in the Vladivostok region.
On 17 April, there is an almost continuous long sinuous band of dust (and pollution) extending from the East Sea along the China coast, over northern Japan and extending up to Kamchatka. The finely featured character of this dust band is interesting and leads one to wonder how these features could be maintained over such a long distance.
TOMS ABSORBING AEROSOL PRODUCT
I attach thumbnails of the TOMS product for this period. I have previously commented on the very high TOMS index values and the large region covered by them. The image for 13 April is especially notable because of the extremely high index values shown in the eastern Pacific off the coast of Alaska and Canada. I do not recall ever having seen anything quite so prominent. Moderately high index values are seen for this region on the 14th and 15th but they are markedly lower than on the 13th. As we shall see below, these high values are consistent with observations of dust in the western US. In my Aerosol Report of 11 April I noted that Westphal's model predicted that the dust would reach the US on 12-13 April; he was right on!
REPORTS FROM OTHER OBSERVERS
There have been many reports from various observers. I here present some excerpts and links:
On April 11, Dong Liu (Anhui Institute of Optics and Fine Mechanics, Hefei,Anhui, China) reports:
"After weekly overcast and rainy days, on the Apr.11th morning we saw the sun but the sky looked yellow and white." They obtained lidar profiles showing heavy dust up to 10-11km. (Hefei is located at 31.87N 117.31E, a short distance west of Nanjing.)
On 12 April Norman Kuring (NASA Goddard: firstname.lastname@example.org) sent a link to a high resolution Seawifs image showing a heavy band of dust off the west coast of the US. I provide the link here but be forewarned that these files are HUGE (10's Mb).
Please note the following credits and restrictions for the Seawifs images:
Credit line for all images:
Provided by the SeaWiFS Project,
NASA/Goddard Space Flight Center, and ORBIMAGE
NOTE: All SeaWiFS images and data presented or referred to in
this email message are for research and educational use only.
All commercial use of SeaWiFS data must be coordinated with
April Norman Kuring presents this link to a high resolution Seawifs image
of dust pouring off the east coast of China:
On 15 April Ken Sassen ("email@example.com" <firstname.lastname@example.org>) reports:
Subject: Dust over Salt Lake City, Utah
We have had hazy skys for the past three days, with reduced
visibility today. At 2000 UTC today (15 April) my lidars detected aerosols
from ~2.0 to 6.3 km MSL. The strongest backscattering region from 4.2 to
4.7 km MSL produced strong depolarization at 0.532 micron, indicating
relatively large nonspherical particles.
On 16 April Liu Dong, Hefei, Anhui (31.87N 117.31E) reported:
In April 14th night, we observed a thick aerosol layer over Hefei from the altitude 3km to 7km by our L300 lidar.The peak extinction coefficient amount to 0.3(1/km). During the period of measurement, the four profiles kept similar and this layer was very stable in the five hours.
April, Rudi Husar announces that he is hosting an open case study of the
"Perfect Storm". Anyone can contribute. See:
He already has accumulated materials in this project. Check it out.
On 16 April Tom Gill (Texas Tech Univ., <tgill@TTU.EDU>) writes:
Some inferrence of SLIGHT milkiness and increased scattering around the
sun at sunrise and sunset here in Lubbock the last few days here in
Lubbock Texas- but NOTHING like the spectacular milky sky created by the
Chinese dust storm of 1998.
Tom passes this on from Colorado from Jason C Neff US Geological Survey Denver
> Jason C Neff
> 04/16/01 02:20
> Yesterday it was incredibly hazy up in the mountains. I didn't notice it
> down on the plains but from the top of Copper Mountain, the distant peaks
> looked brown from the particulates.
On 17 April I received this from Zev Levin. Zev has seen
many dust storms, so his observations are decidedly relevant. He was clearly
Zev Levin <email@example.com>
I just want to inform you that I experienced the heaviest dust storm in my life in China. Susie and I just returned from a visit to China with a visit (with lectures) to northern China, the Province of Jilin. When we were at Baichen [275 km west of Harbin] we fell into this dust storm of the 7-9 April. When I get settled I will send you some photos of the storm from ground level.
