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GOME-2 surface LER & DLER database |
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Tropospheric
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NO2
- global CH2O - global CO - global |
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UV
- UV index - UV dose |
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Ozone
- total column - global field - ozone bulletin - ozone profiles - tropospheric |
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Aerosol
- ADRE - aerosol index Methane - global CO2 - global Clouds - cloud info Surface - solar irradiance |
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Volcanic plume
- SO2 & AAI |
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Albedo
- climatologies Fluorescence - sun-induced |
The GOME-2 surface LER database contains the Lambertian-equivalent
reflectivity (LER) of the Earth's surface at 27 one-nm wide wavelength
bins between 328 and 772 nm. The LER albedo values were derived from
GOME-2 data using the Doubling-Adding KNMI (DAK) polarised radiative
transfer code. The model consists of an atmosphere for which Rayleigh
scattering and ozone absorption are taken into account, and which is
bounded below by a Lambertian surface. The surface LER is available for
each month of the year and for the following wavelengths: 328, 335, 340,
354, 367, 380, 388, 416, 425, 440, 463, 494, 510, 526, 546, 555, 564,
585, 610, 640, 670, 685, 697, 712, 747, 758, and 772 nm. Next to this,
we also provide a GOME-2 surface LER database which is based on PMD band
measurements.
Since version 3.0 the GOME-2 surface LER database additionally contains
the so-called directionally dependent Lambertian-equivalent reflectivity
(DLER) of the surface. In the GOME-2 surface DLER product, the
viewing-angle dependence of the reflectivity of the surface, due to the
BRDF of the surface, is taken into account, which improves the product
considerably, especially for the longer wavelengths.
Some examples of
the database:
Examples of the GOME-2 surface LER: dependence on the month of the year (left) and dependence on the wavelength (right). |
Archive:
The following databases based on GOME-2A + GOME-2B + GOME-2C observations are available:
GOME-2_MetOp-ABC_MSC_025x025_surface_LER_v4.0.nc (2.3 GB)
GOME-2_MetOp-ABC_PMD_025x025_surface_LER_v4.0.nc (1.6 GB)
Previous versions of the databases can be downloaded here.
Most users will only be interested in the GOME-2 surface LER database
that was based on Main Science Channel (MSC) observations. The
wavelength bands (listed above) are more or less monochromatic (one nm
wide) and suitable as input for the retrieval of most atmospheric
species. The intrinsic resolution of the MSC-LER database is
1°×1°, but increased to 0.25°×0.25° near
coastlines and certain snow covered mountain ranges. The spatial
resolution of the database grid therefore is 0.25°×0.25°.
Next to the normal MSC-LER database, there also exists a GOME-2 surface
LER database based on the PMD bands. This PMD-LER database is mostly
relevant to users that use GOME-2 PMD band measurements for their
retrievals. Note that some discrepancies between the radiometric
calibration of the main science channels and the PMD bands have been
reported in the past (PDF). The intrinsic resolution of
the PMD-LER database is 0.5°×0.5°, but increased to
0.25°×0.25° near coastlines and over the Sahara desert.
The spatial resolution of the database grid therefore is
0.25°×0.25°.
The format and the contents of the files are explained here. The current version of the
database is 4.0.
Developments / Improvements:
In version 2.0 the concept of dynamical gridding was introduced,
resulting in an increased spatial resolution near coastlines and for
other specific regions. In version 2.3 new wavelength bands at 328, 585,
685, 697, and 712 nm were added. The new wavelength bands at 685, 697,
and 712 nm, together with the already existing wavelength band at 670
nm, are meant to support the retrieval of cloud and/or aerosol
information from the oxygen B-band. To achieve an optimal retrieval of
the surface LER for the wavelength bands at 697 and 712 nm we included
water vapour absorption in the radiative transfer calculations. Since
version 2.5 a bilinear interpolation scheme smoothens the low-resolution
regions to the high-resolution database grid which makes it easier for
users to handle the data. Also, the error calculation has been improved
and now the product contains systematic and statistical uncertainty
estimates. In version 3.0 the DLER was introduced. Since version 3.1 the
file format used is NetCDF-4. In version 4.0 an additional wavelength
band at 747 nm was introduced.
Origin / Creator:
The GOME-2 surface LER databases are provided by KNMI in the framework
of the EUMETSAT Satellite
Application Facility on Atmospheric Composition Monitoring (AC SAF).
Data use /
License / Citation:
The GOME-2 surface LER databases are free to use for commercial and
non-commercial purposes. If you use any of the databases for a
publication (research or otherwise), or for any other purpose, please
refer to the following publications:
L.G. Tilstra, O.N.E. Tuinder, P. Wang, and P. Stammes, Surface
reflectivity climatologies from UV to NIR determined from Earth
observations by GOME-2 and SCIAMACHY, J. Geophys. Res. Atmos. 122,
4084-4111,
doi:10.1002/2016JD025940, 2017. (PDF)
L.G. Tilstra, O.N.E. Tuinder, P. Wang, and P. Stammes, Directionally
dependent Lambertian-equivalent reflectivity (DLER) of the Earth's
surface measured by the GOME-2 satellite instruments, Atmos. Meas.
Tech. 14, 4219-4238,
doi:10.5194/amt-14-4219-2021, 2021. (PDF)
We suggest that you include the following acknowledgement: "We
acknowledge the free use of the GOME-2 surface LER database provided
through the AC SAF of EUMETSAT. The GOME-2 surface LER database was
created by the Royal Netherlands Meteorological Institute (KNMI)."
Documentation: