Hurricane intensity: new measurement methods

"The strongest ever hurricane in the North Atlantic". This recent statement about Irma is catchy, but how do we know it is stronger than previous storms? Measuring in hurricanes is very difficult. A simple parameter is the atmospheric pressure in the eye (but you have to get there), and it is not always the best indicator of the possible damage due to winds. Wind speed estimates are given by various instruments, usually radiometers or scatterometers that sense the ocean surface. Scatterometers measure the power of radar pulses reflected of the ocean and can give high resolution when using synthetic aperture processing (as done on Sentinel 1 instruments). What this new study adds is the use of both co-polarized and cross-polarized echoes, which give a very good sensitivity up to very high wind speed.  Here is an example of application  for hurricane  Irma, as observed on September 7, 2017 by Sentinel 1 (ESA  / EU, Copernicus program)

The validation of the method is based on comparisons with an other instrument, a radiometer (SMAP), and is the topic of a paper just published:

Mouche Alexis, Chapron Bertrand, Zhang Biao, Husson Romain Combined Co- and Cross-Polarized SAR Measurements Under Extreme Wind Conditions . IEEE Transactions on Geoscience and Remote Sensing .