Enhanced Natural Colour RGB, Tropical Airmass, H SAF H90 product, True Colour RGB, Nighttime Light, Bands 7, 2 and 1
Since the beginning of June, Pakistan has seen major flooding associated with the 2022 Monsoon.
21 February 2023
13 September 2022
By Ivan Smiljanic (Exostaff), Mark Higgins (EUMETSAT), Davide Melfi (H SAF) and Ibrahim Al Abdulsalam (CAA Oman)
Having a third of the country like Pakistan under water, it is hard not to notice such a massive flood event from as far away as 36 000km above the Earth — where geostationary satellites are located. It doesn't even require cutting edge technology to spot the floods, even the older SEVIRI imaging instruments onboard the Meteosat Second Generation (MSG) satellites can see them clearly.
Figure 1 showing a comparison of The Meteosat-9 SEVIRI Natural Colour RGB imagery over the flooded area at end of August 2022 and from two years ago, at nominal resolution of 4km per pixel. Dark to pale blue and mixed green shades in this RGB show the areas that are covered (perhaps even partially) by water, with less or more turbidity, and/or depth. Mostly these areas are following the wider Indus river valley (Figure 6).
Animated SEVIRI imagery covers the flood development from the beginning of June until the end of August, with looping Natural Colour RGB imagery for each day at 06:00 UTC (Figure 2).
The more than double monsoon rainfall (on average, over the whole country, and attributed to climate change) was not the only driver for such a tragic flood outcome — melting glaciers, deforestation, and even urban planning are cumulative factors that also contributed.
Meteosat Second Generation satellites do not only contribute to flood assessment by providing useful imagery, such as the Tropical Airmass (Figure 3), but also with quantitative rainfall products. These products, based on MSG data, provide local authorities and operational staff with real numbers related to rainfall amounts (Figure 4).
The H90 product (P-AC-SEVIRI_E) integrates the instantaneous precipitation maps generated by the H63 product (based on inter-calibrated Level 2 PMW instantaneous precipitation rate estimates blended with the 10.8 channel from IODC SEVIRI).
Sub-kilometer resolution geostationary imagery can not be acquired from contemporary Meteosat satellites, but will be possible with the coming Meteosat Third Generation mission, planned to be launched in late 2022. For now the proxy imagery can be easily obtained from LEO instruments, such as Sentinel-3 (Figure 5).
Figure 6 uses MODIS RGB and VIIRS Nighttime light imagery to show the extent of flood v the density of population in the Indus river valley.