Title: ACE-Asia Database_Dunhuang LowVol_1.3

This database includes the PM5.0 and PM2.5 mass, 
elemental carbon, organic carbon, and carbonate 
carbon concentrations collected from sampling in 
Dunhuang, China (40.20N, 94.48E, Elevation of 1374m) 
during March 24 to April 4, 2001 as part the ACE-Asia 
Experiment. The times and dates included in this 
database are UTC.  

Please direct any questions about the data to:

Rachelle Duvall 
Water Science and Engineering Laboratory RM 152
660 N. Park Street
Madison, WI 53706
(608) 262-4322 (office)
(608) 262-0454 (fax)
Email Address: rmduvall@students.wisc.edu

Samples were collected each day for 24-hrs using a Low Volume Sampler 
(University of Wisconsin-Madison). Mass was measured at a Temperature 
of 70 C (68-73) and Rh of 38 %RH (30-40%). ECOC was measured by the 
ACE-Asia ECOC method based on NIOSH 5040.  Columns 1 and 2 contain the 
start and stop sampling times in UTC for the corresponding sample 
number. Column 6 lists the type of sample (either PM5.0, or PM2.5) that 
correspond to the sample number. The mass uncertainty was calculated 
using the following formula: 

SQRT (STDev Initial weight^2+ STDev Final Weight ^2). 

A 5% uncertainty was accounted for in the mass measurement resulting 
from uncertainty in the sampler airflow rate measurements. 
Uncertainties for elemental and organic carbon were reported by 
instrumental analysis. In comparing our elemental carbon 
concentrations to that obtained by collaborators on the ACE-Asia 
project, we found that our EC concentrations were slightly higher. 
Therefore, we added an additional 5% uncertainty to the EC uncertainty 
to account for those concentration differences.

Rachelle Duvall
Last Revised April 2, 2003