On the latitudinal extent of upwelling caused by the extratropical wave pump

It is now commonly understood that the tropical upwelling branch of the Brewer-Dobson circulation is influenced remotely by the extra-tropical wave drag. What is less commonly known is that this upwelling is not restricted latitudinally to the tropics, but extends well into the midlatitudes of the summer hemisphere in response to the extratropical wave drag in the winter stratosphere. We will first present observational evidence to support this claim of upwelling in the opposite hemisphere, and then present model results to highlight the mechanism for the necessary cross-equatorial flow.