Abstract
Indian monsoon depressions are synoptic-scale storms that form primarily over the Bay of Bengal and propagate westward over the subcontinent, producing a large fraction of India's total summer precipitation. We recently showed that, contrary to long-standing ideas, the westward propagation of Indian monsoon depressions is accomplished primarily by horizontal adiabatic advection of potential vorticity (PV), not by vortex stretching or diabatic PV generation that occurs in the region of quasi-geostrophic ascent southwest of the vortex center. This chapter extends that work by using several reanalysis products to examine case studies of Indian monsoon depressions. In all reanalyses examined, monsoon depressions have maximum PV in the middle troposphere, at higher altitudes than the level of maximum relative vorticity. The horizontal structure of mid-tropospheric PV suggests that the axial asymmetry of the vortex that produces the nonlinear westward advection may result at least partly from diabatic heating. Thus, although storm motion is produced primarily by horizontal adiabatic advection, diabatic heating can play an indirect role by shaping the PV field that produces this advection.
| Original language | English (US) |
|---|---|
| Title of host publication | World Scientific Series on Asia-Pacific Weather and Climate |
| Publisher | World Scientific Publishing Co. Pte Ltd |
| Pages | 187-199 |
| Number of pages | 13 |
| Volume | Volume 9 |
| DOIs | |
| State | Published - 2017 |
Publication series
| Name | World Scientific Series on Asia-Pacific Weather and Climate |
|---|---|
| Volume | Volume 9 |
| ISSN (Print) | 2010-2763 |
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ASJC Scopus subject areas
- Atmospheric Science
- Global and Planetary Change
Cite this
Potential vorticity structure and propagation mechanism of Indian monsoon depressions. / Boos, William R.; Mapes, Brian E; Murthy, Varun S.
World Scientific Series on Asia-Pacific Weather and Climate. Vol. Volume 9 World Scientific Publishing Co. Pte Ltd, 2017. p. 187-199 (World Scientific Series on Asia-Pacific Weather and Climate; Vol. Volume 9).Research output: Chapter in Book/Report/Conference proceeding › Chapter
}
TY - CHAP
T1 - Potential vorticity structure and propagation mechanism of Indian monsoon depressions
AU - Boos, William R.
AU - Mapes, Brian E
AU - Murthy, Varun S.
PY - 2017
Y1 - 2017
N2 - Indian monsoon depressions are synoptic-scale storms that form primarily over the Bay of Bengal and propagate westward over the subcontinent, producing a large fraction of India's total summer precipitation. We recently showed that, contrary to long-standing ideas, the westward propagation of Indian monsoon depressions is accomplished primarily by horizontal adiabatic advection of potential vorticity (PV), not by vortex stretching or diabatic PV generation that occurs in the region of quasi-geostrophic ascent southwest of the vortex center. This chapter extends that work by using several reanalysis products to examine case studies of Indian monsoon depressions. In all reanalyses examined, monsoon depressions have maximum PV in the middle troposphere, at higher altitudes than the level of maximum relative vorticity. The horizontal structure of mid-tropospheric PV suggests that the axial asymmetry of the vortex that produces the nonlinear westward advection may result at least partly from diabatic heating. Thus, although storm motion is produced primarily by horizontal adiabatic advection, diabatic heating can play an indirect role by shaping the PV field that produces this advection.
AB - Indian monsoon depressions are synoptic-scale storms that form primarily over the Bay of Bengal and propagate westward over the subcontinent, producing a large fraction of India's total summer precipitation. We recently showed that, contrary to long-standing ideas, the westward propagation of Indian monsoon depressions is accomplished primarily by horizontal adiabatic advection of potential vorticity (PV), not by vortex stretching or diabatic PV generation that occurs in the region of quasi-geostrophic ascent southwest of the vortex center. This chapter extends that work by using several reanalysis products to examine case studies of Indian monsoon depressions. In all reanalyses examined, monsoon depressions have maximum PV in the middle troposphere, at higher altitudes than the level of maximum relative vorticity. The horizontal structure of mid-tropospheric PV suggests that the axial asymmetry of the vortex that produces the nonlinear westward advection may result at least partly from diabatic heating. Thus, although storm motion is produced primarily by horizontal adiabatic advection, diabatic heating can play an indirect role by shaping the PV field that produces this advection.
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UR - http://www.scopus.com/inward/citedby.url?scp=85020291213&partnerID=8YFLogxK
U2 - 10.1142/9789813200913_0015
DO - 10.1142/9789813200913_0015
M3 - Chapter
AN - SCOPUS:85020291213
VL - Volume 9
T3 - World Scientific Series on Asia-Pacific Weather and Climate
SP - 187
EP - 199
BT - World Scientific Series on Asia-Pacific Weather and Climate
PB - World Scientific Publishing Co. Pte Ltd
ER -