earth observation science recent and potential scientific achievements of the (a)atsr series - and...
TRANSCRIPT
Earth Observation Science
Recent and potential scientific achievements of the (A)ATSR Series
- and some possibilities for synergy with MERIS
David Llewellyn-JonesSpace Research CentreUniversity 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 3.7.10.5 7 12 µm
• Tour reflected infrared channels
• High quality on-board calibration systems
Scientific Highlights of the ATSR-1, ATSR-2, AATSR
programmesOcean 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)
AVHRR (solid): 0.09°K/decadeATSR (dashed): 0.13°K/decade
Residual Trends in ATSR and AVHRR SST recordsMeasurement of Residual Trends in Global SSTfrom AVHRR and ATSR data
Lawrence et al
Western Boundary Currents of the Northern HemisphereGulf Stream
Kuroshio
Thermohaline Ocean Circulation
http://oceansjsu.com/105d/exped_circulation/21.html
The Gulf Stream in 2003 (Biweekly Averages, Feb - July)
KuroShio from AATSR on ENVISAT: 2002-2005
Movements of the Kuroshio: 1995-2005
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 ChannelsMERIS Ch.
Wavelength ± BW (nm)
AATSR channels
MERIS Application
55 556600 ±± 1100
555500 ±± 1100
CChhlloorroopphhyyllll aabbssoorrppttiioonn mmiinniimmuumm
77 666655 ±± 1100
665599 ±± 1100
CChhlloorroopphhyyllll aabbssoorrppttiioonn aanndd fflluuoorreesscceennccee
rreeffeerreennccee
1133 886655 ±± 2200
886655 ±±1100
VVeeggeettaattiioonn,, wwaatteerr vvaappoouurr rreeffeerreennccee
11661100 ±± 3300
AAAATTSSRR cclloouudd ddeetteeccttiioonn ((ddaayyttiimmee))
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 2003 - Monthly means
AATSR SST MERIS Chlorophyll
Separation of Bi-directional Reflectance from atmospheric effects using dual view
Top ofatmosphere
= 555nm
Forward and Nadir ToA reflectancesGerund reflectance
Optical Depth
Retrieved ground reflectance
North et al
Total Atmosphe
ricWater
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 -
2AATSR 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.