scholarly journals True Along-Track Scan to Improve Radiation Budget Estimations

2006 ◽  
Vol 23 (8) ◽  
pp. 1093-1103 ◽  
Author(s):  
Michel Capderou ◽  
Michel Viollier
Keyword(s):  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Steering Angle ◽  
Earth Radiation Budget ◽  
Along Track ◽  
Earth Radiation

Abstract Multiangle approaches for radiance-to-flux conversion require accurate coregistration between the observations from nadir- and oblique-viewing directions. The along-track mode of Earth Radiation Budget (ERB) scanning instruments, such as the Clouds and the Earth’s Radiant Energy System (CERES), provides some multiangular observations with almost the same target observed from nadir, aft, and fore directions. To improve the overlaps of multiangle observations, this study explains how to introduce a yaw steering angle in the along-track scan mode so as to reduce the residual collocations errors. The implementation of this correction to the CERES/Terra along-track mode shows that the distances between the nadir and the oblique (55°) observations are reduced from about 40 to 2 km. Both oblique radiances are shown to be equal with small rms differences: 3.9% (all scenes) and 1.8% (homogeneous scenes), compared, respectively, to 7.0% and 3.5% before the scan adjustment.

scholarly journals Decadal Changes of Earth’s Outgoing Longwave Radiation

2018 ◽  
Vol 10 (10) ◽  
pp. 1539 ◽  
Author(s):  
Steven Dewitte ◽  
Nicolas Clerbaux
Keyword(s):  
Outgoing Longwave Radiation ◽  
Radiant Energy ◽  
Longwave Radiation ◽  
Energy System ◽  
Radiation Budget ◽  
The Arctic ◽  
Regional Patterns ◽  
The Earth ◽  
Earth Radiation Budget ◽  
Earth Radiation

The Earth Radiation Budget (ERB) at the top of the atmosphere quantifies how the earth gains energy from the sun and loses energy to space. Its monitoring is of fundamental importance for understanding ongoing climate change. In this paper, decadal changes of the Outgoing Longwave Radiation (OLR) as measured by the Clouds and Earth’s Radiant Energy System from 2000 to 2018, the Earth Radiation Budget Experiment from 1985 to 1998, and the High-resolution Infrared Radiation Sounder from 1985 to 2018 are analysed. The OLR has been rising since 1985, and correlates well with the rising global temperature. An observational estimate of the derivative of the OLR with respect to temperature of 2.93 +/− 0.3 W/m 2 K is obtained. The regional patterns of the observed OLR change from 1985–2000 to 2001–2017 show a warming pattern in the Northern Hemisphere in particular in the Arctic, as well as tropical cloudiness changes related to a strengthening of La Niña.

The Annual Cycle of Earth Radiation Budget from Clouds and the Earth’s Radiant Energy System (CERES) Data

2011 ◽  
Vol 50 (12) ◽  
pp. 2490-2503 ◽  
Author(s):  
Pamela E. Mlynczak ◽  
G. Louis Smith ◽  
David R. Doelling
Keyword(s):  
Principal Components ◽  
Seasonal Cycle ◽  
Radiant Energy ◽  
Principal Component ◽  
Energy System ◽  
Radiation Budget ◽  
Seasonal Cycles ◽  
Net Radiation ◽  
Earth Radiation Budget ◽  
Earth Radiation

AbstractThe seasonal cycle of the Earth radiation budget is investigated by use of data from the Clouds and the Earth’s Radiant Energy System (CERES). Monthly mean maps of reflected solar flux and Earth-emitted flux on a 1° equal-angle grid are used for the study. The seasonal cycles of absorbed solar radiation (ASR), outgoing longwave radiation (OLR), and net radiation are described by use of principal components for the time variations, for which the corresponding geographic variations are the empirical orthogonal functions. Earth’s surface is partitioned into land and ocean for the analysis. The first principal component describes more than 95% of the variance in the seasonal cycle of ASR and the net radiation fluxes and nearly 90% of the variance of OLR over land. Because one term can express so much of the variance, principal component analysis is very useful to describe these seasonal cycles. The annual cycles of ASR are about 100 W m−2 over land and ocean, but the amplitudes of OLR are about 27 W m−2 over land and 15 W m−2 over ocean. The magnitude of OLR and its time lag relative to that of ASR are important descriptors of the climate system and are computed for the first principal components. OLR lags ASR by about 26 days over land and 42 days over ocean. The principal components are useful for comparing the observed radiation budget with that computed by a model.

