How Long Is Too Long? Variogram Analysis of AERONET Data to Aid Aerosol Validation and Intercomparison Studies ...

• Main Author: Sayer, Andrew
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: AGU 2020
• Subjects: Aerosol Robotic Network
• Online Access: https://dx.doi.org/10.13016/m2if3h-unok; https://mdsoar.org/handle/11603/26237

Geophysical data sets derived from satellite sensors, ground/airborne instrumentation, andcomputational models are often compared against each other. A common example is the validation ofsatellite aerosol optical depth (AOD) retrievals against measurements from Aerosol Robotic Network(AERONET) Sun photometers. Spatiotemporal mismatch between data set sampling means that uncapturedvariation in the underlying geophysicalfield introduces apparent disagreement into such comparisons,known as representation or collocation matchup uncertainty. This study uses variogram analysis ofAERONET data to estimate temporal mismatch uncertainties and decorrelation time scales for the globalAERONET record. As well as total AOD, thefine‐and coarse‐mode AODs, Ångström Exponent (AE), andfine‐mode fraction (FMF) of AOD are analyzed. Globally, a time difference of 30 min typically induces from0.011–0.035 variation in AOD. For total,fine, and coarse AODs the typical time to decorrelation is around2–10 days. For AE and FMF it is 3–33 ...