South Asian summer monsoon variability : a modelling study with the atmospheric regional climate model HIRHAM5 The lives of more than 1 6 th of the world population is directly affected by the caprices of the South Asian summer monsoon rainfall. India receives around 78 % of the annual precipitation during the June September months the summer monsoon season of South Asia. But the monsoon circulation is not consistent throughout the entire summer season. Episodes of heavy rainfall (active periods) and low rainfall (break periods) are inherent to the intraseasonal variability of the South Asian summer monsoon. Extended breaks or long lasting dryness can result in droughts and hence trigger crop failures and in turn famines. Furthermore Indias electricity generation from renewable sources (wind and hydro power) which is increasingly important in order to satisfy the rapidly rising demand for energy is highly reliant on the prevailing meteorology. The major drought years 2002 and 2009 for the Indian summer monsoon during the last decades which are results of the occurrence of multiple extended breaks emphasise exemplary that the understand…