CHANGELOG.TXT

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                           # Polymer changelog #
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v4.17beta2
----------

- Release date: 2023-12-22

* MSI: allow using embedded ECMWF auxiliary data
* Fix an error to access the Earthdata API

v4.17beta1
----------

- Release date: 2023-07-11

* Optimise the experimental processing mode (minabs2)
* General optimisations in the cython code
* Add PRISMA processing


v4.16
-----

- Release date: 2023-03-30

* Added support for GMAO_FP NASA auxiliary files (https://oceancolor.gsfc.nasa.gov/docs/ancillary/)
* Updated the experimental configuration for coastal and complex waters "minabs2" for MSI
  (see release note of v4.15). 


Bugfix release 4.16.1 (2023-04-07): fix a bug in GMAO_FP reader (surface pressure unit conversion)


v4.15
-----

Release date: 2023-01-18

1) Added uncertainty propagation for MSI and OLCI:
Uncertainties are provided at TOA, and propagated through the atmospheric correction process.
They are provided at output through the (optional) parameters logchl_unc, logfb_unc and rho_w_unc.
Uncertainty calculation is activated like so:
    run_atm_corr(
        <Level1>,
        Level2(..., datasets=default_datasets+uncertainty_datasets),  # imported from level2.py
        uncertainties=1
    )

2) Added experimental (optional) processing mode for complex costal and
inland waters:
* Added optional parameterization of mineral absorption switching
  for chl>10 (option min_abs=-2)
* Updated first guess: don't reuse result of previous pixel. Test several
  points across the cost function (option initial_points)
* Include SWIR bands (1020 for OLCI and 1610 for MSI) for bands_corr
  and bands_oc.
The corresponding configuration is stored in dedicated dictionaries in params.py
Summary of the experimental configuration:
* OLCI:
  from polymer.params import params_minabs2_OLCI
  run_atm_corr(..., **params_minabs2_OLCI)
* MSI:
  from polymer.params import params_minabs2_MSI
  run_atm_corr(..., **params_minabs2_MSI)
Flagging: with this experimental processing mode, it is recommended to also filter
out pixels such that Rw560 > 0.2

3) Added experimental (optional) processing of vegetation adjacency:
This option is activated by passing the option atm_model='T0,-1,-4,veg'
to the function run_atm_corr.
Example:
    run_atm_corr(
        <level1>, <level2>,
        atm_model='T0,-1,-4,veg'
    )

Other changes:
- Default format for Level2 is now set to NetCDF
- Updated make_L1C for newer SeaDAS versions
- Support MSI processing baseline 4.00 (account for the offset in TOA reflectance)
- Allow writing Ci (atmospheric parameters) to output. Add "Ci" to the list of
  datasets passed to Level2.
- Include OLCI bands 674 and 885 in output by default
- MODIS: fix interpolation of relative azimuth angles
  (could affect MODIS L1C products from recent SeaDAS releases)
- parameter bbs is renamed to logfb
- updates in luts.py


v4.14
-----

Release date: 2021-12-17

Various fixes and updates:

* Added support for MERIS 4th reprocessing. The class `Level1_MERIS` can be used for both 3rd and 4th reprocessing

* Add a flag called ANOMALY_RWMOD_BLUE (value 4096), designed to filter anomalous pixels on MODIS, especially
  for recent years and high sun zenith angles. Improved the README section regarding the quality flags.

* OLCI: avoid flagging inland waters by default

* Ancillary_NASA: General rework of the module, allowing support for NCEP forecast files.

* Updated dependencies installation script (see README)

* Landsat8: support level1 products from collection 2

Other fixes:
* Fix ozone unit in Level1_NETCDF
* Support land bands in MODIS
  MODIS land bands (469, 555... ) are now supported, though not provided by default in the output
  They can be processed by tuning the parameter `bands_rw`.
* Fixed Level1_ASCII
* Fixes for Landsat8:
  - Fixed lat/lon swapping when using gdal v3
  - Added support for Landsat8 SWIR bands
  - Added autodetection in Level1 class
* Sentinel-2 MSI: fixed an offset of half a pixel in lat/lon