scholarly journals Developing Clear-Sky Flux Products for the Geostationary Earth Radiation Budget Experiment

2005 ◽  
Vol 44 (9) ◽  
pp. 1361-1374 ◽  
Author(s):  
J. M. Futyan ◽  
J. E. Russell
Keyword(s):  
Diurnal Cycle ◽  
Radiant Energy ◽  
Longwave Radiation ◽  
Energy System ◽  
Radiation Budget ◽  
Sampling Errors ◽  
Clear Sky ◽  
Temporal Sampling ◽  
Earth Radiation Budget ◽  
Earth Radiation

Abstract This paper describes the planned processing of monthly mean and monthly mean diurnal cycle flux products for the Geostationary Earth Radiation Budget (GERB) experiment. The use of higher-spatial-resolution flux estimates based on multichannel narrowband imager data to improve clear-sky sampling is investigated. Significant improvements in temporal sampling are found, leading to reduced temporal sampling errors and less dependence on diurnal models for the monthly mean products. The reduction in temporal sampling errors is found to outweigh any spatial sampling errors that are introduced. The resulting flux estimates are used to develop an improved version of the half-sine model that is used for the diurnal interpolation of clear-sky longwave fluxes over land in the Earth Radiation Budget Experiment (ERBE) and Clouds and the Earth’s Radiant Energy System (CERES) missions. Maximum outgoing longwave radiation occurs from 45 min to 1.5 h after local noon for most of the GERB field of view. Use of the ERBE half-sine model for interpolation therefore results in significant distortion of the diurnal cycle shape. The model that is proposed here provides a well-constrained fit to the true diurnal shape, even for limited clear-sky sampling, making it suitable for use in the processing of both GERB and CERES second-generation monthly mean clear-sky data products.

scholarly journals Global Daytime Mean Shortwave Flux Consistency Under Varying EPIC Viewing Geometries

2021 ◽  
Vol 2 ◽  
Author(s):  
Wenying Su ◽  
Lusheng Liang ◽  
David P. Duda ◽  
Konstantin Khlopenkov ◽  
Mandana M. Thieman
Keyword(s):  
Radiant Energy ◽  
Energy System ◽  
Field Of View ◽  
Radiation Budget ◽  
Distribution Models ◽  
The Earth ◽  
Imaging Camera ◽  
Earth Radiation Budget ◽  
Mean Square Errors ◽  
Earth Radiation

One of the most crucial tasks of measuring top-of-atmosphere (TOA) radiative flux is to understand the relationships between radiances and fluxes, particularly for the reflected shortwave (SW) fluxes. The radiance-to-flux conversion is accomplished by constructing angular distribution models (ADMs). This conversion depends on solar-viewing geometries as well as the scene types within the field of view. To date, the most comprehensive observation-based ADMs are developed using the Clouds and the Earth’s Radiant Energy System (CERES) observations. These ADMs are used to derive TOA SW fluxes from CERES and other Earth radiation budget instruments which observe the Earth mostly from side-scattering angles. The Earth Polychromatic Imaging Camera (EPIC) onboard Deep Space Climate Observatory observes the Earth at the Lagrange-1 point in the near-backscattering directions and offers a testbed for the CERES ADMs. As the EPIC relative azimuth angles change from 168◦ to 178◦, the global daytime mean SW radiances can increase by as much as 10% though no notable cloud changes are observed. The global daytime mean SW fluxes derived after considering the radiance anisotropies at relative azimuth angles of 168◦ and 178◦ show much smaller differences (<1%), indicating increases in EPIC SW radiances are due mostly to changes in viewing geometries. Furthermore, annual global daytime mean SW fluxes from EPIC agree with the CERES equivalents to within 0.5 Wm−2 with root-mean-square errors less than 3.0 Wm−2. Consistency between SW fluxes from EPIC and CERES inverted from very different viewing geometries indicates that the CERES ADMs accurately quantify the radiance anisotropy and can be used for flux inversion from different viewing perspectives.

