Introduction

Extremes have always been a concern of GEWEX. At its first meeting in 1995, one of the GEWEX Hydrometeorology Panel’s (GHP) overall scientific issues was given as:

What feedback mechanisms affect the water cycle and how do these influence wet and dry periods?

Although some work on extremes has been conducted within the various components of GEWEX, a collective effort has not been established. The strategy of GHP has been to first of all concentrate on addressing water and energy budgets which consider longer-term averages as opposed to variability issues.

In 2005 a formal working group was established as part of the WISE project to “promote extremes-related efforts within GHP and GEWEX”.

This group’s focus was:

To better understand and model the occurrence, evolution and role of extremes within the climate system and to contribute to their better prediction

The effort initially focused on droughts and extended wet periods.

The activity has now (2007) been integrated into CEOP and will utilize the data facilities and data sets provided through CEOP. With the approval of a WCRP Cross-cut on monsoons, GEWEX has decided to rely on the CEOP Extreme Group to provide the bulk of its inputs and interactions to WCRP.