...
More details on the estimation of errors and uncertainty parameters are given in the Report on Updated KPIs (D3).
Product requirements
Depending on the data record producer, different product requirements may be applied and they are used to evaluate validation results. An often-used way to handle this is to define several levels of requirements where each level is linked to specific needs or priorities. A three-level approach like the following is rather common:
Requirement | Description |
---|---|
Threshold requirement: | A product should at least fulfill this level to be considered useful at all. Sometimes the term ‘Breakthrough” is used instead. |
Target requirement: | This is the main quality goal for a product. It should reach this level based on the current knowledge on what is reasonable to achieve. |
Optimal requirement: | This is a level where a product is considered to perform much better than expected given the current knowledge. |
Satellite product levels
Satellite-based products are often described as belonging to the following condensed description of processing levels, each one with different complexity and information content:
Level | Description |
---|---|
Level-0: | Raw data coming directly from satellite sensors, often described as sensor counts. |
Level-1: | Data being enhanced with information on calibration and geolocation. Level-1a: Data with attached calibration and geolocation information Level-1b: Data with applied calibration and attached geolocation information Level-1c: Data with applied calibration and additional layers of geolocation, satellite viewing and solar angle information |
Level-2: | Derived geophysical variables at the same resolution and location as L1 source data. An often-used Level-2 variety is the following: Level-2b: Globally resampled images, two per day per satellite, describing both ascending (passing equator from south) and descending (passing equator from north) nodes. Resampling is based on the principle that the value for the pixel with the lowest satellite zenith angle is chosen in case two or several swaths are overlapping. |
Level-3: | Gridded data with results accumulated over time (e.g., monthly means). |
A more comprehensive definition of all processing levels is given here:
...
This document provides relevant information on requirements and gaps for the Earth Radiation Budget (ERB) Essential Climate Variable (ECV).
The document is divided into three parts. Part 1 describes products the present document refers to. Part 2 provides target requirements for the products. Part 3 provides a past, present, and future gap analysis for the products and covers both gaps in the data availability and scientific gaps that could be addressed by further research activities (outside C3S).
...
Four different ERB data records are provided. These are
- Earth Radiation Budget CERES TCDR v1.0 and v2.0 + ICDR v2.x
- The HIRS OLR TCDR v1.0 and v2.0
- Earth Radiation Budget ESA_CCI_AATSR TCDR v3.0 + SLSTR-based ICDR v3.1.1 + v4.0
- Earth Radiation Budget TSI TOA ICDR v2.x + TCDR v3.0
...
C3S internal version (not to be shown to CDS users) | CERES edition | Input data (FM = Flight Model) |
v1.0 | Ed 4.1 |
|
v2.0 v2.x (ICDR) | Ed 4.2 |
|
1.1.1 The CERES EBAF CDR
The CERES Energy Balanced and Filled (EBAF) data is “brokered” in the Copernicus Climate Data Store (CDS). The EBAF product is based on the data acquired by the Cloud and Earth’s Radiant Energy System (CERES) instruments (Figure 1‑1). The CERES instruments are broadband radiometers developed as part of the NASA's Earth Observing System (EOS) program. Wielicki et al. (1996) provide a description of the CERES instrument as well as of the CERES mission.
Figure 1‑1: CERES instrument (left) and program logo (right). Anchor figure1_1 figure1_1
The Top-of-Atmosphere (TOA) EBAF file provides a total of 14 parameters which are given in Table 1‑2. Among those, only the shortwave and longwave fluxes in all-sky condition are accessible via the CDS. The incoming solar flux is also available via the CDS but as an ancillary field of the RSF. It is worth mentioning that these fluxes are provided at a reference level of 20km, to ease the comparison with climate/NWP models (see Loeb et al, 2002).