Summary of products evolution:
* lat/lon coordinates of S2 and L8.
* inland waters flagging for OLCI
* added flag ANOMALY_RWMOD_BLUE

v4.13
-----

Release date: 2020-03-25

This release fixes some bugs, and do not involve product modification
(except when using ERA5 ancillary data)

* OLCI: Fix a bug involving masked arrays when using ancillary data

* ERA5 ancillary data: fix a bug in the interpolation of ERA5 ancillary data

* NASA ancillary data: support EarthData authentication

Minor changes:
* MSI: Add band 842 by default in the outputs
* Consistently use float32 dtype for Rgli output variable

Summary of products evolution:
* No impact, except when using ERA5 ancillary data.


v4.12
-----

Release date: 2019-09-11

* Updated OLCI-A SVC
  Note: OLCI-A gains are also applied by default to OLCI-B.

* Ancillary data: added support for ECMWF ERA5 in polymer/ancillary_era5.py
  (https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5)
  
* VIIRS: use more stringent cloud masking options by default
  (thres_Rcloud_std = 0.005)

* Add support for VIIRS/JPSS1
  
* README file: add a summary of the recommended flags for each sensor

* Fix a problem with flagging of invalid pixels in landsat8 reader

* Fix a bug in HICO reader

Summary of the product evolution:
* OLCI: significant changes due to updated SVC.
  Improved stability in the sun glint.
  Water reflectances may be slightly overestimated.
* VIIRS: evolution of the default cloud mask
* HICO: major improvement due to bugfix
* Other sensors: no evolution


v4.11
-----

Release date: 2019-05-14

* OLCI: updated spectral bands usage.
  Band 412 is not used for atmospheric correction anymore (but still provided
  as an output), following what is done for VIIRS.
  This solves occasional unstability issues.
  SVC coefficients for OLCI are reset to 1 until OLCI SVC is re-generated.

* SeaWiFS, MODIS, VIIRS: updated System Vicarious Coefficients (SVC) by
  Constant Mazeran with NASA Reprocessing R2018, updated in-situ database and ERA-Interim parameters.
  Only use this version with L1C files generated with SeaDAS configured for R2018!
  Previous versions should only use L1C files generated with SeaDAS configured for R2014.

* Add landsat8 reader
  from polymer.level1_landsat8 import Level1_OLI
  Landsat8 processing requires prior angle generation for band 1 in ENVI format.

* HICO: Level1 reader is updated to the newer NetCDF format.

* Fix a bug affecting Polymer's (basic) cloud mask
  Rayleigh correction of the NIR bands used for cloud masking was affected by a
  bug, resulting in over-correction, and therefore cloud mask was less strict than it should have.
  This bug was introduced in version 4.8.

Summary of the product evolution:
    * All NASA sensors (MODIS, SeaWiFS, VIIRS) are affected by SVC gains update
      and concomitant Level1 update
    * OLCI is affected by bands configuration update and concomitant SVC gains reset
    * MERIS and MSI results do not evolve, but:
    * Change in Polymer's cloud mask for all sensors


v4.10
-----

Release date: 2019-01-24

* SeaWiFS, MODIS, VIIRS: Updated central wavelengths to be equal to the values
  provided in SeaDAS (disactivate dynamic central wavelength calculation from
  SRF files)
* Updated Level1_ASCII to be able to process SeaWiFS, MODIS and VIIRS extractions.
  Allow specifying units of ozone if Level1_ASCII.

Summary of the impact on products (water reflectance) with default options:
- MODIS, SeaWiFS, VIIRS: small changes
- other sensors: no change


v4.9
----

Release date: 2018-11-22

* Updated OLCI vicarious calibration gains
  This leads to a significant improvement of the validation results in the blue bands
* Added HICO processing [EXPERIMENTAL]
  The HICO reader is the class Level1_HICO in module Level1_hico.py
* Added bands 681 and 709 by default for MERIS and OLCI
* Other fixes:
    * Fix Level1_NASA with netCDF-1.4
    * Fix flagging of MSI out-of-swath pixels
    * Fix flagging of OLCI invalid pixels
    * Fix a bug in Leve1_ASCII when reading OLCI extracted data
    * Deal with a formatting issue of SeaWiFS Level 1C
      https://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?tid=8804

