Weekly Report for the Week of June 23, 2008
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GSFC Laboratory for Atmospheres, Code 613
Items of Interest
"Airborne Dust: Phase-I AAF/SMART-COMMIT Measurements"
URL: http://climate.gsfc.nasa.gov/viewImage.php?id=237
The U.S. Department of Energy Atmospheric Radiation Measurements (ARM) Mobile Facility (DOE/AMF) and ARM Ancillary Facility (AAF/SMART-COMMIT), upper left and right images, are currently being deployed simultaneously in China during the Asian Monsoon Year (AMY-2008) to acquire comprehensive ground-based observations for aerosol-cloud-water cycle studies. The Phase-I AAF/SMART-COMMIT measurements are being taken at Zhangye, China (39.082° N, 100.276° E, 1461m elevation), for dust aerosols originating at the Taklimakan and the great Gobi deserts. The AAF is also closely collaborating with the Lanzhou University, China, which operates a supersite of the Semi-Arid Climate & environment Observatory-Lanzhou, SACOL, (35.95° N, 104.13° E at an altitude of 1966m and ~40km east of Lanzhou city) and a mobile facility of subset SACOL at Jingtai (37.35° N, 104.01° E at an altitude of 1604m and ~200km north of Lanzhou city). Thus, analyses of simultaneous measurements from these three sites will provide a better understanding of dust properties near different source regions, as well as properties downwind due to the mega-city (Lanzhou’s) influence.
Periodic dust episodes around the AAF/SMART-COMMIT site have been observed from MODIS images (see satellite images). The color appearance exhibits a bit of brown/yellow for the Gobi/local dust, but pale or beige for the transported dust from the Taklimakan. Using the May 2nd case as an example, the two images show true-color MODIS images of Terra (0335UTC) and Aqua (0650UTC) around the AAF site, indicating two dusty areas following respective frontal cloud-bands. Surface observations in the morning started off calm and somewhat hazy. Temperatures warmed until ~2PM (0600UTC) when clouds started to roll in and the winds began to pick up from the NW, with steady winds ~7 m/s (gusts 10-15 m/s). Local surface dust was being visibly lifted especially in the dry seasonal riverbed. Instruments on the ground provided exceptional documentation of the impressive evolution in the atmosphere’s contents and structure during the day. The air was quite laden with dust (6PM or 1000UTC) and visibility dropped to less then 2 miles (see lower right image). Preliminary estimates from the Aqua image, are that the dust aerosols may have come from the Taklimakan deserts, which escaped from the Tarim Basin and were transported quickly over the AAF/SMART-COMMIT site. To fully characterize the properties of airborne dust near desert regions in the field is an important but challenging task.
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