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

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

3. 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!

4. 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.

5. 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

6. 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.

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

8. 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.

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

10. 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.

11. Moisture stress
Richard Ellis et al.

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