Articles | Volume 33, issue 9
https://doi.org/10.5194/angeo-33-1081-2015
https://doi.org/10.5194/angeo-33-1081-2015
Regular paper
 | 
03 Sep 2015
Regular paper |  | 03 Sep 2015

Tropical upper tropospheric humidity variations due to potential vorticity intrusions

M. Sandhya, S. Sridharan, and M. Indira Devi

Abstract. Four cases (March 2009, May 2009, April 2010 and February 2012) are presented in which the ERA-interim relative humidity (RH) shows consistent increase by more than 50 % in the upper troposphere (200–250 hPa) over tropics at the eastward side of the potential vorticity (PV) intrusion region. The increase in RH is confirmed with the spaceborne microwave limb sounder observations and radiosonde observations over Gadanki (13.5° N, 79.2° E) and is observed irrespective of whether the PV intrusions are accompanied by deep convection or not. It is demonstrated that the increase in RH is due to poleward advection induced by the PV intrusions in their eastward side at the upper tropospheric heights. It is suggested that the low-latitude convection, which is not necessarily triggered by the PV intrusion, might have transported water vapour to the upper tropospheric heights.

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Short summary
Four cases are presented in which the relative humidity (RH) shows consistent increase by more than 50% in the upper troposphere (200-250 hPa) over tropics at the eastward side of the potential vorticity (PV) intrusion region. The increase in RH is observed irrespective of whether the PV intrusions are accompanied by deep convection or not and is suggested to be due to poleward advection induced by the PV intrusions.