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    24-Jul-2014
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SST record 50 km cell MDS
BT/TOA Sea record 17 km cell MDS
ATS_TOA_1P_MDSR_conf
ATS_TOA_1P_MDSR_cl
ATS_TOA_1P_ADSR_pix
ATS_SST_AX_GADSR
Vegetation fraction for Land Surface Temperature Retrieval GADS
Topographic Variance data for Land Surface Temperature Retrieval GADS
Land Surface Temperature retrieval coefficients GADS
General Parameters for Land Surface Temperature Retrieval GADS
Climatology Variance Data for Land Surface Temperature Retrieval GADS
Level 0 SPH
Level 0 MDSR
Auxilliary Data SPH with N = 1
1.6 micron nadir view MDS
Summary Quality ADS
Scan pixel x and y ADS
Grid pixel latitude and longtitude topographic corrections ADS
Across-track Band Mapping Look-up Table
Configuration Data GADS
Processor configuration GADS
LST record 50 km cell MDS
Distributed product MDS
Level 2 SPH
SPH
10-arcminute mds
Limits GADS
Validation Parameters GADS
BT/TOA Land record 17 km cell MDS
General Parameters GADS
Temperature to Radiance LUT GADS
Radiance to Brightness Temperature LUT GADS
Medium/High Level Test LUT GADS
Infrared Histogram Test LUT GADS
11 Micron Spatial Coherence Test LUT GADS
11/3.7 Micron Nadir/Forward Test LUT GADS
11/12 Micron Nadir/Forward Test LUT GADS
Characterisation GADS
Browse Day_Time Colour LUT GADS
Browse SPH
Grid pixel latitude and longtitude topographic correction ADS
Level 2 SPH
Auxilliary Products
ATS_VC1_AX: Visible Calibration data
ATS_SST_AX: SST Retrieval Coeficients data
ATS_PC1_AX: Level-1B Processing configuration data
ATS_INS_AX: AATSR Instrument data
ATS_GC1_AX: General Calibration data
ATS_CH1_AX: Level-1B Characterization data
ATS_BRW_AX: Browse Product LUT data
Level 0 Products
ATS_NL__0P: AATSR Level 0 product
Browse Products
ATS_AST_BP: AATSR browse image
Level 1 Products
ATS_TOA_1P: AATSR Gridded brightness temperature and reflectance
Level 2 Products
ATS_NR__2P: AATSR geophysical product (full resolution)
ATS_MET_2P: AATSR Spatially Averaged Sea Surface Temperature for Meteo Users
ATS_AR__2P: AATSR averaged geophysical product
Frequently Asked Questions
The AATSR Instrument
Instrument Characteristics and Performance
In-flight performance verification
Instrument Description
Internal Data Flow
Instrument Functionality
AATSR Products and Algorithms
Common Auxiliary data sets
Auxiliary Data Sets for Level 2 processing
Instrument Specific Topics
Level 2 Products
Level 1B Products and Algorithms
Level 1B Products
Algorithms
Instrument Pixel Geolocation
Availability
The Level 0 Product
Differences Between ATSR-2 and AATSR Source Packets
Definitions and Conventions
Conventions
Organisation of Products
Relationship Between AATSR and ATSR Products
AATSR Product Organisation
Data Handling Cookbook
Characterisation and Calibration
Monitoring of AATSR VISCAL Parameters
Latency, Throughput and Data Volume
Throughput
Introduction
Heritage
Data Processing Software
Data Processing Centres
The AATSR Products User Guide
Image Gallery
Breakup of the Ross Ice Shelf
Land cover in the Middle East
Typhoon Saomai
Mutsu Bay, Japan
Deforestation in Brazil
Spatially Averaged Global SST, September 1993
Further Reading
How to use AATSR data
Why Choose AATSR Data?
Why Choose AATSR Data?
Special Features of AATSR
Principles of Measurement
Scientific Background
The AATSR Handbook
SST record 17 km cell MDS
Surface Vegetation class for Land Surface Temperature Retrieval GADS
1.6 micron forward view MDS
12 micron nadir view MDS
12 micron forward view MDS
Summary Quality ADS
Surveillance Limits GADS
Master Unpacking Definition Table GADS
1.6 micron Non-Linearity Correction LUT GADS
General Parameters GADS
Thin Cirrus Test LUT GADS
Fog/low Stratus Test LUT GADS
1.6 Micron Histogram
Browse MDS
ATS_CL1_AX: Cloud LUT data
Glossary
Pre-flight characteristics and expected performance
Payload description, position on the platform
Auxiliary products
Auxiliary Data Sets for Level 1B processing
Summary of auxiliary data sets
Calculate Solar Angles
Image Pixel Geolocation
Level 0 Products
Acquisition and On-Board Data Processing
Product Evolution History
Hints and Algorithms for Higher Level Processing
Data Volume
Software tools
Summary of Applications vs Products
Geophysical Coverage
Geophysical Measurements
ATS_TOA_1P_ADSR_sa
Visible calibration coefficients GADS
Level 1B SPH
LST record 17 km cell MDS
Conversion Parameters GADS
12 Micron Gross Cloud Test LUT GADS
ATS_PC2_AX: Level-2 Processor Configuration data
Level 2 Products
Hints and Algorithms for Data Use
BT/TOA Sea record 50 km cell MDS
BT/TOA Land record 50 km cell MDS
Level 2 Algorithms
Signal Calibration
Services
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Frequently asked questions
Glossary
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1.1.1 Geophysical Measurements

