A critical look at spatial scale choices in satellite-based aerosol indirect effect studies
Item
Title (Dublin Core)
A critical look at spatial scale choices in satellite-based aerosol indirect effect studies
Description (Dublin Core)
Analysing satellite datasets over large regions may introduce spurious relationships between aerosol and cloud properties due to spatial variations in aerosol type, cloud regime and synoptic regime climatologies. Using MODerate resolution Imaging Spectroradiometer data, we calculate relationships between aerosol optical depth τ<sub>a</sub> derived liquid cloud droplet effective number concentration <i>N</i><sub>e</sub> and liquid cloud droplet effective radius <i>r</i><sub>e</sub> at different spatial scales. Generally, positive values of <span style="border-bottom: 1px solid #000; vertical-align: 50%; font-size: 10px; color: #000;">dln<i>N</i><sub>e</sub></span><span style="margin-left: -3em; margin-right: .5em; vertical-align: -15%; font-size: 10px; color: #000;">dlnτ<sub>a</sub></span> are found for ocean regions, whilst negative values occur for many land regions. The spatial distribution of <span style="border-bottom: 1px solid #000; vertical-align: 50%; font-size: 10px; color: #000;">dln<i>r</i><sub>e</sub></span><span style="margin-left: -2.7em; margin-right: .5em; vertical-align: -15%; font-size: 10px; color: #000;">dlnτ<sub>a</sub></span> shows approximately the opposite pattern, with generally postive values for land regions and negative values for ocean regions. We find that for region sizes larger than 4° × 4°, spurious spatial variations in retrieved cloud and aerosol properties can introduce widespread significant errors to calculations of <span style="border-bottom: 1px solid #000; vertical-align: 50%; font-size: 10px; color: #000;">dln<i>N</i><sub>e</sub></span><span style="margin-left: -3em; margin-right: .5em; vertical-align: -15%; font-size: 10px; color: #000;">dlnτ<sub>a</sub></span> and <span style="border-bottom: 1px solid #000; vertical-align: 50%; font-size: 10px; color: #000;">dln<i>r</i><sub>e</sub></span><span style="margin-left: -2.7em; margin-right: .5em; vertical-align: -15%; font-size: 10px; color: #000;">dlnτ<sub>a</sub></span>. For regions on the scale of 60° × 60°, these methodological errors may lead to an overestimate in global cloud albedo effect radiative forcing of order 80% relative to that calculated for regions on the scale of 1° × 1°.
Creator (Dublin Core)
Grandey, B. S.
Stier, P.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-10-11459-2010
https://acp.copernicus.org/articles/10/11459/2010/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
