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Fig. 4 shows the ERA5 zonal mean zonal wind (contours) and difference between the final product and the warm up (colours). In the troposphere and lower stratosphere, between 1000 hPa and 10 hPa, the only region with differences greater than 0.2 ms-1 is a latitudinally confined region near the equator, above about 50 hPa, where the differences of alternating sign are no larger than about 1 ms-1. From the mid-stratosphere to the stratopause (from 10 hPa to 1 hPa), the equatorial differences are slightly larger, with a larger latitudinal extent. However, in the mesosphere (from 1 hPa to 0.01 hPa), the differences are much larger, with values of order 100 ms-1 CHECK near the equator and values greater than 2 ms-1 being widespread.
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