Table 1‑2: Content of the CERES EBAF file. Variables used in the C3S product are marked in green. Anchor table1_2 table1_2
Variable | Long name | Units | Brokered in CDS |
toa_sw_all_mon | Top of The Atmosphere Shortwave Flux, Monthly Means, All-Sky conditions | W/m² | yes |
toa_lw_all_mon | Top of The Atmosphere Longwave Flux, Monthly Means, All-Sky conditions | W/m² | yes |
toa_net_all_mon | Top of The Atmosphere Net Flux, Monthly Means, All-Sky condition | W/m² | no |
toa_sw_clr_mon | Top of The Atmosphere Shortwave Flux, Monthly Means, Clear-Sky conditions | W/m² | no |
toa_lw_clr_mon | Top of The Atmosphere Longwave Flux, Monthly Means, Clear-Sky conditions | W/m² | no |
toa_net_clr_mon | Top of The Atmosphere Net Flux, Monthly Means, Clear-Sky conditions | W/m² | no |
toa_cre_sw_mon | Top of The Atmosphere Cloud Radiative Effects Shortwave Flux, Monthly Means | W/m² | no |
toa_cre_lw_mon | Top of The Atmosphere Cloud Radiative Effects Longwave Flux, Monthly Means | W/m² | no |
toa_cre_net_mon | Top of The Atmosphere Cloud Radiative Effects Net Flux, Monthly Means | W/m² | no |
solar_mon | Incoming Solar Flux, Monthly Means | W/m² | yes |
cldarea_total_daynight_mon | Cloud Area Fraction, Monthly Means, Daytime-and-Nighttime conditions | percent | no |
cldpress_total_daynight_mon | Cloud Effective Pressure, Monthly Means, Daytime-and-Nighttime conditions | hPa | no |
cldtemp_total_daynight_mon | Cloud Effective Temperature, Monthly Means, Daytime-and-Nighttime conditions | K | no |
cldtau_total_day_mon | Cloud Visible Optical Depth, Monthly Means, Daytime conditions | dimensionless | no |
1.1.2 Input data
Table 1‑3 details the instrument names and platforms on which the 7 CERES instruments have been launched. The CERES EBAF edition 4.1 relies on the FM1 to FM4 instruments from the EOS Terra and Aqua satellites. The edition 4.2 add data from FM6 on NOAA-20.
...
Instrument | Platform | Operation period | Used in EBAF edition 4.1 | Used in EBAF edition 4.2 |
PFM | TRMM | Jan. to Aug. 1998 (+limited oper. in 1999 and 2000) | no | no |
FM1 | Terra | Mar. 2000 onward | yes | yes |
FM2 | Terra | Mar. 2000 onward | yes | yes |
FM3 | Aqua | Jul. 2002 onward | yes | yes |
FM4 | Aqua | Jul. 2002 onward | yes | yes |
FM5 | NPP Suomi | Feb. 2012 onward | no | no |
FM6 | NOAA-20 | Jan. 2018 onward | no | yes |
A brief summary of the input data is given in Table 1‑4, while a comprehensive description is provided by Loeb et al. (2018) [D1].
Table 1‑4: Main input and auxiliary data used in processing the CERES EBAF edition 4 CDR. Anchor table1_4 table1_4
Input and auxiliary data used in processing the CERES EBAF edition 4 | |
CERES | The CERES shortwave (SW) and total wave (TOT) filtered radiances are the main input of the processing. By subtraction, the longwave (LW) radiance can be estimated. The SW and LW radiance are then “unfiltered” to account for some spectral variation of the instrument sensitivity. Then, empirical Angular Dependency Models (ADM) are used to estimate the hemispheric fluxes. Starting from the instantaneous fluxes, the Time Interpolation and Spatial Averaging (TISA, Doelling et al., 2013 and 2016) is used to estimate daily and monthly means values of the flux. This processing makes used of data from geostationary satellites (GEO hereafter). Finally, the fluxes are “balanced” to create the EBAF CDR (Loeb et al., 2009). |
MODIS | The MODIS observations are processed by the CERES team to estimate cloud properties in each CERES footprint. This is an important input to apply ADM. The CERES cloud processing is described in various papers (e.g. Minnis et al., 2011). |
GEO | The geostationary data are used in the TISA subsystem to improve the diurnal cycle modelling, especially in regions that exhibit diurnal cycles of cloud properties (e.g., convection). |
Meteorological data | Meteorological data are used in different parts of the processing. For CERES EBAF, the GEOS 5.4.1, a CERES-restricted effort of the Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center, is used. |
1.1.3 Algorithm name and version, bias correction
...