1.1.1.1 Primary Geophysical Measurement

The primary mission objective of the AATSR instrument is to extend the long-term consistent set of global SST measurements started with ATSR-1 and continued with ATSR-2.

Sea Surface Temperature (SST)

AATSR has thermal infrared channels measuring upwelling radiance from the sea surface and the atmosphere at 3.7, 11 and 12 µm. From the calibrated top of the atmosphere Brightness Temperatures (BT) available from these bands, SST is calculated using the 11 and 12 µm channels during the day and the 11, 12 and 3.7 µm channels at night.

Very high levels of accuracy and precision are required to support global climate monitoring and change detection. Therefore, the AATSR instrument and ground processing system are required to produce SST retrievals routinely from the corresponding BTs with an absolute accuracy of better than 0.3K, globally, both for a single sample and when averaged over areas of 0.5° longitude by 0.5° latitude, under certain cloud free conditions (i.e. >20% cloud free samples within each area). The AATSR programme also aims to maintain an instrument stability of 0.1K during the mission lifetime.

It is important to note that the (A)ATSR instruments return SST measurements for the ocean's 'skin' and that the temperature of the sea skin surface is typically a few tenths of a degree cooler than the temperature a few centimetres below. Due to the limited penetration of thermal infrared radiation through the water column, the infrared radiometric temperature will be that of only the top few tens of micrometres, whereas the oceanographically understood SST is a measure of the temperature in the top 10 cm.

1.1.1.2 Additional Capabilities

Land Remote Sensing

AATSR also includes three visible/near infrared channels centred at 0.55, 0.67 and 0.87µm. These were first introduced on ATSR-2 and have extended the instrument's capabilities over land, particularly for the study of vegetation.

Much of the time, the basic calibrated top of the atmosphere reflectance measurements from the AATSR visible and near infrared channels are used for studies of vegetation quantity and quality. In order to cope with all possible normal variations in brightness over the Earth's surface without saturation whilst maximising the precision of the measurements, the gain and offset of the visible channels is selectable in flight. These channels have a signal to noise ratio of 20:1 at 0.5% spectral albedo and measure top of the atmosphere radiances to an absolute accuracy of 5% over its entire range.

Two specific geophysical parameters are also available in the AATSR products over land:

NDVI

The standard AATSR Level 2 product includes the Normalised Difference Vegetation Index (NDVI) using the 0.67 and 0.87 µm channels.

Land Surface Temperature

The AATSR thermal bands used for SST retrieval are also available over land and are used to retrieve Land Surface Temperature (LST) in the AATSR gridded (1 km) product. Algorithms for deriving LST using split-window radiances are sufficiently advanced that accuracies of 1-3 K are possible. Better accuracies (about 1 K) are obtained at night when differential surface heating is absent.

Measurements of radiance over exceptionally hot targets such as deserts, burning vegetation and volcanic eruptions are also possible using AATSR's 'low-gain' mode.  This prevents saturation of the thermal channels and applies to targets with an upper limit of 500°C.

1.1.1.3 Cloud and Atmospheric Measurements

Currently AATSR does not retrieve cloud and atmospheric parameters on a routine basis. However, the different AATSR channels can be used directly to provide information on the basic location, extent and structure of clouds. Two fields in the Level 2 product have also been reserved for Cloud Top Temperature (CTT) and Cloud Top Height (CTH), should suitable retrieval algorithms become available in the future.

Work with ATSR-2 data has also demonstrated that the visible and thermal channels can be combined to estimate a number of specific properties within the cloud field. These include:

  • Optical Depth, broadly related to the vertical dimension of the cloud;
  • Phase, which determines whether the cloud contains ice or water;
  • Particle Size, the effective radiative dimension of the cloud particles; and,
  • Pressure, reflecting cloud top pressure or altitude.

The dual views provided by AATSR also offer a stereo viewing capability that can be used to discriminate between the different layers and structures within the cloud and also to estimate cloud top height.

1.1.1.4 Cryosphere

AATSR visible and thermal channel data can be used for studies of the cryosphere. Used on their own, or more often synergistically with other sensors, potential applications include snow cover monitoring, monitoring variations in annual sea ice growth and decay, location of boundaries and features of the Antarctic ice sheet, and feature mapping for radar altimetry over land and ice. The discriminatory power of the 1.6 µm channel for cloud and ice/snow is a topic of particular research interest.