Articles | Volume 33, issue 5
https://doi.org/10.5194/angeo-33-599-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-33-599-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
ANGEO Communicates
| 
29 May 2015
ANGEO Communicates |
| 29 May 2015
A case study of formation and maintenance of a lower stratospheric cirrus cloud over the tropics
M. Sandhya
National Atmospheric Research Laboratory, Gadanki 517 112, Pakala Mandal, Chittoor District, Andhra Pradesh, India
Department of Physics, Andhra University, Visakhapatnam, Andhra Pradesh 530003 India
National Atmospheric Research Laboratory, Gadanki 517 112, Pakala Mandal, Chittoor District, Andhra Pradesh, India
M. Indira Devi
Department of Physics, Andhra University, Visakhapatnam, Andhra Pradesh 530003 India
K. Niranjan
Department of Physics, Andhra University, Visakhapatnam, Andhra Pradesh 530003 India
A. Jayaraman
National Atmospheric Research Laboratory, Gadanki 517 112, Pakala Mandal, Chittoor District, Andhra Pradesh, India
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M. Sandhya, S. Sridharan, and M. Indira Devi
Ann. Geophys., 33, 1081–1089, https://doi.org/10.5194/angeo-33-1081-2015, https://doi.org/10.5194/angeo-33-1081-2015, 2015
Short summary
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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.
S. Sridharan and M. Sandhya
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acpd-15-15137-2015, https://doi.org/10.5194/acpd-15-15137-2015, 2015
Revised manuscript not accepted
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Eastward propagating 18-day waves of zonal wavenumbers (k=1-5) are observed in mid-latitude meridional winds at 200 hPa during December 2012-February 2013. Among these, the 18-day wave of k=5 propagates equatorward. Presence of wave of similar periodicity (18-day) and zonal structure (k=5) in tropical OLR as that of extratropical wave disturbance is first reported. We suggest that the selective response of the tropical wave forcing is due to the lateral forcing of the extra-tropical wave.
O. Nath and S. Sridharan
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acpd-15-23969-2015, https://doi.org/10.5194/acpd-15-23969-2015, 2015
Revised manuscript not accepted
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Chemical composition changes over equator during SSW events are investigated using MLS and MIPAS data sets. It is found that the O3 VMR increases whereas H2O VMR decreases. In the upper stratosphere, the source of water vapor is oxidation of CH4 by OH or O. But, OH does not vary during SSW. The temperature decrease over equator during SSW increases the reaction rate of ozone production to shift the O/O3 ratio towards O3, resulting in decrease of CH4 oxidation and consequent decrease in H2O.
M. Sandhya, S. Sridharan, and M. Indira Devi
Ann. Geophys., 33, 1081–1089, https://doi.org/10.5194/angeo-33-1081-2015, https://doi.org/10.5194/angeo-33-1081-2015, 2015
Short summary
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.
S. Sridharan and M. Sandhya
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acpd-15-15137-2015, https://doi.org/10.5194/acpd-15-15137-2015, 2015
Revised manuscript not accepted
Short summary
Short summary
Eastward propagating 18-day waves of zonal wavenumbers (k=1-5) are observed in mid-latitude meridional winds at 200 hPa during December 2012-February 2013. Among these, the 18-day wave of k=5 propagates equatorward. Presence of wave of similar periodicity (18-day) and zonal structure (k=5) in tropical OLR as that of extratropical wave disturbance is first reported. We suggest that the selective response of the tropical wave forcing is due to the lateral forcing of the extra-tropical wave.
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A rare occurrence of stratospheric cirrus at 18.6km persisting for about 5 days is observed over India from 3 to 7 March 2014. Due to potential vorticity intrusion, large-scale updrafts and increase in humidity are observed at 18.6km. Relative humidity with respect to ice is ~ 150%, indicating that the cirrus cloud may be formed though homogeneous nucleation of sulfuric acid. The persistence of the cirrus cloud is due to the cold anomaly associated with the presence of a 4-day wave.
A rare occurrence of stratospheric cirrus at 18.6km persisting for about 5 days is observed over...
