1Earth System Analysis, Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany
2Institute of Physics, University of Potsdam, 14476 Potsdam, Germany
3Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, 710049, China
4Department of Geology and Geophysics, University of Minnesota, Minneapolis, 55455, USA
Received: 04 May 2011 – Published in Clim. Past Discuss.: 30 May 2011
Abstract. Monsoon systems around the world are governed by the so-called moisture-advection feedback. Here we show that, in a minimal conceptual model, this feedback implies a critical threshold with respect to the atmospheric specific humidity qo over the ocean adjacent to the monsoon region. If qo falls short of this critical value qoc, monsoon rainfall over land cannot be sustained. Such a case could occur if evaporation from the ocean was reduced, e.g. due to low sea surface temperatures. Within the restrictions of the conceptual model, we estimate qoc from present-day reanalysis data for four major monsoon systems, and demonstrate how this concept can help understand abrupt variations in monsoon strength on orbital timescales as found in proxy records.
Revised: 20 Feb 2012 – Accepted: 28 Feb 2012 – Published: 15 Mar 2012
Schewe, J., Levermann, A., and Cheng, H.: A critical humidity threshold for monsoon transitions, Clim. Past, 8, 535-544, doi:10.5194/cp-8-535-2012, 2012.