Summary of the impact on products (water reflectance) with default options:
    - OLCI: significant changes
    - Others: no change


v4.8
----

Release date: 2018-04-27

* Reworked Rayleigh correction.
  Now Polymer uses a single Rayleigh Look-Up-Table for all sensors, tabulated
  in Rayleigh optical thickness instead of sensors spectral bands.
  This allows better accounting for per-pixel variations of wavelength (MERIS,
  OLCI) and surface pressure.
  Surface pressure can now take the elevation into account (see added DEMs).
  Rayleigh optical thickness is calculated on the fly pixel by pixel using [Bodhaine,99].

* Added Digital Elevation Model interfaces (DEM), used for modulation of
  Rayleigh optical thickness.
    - SRTM3: SRTM3 digital elevation model, version 2.1
      Spatial resolution of 3arc-seconds (93m at equator), 56°S to 60°N
    - GLOBE: NOAA Global Land One-km Base Elevation Project (GLOBE)
      Spatial resolution of 1km, global.
      Can be used as a fallback to SRTM3.

* Added an independent landmask, based on global surface water (GSW: https://global-surface-water.appspot.com/).
  This is particularly useful for Sentinel-2 which does not have a landmask in L1C.
  It should be passed as a parameter to Level1 instances. Example:
      from polymer.gsw import GSW
      Level1_MSI('<L1C product>', landmask=GSW('<gsw tiles storage directory>'))

* OLCI: avoid duplicate correction for sun-earth distance.
  This has an impact on the retrieved Rw.

* Use MSI SRF (spectral response functions) to calculate accurate central
  wavelengths (different for S2A and S2B)
  This has a significant impact on the water reflectance retrieval, especially
  in the blue, mainly because of the change in equivalent wavelength of B2
  (490nm, 60nm wide).

* Optionnally use MODIS, SeaWiFS and VIIRS SRF to calculate central wavelengths
  for each band. This leads to significant changes of the Rayleigh optical
  thickness estimation, thus on Rayleigh correction.

* Added the central wavelengths for each band in the product attributes

* Added an anaconda installation helper (automates the installation of anaconda
  dependencies required by Polymer)

* Bug fixes, in particular avoid an occasional bug when reading pope97.dat

* Caveat: Level1_ASCII does not yet take properly into account spectral
  information for all sensors in the new Rayleigh correction scheme. A warning
  is issued when it is the case.

Summary of the impact on products (on Rw) with default options:
    - MERIS: minor changes
    - OLCI: moderate changes due to correction of duplicate sun-earth
      distance correction (bias of a few percents)
    - MSI: significant changes because of better accounting for spectral information
    - VIIRS, MODIS, SeaWiFS:
        - minor change with default options (use_srf=False)
        - if use_srf=True, significant changes due to different accounting
          for the sensors spectral response functions for Rayleigh correction).
          This modification is still experimental. Consolidation and validation
          are on-going.


v4.7
----

Release date: 2018-02-02

This release introduces vicarious calibration coefficients for OLCI, and
corrects a few issues with previous version:

* Added OLCI SVC coefficients provided by C. Mazeran
  These coefficients are now used by default
  The previous coefficients (gains=1) can be restored by passing the argument "calib=None" to run_atm_corr.
* OLCI: fix a problem when using auxiliary data embedded in OLCI level1 (the default).
  3rd order interpolation of the auxiliary data fields was used, which could result in negative wind speeds in some cases.
  Now using linear interpolation.
* Added support for OLCI in Level1_ASCII
* Fix a problem in Level2 cleanup in case of code error
* Level1_NETCDF:
    - Fix a compatibility problem with older versions of libnetcdf
    - Allow to specify the ozone unit


v4.6
----

Release date: 2017-11-23

New features:

    * Now supporting Sentinel 2 processing at 10 and 20m spatial resolution
      To activate high resolution processing, pass the option resolution=10 or
      resolution=20 to Level1_MSI.