On 17 April April Norman Kuring <firstname.lastname@example.org>
sends two high resolution Seawifs image links for the 15th
of April; these show dust off the west coast of the US. Concentrations are
lower than on the 12th and 13th but they are significant.
Norman also forwards an observers comment.
Larry O'Hanlon wrote:
> Hi Norm,
> I was out in Death Valley and along the east side of the Sierra Nevada over
> the weekend and everyone was puzzled by an extraordinary haze that lasted
> through yesterday. The visibility in Death Valley, normally limitless, was
> down to ten miles or less. Some folks -- including the National Park Service
> rangers -- thought it was from fires somewhere, except there were no large
> fires burning. I'm curious whether it was the dust from China. That last
> picture you sent of the dust behind the cloud front off the Pacific coast is
> compelling. Any other imagery that would clinch the case?
The image on the 15th and 16th do clinch the case!
On 17th April Ken Sassen "email@example.com" <firstname.lastname@example.org> sends:
Preliminary (hurried) lidar images of the 15 April dust layer over
Salt Lake CIty can be found at-
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. Todays data (to be posted soon) show much less aerosol at
low levels, so this pulse of dust is passing.
On 17 April, Doug Westphal writes:
There is no doubt about the Asian origins of the recent haze over the Western N. America. It originated between the 6th and 9th of April. Remember too that Asian anthropogenic aerosols are also present. A few SeaWiFS/NAAPS comparisons and model forecasts can be found at:
On 17 April Tom Gill sends a message:
> ----- Forwarded by Marith Reheis/GD/USGS/DOI on 04/17/01 09:01 AM -----
> Sue_Phillips@nps.gov (Sue Phillips)
> Subject: our big dust cloud
> 04/17/01 06:36 AM
> Have you heard about the massive cloud of Gobi dust that's been sitting
> over Utah for the last few days? We've barely been able to see the La Sals
> from downtown this week. Pretty cool, now that we know it's not caused by
> Jeep Week.
Tom Gill also sends this from Richard L Reynolds in California (which I excerpt):
> Wednesday was calmer and generally clear in the study area. By late
> afternoon, however, the area north of Baker [California} became very hazy, as seen from
> the N Soda Lake met station. We went north, mainly scouting out potential
> Zo sites around Silver Lake. Haziness seemed to increase dramatically as
> we drove north of Baker about 4:30 pm; even nearby hills (Avawatz, Valjean
> Hills, etc) were at times nearly completely obscured by haze. The source
> of haze strongly appeared to Dave and me to be dust coming over the western
> hills from Ft Irwin. No dust was generated in or near the playas, despite
> avg. winds about 6 m/sec, based on measurement by my portable, hand-held
> Friday's sunset along the Front Range was noticeably hazy. I had several
> excellent vantage points and could tell that the haze was high and diffuse
> (within and above the peaks), as opposed to ground-hugging vehicular
> pollution?it was not Denver's infamous brown cloud. I took several photos.
> The morning air on Saturday was calm and very hazy, with a distinctly
> yellow caste. The phenomenon appeared to be rather widespread?observed
> from Boulder to Greeley--and long-lasting, from at least 7 am to about 11
> am, when wind and clouds changed the picture.
Tom Gill also sends this (keep up the good work Tom!):
>Dave DuBois wrote:
> Thanks for the tip Tom. It has been hazy here in central NM for the
> past 5 days (April 12-16). The cold front that passed through last
> night cleaned things up somewhat but there still some dust lingering
> looking out of the window. Since putting together our state-wide
> prescribed fire database, I can leave out the cause due to biomass
> burning contributing to this haze. I ran HYSPLIT out to 120 hours and
> it's consistent with the SeaWiFS and GOES satellite images. I've
> noticed the same sunsets as when the Gobi one came in 1998 (I was in
> Reno at the time). I'm going to look at our PM TEOMs and see if I can
> pick out this event. (Dave DuBois, Dispersion Modeling Section, Air Quality Bureau, >New Mexico Environment Department, Santa Fe, NM 87505)
This has been a remarkable event. And it appears that it is not over yet. Stay tuned!