Do diurnal aerosol changes affect daily average radiative forcing?
Article first published online: 17 JUN 2013
©2013. American Geophysical Union. All Rights Reserved.
Geophysical Research Letters
Volume 40, Issue 12, pages 3265–3269, 28 June 2013
How to Cite
2013), Do diurnal aerosol changes affect daily average radiative forcing?, Geophys. Res. Lett., 40, 3265–3269, doi:10.1002/grl.50567., , , , , , and (
- Issue published online: 18 JUL 2013
- Article first published online: 17 JUN 2013
- Accepted manuscript online: 17 MAY 2013 10:26AM EST
- Manuscript Accepted: 15 MAY 2013
- Manuscript Revised: 13 MAY 2013
- Manuscript Received: 19 APR 2013
- diurnal variability of aerosol;
- remote sensing;
- time-averaged direct aerosol radiative forcing;
- Two-Column Aerosol Project (TCAP)
 Strong diurnal variability of aerosol has been observed frequently for many urban/industrial regions. How this variability may alter the direct aerosol radiative forcing (DARF), however, is largely unknown. To quantify changes in the time-averaged DARF, we perform an assessment of 29 days of high temporal resolution ground-based data collected during the Two-Column Aerosol Project on Cape Cod, which is downwind of metropolitan areas. We demonstrate that strong diurnal changes of aerosol loading (about 20% on average) have a negligible impact on the 24-h average DARF when daily averaged optical properties are used to find this quantity. However, when there is a sparse temporal sampling of aerosol properties, which may preclude the calculation of daily averaged optical properties, large errors (up to 100%) in the computed DARF may occur. We describe a simple way of reducing these errors, which suggests the minimal temporal sampling needed to accurately find the forcing.