Articles | Volume 32, issue 2
ANGEO Communicates
21 Feb 2014
ANGEO Communicates |  | 21 Feb 2014

Signatures of Rossby wave modulations in aerosol optical depth over the central Himalayan region

D. V. Phanikumar, K. Niranjan Kumar, K. K. Shukla, H. Joshi, M. Venkat Ratnam, M. Naja, and K. Reddy

Abstract. Long-period modulations are shown in aerosol optical depth measured by the Microtops II Sun photometer over a high-altitude site the central Himalayan region (Nainital, 29.4° N, 79.5° E, 1958 m a.m.s.l.) for the first time. Fourier analysis of aerosol optical depth showed dominant 25–45 day oscillations observed in MODerate-resolution Imaging Spectro radiometer data. Further, a Hovmiller diagram showed westward (northward) propagation at a different longitude (latitude), confirming that the modulations are associated with Rossby waves. It is also shown that the Rossby wave amplitude causes an additional warming of 4.16 ± 0.98 W m−2 over the observational site. Hence, the present study illustrates the importance of wave-induced aerosol dynamics and the corresponding radiative effects.