    * Wavelength normalization for MERIS and OLCI.
      In Polymer, the atmospheric correction is performed at each detector
      wavelength (instead of applying smile correction to the TOA radiance). A new
      spectral correction is applied to the final water reflectance, simultaneously with
      the already existing bidirectional reflectance correction:
          Rw_normalized = Rw(lam,geom)*(Rwmod(lam0,nadir)/Rwmod(lam,geom))
          where:
             lam is the measured wavelength (for a given detector)
             lam0 is the central wavelength for the considered band
             geom is the observation geometry
             nadir is the normalization geometry, where the sun and sensor are both at nadir
             Rw is the non-normalized water reflectance
             Rw_mod is the water reflectance provided by Polymer's model for the current ocean parameters
             Rw_normalized is the water reflectance, normalized for the 'nadir' observation geometry and the wavelength lam0
      This correction is applied by default, and can be disactivated using the keyword normalize.

    * Added ERA-Interim interface: interface with ECMWF ERA-Interim dataset.
      Use it by passing an instance of Ancillary_ERA to the Level1.
          from polymer.ancillary_era import Ancillary_ERA
          Level1(<filename>, ancillary=Ancillary_ERA())
      See the relevent section of README.TXT

    * Add options to activate an optional "Arctic" mode in the ParkRuddick
      model (credits Atsushi Matsuoka).
      To activate it, pass the following arguments to run_atm_corr:
        absorption='matsuoka': use aphy from Matsuoka et al, JGR 2011
                               and Scdm from Matsuoka et al., 2013, BG
        bbopt=2 : set the particle backscattering spectral dependency to eta=1

    * Added support for Sentinel 2 products in netCDF4 format, as written by SNAP (Level1_NETCDF)

Corrections:

    * OLCI: fix flagging issues. Add an option to disactivate land masking in Level1_OLCI and Level1_NETCDF
      (when providing the land mask through external masking)
    * OLCI: use nearest neighbour interpolation for reading azimuth angles from tiepoint grids
      This avoids incorrect interpolation when an azimuth changes sign.
    * OLCI: fixed incorrect usage of ancillary data.
      Now properly read all ancillary data from OLCI Level1, and switch to NASA
      or ERA-Interim when passing the appropriate option (see README)
    * Improved autodetection of Sentinel2 products.
      The product autodetection feature is used when using the Level1 class, or polymer_cli.py
    * Some minor fixes regarding Sentinel 2 products attributes


v4.5
----

Release date: 2017-08-25

Bug fixes:
  * Fix improper flagging of NASA L1C
    Was resulting in rows improperly flagged as CLOUD for VIIRS around trimmed pixels
  * Fix for MM01 model: improper initialization could result in errors in high chl conditions
  * Fix for compatibility with older versions of cython (0.23)

v4.4
----

Release date: 2017-07-27

* Add support for Level1 MERIS and OLCI files subsetted by SNAP, in NetCDF4 format.
  Example:
    from polymer.level1_netcdf import Level1_NETCDF
    run_atm_corr(
        Level1_NETCDF('subset_0_of_MER_FRS_1PPEPA20080806_094519_000005122071_00022_33643_2741.nc'),
        Level2(),
        )
* Reintroduce support for external masking.
  The relevant keyword to pass to run_atm_corr is external_mask.
  external_mask can be:
    * None
    * a string: the filename of a hdf4 file containing an integer dataset 'mask'
    * an integer or boolean numpy array
    In the latter two cases, the shape of the mask shall be the same as the Level1 product.
* Allow to select columns in MERIS and OLCI products.
  Example for OLCI:
    run_atm_corr(
        Level1_OLCI(
            filename,
            sline=1117,     scol=2871,
            eline=1117+100, ecol=2871+100,
            ),
        Level2(),
        )
* VIIRS: small change in params.py for backward compatibility (params_v3_5_VIIRS_MM01)
* Add requirements.txt for python dependencies installation with 'pip install -r requirements.txt'
* Minor consistency fix in OLCI params (bands definition)


