Near real-time IASI SO2 altitude
Example images of IASI SO2 altitude measurements (Nabro eruption)
Description
The near real-time (NRT) sulphur dioxide (SO2) altitude product from IASI provides retrieved SO2 altitudes and is a part of the Brescia SO2 column retrieval algorithm. It is included in the NRT SO2 column product.
Type
Near real-time. Based on product requirements, the product files must be available to users within three hours after observation.
Satellites and instruments
IASI/Metop-B and IASI/Metop-C
Algorithm version
Brescia v20211010
Theoretical basis
The NRT SO2 altitude product from IASI is based on a spectral feedback function approach (Clarisse et al., 2014). Recently it was shown that IASI radiances contain information on altitude in volcanic SO2 plumes which can be extracted using optimal estimation approaches. The algorithm outlined in Clarisse et al. (2014) however, does not rely in iterative fitting but instead uses spectral feedback functions based on pre-calculated Jacobians.
Processing
The Brescia algorithm is a dedicated radiative transfer and retrieval software for IASI. It was developed at ULB in collaboration with LATMOS, with the objective to provide global distributions of SO2.
Units and spatial resolution
SO2 altitudes are given in kilometres. In 8 seconds a total of 120 views are collected over a swath of ∼2200 km, divided as 30 arrays of four individual pixels varying in size from 36 x π km2 at nadir (circular pixel 12 km in diameter) to 10 x 20 x π km2 at larger viewing angles.
Validation
This product is validated by AUTH and BIRA-IASB. Validation is based on detailed comparisons with ground-based and satellite data. See the validation report for more details.
Dissemination
File format
This product is available within the HDF5 file of the NRT SO2 total column product.