The content of the ARM website is available to any browser, but for the best experience we highly recommend you upgrade to a standards-compliant browser such as Firefox, Opera or Safari.
VIEW CART
primary link menu HOME SITE INDEX PEOPLE
skip to main content ABOUT ARMABOUT ACRFSCIENCESITESINSTRUMENTSMEASUREMENTSDATAPUBLICATIONSEDUCATIONFORMS
Cover image

Scale Analysis of Spatial and Temporal Variability of Aerosol Optical Properties Over the SGP Site based on MFRSR and MODIS Data

Alexandrov, M.D.(a,b), Marshak, A.(b), Cairns, B.(a,b), Lacis, A.A.(b), and Carlson, B.E.(b), Columbia University (a), NASA (b)
Thirteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting

We present scale-by-scale analysis of variability of atmospheric aerosol optical thickness (AOT) and (preliminary) of the Angstrom exponent. This analysis is based on retrievals from Multi-Filter Rotating Shadowband Radiometers (MFRSRs) and from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. This type of analysis has been applied to a remote sensing aerosol dataset for the first time. The MFRSR data were collected in September 2000 from SGP Extended Facilities and have 20 sec temporal and about 80 km spatial resolution. The MODIS data are from the Level 2 Aerosol product at 10 km resolution. We found that temporal and spatial variability of AOT can be roughly separated into three scale-invariant regimes: (1) microscale (0.5--15 km) where fluctuations are governed by 3D turbulence; (2) transition towards large-scale 2D turbulence (15--100 km), and (3) mesoscale variability (scales up to 100--600 km) with scaling properties similar to these of bounded cascade models. For synoptic scales (after 600--1000 km), AOT fields become stationary and loose correlation. The temporal evolution of AOT scaling exponents during the month appeared to be well-correlated with changes in aerosol vertical distribution, while their spatial variability reflected that of concavity/convexity of the site topography. Explanations based on dynamical processes in atmospheric convective boundary layer have been suggested. MODIS and MFRSR AOT datasets showed consistency at the intermediate scale range from 10 to 200-300 km, while they complemented each other at larger and smaller scales. Scale covariance analysis of the AOT and the Angstrom exponent shows strong anti-correlation between these parameters at scales up to 100 km (6 hours), that changes to correlation at larger scales. This supports the idea (S. Schwartz) that the convection-driven humidification of aerosol particles plays the main role in small-scale AOT variability.

Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).