...
Contributors: E. Carboni (UKRI-STFC RAL Space), G.E. Thomas (UKRI-STFC RAL Space)produced in
Issued by: STFC RAL Space (UKRI-STFC) / Elisa Carboni
...
Official reference number service contract: 2021/C3S2_312a_Lot1_DWD/SC1
Info | ||||
---|---|---|---|---|
| ||||
Carboni, E., Thomas, G., (2023) C3S Earth Radiation Budget: Product Quality Assessment Report. Copernicus Climate Change Service. Document reference C3S2_D312a_Lot1.2.2.4-v4.0_202305_PQAR_CCIEarthRadiationBudget_v1.2 Last accessed on dd/mm/yyyy |
Info | ||||
---|---|---|---|---|
| ||||
|
| ||||
|
Easy Heading Macro | ||
---|---|---|
| ||
Easy Heading Macro | ||
|
History of modifications
...
Expand | ||||||||
---|---|---|---|---|---|---|---|---|
| ||||||||
|
Acronyms
| ||||||||||||||||||||||||||||||||||||||
Expand | ||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||||||||||||||||||||||||
|
List of tables
Expand | ||
---|---|---|
| ||
Table 2-1: Summary of the TCDR and preliminary assessment of ICDR accuracy of the Earth Radiation Budget dataset. Table 4-1: GCOS targets for Earth Radiation Budget ECVs and CDR values. |
List of figures
Expand | ||
---|---|---|
| ||
Figure 2-1: RSF and OLR from SLSTR (ICDR dataset) for March 2017. Figure 2-2: RSF and OLR from CERES dataset for March 2017. |
|
Acronyms
Expand | ||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||||||||||||||||||||||||
|
List of tables
Expand | ||
---|---|---|
| ||
Table 2-1: Summary of the TCDR and preliminary assessment of ICDR accuracy of the Earth Radiation Budget dataset Table 3-1: Summary of KPI results with 2.5 and 97.5 percentiles and number of ICDR months within the range Table 4-1: GCOS targets for Earth Radiation Budget ECVs and CDR values |
List of figures
Expand | ||
---|---|---|
| ||
Figure 2-1: RSF and OLR from SLSTR (ICDR dataset) for March 2017 Figure 2-2: RSF and OLR from CERES dataset for March 2017 |
General definitions
The "CCI product family" Climate Data Record (CDR) consists of two parts. The ATSR2-AATSR Earth Radiation Budget CDR is formed by a TCDR brokered from the ESA Cloud_cci project and an ICDR derived from the Sea and Land Surface Temperature Radiometer (SLSTR) on board of Sentinel-3A and -B. ICDR uses the same processing and infrastructure as the TCDR. Both TCDR and ICDR data have been produced by STFC RAL Space.
...
Table 1: Definition of processing levels
Processing level | Definition |
Level-1b | The full-resolution geolocated radiometric measurements (for each view and each channel), rebinned onto a regular spatial grid. |
Level-2 (L2) | Retrieved cloud variables at full input data resolution, thus with the same resolution and location as the sensor measurements (Level-1b). |
Level-3C (L3C) | Cloud properties of Level-2 orbits of one single sensor combined (averaged) on a global spatial grid. Both daily and monthly products provided through C3S are Level-3C. |
Table 2: Definition of various technical terms used in the document
Jargon | Definition |
Brokered product | The C3S Climate Data Store (CDS) provides both data produced specifically for C3S and so-called brokered products. The latter are existing products produced under an independent programme or project which are made available through the CDS. |
Climate Data Store (CDS) | The front-end and delivery mechanism for data made available through C3S. |
Retrieval | A numerical data analysis scheme which uses some form of mathematical inversion to derive physical properties from some form of measurement. In this case, the derivation of cloud properties from satellite measured radiances. |
Forward model | A deterministic model which predicts the measurements made of a system, given its physical properties. The forward model is the function which is mathematically inverted by a retrieval scheme. In this case, the forward model predicts the radiances measured by a satellite instrument as a function of atmospheric and surface state, and cloud properties. |
TCDR | It is a consistently-processed time series of a geophysical variable of sufficient length and quality. |
ICDR | An Interim Climate Data Record (ICDR) denotes an extension of TCDR, processed with a processing system as consistent as possible to the generation of TCDR. |
CDR | A Climate Data Record (CDR) is defined as a time series of measurements with sufficient length, consistency, and continuity to determine climate variability and change. |
Scope of the document
This document provides a description of the product validation results for the Climate Data record (CDR) of the Essential Climate Variable (ECV) Earth Radiation Budget. This CDR comprises inputs from two sources: (i) brokered products from the Cloud Climate Change Initiative (ESA's Cloud_cci), namely those coming from processing of the Advanced Along-Track Scanning Radiometer ((A)ATSR) data and (ii) those produced under this contract for the Climate Data Store, specifically those coming from processing of the Sea and Land Surface Temperature Radiometers (SLSTR).
