[1] AICCRA, ILRI, POB 5689, Addis Ababa, Ethiopia
[2] Norwegian Meteorol Inst, N-0313 Oslo, Norway
[3] Univ Quebec Montreal, Dept Earth & Atmospher Sci, 201 President Kennedy Ave, Montreal, PQ H2X 3Y7, Canada
[4] Wageningen Environm Res, POB 47, NL-6700 AA Wageningen, Netherlands
[5] Addis Ababa Univ, IGSSA, King George VI,POB 1176, Addis Ababa, Ethiopia