Instrument | Platform(s) | Used In C3S | Operation period(s) |
TCFM | Mariner-6 Mariner-7 | No | 1969 |
ERB | Nimbus 6 | No | 1975 |
Nimbus 7 | Yes | 1978 | |
ACRIM 1 | SMM | Yes | 1980-1989 |
Solcon 1 | Spacelab 1 | No | 1983 |
ERBE | ERBS | Yes | 1984-2003 |
NOAA-9 | No | 1985-1989 | |
ACRIM 2 | UARS | Yes | 1991-2001 |
SOLCON 2 | Atlas 1 | No | 1992 |
SOVA 1 | Eureca | No | 1992-1993 |
SOVA 2 | Eureca | No | 1992-1993 |
ISP-2 | Meteor-3 7 | No | 1994 |
DIARAD/VIRGO | SOHO | Yes | 1996-present |
PMO06V-A/VIRGO | SOHO | Yes | 1996-present |
ACRIM 3 | ACRIMSAT | Yes | 2000-2014 |
TIM | SORCE | Yes | 2003-2020 |
DIARAD/SOVIM | ISS | No | 2008 |
SIM | FY 3A | No | 2008-2015 |
SOVA | Picard | Yes | 2010-2014 |
PREMOS | Picard | Yes | 2010-2014 |
SIM | FY 3B | No | 2011-present |
TIM | TCTE | Yes | 2013-2019 |
SIM | FY 3C | No | 2013-present |
TIM | TSIS-1 | Yes | 2018 - present |
1.3.3 General characteristics of the product
...
Variable | KPI: lower percentile (2.5 %) | KPI: higher percentile (97.5 %) |
TSI v2.x | 0.869 Wm-2 | 1.829 Wm-2 |
TSI v3.x | 0.130 Wm-2 | 0.562 Wm-2 |
2.3.2 Discussion of requirements with respect to GCOS and other requirements
Concerning the incoming solar energy, the GCOS considers 2 products as essential for the global climate: the Total Solar Irradiance (TSI) and the Solar Spectral Irradiance (SSI). The TSI is defined as the “Flux density of solar radiation at TOA (Wm-2)” while the SSI is defined as “the solar irradiance measured as a function of wavelength (Wm-2μm-1)”. The GCOS requirements are given in Table 2‑7. Currently, the CDS only provides TSI data.
...
Anchorsection2_4_2 section2_4_2
2.4.2 Summary of target requirements (KPIs) - ICDR
section2_4_2 | |
section2_4_2 |
The Cloud_cci (A)ATSR products are brokered from the ESA CCI programme and cannot be altered within the scope of C3S_312b_Lot1. Therefore, target requirements are in this case set identical to the achieved results in previous validation efforts (Table 2‑9).
Table 2‑9: Key Performance Indicators (KPIs) or target requirements (i.e., fulfilled requirements by the ESA-CCI-CLOUDS project) for OLR and RSF products from the ESA_CCI_AATSR TCDR v3.0. Anchor table2_9 table2_9
...
Variable | KPI: lower percentile (2.5 %), W/m2 | KPI: higher percentile (97.5 %), W/m2 |
OLR Monthly mean | -1.17 | 0.898 |
RSF Monthly mean | -1.36 | 1.15 |
2.4.3 Discussion of requirements with respect to GCOS and other requirements
Requirements are consistent with GCOS. See Section 2.4.1.
...
Wielicki, B. A., Barkstrom, B. R., Harrison, E. F., Lee III, R. B., Smith, G. L., & Cooper, J. E., 1996: Clouds and the Earth's Radiant Energy System (CERES): An earth observing system experiment. Bulletin of the American Meteorological Society, 77(5), 853-868.
Info | ||
---|---|---|
| ||
This document has been produced with funding by the European Union in the produced in the context of the Copernicus Climate Change Service (C3S), operated . The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf onof the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided “as is”"as is" and no guarantee ofor warranty is given that the information is fit for any particular purpose. The 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 author's view. |
Related articles
Content by Label | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|