...
Info | ||
---|---|---|
| ||
1 Data available here: https://ceres.larc.nasa.gov/data/ (Last accessed on 28/02/2023). |
...
Anchor | ||||
---|---|---|---|---|
|
The validation results for the TCDR are provided in [D1] section 3 and 5. Table 2-1 provides a summary of the resulting TCDR accuracies.
Table 2-1: Summary of the TCDR and preliminary assessment of ICDR accuracy of the Earth Radiation Budget dataset. Anchor table2_1 table2_1
Product name | Accuracy for the TCDR [W/m²] | Accuracy for the ICDR – SLSTR-A [W/m²] | Accuracy for the ICDR – SLSTR-B [W/m²] | Accuracy for the ICDR – A+B [W/m²] |
Reflected Solar radiation Flux (RSF) | 5.72 | 3.80 | 4.19 | 4.63 |
Outgoing Longwave Radiation (OLR) | 1.72 | -0.97 | -1.32 | -1.03 |
2.1 TCDR validation with CERES satellite data
...
Figure 2-1: RSF and OLR from SLSTR (ICDR dataset) for March 2017. Anchor figure2_1 figure2_1
...
2-1: RSF and OLR from SLSTR (ICDR dataset) for March 2017
Figure 2-2: RSF and OLR from CERES dataset for March 2017 Anchor figure2_2 figure2_2
3. Application(s) specific assessments
In addition to the extensive product validation (see chapter 2 for results and chapter 2/3 in [D5] for validation methodology) a second assessment is introduced to evaluate the Interim Climate Data Record (ICDR) against the Thematic Climate Data Record (TCDR) in terms of consistency. Since frequent ICDR deliveries make detailed validation not feasible, a consistency check against the deeply validated TCDR is used as an indication of quality. This is done by a comparison of the following two evaluations:
- TCDR against a stable, long-term and independent reference dataset
- ICDR against the same stable, long-term and independent reference dataset
The evaluation method is generated to detect differences in the ICDR performance in a quantitative, binary way with so called Key Performance Indicators. The general method is outlined in [D4] chapter 3. The same difference between TCDR/ICDR and the reference dataset would lead to the conclusion that TCDR and ICDR have the same quality (key performance is "good"). Variations or trends in the differences (TCDR/ICDR against reference) would require a further investigation to analyze the reasons. The key performance would be marked as "bad". The binary decision whether the key performance is good or bad is made in a statistical way by a hypotheses test (binomial test). Based on the TCDR/reference comparison (global means, monthly or daily means) a range is defined with 95% of the differences are within. This range (2.5 and 97.5 percentile) is used for the ICDR/reference comparison to check whether the values are in or out of the range. The results could be the following:
- All or a sufficient high number of ICDR/reference differences lies within the range defined by the TCDR/reference comparison: Key performance of the ICDR is "good"
- A smaller number of ICDR/reference differences is within the pre-defined range: Key performance of the ICDR is "bad"
3.1 Results
The results of the KPI test are summarized in Table 3-1.
Table 3-1: Summary of KPI results with 2.5 and 97.5 percentiles and number of ICDR months within the range. Colors green or red mark the results of the binomial tests as good or bad, respectively. Anchor table3_1 table3_1
Outgoing Longwave Radiation | Reflected Shortwave Radiation | ||
---|---|---|---|
Percentiles | p2.5 p97.5 | -1.15 W/m² 0.9 W/m² | -1.36 W/m² 1.15 W/m² |
Sentinel-3A: | |||
01/2017 - 12/2020 | 01/48 | 05/48 | |
01/2017 - 12/2021 | 59/60 | 55/60 | |
01/2017 - 06/2022 | 63/66 | 61/66 | |
Sentinel-3B: | |||
10/2018 - 12/2021 | 36/39 | 36/39 | |
10/2018 - 06/2022 | 39/45 | 42/45 | |
Sentinel-3A+B: | |||
10/2018 - 06/2022 | 39/45 | 21/45 |
Percentiles were calculated based on the comparison of the TCDR using the Advanced Along Track Scanning Radiometer (AATSR) instrument against CERES as reference dataset for the variables Outgoing Longwave Radiation (OLR) and Reflected Shortwave Flux (RSF). Percentiles were based on the time from 2002-2012 with monthly means and applied to the ICDR from 01/2017 (10/2018) to 06/2022 for Sentinel-3A (Sentinel-3B and merged product Sentinel-3A+B) based on measurements of the Sea and Land Surface Temperature Radiometer (SLSTR).
