Abstract
High Asia has experienced strong environmental changes in recent decades, as evident in records of glaciers, lakes, tree rings, and vegetation. The multiscale understanding of the climatic drivers, however, is still incomplete. In particular, few systematic assessments have evaluated to what degree, if at all, the midlatitude westerly circulation modifies local surface climates in the reach of the Indian Summer Monsoon. This paper shows that a southward shift of the upper-tropospheric westerlies contributes significantly to climate variability in the core monsoon season (July–September) by two prominent dipole patterns at the surface: cooling in the west of High Asia contrasts with warming in the east, while moist anomalies in the east and northwest occur with drying along the southwestern margins. Circulation anomalies help to understand the dipoles and coincide with shifts in both the westerly wave train and the South Asian High, which imprint on air mass advection and local energy budgets. The relation of the variabilities to a well-established index of midlatitude climate dynamics allows future research on climate proxies to include a fresh hypothesis for the interpretation of environmental changes.
| Original language | English |
|---|---|
| Pages (from-to) | 12,702-12,712 |
| Journal | Journal of Geophysical Research: Atmospheres |
| Volume | 122 |
| Issue number | 23 |
| DOIs | |
| Publication status | Published - 2017 |
Bibliographical note
Funding Information:This work was supported by the German Research Foundation (DFG) grant MO 2869/1-1 and the National Science Foundation grant AGS-1405479. We thank Yanhong Gao for the discussion on WRF data for Tibet and Kai Uwe Eiselt and Elena Kropač for assisting with the station data analysis. The WRF modeling was conducted at the High-Performance Computing Center (HPC) at the University of Erlangen-Nürnberg’s Regional Computation Center (RRZE). The resultant data are only available upon request due to the very large data size. All other employed data sets are freely available (see section 2) and were obtained from the Earth System Research Laboratory (ESRL), National Aeronautics and Space Agency (NASA), European Centre for Medium-Range Forecast (ECMWF), and Dutch Meteorological Office (KNMI) platforms. The constructive comments of three anonymous reviewers improved the paper.
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© 2017. American Geophysical Union. All Rights Reserved.
