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    24-Jul-2014
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Ocean products
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Global Annotation Data Set - Scaling Factors
Annotation Data Set "Summary Product Quality"
Specific Product Header
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MERIS Land Pixels Processing
MERIS Bottom Of Atmosphere Vegetation Index (BOAVI) (step 2.8)
Atmospheric correction over land (step 2.6.23)
MERIS Top Of Atmosphere Vegetation Index (TOAVI) (step 2.2)
Water Processing
MERIS Ocean Colour Processing (step 2.9)
Clear water atmospheric corrections (step 2.6.9)
Turbid water screening and corrections (steps 2.6.8, 2.6.10)
Water Confidence Checks (step 2.6.5)
Cloud Processing
Cloud type processing (step 2.4.8)
Cloud Optical Thickness processing (step 2.4.3)
Cloud Albedo processing (step 2.4.1)
Total Water Vapour Retrieval
Water vapour polynomial (function)
Range checks (steps 2.3.0, 2.3.6)
Water vapour retrieval over clouds (step 2.3.3)
Water vapour retrieval over water surfaces (steps 2.3.2, 2.3.5)
Water vapour retrieval over land surfaces (step 2.3.1)
MERIS Pixel Identification
Land Identification (step 2.6.26) and Smile Effect Correction (step 2.1.6)
Gaseous absorption corrections (step 2.6.12)
Stratospheric Aerosol Correction (step 2.1.9)
Cloud screening (steps 2.1.2, 2.1.7, 2.1.8)
MERIS Pressure Processing
Atmospheric pressure confidence tests (steps 2.1.2)
Atmospheric pressure estimate (steps 2.1.5, 2.1.12)
MERIS Pre-processing
Pre processing step
Level 1b product check
Level 2 Physical Justification
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Introduction
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2.7.1.1 Level 2 Physical Justification

The MERIS mission is concerned with three broad classes of applications associated respectively to three types of surfaces: ocean, land, and clouds.

These different types of surfaces lie below the stratosphere, which can introduce perturbations to the observations. Only two of them are considered significant enough to justify correction: absorption by ozone and the presence of volcanic aerosols.

When this initial correction has been applied, the next task is to attribute pixels to the three types of surfaces. This classification of pixels is based on a combination of radiometric thresholds, spectral slopes and several pressure estimates that can all be derived from the information contained in the MERIS bands.

When the classification has been performed, each pixel is treated with algorithms appropriate to achieve the MERIS mission objectives. For the oceanic pixels, the main objective is to derive the water constituents, which necessitates a complex atmospheric correction. For cloud pixels, atmospheric correction is not necessary to retrieve cloud optical properties. For land pixels atmospheric correction is considered possible only over dense dark vegetation.

The physical justification of all the algorithms used in the Level 2 ground segment processing can be found in the series of MERIS Algorithm Theoretical Basis Documents (ATBDs). Table 2.23 contains the chapters of the ATBDs stored at the address on ENVISAT web site. They can be viewed with the Adobe Acrobat Reader, free software available on the Adobe web site (http://www.adobe.com/products/acrobat/readstep.html ) which allows users to view, navigate, and print PDF files on all major computing platforms.

Table 2.10 - MERIS ATBD references.

No

Title

Author

PDF size

2.0

Introduction (http://envisat.esa.int/instruments/meris/pdf/cover.pdf)

ACRI

36 kb

2.1 (& 2.2)

Cloud Albedo and Cloud Optical Thickness (http://envisat.esa.int/instruments/meris/pdf/atbd_2_01.pdf)

FUB

526 kb

2.3

Cloud Top Pressure (http://envisat.esa.int/instruments/meris/pdf/atbd_2_03.pdf)

FUB

1323 kb

2.4

Retrieval of Total Water Vapour Content from MERIS Measurements (http://envisat.esa.int/instruments/meris/pdf/atbd_2_04.pdf)

FUB

155 kb

2.5

Case 2 Turbid Waters Flag (http://envisat.esa.int/instruments/meris/pdf/atbd_2_05.pdf)

PML

245 kb

2.6

Case 2 (Sediment) Bright Water Atmospheric Correction http://envisat.esa.int/instruments/meris/pdf/atbd_2_06.pdf)

PML

308 kb

2.7

Atmospheric Correction over the Ocean (Case1 Waters) (http://envisat.esa.int/instruments/meris/pdf/atbd_2_07.pdf)

LPCM

4662 kb

2.8

Case 2 Anomalous Scattering and Gelbstoff Water Flags (http://envisat.esa.int/instruments/meris/pdf/atbd_2_08.pdf)

PML

924 kb

2.9

Pigment Index Retrieval in Case 1 Waters (http://envisat.esa.int/instruments/meris/pdf/atbd_2_09.pdf)

LPCM

614 kb

2.10

MERIS global vegetation Index (http://envisat.esa.int/instruments/meris/pdf/atbd_mgvi_jrc.pdf)

JRC-EC

1502 kb

2.11

Correction of volcanic aerosols

2.12

Pigment index, sediment and gelbstoff retrieval from directional water-leaving radiance reflectances using inverse modelling technique (http://envisat.esa.int/instruments/meris/pdf/atbd_2_12.pdf)

GKSS

697 kb

2.13

Sun Glint Flag Algorithm (http://envisat.esa.int/instruments/meris/pdf/atbd_2_13.pdf)

ACRI

110 kb

2.14

Whitecaps Algorithm

2.15

Atmospheric corrections over land (http://envisat.esa.int/instruments/meris/pdf/atbd_2_15.pdf)

PAMOC

535 kb

2.16

Cloud Reflectance (http://envisat.esa.int/instruments/meris/pdf/atbd_2_16.pdf)

FUB

37 kb

2.17

Pixel Identification (http://envisat.esa.int/instruments/meris/pdf/atbd_2_17.pdf)

LISE

274 kb

2.18

Photosynthetically Available Radiation (PAR) (http://envisat.esa.int/instruments/meris/pdf/atbd_2_18.pdf)

PML

18 kb

2.19

ATMOSPHERIC CORRECTION OVER LAND: CORRECTION OF DIRECTIONAL EFFECTS OVER DDV (http://envisat.esa.int/instruments/meris/pdf/atbd_2_19.pdf)

LISE

3377 kb

2.20

Cirrus cloud detection

LISE

2.21

Adjacency effects in coastal areas

LISE

2.22

MERIS Terrestrial Chlorophyll Index
(http://envisat.esa.int/instruments/meris/pdf/atbd_2_22.pdf)

Univ. Southampton


Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry