Dataset
Sentinel 5P: Suomi-NPP VIIRS cloud level 2 data
Latest Data Update: 2023-04-20
Status: Ongoing
Online Status: ONLINE
Publication State: Published
Publication Date: 2022-08-12
Download Stats: last 12 months
Dataset Size: 177.69K Files | 27TB
Abstract
The S5P NPP Cloud product contains information on cloud and scene homogeneity for TROPOMI scenes, derived from operational products from the VIIRS (Visible Infra-red Imaging Radiometer Suite) on board the Suomi National Polar-orbiting Partnership (S-NPP) platform. S5P operates in loose formation orbit with NPP, so that measurements from VIIRS are well co-located with TROPOMI, with a time difference of about 3.5 minutes. There is no specific validation of auxiliary products within the S5P Mission Performance Centre.
Sentinel 5 Precursor (S5P) was launched on the 13th October 2017 carrying the TROPOspheric Monitoring Instrument (TROPOMI). The TROPOMI instrument onboard S5P is a nadir-viewing, imaging spectrometer covering wavelength bands between the ultraviolet and the shortwave infrared. The instrument uses passive remote sensing techniques to attain its objective by measuring, at the Top Of Atmosphere (TOA), the solar radiation reflected by and radiated from the earth.
The S5P level 2 methane product is dependent on having information on cloud occurrence at spatial resolution finer than that achievable from TROPOMI itself. This information is also useful for other purposes, including assessing the influence of cloud on other L2 products and issues related to spatial co-registration. NPP-Cloud was therefore developed as a level 2 auxiliary product to describe cloud in the TROPOMI field of view (FOV), using co-located observations of VIIRS on the U.S. S-NPP.
The main information contained in the S5P-NPP product is:
1. A statistical summary for each S5P FOV of the NPP-VIIRS L2 Cloud Mask (VCM).
2. The mean and standard deviation of the sun-normalised radiance in a number of VIIRS moderate resolution bands.
This information is provided for three S5P spectral bands (to account for differences in spatial sampling).
Citable as: Copernicus; European Space Agency (2022): Sentinel 5P: Suomi-NPP VIIRS cloud level 2 data. NERC EDS Centre for Environmental Data Analysis, date of citation. https://catalogue.ceda.ac.uk/uuid/d69dccc3b50041bb91a126b85e9154d0/
Abbreviation: Not defined
Keywords: Sentinel, ESA, VIIRS, cloud, Suomi-NPP, S5P
Details
| Previous Info: |
No news update for this record
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| Previously used record identifiers: |
No related previous identifiers.
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| Access rules: |
Public data: access to these data is available to both registered and non-registered users.
Use of these data is covered by the following licence(s): https://sentinel.esa.int/documents/247904/690755/Sentinel_Data_Legal_Notice When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record. |
| Data lineage: |
Data collected and prepared by European Space Agency (ESA). Downloaded from the Collaborative Hub for use by CEDA users. |
| Data Quality: |
See dataset associated documentation
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| File Format: |
These data are in NetCDF format.
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Process overview
This dataset was generated by a combination of instruments deployed on platforms
and computations as detailed below.
