1. Working progress Li Du

2. JJA-aggregated over 2000 to 2005

4. DJF-aggregated over 2000 to 2005

5. ASOS vs AIRNOW comparison Time period: 2010-05-01 to 2010-06-01 ASOS: 1-min resolution visibility data hourly average VS. AIRNOW: hourly PM 2.5 data

6. Adopted RH Correction Curve (To be validated for different locations/seasons) Correction factor: C=8E-08*RH^4-7E-06*RH^3+0.0003*RH^2-0.0032*RH+1.0046 Adopted from Evaluation of the Light Scattering Data from the ASOS Network(ppt) by Rudolf B Husar RH is calculated from T – Temperature, deg C and D – Dewpoint, deg C RH = 100*((112-(0.1*T)+D)/(112+(0.9*T))) 8

8. Selected sites: Orangeburg (33.46167 -79.1419) from ASOS and Cape Romain (32.94167 -79.6578) from AIRNOW Approximated 75 km apart

9. What’s next…(tentative plan) Humidity correction of GSOD as well as ASOS data sets through programming so that the corrected version could be viewed in the browser Importing more ASOS data (for most sites there are only less than one year’s data) and make some comparisons between aggregated data