Articles | Volume 34, issue 1
https://doi.org/10.5194/angeo-34-123-2016
https://doi.org/10.5194/angeo-34-123-2016
Regular paper
 | 
25 Jan 2016
Regular paper |  | 25 Jan 2016

Modulation of surface meteorological parameters by extratropical planetary-scale Rossby waves

K. Niranjan Kumar, D. V. Phanikumar, T. B. M. J. Ouarda, M. Rajeevan, M. Naja, and K. K. Shukla

Abstract. This study examines the link between upper-tropospheric planetary-scale Rossby waves and surface meteorological parameters based on the observations made in association with the Ganges Valley Aerosol Experiment (GVAX) campaign at an extratropical site at Aryabhatta Research Institute of Observational Sciences, Nainital (29.45° N, 79.5° E) during November–December 2011. The spectral analysis of the tropospheric wind field from radiosonde measurements indicates a predominance power of around 8 days in the upper troposphere during the observational period. An analysis of the 200 hPa meridional wind (v200 hPa) anomalies from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis shows distinct Rossby-wave-like structures over a high-altitude site in the central Himalayan region. Furthermore, the spectral analysis of global v200 hPa anomalies indicates the Rossby waves are characterized by zonal wave number 6. The amplification of the Rossby wave packets over the site leads to persistent subtropical jet stream (STJ) patterns, which further affects the surface weather conditions. The propagating Rossby waves in the upper troposphere along with the undulations in the STJ create convergence and divergence regions in the mid-troposphere. Therefore, the surface meteorological parameters such as the relative humidity, wind speeds, and temperature are synchronized with the phase of the propagating Rossby waves. Moreover, the present study finds important implications for medium-range forecasting through the upper-level Rossby waves over the study region.

Download
Short summary
The link between upper-tropospheric planetary-scale Rossby waves and surface meteorological parameters is examined. The propagating Rossby waves along with undulations in the subtropical jet create convergence and divergence regions in the mid-troposphere. The surface relative humidity, wind speeds, and temperature are synchronized with the phase of the propagating Rossby waves. The present study finds important implications for medium-range forecasting through Rossby wave propagation.