Instrument/Platform pairings
| Suomi NPP: Visible Infrared Imaging Radiometer Suite (VIIRS) | Deployed on: SNPP |
Computation Element: 1
| Title | Level 2 (L2) cloud retrieval algorithm applied to Suomi National Polar-orbiting Partnership (SNPP) Visible Infra-red Imaging Radiometer Suite (VIIRS) instrument: level 2 Suomi-NPP VIIRS raw cloud data. |
| Abstract | The computation process for the transformation of cloud data from the VIIRS instrument on board the JPSS (Joint Polar Satellite System) operational meterological satellite prototype SNPP, to To view the retrieval algorithms for these products, visit the following Sentinel/Copernicus page: https://sentinels.copernicus.eu/documents/247904/2476257/Sentinel-5P-NPP-ATBD-NPP-Clouds The S5P-NPP Cloud processor is a stand-alone code separate from other TROPOMI-related computations. The retrieval algorithm requires the following input fields: • Semi-major and semi-minor axis, and eccentricity, of the WGS'84 ellipsoid • Time window of tolerance to identify relevant NPP files for a given S5P scan line • Number of VIIRS cloud classifcations, defined S5P FOVs, and VIIRS moderate resolution channels used in the S5P-NPP product • Maximum and minimum values of transformed coordinates (y & z) which define a specific S5P FOV. • Instantaneous spatial response function • Latitude and longitude of S5P pixel corner, centre or sensor, and altitude of sensor • View zenith angle of S5P pixel and line-of-sight zenith angle of a VIIRS pixel • Sensing time of S5P scan line and a VIIRS scan line • Sensing start and stop time of S5P L1 file • Latitude and longitude of VIIRS pixel • Sensing start and stop time of NPP L1 file • Sensing start and stop time of NPP L1 granule • Sensing start and stop centre-scan latitude and longitude of NPP L1 granule • VIIRS pixel level geolocation, radiance and cloud mask data quality flags • VIIRS band averaged spectral radiance • VIIRS pixel cloud mask • Ratio of nominal FOV extent to that of L1GPC in across- and along-track directions • Spatial response function (SRF), including effects of satellite motion The retrieval is performed in 3 steps: 1) S5P L1 file is ingested, containing the geolocation of each scene for which the S5P-NPP-Cloud information is required. 2) The time difference, ∆tsat, between S5P centre-swath observations and those of spatially co-located VIIRS measurements is calculated to an accuracy of ≈1 minute using metadata in the VIIRS geololcation file. 3) S5P scan lines are looped over: a) VIIRS files which contain information relevant to these scan lines are identified b) The relevant information from these VIIRS files is read and stored in memory c) S5P across-track pixels within the current scan line are looped over. The NPP-Cloud product is then the re-gridding of the VIIRS L1 and cloud mask products from the SNPP to the resolution acquired by the TROPOMI instrument on the Sentinel 5P satellite. For more information on the processing algorithm please look at the ATBD (Algorithm Theoretical Baseline Document) on the Sentinel Copernicus webpage, URL linked in the documentation. |
| Input Description | None |
| Output Description | None |
| Software Reference | None |
| Output Description | None |
- units: 1
- var_id: SRF_coverage_histogram_axis
- long_name: Axis for histograms of SRF coverage
- units: 1
- var_id: cloud_fraction_histogram_axis
- long_name: Axis for histograms of cloud fraction
- units: 1
- var_id: sun_normalised_radiance_histogram_axis
- long_name: Axis for histograms of sun-normalised radiance
- units: 1
- var_id: number_viirs_pixels_histogram_axis
- long_name: Axis for histograms of the number of VIIRS pixels
- units: s
- var_id: VIIRS_delta_time_histogram_axis
- long_name: Axis for the histogram of the Time difference from S5P observation
- units: degrees
- var_id: VIIRS_view_zenith_histogram_axis
- long_name: Axis for the histogram of the VIIRS viewing zenith angle
- units: 1
- var_id: SRF_coverage_histogram_axis_bounds
- long_name: Bounds for histograms of SRF coverage
- units: 1
- var_id: cloud_fraction_histogram_axis_bounds
- long_name: Bounds for histograms of cloud fraction
- units: 1
- var_id: sun_normalised_radiance_histogram_axis_bounds
- long_name: Bounds for histograms of sun-normalised radiance
- units: 1
- var_id: number_viirs_pixels_histogram_axis_bounds
- long_name: Bounds for histograms of the number of VIIRS pixels
- units: s
- var_id: VIIRS_delta_time_histogram_axis_bounds
- long_name: Bounds for the histogram of the Time difference from S5P observation
- units: degrees
- var_id: VIIRS_view_zenith_histogram_axis_bounds
- long_name: Bounds for the histogram of the VIIRS viewing zenith angle
- units: 1
- var_id: band07_srf_coverage
- long_name: Fractional energy of SRF covered by valid VIIRS band M07 radiances
- units: 1
- var_id: band09_srf_coverage
- long_name: Fractional energy of SRF covered by valid VIIRS band M09 radiances
- units: 1
- var_id: band11_srf_coverage
- long_name: Fractional energy of SRF covered by valid VIIRS band M11 radiances
- var_id: band07_srf_coverage_histogram
- long_name: Histogram of the Fractional energy of SRF covered by valid VIIRS band M07 radiances
- var_id: band09_srf_coverage_histogram
- long_name: Histogram of the Fractional energy of SRF covered by valid VIIRS band M09 radiances
- var_id: band11_srf_coverage_histogram
- long_name: Histogram of the Fractional energy of SRF covered by valid VIIRS band M11 radiances
- var_id: band07_fov_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M07 sun-normalisd radiances in each S5P scaled field-of-view
- var_id: band07_srf_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M07 sun-normalised radiances weighted by the S5P spatial response function
- var_id: band09_fov_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M09 sun-normalisd radiances in each S5P scaled field-of-view
- var_id: band09_srf_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M09 sun-normalised radiances weighted by the S5P spatial response function
- var_id: band11_fov_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M11 sun-normalisd radiances in each S5P scaled field-of-view
- var_id: band11_srf_mean_histogram
- long_name: Histogram of the Mean of valid VIIRS band M11 sun-normalised radiances weighted by the S5P spatial response function
- var_id: vcm_confidently_clear_histogram
- long_name: Histogram of the Number of VIIRS pixels classified as CONFIDENTLY_CLEAR
- var_id: vcm_confidently_cloudy_histogram
- long_name: Histogram of the Number of VIIRS pixels classified as CONFIDENTLY_CLOUDY
- var_id: vcm_probably_clear_histogram
- long_name: Histogram of the Number of VIIRS pixels classified as PROBABLY_CLEAR
- var_id: vcm_probably_cloudy_histogram
- long_name: Histogram of the Number of VIIRS pixels classified as PROBABLY_CLOUDY
- var_id: band07_fov_nvalid_histogram
- long_name: Histogram of the Number of valid VIIRS band M07 pixels in each S5P scaled field-of-view
- var_id: band09_fov_nvalid_histogram
- long_name: Histogram of the Number of valid VIIRS band M09 pixels in each S5P scaled field-of-view
- var_id: band11_fov_nvalid_histogram
- long_name: Histogram of the Number of valid VIIRS band M11 pixels in each S5P scaled field-of-view
- var_id: band07_fov_stdev_histogram
- long_name: Histogram of the Standard deviation of valid VIIRS band M07 sun-normalised radiances in each S5P scaled field-of-view
- var_id: band09_fov_stdev_histogram
- long_name: Histogram of the Standard deviation of valid VIIRS band M09 sun-normalised radiances in each S5P scaled field-of-view
- var_id: band11_fov_stdev_histogram
- long_name: Histogram of the Standard deviation of valid VIIRS band M11 sun-normalised radiances in each S5P scaled field-of-view
- var_id: viirs_delta_time_histogram
- long_name: Histogram of the Time difference from S5P observation
- var_id: viirs_viewing_zenith_angle_histogram
- long_name: Histogram of the VIIRS viewing zenith angle
- units: 1
- var_id: band07_fov_mean
- long_name: Mean of valid VIIRS band M07 sun-normalisd radiances in each S5P scaled field-of-view
