Brigthness Temperature Difference
The presence of upper tropospheric - lower stratospheric SO2 is almost always associated with a volcanic eruption. With the advent of the InfraRed (IR) sounders, AIRS and IASI detection of SO2 is reliable and straightforward.
The near real-time and archive services show also images of the SO2 Brigthness Temperature Difference (DBT), taken from AIRS and IASI instruments.
The DBT indicates the presence of SO2 in the Earth's atmosphere. The DBTs provided here are derived from two sorts of differences of brigthness temperature:
for IASI: DBT corresponds to the vibrationnal mode V3 (1362 cm-1)
for AIRS DBT = Tb(1361.44 cm-1) - Tb(1433.06 cm-1)
Image of the SO2 DBT by IASI (top) and AIRS (bottom) intruments the 6 November 2010 after the eruption of the Merapi volcano.