v4.3
----

Release date: 2017-07-17

* Reintroduce bidirectional water reflectances in MM01
  Directional model is used with water_model='MM01_FOQ'
  Non-directional model is used with water_model='MM01'
* Define parameters for VIIRS and OLCI, consistent with v3.5 with MM01 model (in params.py)
  Use them like so:
      from polymer.params import params_v3_5_VIIRS_MM01
      run_atm_corr(..., **params_v3_5_VIIRS_MM01)
* Some improvements in ancillary data management
  (don't fail when no meteo file is available after the file date)
* Keep build files in separate directory 'build'
* Better filter out invalid pixels at high sza
  (avoid raising a division by zero warning)
* Allow writing partial spectra in Level2 output datasets
  Example: Level2(..., datasets=['Rw',       # write all Rw bands
                                 'Rtoa560',  # write only band Rtoa at 560
                                        ])

v4.2
----

Release date: 2017-04-26

* Fixes to Sentinel-2 processing
* Some functions are modules renaming.
  previous import: from polymer.polymer import polymer
  new import: from polymer.main import run_atm_corr
  (previous import kept for backward compatibility)
* Improved command line interface.
* README update
* Various cleanup and fixes
    - netcdf output format improvements
    - ancillary data handling
    - python3 compatibility
    - add script make_L1C.py


v4.1
----

Release date: 2016-12-23

* Updated SVC coefficients for using NCEP data instead of ERA
* Improved netCDF4 support:
    - support NETCDF_CLASSIC format (activated by default in netcdf output)
      added keyword to switch to standard netcdf output
    - write attributes in netCDF4 files
* Improved attributes in output:
    - write bitmask description
    - write scene start and end times
* Improved meteo and ozone files support
    - support meteo interpolation in ancillary.py
    - improved ancillary file search
    - allow to provide explicitly couples of meteo files for interpolation
    - interpolation is not activated for ozone files as NASA files are not
      provided at a fixed date
    - write names of ancillary files in the output attributes
    - added offline mode to ancillary.py
* MODIS: don't fail on grazing angles/night pixels
  Flag such pixels as 'EXCEPTION', as was done before v4
* Add a flag HIGH_AIR_MASS to flag air masses higher than 5
  (rejects pixels when applying rejection bitmask expression "bitmask & 1023")
* Embed rejection bitmask in bitmask attributes
* Improvement in makefile
* Various fixes, including python2/3 compatibility


v4.0
----

Release date: 2016-10-18

* Updated vicarious calibration coefficients (oct 2016)
* Implemented the "thick aerosol" flag (problem detected for CCI QA, for
  example MERIS orbit 14935)
  Flag value is 64, applied by removing pixels such that bitmask & 1023 != 0


v4.0beta5
---------

Release date: 2016-10-06

* VIIRS: don't use band 412 by default
  'Solves' problem of stability over clear waters (MOBY)
* Use by default Rprime_consistency:
  Check for inconsistent results (t*Rw or atmospheric signal Ratm exceeds TOA
  corrected for Rayleigh only - at any band), triggers reinitialization.
  Raises flag 2048.
  Significant stability improvement for SeaWiFS - minor changes for other sensors.
* Phytoplankton absorption: use Bricaud98 instead of Bricaud95
* Add options to water model
* Allow for 3 parameters inversion (chl, backscattering, absorption)
  (not used by default)


v4.0beta4
---------

Release date: 2016-09-16

* fix a memory leak in multiprocessing mode
* generalization of level1_ascii
* Improved level1_msi
* python3 fixes
* packaging improvements (sources in the polymer/ directory).
* Various fixes


v4.0beta3
---------

Release date: 2016-07-29

* added an inconsistency test which raises a flag (64) and reinitializes the pixel parameters.
  Some unstable results for SeaWiFS are avoided. Some dubious pixels are flagged out.
* improved the definition of the cost function by normalizing by the sum of
  weights. This has an impact on backscattering constraint for clear waters and
  should improve the inter-sensor consistency over clear waters.  The amplitude
  of the constraint is modified accordingly.
* Bugfix in Level1_ASCII (only affecting v4)
* Fix month determination in NO2 calculation
* Slight improvement in water reflectance calculation, improves consistency with C code.
* Allow to pass external ancillary data to MERIS, as was already the case for
  NASA sensors (see parameter ancillary of Level1_* classes)
* Minor changes


v4.0beta2
---------

Release date: 2016-07-25

A few fixes:
* Add a missing auxiliary file
* Level1_ASCII: Deal with ASCII extractions of multiple sensors
+ a few more corrections


