HiGEM land surface paper Douglas Clark Christopher Taylor Centre for Ecology and Hydrology, Wallingford

Progress Contribution to HiGEM overview paper Work in progress Finish in first 2 weeks Feb Land surface paper Still at an early stage

Outline of land surface paper Description of climate over land Look at “drivers” of the land model – precip, T, radiation. Snow extent in coupled and uncoupled runs River flow in coupled and uncoupled runs Soil moisture stress in coupled and uncoupled runs Compare with EO product. Can we relate biases in different fields? Focus on key regions/catchments What’s the story? Need to emphasise/develop new aspects – if we want to get published!

Precipitation and temperature (on land) Annual averages Precipitation (mm d-1) HiGEM has smaller wet bias – all seasons, global and tropics. >50N not much difference HiGEM-HadGEM, wet bias slightly worse in HiGEM. CMAP 2.16 HiGEM 2.48 HadGEM 2.53 Temperature (K) CRU 286.2 HiGEM 284.6 HadGEM 284.1 HiGEM has smaller cool bias – all seasons, global and tropics. >50N smaller cool bias, except JJA now has larger warm bias.

Precipitation (on land) Wet bias, worse in HiGEM: USA, Brazilian highlands, Uruguay Wet bias, better in HiGEM: Indonesia, Siberia, southern Africa, central S.America, SW. Europe, E.China Dry bias, worse in HiGEM: W.Africa

50 major catchments with (relatively) long-term riverflow data. Precipitation 50 major catchments with (relatively) long-term riverflow data. Exclude those with most obvious flow regulation/abstraction – e.g. Parana.

Precipitation Brahmaputra Irrawaddy Amazon Yangtze Xi Jiang Columbia Murray Ganges Senegal Columbia

River flow – the four largest catchments GCMs too wet in all of these. Poor offline suggests model deficiencies. River flow – the four largest catchments HiGEM better. Offline poor. GCMs poor. Offline better. GCM volumes good, but too late.

River flow Too much E? Offline far from perfect! Yangtze Ganges Anadyr Khatanga Orinoco Yangtze Anadyr Offline far from perfect!

River flow – high latitudes Slightly too little flow, too late. Offline timing better with “old soil”. Issues include: Infiltration into partially frozen soil. Simple runoff model.

Moisture stress Richard Ellis et al.

Snow extent HiGEM HadGEM Offline (1deg) GCMs – wet bias (small & difficulty with obs) and cold bias.