- units: 1
- var_id: band07_srf_mean
- long_name: Mean of valid VIIRS band M07 sun-normalised radiances weighted by the S5P spatial response function
- units: 1
- var_id: band09_fov_mean
- long_name: Mean of valid VIIRS band M09 sun-normalisd radiances in each S5P scaled field-of-view
- units: 1
- var_id: band09_srf_mean
- long_name: Mean of valid VIIRS band M09 sun-normalised radiances weighted by the S5P spatial response function
- units: 1
- var_id: band11_fov_mean
- long_name: Mean of valid VIIRS band M11 sun-normalisd radiances in each S5P scaled field-of-view
- units: 1
- var_id: band11_srf_mean
- long_name: Mean of valid VIIRS band M11 sun-normalised radiances weighted by the S5P spatial response function
- var_id: vcm_confidently_clear
- long_name: Number of VIIRS pixels classified as CONFIDENTLY_CLEAR
- var_id: vcm_confidently_cloudy
- long_name: Number of VIIRS pixels classified as CONFIDENTLY_CLOUDY
- var_id: vcm_probably_clear
- long_name: Number of VIIRS pixels classified as PROBABLY_CLEAR
- var_id: vcm_probably_cloudy
- long_name: Number of VIIRS pixels classified as PROBABLY_CLOUDY
- var_id: band07_fov_nvalid
- long_name: Number of valid VIIRS band M07 pixels in each S5P scaled field-of-view
- var_id: band09_fov_nvalid
- long_name: Number of valid VIIRS band M09 pixels in each S5P scaled field-of-view
- var_id: band11_fov_nvalid
- long_name: Number of valid VIIRS band M11 pixels in each S5P scaled field-of-view
- var_id: scaled_field_of_view_ymax
- long_name: S5P scaled field-of-view normalised coordinate: Maximum across-track
- var_id: scaled_field_of_view_zmax
- long_name: S5P scaled field-of-view normalised coordinate: Maximum along-track
- var_id: scaled_field_of_view_ymin
- long_name: S5P scaled field-of-view normalised coordinate: Minimum across-track
- var_id: scaled_field_of_view_zmin
- long_name: S5P scaled field-of-view normalised coordinate: Minimum along-track
- units: 1
- var_id: band07_fov_stdev
- long_name: Standard deviation of valid VIIRS band M07 sun-normalised radiances in each S5P scaled field-of-view
- units: 1
- var_id: band09_fov_stdev
- long_name: Standard deviation of valid VIIRS band M09 sun-normalised radiances in each S5P scaled field-of-view
- units: 1
- var_id: band11_fov_stdev
- long_name: Standard deviation of valid VIIRS band M11 sun-normalised radiances in each S5P scaled field-of-view
- units: degree
- standard_name: platform_zenith_angle
- var_id: viirs_viewing_zenith_angle
- long_name: VIIRS viewing zenith angle
- units: 1
- long_name: across track dimension index
- var_id: ground_pixel
- units: 1
- long_name: along track dimension index
- var_id: scanline
- units: 1
- var_id: qa_value
- long_name: data quality value
- units: 1
- var_id: scaled_field_of_view
- long_name: dimension index corresponding to each defined geometric scaling of the S5P nominal field of view for which VIIRS statistics are summarised
- units: degrees_north
- var_id: latitude_bounds
- units: degrees_east
- var_id: longitude_bounds
- units: milliseconds
- var_id: delta_time
- long_name: offset from the reference start time of measurement
- units: degree
- long_name: solar zenith angle
- var_id: solar_zenith_angle
- standard_name: solar_zenith_angle
- units: degree
- long_name: viewing zenith angle
- standard_name: platform_zenith_angle
- var_id: viewing_zenith_angle
Co-ordinate Variables
- standard_name: time
- units: s
- var_id: viirs_delta_time
- long_name: Time difference from S5P observation
- units: degrees_north
- standard_name: latitude
- var_id: latitude
- long_name: pixel center latitude
- units: degrees_east
- standard_name: longitude
- var_id: longitude
- long_name: pixel center longitude
- standard_name: time
- var_id: time
- units: seconds
- long_name: reference start time of measurement
Coverage
Temporal Range
Start time:
2018-05-04T00:00:00
End time:
Ongoing
Geographic Extent
90.0000° |
||
-180.0000° |
180.0000° |
|
-90.0000° |
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