v4.0beta1
---------

Release date: 2016-07-22

* Complete rewrite in python+cython:
    * Processing speed is similar to the C version (about 5% slower)
    * Results should be quasi-identical to the results of v3.5
        (verified thoroughly for MERIS, and roughly for NASA sensors)
    * multiprocessing mode: can use several CPUs available on local machine to
      speed-up processing
    * command files are no longer used. Parameters are passed directly to the
      python function 'polymer'.
    * Support all previous sensors: MERIS, MODIS, SeaWiFS, VIIRS
    * Support OLCI (Sentinel 3) and MSI (Sentinel 2)
    * Support ASCII files (MERIS only)
* Minor algorithm chage: avoid re-initializing minimizer when a negative
  reflectance is obtained.
  => Results are almost unchanged. Processing speed increases by about 30%.
  (because slightly negative reflectances in the NIR are often obtained)


v3.5
----

* LICENCE updated and included in the package
* cleanup in README and run scripts
* MODIS: avoid failing over granules containing ths>90
* Fixed start/stop attributes in output (J. Dingle)
* added missing command files command_meris_MM01.txt


v3.4
----

* Cleanup of command files, especially for SeaWiFS
* Split command files using old & new water models: MM01 and PR05
  MM01 reproduces results from v3.2
  PR05 reproduces results from v3.3
* Add SeaWiFS support in make_L1C.py

v3.3
----

* Added new ocean model (PR05) based on Park&Ruddick, 2005.
  This model is adapted to case 1 and case 2 processing
  Added necessary auxiliary files.
* Added "full" normalization with this model
* Switch between "case 1" and "case 2" modes (pixel initialization adapted to
  resp. case 1 and case 2.
  Added a flag 1024 when case 2 mode is used (this flag does not invalidate a pixel).
* Added Raman scattering in PR05, based on simulations from Westberry et al, 2013
* Updated atmospheric model: now use Rmol instead of lambda^-4
  This reduces the bias at high latitudes
  The command file parameter is changed from
        POLY_EXPO         0. -1. -4.
    to
        POLY_EXPO         0. -1. 0.
* Add support for L1C files in netcdf format (J. Dingle)
* Updated MERIS, MODIS and VIIRS command files
* Some cleanup


v3.2
----

* VIIRS and MODIS: now use 'L1C' files produced by l2gen, which brings all
  radiometric corrections to MODIS and VIIRS.
  A sample file producing L1C files is provided in tools/make_L1C.py
  A new class is added as an interface to these files: level1_l2gen.
  The classes level1_modis and level1_viirs are no longer used and may be deleted.
  The run and command files are updated accordingly.
* minor update in MODIS LUTs: update wavelength 551 -> 547.
  Only the wavelength is updated, the Rayleigh optical thickness (thus the
  values of the LUT) is unchanged.


v3.1
----

* Add VIIRS destriping
  Uses VIIRS XCAL tables provided in SeaDAS
  (added to Polymer's data package)
* Write the meteo and ozone files in the level2 attributes


v3.0
----

* support VIIRS processing
  new dependency: requires hdf5 library (VIIRS processing can be deactivated in Makefile)
  added new VIIRS auxiliary data (see checksums/data_viirs.md5)
* (minor) fix a valgrind warning
* add MERIS full resolution data
  to process MERIS FR data, adjust FILE_SUN_SPEC_FLUX and
  FILE_DETECTOR_WAVELENGTH in command file to use the FR version.
* bugfix: properly read NO2 data when in ascii mode.
  the NO2 correction did not work correctly when in ascii mode (which requires
  reading 12 months of NO2 climatology instead of just 1).
  => slight change of the results processed in ascii mode.
Note: this version brings no change of the MERIS, MODIS and SeaWiFS results.


v3.0beta8
---------

* fix reading of MODIS level 1. Now read radiances and convert to reflectance
  instead of incorrectly directly reading 'reflectances'.
  => change of results
  Also updates MODIS F0 values:
  auxdata/modis/sun_spectral_flux_2.txt replaces auxdata/modis/sun_spectral_flux.txt
  and is provided in data package
* update CALIB in command_modis.txt to match current values of NASA's vicarious coefficients


v3.0beta7
---------

* NetCDF output: allow 'classic' NetCDF4 output
  Activated by specifying 'OUTPUT_FORMAT NETCDF_CLASSIC' in command file
* NetCDF output: change compression from 9 to 4
* MODIS and SeaWiFS: write attributes 'start_time' and 'stop_time'
* minor: fix tmpfiles includes in get_meteo and get_era_interim


v3.0beta6
---------

* Bugfix
* Minor Makefile tweak (Mike)


v3.0beta5
---------

* do not stop processing when encountering a grazing angle (outside of the LUT
  boundaries)
  => this was preventing processing MODIS granules containing pixels with
  grazing sun angle.
  A new bitmask ("EXCEPTION") is dedicated to flagging such invalid pixels.
* minor corrections and clean-up

v3.0beta4
---------

* Add support for MERMAID (ASCII) input files.


v3.0beta3
---------

* Added python script tools/get_era_interim.py
    - download and interpolate ERA-Interim data (GRIB format)
    - This script has the same functionality as get_meteo.py
    - additional requirement: python library "pygrib"
    - updated the sample python scripts run*.py to use optionally ERA-Interim

* Minor change
    - add option to write water reflectance from the model (for debugging)
    - add option to skip normalization of the reflectances (for debugging)



v3.0beta2
---------

* General changes

    - fixed normalization of water reflectance (account for the gothic-R term)
      => PRODUCT CHANGE, affects ALL PRODUCTS
      The surface transmission in the sun direction is modeled after Wang2006
      The command files have been updated to include a keyword related to this
      normalization correction (BRDF_OPT)

    - several minor corrections

    - fixed a minor bug related to band indexing in the normalization step.
      This bug could introduce a minor product change if BANDS_CORR, BANDS_OC and
      BANDS_RW are not all identical in the command file.

    - add the possibility to write intermediary products for debugging
      (command file keywords WRITE_RTOA, WRITE_RTOAGC)

* MERIS processing

    - The values of Rayleigh optical thickness used to generate the look-up
      tables have been updated to follow the SeaDAS values (derived from
      Bodaine et al 1999).
      => PRODUCT CHANGE
      => The MERIS look-up table has been updated from LUTS/MERIS/LUT.hdf to
         LUTS/MERIS/LUTB.hdf

* Added processing of SeaWiFS data from level 1B.

    - Added SeaWiFS command file (command_seawifs.txt)
    - Added SeaWiFS sample run script (run_seawifs.py)
    - Added SeaWiFS auxiliary data (see checksums/data_seawifs.md5)
    - the 'invalid' SeaWiFS data is considered to be NAVWARN+NAVFAIL+HILT
      (adjustable in src/main.cpp)




v3.0beta1 (since v2.7)
----------------------

* General changes

    - Changed LUT format: now using hdf format instead of binary, which is more
      compact and flexible. The axes are stored along the LUT. The list of
      auxiliary files (listed in checksums/*.md5) has thus changed. There is now an
      optional distinction between solar and view zenith angles in the LUTs, in
      view of using spherical LUTs where the principle of reciprocity is not valid.

    - Improved debugging mode where all info is printed for one pixel specified by
      lat/lon (required compilation in debug mode). The coordinates of the target
      pixel are provided by the keyword "DEBUG_POINT <lat> <lon>" in the command
      file. Only the debug_point is processed.

    - Improved the base Array classes. Provide 2 different classes for storing data
      in row-major order (ArrayC) or column-major order (ArrayF).

    - Allow writing (optionally) the observation angles in the output file.

    - Added consistency checks for the input parameters and files.

    - Code cleanup and other small fixes.

* MERIS processing:
    - now properly flag out COSMETIC pixels
    - otherwise, the products should be identical to v2.7

* Added processing of MODIS data from level 1B. The GEO file must be present
  alongside the L1B.

* Changed auxiliary files according to the change of LUT format and presence of
  MODIS processing. MODIS processing requires providing a FILE_METEO and a
  FILE_OZONE, the same way as for MERIS when using TOMS+NCEP files.