Earth Observation Science Recent and potential scientific achievements of the (A)ATSR Series - and some possibilities for synergy with MERIS David Llewellyn-Jones Space Research Centre University of Leicester

AATSR Science – and MERIS What can AATSR do? Some Scientific Highlights AATSR and MERIS –What can AATSR do for MERIS? –What can MERIS do for AATSR? The Future prospects –Archive –Data continuity

What does AATSR do? It is an imager co-registered with MERIS Spatial Resolution of 1Km Swath width 500km Dual angle view: at nadir, like MERIS and at 55º to nadir Three thermal IR channels, at µm Tour reflected infrared channels High quality on-board calibration systems

Scientific Highlights of the ATSR- 1, ATSR-2, AATSR programmes Ocean Science  Tropical Instability Waves  Observation of thermal signature of Rossby Waves  Global change in SST Atmospheric Science  Atmospheric Water Vapour  Aerosols and clouds  ATSR-2 cloud data key to retrieval of GOME Ozone Land Applications  Enhanced atmospheric correction from dual-angle view  Improved calibration of AVHRR and MODIS visible channels

Rossby waves detected also in the SST anomaly field (Hill et al, 2000) Tropical Instability Waves (2½ Years) ( Allen et al 1995)

Measurement of Residual Trends in Global SST from AVHRR and ATSR data Lawrence et al

Western Boundary Currents of the Northern Hemisphere Gulf Stream Kuroshio

Thermohaline Ocean Circulation

The Gulf Stream in 2003 (Biweekly Averages, Feb - July)

KuroShio from AATSR on ENVISAT:

Movements of the Kuroshio: data source: ATSR-2 and AATSR

KuroShio Position and Wind- field curl  From ATSR-2 and AATSR  From ECMWF wind-fields

KuroShio meanders – preliminary conclusions Kuroshio position can be quantitatively monitored using (A)AATSR data study of 10-year time series suggests some possibility of correlation between wind-stress curl and Kuroshio position However, other possible mechanisms (including ocean gyres) must be investigated Cloud contamination a problem – need for a new approach?

Recent applications of AATSAR data See Simon Good’s poster Precursor work to investigation of W Boundary Currents Compares AATSR SSTs with SSTs from other satellites Demonstrates the value of Medspiration/GHRSST

AATSR and MERIS Main differences & similarities Potential synergy: –What can MERIS do for AATSR? –What can AATSR do for MERIS?

Main differences & similarities Co-registered 250km each side of nadir Swath width: MERIS has over twice AATSR’s –MERIS 1150km; AATSR 500km Pixel size – over 10 MERIS pixels per AATSR –MERIS 0.29km; AATSR 1km AATSR has thermal channels AATSR has dual-angle view

Overlapping Channels

AATSR/MERIS – potential synergy Ocean productivity: Temperature has influence on bio-activity (biophysical interactions) Atmospheric water vapour MERIS product, can also be derived from A ATSR Atmospheric aerosols AATSR can detect aerosols but cannot constrain all the variables MERIS aerosol product would elucidate this Along-track view has potential for atmos correction over land

ENVISAT Monthly means AATSR SST MERIS Chlorophyll

Separation of Bi-directional Reflectance from atmospheric effects using dual view Top of atmosphere = 555nm Forward and Nadir ToA reflectances Gerund reflectance Optical Depth Retrieved ground reflectance North et al

Total Atmospheric Water Vapour from ATSR I J Barton, CSIRO

Atmospheric Aerosols - from ATSR dual-nadir SST difference

ATSR2 SST (dual-nadir) vs TOMS Aerosol Comparison

AATSR/MERIS – potential synergy - 2 AATSR cloud detection Analysis and refinement of AATSR cloud- clearance scheme could benefit from MERIS ‘sub-pixel resolution AATSR Land-surface temperature Land non-uniformity is a major issue MERIS could provide indication of non- umiformity at AATSR sub-pixels scale

Summary and Conclusions AATSR exploitation programme now mature Co-registration of MERIS offers great opportunities Several projects already exist with strong need or alternative. Co-registered aerosol measurements. AATSR has archive (15+ years of SST/LST; 10+ of land reflectivity) can, in principle, allow MERIS records to extrapolated backwards. Data continuity is an urgent issue GMES-1 and Sentinel 3 satellite are key to future data availability.