scholarly journals Unfiltering of the Geostationary Earth Radiation Budget (GERB) Data. Part I: Shortwave Radiation

2008 ◽  
Vol 25 (7) ◽  
pp. 1087-1105 ◽  
Author(s):  
N. Clerbaux ◽  
S. Dewitte ◽  
C. Bertrand ◽  
D. Caprion ◽  
B. De Paepe ◽  
...  
Keyword(s):  
Spectral Response ◽  
Radiant Energy ◽  
Absolute Error ◽  
Energy System ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Spectral Radiance ◽  
Visible Part ◽  
Earth Radiation Budget ◽  
Earth Radiation

Abstract The method used to estimate the unfiltered shortwave broadband radiance from the filtered radiances measured by the Geostationary Earth Radiation Budget (GERB) instrument is presented. This unfiltering method is used to generate the first released edition of the GERB-2 dataset. The method involves a set of regressions between the unfiltering factor (i.e., the ratio of the unfiltered and filtered broadband radiances) and the narrowband observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument. The regressions are theoretically derived from a large database of simulated spectral radiance curves obtained by radiative transfer computations. The generation of the database is fully described. Different sources of error that may affect the GERB unfiltering have been identified and the associated error magnitudes are assessed on this database. For most of the earth–atmosphere conditions, the error introduced during the unfiltering process is below 1%. In some conditions (e.g., low sun elevation above the horizon) the error can present a higher relative value, but the absolute error value remains well under the accuracy goal of 1% of the full instrument scale (2.4 W m−2 sr−1). To increase the confidence level, the edition 1 unfiltered radiances of GERB-2 are validated by cross comparison with collocated and coangular Clouds and the Earth’s Radiant Energy System (CERES) observations for different scene types. In addition to an overall offset between the two instruments, the intercomparisons indicate a scene-type dependency up to 4% in unfiltered radiance. Further studies are required to confirm the cause, but an insufficiently accurate characterization of the shortwave spectral response of the GERB instrument in the visible part of the spectrum is one area under further investigation.

scholarly journals Generation of a Seamless Earth Radiation Budget Climate Data Record: A New Methodology for Placing Overlapping Satellite Instruments on the Same Radiometric Scale

2020 ◽  
Vol 12 (17) ◽  
pp. 2787
Author(s):  
Mohan Shankar ◽  
Wenying Su ◽  
Natividad Manalo-Smith ◽  
Norman G. Loeb
Keyword(s):  
Spectral Response ◽  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Climate Data ◽  
Data Record ◽  
Earth Radiation Budget ◽  
Climate Data Record ◽  
Earth Radiation

The Clouds and the Earth’s Radiant Energy System (CERES) instruments have enabled the generation of a multi-decadal Earth radiation budget (ERB) climate data record (CDR) at the top of the Earth’s atmosphere, within the atmosphere, and at the Earth’s surface. Six CERES instruments have been launched over the course of twenty years, starting in 1999. To seamlessly continue the data record into the future, there is a need to radiometrically scale observations from newly launched instruments to observations from the existing data record. In this work, we describe a methodology to place the CERES Flight Model (FM) 5 instrument on the Suomi National Polar-orbiting Partnership (SNPP) spacecraft on the same radiometric scale as the FM3 instrument on the Aqua spacecraft. We determine the required magnitude of radiometric scaling by using spatially and temporally matched observations from these two instruments and describe the process to radiometrically scale SNPP/FM5 to Aqua/FM3 through the instrument spectral response functions. We also present validation results after application of this radiometric scaling and demonstrate the long-term consistency of the SNPP/FM5 record in comparison with the CERES instruments on Aqua and Terra.

