Predictability – a problem partly solved

Ed Lorenz, pioneer of chaos theory, presented this work at an earlier ECMWF workshop on predictability. The paper, which has never been published externally, presents what is widely known as the Lorenz 1996 model. Ed was unable to come to the 2002 meeting, but we decided it would be proper to acknowledge Ed's unrivalled contribution to the field of weather and climate predictability by publishing his 1996 paper in this volume.