Table 2.
MERRA-2 Aerosol Optical Depth (AOD) Observing System
| Sensor | Temporal Coverage | Description |
|---|---|---|
| AVHRR NNRa | 1980 – August 2002 | PATMOS-x radiances over ocean only (PM orbit) |
| AERONETb,c | Station dependent (1999 – October 2014) | AOD from land station network |
| MISRc | February 2000 – June 2014 | AOD over bright land surfaces only (albedo > 0.15) |
| MODIS Terra NNRa | March 2000 – onwards (NRTd) | Collection 5 “Dark Target” land and ocean radiances (AM orbit) |
| MODIS Aqua NNRa | August 2002 – onwards (NRTd) | Collection 5 “Dark Target” land and ocean radiances (PM orbit) |
a
NNR refers to Neural Net Retrieval algorithm that computes AERONET-calibrated AOD from radiances.
b
AERONET AOD is converted to 550 nm using an Angström-based interpolation and AOD reported at adjacent channels (500 and 675, typically).
c
We do not bias-correct AERONET or MISR AOD.
d
MODIS data is available in Near Real Time (NRT)