Unfiltering of the Geostationary Earth Radiation Budget (GERB) Data. Part II: Longwave Radiation

2008 ◽  
Vol 25 (7) ◽  
pp. 1106-1117 ◽  
Author(s):  
N. Clerbaux ◽  
S. Dewitte ◽  
C. Bertrand ◽  
D. Caprion ◽  
B. De Paepe ◽  
...  
Keyword(s):  
Radiant Energy ◽  
Longwave Radiation ◽  
Energy System ◽  
Radiation Budget ◽  
Spectral Radiance ◽  
Infrared Imager ◽  
Earth Radiation Budget ◽  
Different Sources ◽  
Flight Model ◽  
Earth Radiation

Abstract The method used to estimate the unfiltered longwave broadband radiance from the filtered radiances measured by the Geostationary Earth Radiation Budget (GERB) instrument is presented. This unfiltering method is used to generate the first released edition of the GERB-2 dataset. This method involves a set of regressions between the unfiltering factor (i.e., the ratio of the unfiltered and filtered broadband radiances) and the narrowband observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument. The regressions are theoretically derived from a large database of simulated spectral radiance curves obtained by radiative transfer computations. The generation of this database is fully described. Different sources of error that may affect the GERB unfiltering have been identified and the associated error magnitudes are assessed on the database. For most of the earth–atmosphere conditions, the error introduced during the unfiltering processes is well under 0.5% (RMS error of about 0.1%). For more confidence, the unfiltered radiances of GERB-2 are validated by cross comparison with collocated and coangular Clouds and the Earth’s Radiant Energy System (CERES) observations. The agreement between the unfiltered radiances is within the science goals (1% accuracy for GERB and 0.5% for CERES) for the Flight Model 2 (FM2). For the CERES Flight Model 3 (FM3) instrument, an overall difference of 1.8% is observed. The intercomparisons indicate some scene-type dependency, which is due to the unfiltering for the cloudy scenes. This should be corrected for subsequent editions of the database.

scholarly journals Unfiltering Earth Radiation Budget Experiment (ERBE) Scanner Radiances Using the CERES Algorithm and Its Evaluation with Nonscanner Observations

2014 ◽  
Vol 31 (4) ◽  
pp. 843-859 ◽  
Author(s):  
Alok K. Shrestha ◽  
Seiji Kato ◽  
Takmeng Wong ◽  
David A. Rutan ◽  
Walter F. Miller ◽  
...  
Keyword(s):  
Critical Role ◽  
Radiant Energy ◽  
Energy System ◽  
Sensitivity Study ◽  
Radiation Budget ◽  
Cloud Properties ◽  
Earth Radiation Budget ◽  
The One ◽  
Observational Record ◽  
Earth Radiation

Abstract The NOAA-9 Earth Radiation Budget Experiment (ERBE) scanner measured broadband shortwave, longwave, and total radiances from February 1985 through January 1987. These scanner radiances are reprocessed using the more recent Clouds and the Earth’s Radiant Energy System (CERES) unfiltering algorithm. The scene information, including cloud properties, required for reprocessing is derived using Advanced Very High Resolution Radiometer (AVHRR) data on board NOAA-9, while no imager data were used in the original ERBE unfiltering. The reprocessing increases the NOAA-9 ERBE scanner unfiltered longwave radiances by 1.4%–2.0% during daytime and 0.2%–0.3% during nighttime relative to those derived from the ERBE unfiltering algorithm. Similarly, the scanner unfiltered shortwave radiances increase by ~1% for clear ocean and land and decrease for all-sky ocean, land, and snow/ice by ~1%. The resulting NOAA-9 ERBE scanner unfiltered radiances are then compared with NOAA-9 nonscanner irradiances by integrating the ERBE scanner radiance over the nonscanner field of view. The comparison indicates that the integrated scanner radiances are larger by 0.9% for shortwave and 0.7% smaller for longwave. A sensitivity study shows that the one-standard-deviation uncertainties in the agreement are ±2.5%, ±1.2%, and ±1.8% for the shortwave, nighttime longwave, and daytime longwave irradiances, respectively. The NOAA-9 and ERBS nonscanner irradiances are also compared using 2 years of data. The comparison indicates that the NOAA-9 nonscanner shortwave, nighttime longwave, and daytime longwave irradiances are 0.3% larger, 0.6% smaller, and 0.4% larger, respectively. The longer observational record provided by the ERBS nonscanner plays a critical role in tying the CERES-like NOAA-9 ERBE scanner dataset from the mid-1980s to the present-day CERES scanner data record.

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