The Asian Dust Event of April 1998 A preliminary report prepared
by an Ad Hoc Virtual Workgroup May 11, 1998 Draft - Please use the
Feedback page for commentsFeedback Slide 2 This preliminary account
of the extreme Asian dust event of April 1998 is the result of a
collaboration (sharing of resources) by a virtual web- based
community that was created spontaneously during the dust event. The
shared workspace of the community was the Dust Event website,
http://capita.wustl.edu/ASIA-FAREAST/.http://capita.wustl.edu/ASIA-FAREAST/
Virtually all of the forty registered and many non-registered
participants have contributed observations, monitoring data,
interpretation or helped the creation of the virtual community. The
institutions of the participants included state air quality
management agencies, government laboratories, universities, and
private citizens. This is an evolving document, subject to changes
based on the feedback from the community.feedback Slide 3 The Dust
Storm in Western China and its Transport Across the Pacific Ocean
Slide 4 On April 15th, 1998 an unusually intense dust storm began
in the western Chinese Province of Xinjiang, just in time for the
east Asian dust season. CNN reported that 12 people were missing
from that singular event. Area Map of Xinjiang ProvinceCNN Video
Clip of Dust Storm Slide 5 On April 16th, routine examination by
Washington University of SeaWiFS satellite images first detected a
distinct yellow dust cloud over central China. SeaWiFS SeaWiFS
Image of Dust Cloud over China on April 16 Animation of the Dust
Cloud from GMS-5 (Geostationary Satellite on April 19 Slide 6 On
April 19th another dust front moved across China. By April 20th,
the elongated dust cloud covered a 1000 mile stretch of the east
coast of China. The Chinese Academy of Sciences reported a yellow
rain in Beijing. SeaWiFS Image of Dust Cloud on April 19SeaWiFS
Image of Elongated Cloud on April 20 Slide 7 On April 23rd and
24th, the dust storm was rapidly moving across the Pacific Ocean.
The dust cloud appeared as a yellow dye and visualized its own path
across the Pacific. Approximate path of the dust cloud as it
transited the Pacific Ocean SeaWiFS Image of Cloud Approaching
North America on April 24 Slide 8 During the trans-Pacific transit
the dust plume was also tracked independently by Washington
University and University of Wisconsin using GMS-5 and GOES-9
geostationary satellites, respectively.University of
WisconsinGOES-9 geostationary GMS-5 Image of Dust over the Central
Pacific on April 24 GOES-9 images of Dust over the Central Pacific
on April 24 Slide 9 Observations of the Asian Dust Event Over the
Pacific Coast of North America Slide 10 By April 27th, the dust
cloud rolled into North America. Goes-10 and SeaWiFS images
indicate that the dust plume split once it reached land - one
branch heading southward along the California coast and another
branch continued eastward across the Canadian Rockies.Goes-10
SeaWiFS GOES-10 Image of Dust Cloud on April 27SeaWiFS Image of
Dust Cloud on April 27 Slide 11 The normally blue sky was observed
to be notably milky and washed out over much of the West on April
27th. University of Nevada monitored the aerosol optical depth
prior and during the event.University of Nevada Milky Appearance of
Sky at Sunset in Reno on April 27 Aerosol Optical Depth Monitoring
at Reno Show AOT in Excess of 0.5 During Dust Event Slide 12 By
serendipity, the size distribution of the Asian dust was measured
by the University of Washington aircraft. The State of Washington
Dept. of Ecology conducted routine monitoring of PM10 and PM2.5
concentrations. University of Washington Size distribution data of
the dust indicate that most of the mass is above 2.5umin diameter.
Surface based monitoring of PM10 and PM2.5 indicates that during
the dust event 2/3 of the PM10 mass was above 2.5um Slide 13 LIDAR
aerosol data by the Jet Propulsion Laboratory reveals that height
of the dust layer on April 27 at Pasadena, CA was in the range of 6
- 10 km above sea level.Jet Propulsion Laboratory Slide 14 Air
Quality Management Activities Slide 15 The Activities of AQ
Management Agencies Based on public complaints and monitoring data,
the State of Washington Department of Ecology issued a ban on open
burning on April 29th. On April 29th, the PM alarm went off at
several continuous monitoring stations around Vancouver, BC,
because the concentration exceeded 50 ug/m3. The British Columbia
Ministry of the Environment has investigated the underlying causes
of the particulate matter event. California Air Resources Board
scientist have explored whether the cause of the high PM10
concentrations (. 50ug/m3) at many sites could be attributed to
large prescribed burns in Oregon, Idaho, and Washington. At the
South Coast Air Quality Management District in Los Angeles, reduced
visibility and elevated PM10 measurements were initially attributed
to large scale prescribed burns in Idaho and later to the Asian
dust. United States Department of Agriculture - Forest Service in
Idaho was concerned about intense haze around Salmon and Challis
National Forests and the possibility of smoke impact from
prescribed fires. By April 29th, the Idaho Department of
Environmental Quality has advised that the haze may be due to the
Asian dust event. Slide 16 The Role of the Virtual Community
Virtually all the Air Quality management agencies have participated
in creating an instant virtual community and have benefited from
the information resources on the Website in making their quick
decisions. On April 30, the State has issued an explanation to the
public that now seems fairly certain that the Eastern Washington
air stagnation event is due mostly to Chinese dust rather than
locally generated pollutants. In the press release, the Dust Event
Website address was given to the public for further information on
the event. It could be said that the community and its shared web
resources have contributed certain amount of JITERS (Just In Time
Environmentally Relevant Science) to the AQ managers. Evidently,
the trust of the managers in the available science support arose
from the multiplicity of independent observations, and from weight
of the evidence. (Managers, is this true?) Slide 17
Acknowledgements Anderson, T. Arimoto, R. Bachmeier, s. Brock, C.
Chavez, P. Conel, J. Dubois, D. Durkee, K. Falke, S. Gasso, S.
Gill, T. Hansen, T. Helmlinger, M. Hennessey, J. Holben, B.
Huebert, B. Husar, R. Husar, M. Jackson, G. Jaffe, D. Johnson, B.
Juric, S. Li, F. Lyle, K. Lyons, W. Merrill, J. Miller, R. Mims, F.
Porter, J. Redmond, K. Reheis, M. Reynolds, R. Rogers, W. Sakiyama,
S. Schichtel, B. Schnell, R. Tratt, D Van Hook, B. VanArsdale, A.
and many others