A part of the ICDR months are outside the TCDR-based KPI limits and leading to “bad” KPI tests. For these, the ICDR is not stable in relation to the TCDR. This is due to multiple reasons starting with the fact of a five year gap (2012-2016) between TCDR and ICDR. In addition, TCDR and ICDR are based on different instruments with SLSTR on Sentinel-3 and (A)ATSR/ATSR-2 on Envisat/ERS-2, respectively. Differences occur due to a lower bias between ICDR and reference dataset and a subtraction of the monthly means (based on the TCDR) to remove the annual cycle leads to values outside of the KPI range (see method in [D4], chapter 3.2.2). Please note that significant changes between 01/2017 - 12/2020 and 01/2017 - 12/2021 are due to bugfixes
3. Application(s) specific assessments
This section is not applicable. There are no additional specific assessments known since the dataset has just been published.
4. Compliance with user requirements
There are no direct user requirements for the Earth Radiation Budget defined in the Cloud_cci project. Looking at the GCOS ECV requirements for Earth Radiation Budget [https://gcos.wmo.int/en/essential-climate-variables/earth-radiation/ecv-requirements|https://gcos.wmo.int/en/essential-climate-variables/earth-radiation/ecv-requirements] (Last accessed on 28/02/2023) the values for RSF and OLR are 1 W/m² uncertainty, while the TCDR dataset achieves an accuracy of 5.72 W/m² for RSF and 1.72 W/m² for OLR, therefore they currently do not meet the GCOS requirements. ICDR accuracies (estimate with the dataset up to march 2022) are consistent with TCDR accuracy for OLR and slightly lower for RSF. Please find more detailed information about the target requirements in the corresponding (Target Requirement and Gap Analysis Document) TRGAD [D2].
...
Table 4-1: GCOS targets for Earth Radiation Budget ECVs and CDR values. Anchor table4_1 table4_1
Product name | GCOS targets | Cloud_cci dataset | |
RSF | Frequency | Monthly (resolving diurnal cycle) | Cloud_cci products do not meet the requirement for resolving the diurnal cycle. |
Resolution | 100 km | Cloud_cci products exceed the spatial resolution. | |
Measurement uncertainty | 1 W/m² on global mean | Uncertainty: 5.72 W/m² | |
Stability | 0.3 W/m²/decade | -0.15 W/m²/decade (Validation with CERES) | |
OLR | Frequency | Monthly (resolving diurnal cycle) | Cloud_cci products do not meet the requirement for resolving the diurnal cycle. |
Resolution | 100 km | Cloud_cci products exceed the spatial resolution. | |
Measurement uncertainty | 1 W/m² on global mean | Uncertainty: 1.72 W/m² | |
Stability | 0.2 W/m²/decade | -0.52 W/m²/decade (Validation with CERES) |
Known limitations [From D1 table 7.1]:
...
Loeb, N.G., Doelling, D.R., Wang, H., Su, W., Nguyen, C., Corbett, J.G., Liang, L., Mitrescu, C., Rose, F.G., and Kato, S.: Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition 4.0 Data Product, J.Climate, 31(2), 895–918, doi:10.1175/JCLI-D-17-0208.1, 2018.
Info | ||
---|---|---|
| ||
This document has been produced with funding by the European Union in the context of the Copernicus Climate Change Service (C3S) .The activities leading to these results have been contracted, operated by the European Centre for Medium-Range Weather Forecasts , operator of C3Son behalf ofon the European Union ( Delegation Agreement signed on 11/11/2014 andContribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee orof warranty is given that the information is fit for any particular purpose. The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium-Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view. |
Related articles
Content by Label | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|