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Table 1: Summary of variables and definitions
Variables | Abbreviation | Definition |
Surface incoming solar radiation | SIS | The total incoming solar flux, measured at the Earth’s surface. |
Surface reflected solar radiation | SRS | The total upwelling shortwave flux, measured at the Earth’s surface. |
Surface net solar radiation | SNS | The net downwelling solar flux, measured at the surface (equal to SIS – SRS). |
Surface downwelling longwave radiation | SDL
| The total downwelling thermal infrared flux, measured at the Earth’s surface. |
Surface outgoing longwave radiation
| SOL
| The total upwelling thermal infrared flux, measured at the Earth’s surface. |
Surface net longwave radiation | SNL | The net downwelling thermal infrared flux, measured at the Earth’s surface (equal to SDL-SOL). |
Total surface radiation budget | SRB | The total net downwelling radiative flux, measured at the Earth’s surface (equal to (SIS+SDL) – (SRS+SOL)). |
Table 2: 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 3: 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) Surface 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).
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Table 1-1: Summary of methodologies used to estimate the accuracies, for TCDR and ICDR datasets.Anchor table1_1 table1_1
Product name | Validation with BSRN | Comparison with CERES | Uncertainty propagation |
Surface Incoming Shortwave radiation (SIS) | TCDR | TCDR and ICDR |
|
Surface Reflected Shortwave radiation (SRS) |
| TCDR and ICDR | TCDR and ICDR |
Surface Net Shortwave radiation (SNS) |
|
| TCDR and ICDR |
Surface Outgoing Longwave radiation (SOL) |
| TCDR and ICDR |
|
Surface Downwelling Longwave radiation (SDL) | TCDR | TCDR and ICDR |
|
Surface Net Longwave radiation (SNL) | TCDR and ICDR | ||
Surface Radiation Budget (SRB) |
|
| TCDR and ICDR |
The Product Validation and Intercomparison Report [D1] includes the validation and intercomparison of the TCDR Surface Radiation Budget versus the CERES satellite dataset. The same methodology is used for the ICDR.
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Table 2-1: Summary of the accuracy of the Surface Radiation Budget dataset. The ‘bold’ accuracies come from direct validation with a ground measurement network (BSRN), the others come from the intercomparison with similar datasets (CERES) or with an uncertainty propagation. ICDR values are obtained from data between January 2017 and December 2021 for SLSTR-A and between October 2018 and December 2021 for SLSTR-B.Anchor table2_1 table2_1
Product name | TCDR Accuracy [W/m2] | ICDR SLSTR-A Accuracy [W/m2] | ICDR SLSTR-B Accuracy [W/m2] | ICDR A+B Accuracy [W/m2] |
Surface Incoming Shortwave radiation (SIS) | 8.2 | 1.8 | 0.23 | 0.51 |
Surface Reflected Shortwave radiation (SRS) | 4.6 | 1.6 | 2.1 | 2.2 |
Surface Net Shortwave radiation (SNS) | 13 | 3.4 | 2.3 | 2.7 |
Surface Outgoing Longwave radiation (SOL) | 11 | 1.6 | 4.1 | 3.8 |
Surface Downwelling Longwave radiation (SDL) | 12 | 9.7 | 11 | 11 |
Surface Net Longwave radiation (SNL) | 23 | 11 | 15 | 15 |
Surface Radiation Budget (SRB) | 36 | 14 | 17 | 18 |
The ICDR data of SIS, SRS, SOL and SDL are compared with CERES, using the methodology described in [D1] section 5.3 and 5.4, and results are presented here in section 2.2.
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Table 4-1: GCOS targets for Earth Radiation Budget ECVs and CDR values. TCDR values taken from Table 5-4 and Table 5-5 in [D1].Anchor table4_1 table4_1
Product name |
| GCOS targets | Cloud_cci dataset |
SIS | Frequency | Monthly (resolving diurnal cycles) | 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: 8.2 W/m² Standard Deviation: 24 W/m² on global mean (Validation with BSRN ground base measurements) | |
Stability | 0.2 W/m²/decade | 0.97 W/m²/decade (Comparison with CERES) | |
SDL | Frequency | Monthly (resolving diurnal cycles) | 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: 12 W/m2 Standard Deviation: 15 W/m2 on global mean (Validation with BSRN ground base measurements) | |
Stability | 0.2 W/m²/decade | 2.76 W/m2/decade (Comparison with CERES) |
Known limitations [From D1 table 7.1]:
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