The opening session was dedicated to welcome and presentations by SKLEC and ECNU, NRSCC, and ESA officials. Background and access to current and future Chinese, ESA and TPM satellite missions in Ocean remote sensing were presented. Dragon 2 lead investigators from Europe and P.R. China provided the results and achievements on the Dragon 2 programme ocean and coastal zone projects.
These days were dedicated to lectures and practical sessions on the MERIS, AATSR, ASAR and RA instruments. One day was dedicated to each of the instruments. There was a 50:50 split between lectures and practical sessions with 1.5h for lectures followed by 1.5 hrs for practical sessions in the morning and in the afternoon. The topics covered during the training were as follows:
The morning of the final day covered lectures on data assimilation, data synergy, data validation and Essential Climate Variables (ECVs). This was followed by a course summary session and the official closing plenary session.
OCEAN TRAINING 2011 TOPICS
ESA Satellite Missions
ESA has a established a heritage in developing successful satellite missions that enable scientific study of the oceans. Importantly, the post- ERS and Envisat era will see a succession of exciting, new science- driven Earth Explorer missions developed as part of ESA's Living Planet Programme, as well as the operational series of GMES Sentinel monitoring satellites. The first three approved Explorer missions will make specific contributions to the study of ocean circulation and dynamics, and the high latitude sea-ice covered oceans. This lecture will briefly review the objectives of the GOCE, SMOS and CryoSat-2 missions, and will indicate some of the scientific applications that shall result from their data. In addition, the presentation will indicate current plans for establishing continuity in the valuable Ku-band radar altimeter, C-band SAR, ATSR and MERIS climate monitoring data streams, in the form of the Earthwatch GMES Sentinel-3 satellite.
MERIS Ocean Colour Principles
The MERIS session addressed principles and applications of ocean colour remote sensing with special focus of the usage of MERIS data for coastal waters. The main topic was the determination of the concentrations of water constituents and optical properties from reflectance spectra of MERIS.
With its 15 spectral bands of high radiometric performance, a spatial resolution of 300 m (full resolution mode) and a revisit period of 1-3 days (latitude dependent) MERIS is in particular suited for coastal waters. However, the user of the data has to be aware of a number of problems, which are related to the variable optical properties of phytoplankton, of all kind of suspended matter and of dissolved organic compounds, all of which change the spectral reflectance. In addition these waters require a special treatment for the correction of the influence of the atmosphere.
The application ranges from water quality monitoring, determination of primary production, determination of water transparency, solar energy absorption, suspended matter transport, determination of exceptional plankton blooms etc.
Within the course all details which are necessary for a useful and critical use of MERIS data were presented and discussed. This included:
Principles of ocean colour remote sensing
Basic algorithms for open ocean and coastal waters, bio-optical models
Basic atmospheric correction for open ocean and coastal waters
MERIS water algorithms for case 1 and case 2, atmospheric correction case 1 and case 2
MERIS products overview (RR, FR, L1, L2, L3)
MERIS flagging system
What to find in and how to use MERIS documents: MERIS Handbook, Cyclic report, disclaimers, ATBDs, Model reference, Validation handbook
Where are the limits of MERIS water products (e.g. concentration ranges and mixtures, atmospheric correction, sun glint)
How to apply local algorithms
MERIS validation procedures
Applications - examples
The use of BEAM software with exercises
The Synthetic Aperture Radar - A(SAR) session will address principles and application of the imaging radars that achieve high resolution by using a synthetic aperture processing technique. Their view of the ocean is unhindered by clouds, and they have so called all-weather day and night capabilities. Via resonant Bragg backscattering from centimetre long waves the imaging radars measure the spatial distribution of sea surface roughness with a horizontal resolution of a few tens of meters. This fine- scale resolution gives the SAR the unique capability to observe a number of oceanic and atmospheric phenomena whose characteristic signatures appear in the patterns of sea surface roughness such as surface and internal waves, current fronts, surface wind variability, oil or natural slicks.
The first part of the session presented the basic principles of SAR imaging mechanisms. The second part explained how to interpret radar images and provide quantitative estimates of waves, near surface wind, current features, oil spill, and sea ice.
There was interactive practical training in which both the interpretation of oceanic signatures and the transformation of SAR images to geophysical quantities (wind, waves, current, etc.) was demonstrated using real data from the Envisat/ERS archive.
The Advanced Along-Track Scanning Radiometer (AATSR), now flying on ENVISAT, is the third in a series of accurate infrared radiometer sensors designed to deliver sea surface temperature (SST) measurements of sufficient accuracy, better than 0.3K, combined with great stability, that they can be used as climate data records. The (A)ATSR instruments are unique in terms of their design and their ability to deliver extremely accurate SST skin observations. This short introduction will provide students with an overview of the (A)ATSR, its application and practical experience handling AATSR data.
The basic principles of remote sensing in the infra-red region of the electromagnetic spectrum were be reviewed and used to introduce and explore the innovative design of the (A)TSR series of instruments.
There was a review of the modern definitions for SST including a review of the surface skin temperature deviation, SST at depth and diurnal variability. The particular SST retrieval process used by the (A)ATSR (which retrieves an estimate of the SST skin temperature) was presented.
Finally, the (A)ATSR data set and applications of (A)ATSR were presented.
Practical sessions covered the following.
Introduction to the UNESCO Bilko image processing system and explore the various elements of this system using (A)ATSR data.
End-to-end process of deriving SST skin from (A)ATSR Brightness temperatures will be given. If time is available, a second Bilko lesson exploring ATSR-2 monthly mean SST will be available.
Some of the basic operations of examining global data. The data to be examined will be AATSR level 3 products, in the form of monthly means of Global SST. These can be obtained from: http://envisat.esa.int/level3/aatsr/
The operations to be demonstrated were those of examining inter-seasonal variability, searching for anomalies, creation of Hovmueller diagrams (time-longitude plots) to examine the progression annual or periodic phenomena such as the Tropical East Pacific upwelling. This lecture demonstrated the ATSR Global Analyser, an IDL tool specially developed for training purposes. As an alternative, the Bilko package can also be used for this purpose and its use was demonstrated.
Collectively, this course provided sufficient background information, practical instruction and tools to apply (A)ATSR SST data products in a variety of applications.
Principles of Radar Altimetry
Radar altimeters have been flown on satellites for many years and have become a firm part of the climate and ocean observing system. The RA session will address principles and applications of radar altimetry with focus on open and costal ocean applications. In addition some of the emerging new applications over ice and land will also be reviewed. As for all microwave instruments, their observing capability is unaffected by the atmosphere and therefore allows to observe dynamical features of the ocean with high along- track resolution (10 km). A RA is known for its high-precision measurements of sea surface height (the shape of the surface), but provides also important information about surface wave height and about surface wind speed.
The session presented first the basic principles of RA measurements and discussed important interaction processes of the radar pulse with the atmosphere and geophysical phenomena that need to be known in order to obtain high accuracy data.
The session then discussed additional information that is required to use RA data for dynamical ocean studies, such as marine geoid fields or in situ data.
Finally the session presented various ongoing and anticipated applications of RA.
The last part of the session included interactive practical training using ESAs BRAT tool box to train students in the interpretation of oceanic signatures of RA data (SSH, waves, wind speed) using real data from the Envisat/ERS archive.
This course provided background information, practical instruction and tools sufficient to apply RA data products in a variety of applications.