AMMA-UK Kick-off meeting 20-21 Jan 2005

WP1 Land surface and atmosphere interactions

Chris Taylor

Phil Harris

AMMA-UK Kick-off meeting 20-21 Jan 2005

Aim of WP1

• Quantify the seasonal energy cycle responsible for the WAM, using detailed in-situ observations, remote sensing, and surface modelling

• Aim to provide to rest of project– realistic surface boundary conditions for atmospheric

modelling– surface wetness and temperature conditions for

malaria studies– quantitative estimates of surface conditions beneath

aircraft for boundary layer meteorology and chemistry studies

AMMA-UK Kick-off meeting 20-21 Jan 2005

Seasonal Cycle of West African Monsoon10W-10E 1992 in Observations and ERA40

AMMA-UK Kick-off meeting 20-21 Jan 2005

Surface Variability and RainfallDaily variability

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Interannual variability

AMMA-UK Kick-off meeting 20-21 Jan 2005

Limitations of Current Knowledge of Land Surface Properties and Fluxes

• Variability in surface properties can be large providing potential for feed back on atmosphere at range of scales

• Surface heterogeneity (soil, topography, rainfall, vegetation) makes local measurements of limited use by themselves

• Soil moisture analyses of poor quality due to e.g. nudging, inadequate surface parameterisation, poor inputs

• As a result temporal and spatial variability of soil moisture and surface fluxes poorly quantified, little idea of behaviour at monsoon scale

AMMA-UK Kick-off meeting 20-21 Jan 2005

JULES Land Surface Model(Joint UK Land Environment Simulator)

• Use surface model (JULES) uncoupled from host atmospheric model (Unified Model)

• Updates soil moisture and temperature on 4 layers, canopy water store, and calculates runoff, turbulent and radiative fluxes into atmosphere

• Forced by precipitation, radiation, near surface temperature, humidity, wind speed

• Requires additional data – soil and vegetation properties

AMMA-UK Kick-off meeting 20-21 Jan 2005

Implementation of JULES in AMMA

• Run JULES as distributed model across West Africa

• Run at fine scale (2.5km?) – limited by quality of input data (e.g. MODIS, MSG)

• Duration EOP (2005-7)

AMMA-UK Kick-off meeting 20-21 Jan 2005

Major drawbacks of surface modelling across West Africa

• Surface very sensitive to precipitation, which is poorly known, and (to lesser extent) downwelling radiation

• Partition between sensible and latent heat sensitive to parameterisations of transpiration, bare soil evaporation and vegetation growth – dependant on vegetation and soil properties

AMMA-UK Kick-off meeting 20-21 Jan 2005

Approach in AMMA

• Run JULES at transect of sites forced by in situ obs. and develop / calibrate parameterisations based on comparison with observed fluxes

• At regional scale, use forcing data generated from EO, notably precipitation (AMMA-EU)

• Assimilate remote measurements (IR surface temperature, microwave-derived surface soil moisture, NDVI) from satellite (and aircraft?)

AMMA-UK Kick-off meeting 20-21 Jan 2005

Cloud-Screened Brightness Temperatures from Meteosat

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Cold cloud can provide useful indication of location of organised mesoscale systems but little information about

rain amount and spatial variability within storm

AMMA-UK Kick-off meeting 20-21 Jan 2005

AMSR-E surface soil moisture Daily data Aug2004

AMMA-UK Kick-off meeting 20-21 Jan 2005

Links with work outside NERC consortium

• Strong links with AMMA-EU– WP4.2 land data assimilation (CEH, ECMWF, Meteo-France…)– WP1.3 surface-atmosphere feedbacks (CEH, Leeds, LMD…)

• Vegetation growth modelling, interannual/decadal climate feedbacks - CLASSIC, Lina Mercado, Richard Ellis (Wallingford), NDVI Sietse Los (Swansea)

• Soil moisture initialisation - Met Office, Martin Best (Wallingford), Sean Milton (Exeter)

• Estimating surface radiation proposal (Imperial, Richard Bantges)

• RADAGAST (ESSC, Tony Slingo)• etc

AMMA-UK Kick-off meeting 20-21 Jan 2005

Provisional timetable

Start model development work, explore usage of EO data May 2005 onwards

Field obs. start coming online summer 2005Definition and development of database of forcing

data Dec 2005Intercomparison of land surface schemes June

2006 (AMMA-EU)Preliminary surface products for AMMA-UK Feb

2007Complete analysis of EOP Spring 2008