<title>Far-IR spectral response measurements of the Clouds and the Earth's Radiant Energy System (CERES) sensors using a Fourier transform spectrometer and pyroelectric reference detector</title>

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.

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

Remote Sensing ◽

10.3390/rs12172787 ◽

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.

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Clouds and the Earth's Radiant Energy System (CERES) spectral response characterizations

10.1117/12.494240 ◽

2000 ◽

Author(s):

Aiman Al-Hajjah ◽

Kory J. Priestley ◽

Susan Thomas ◽

Robert B. Lee III ◽

Bruce R. Barkstrom ◽

...

Keyword(s):

Spectral Response ◽

Radiant Energy ◽

Energy System

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An Infinity Corrected All-Reflecting Microscope for Infrared Microspectrometry

Microscopy and Microanalysis ◽

10.1017/s1431927600022170 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 410-411

Author(s):

John A. Reffher ◽

Steven H. Vogel

Keyword(s):

Fourier Transform ◽

Light Microscopy ◽

Beam Splitter ◽

Infrared Detector ◽

Radiant Energy ◽

Geometrical Shape ◽

Fourier Transform Spectrometer ◽

Reflection Mode ◽

Optical Components ◽

The Cost

A confocal, all-reflecting, infinity corrected microscope was developed to improve infrared microspectrometer (IMS) systems. This system consists of a Fourier transform spectrometer, an infinity corrected all-reflecting microscope, a viewing system for visible light microscopy, a single remote confocal mask for aperturing in either a transmission or reflection mode and an infrared detector. The radiant energy passes through a confocal aperture mask as it travels from the source to the sample and through the same confocal aperture mask as it travels from the sample to the radiant energy detector. A single confocal mask insures that the sample defining mask's size, geometrical shape and orientation are always matched. Mask alignment is assured and simplified since only one adjustment is needed. An aperture beam-splitter is used for reflection measurements. This system simplifies the operation of the microspectrometer, permits the use of standard commercial infinity corrected microscope optical components and reduces the cost of IMS accessory microscopes.

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Evaluation of net shortwave radiation over China with a regional climate model

Climate Research ◽

10.3354/cr01598 ◽

2020 ◽

Vol 80 (2) ◽

pp. 147-163

Author(s):

X Liu ◽

Y Kang ◽

Q Liu ◽

Z Guo ◽

Y Chen ◽

...

Keyword(s):

Regional Climate Model ◽

Climate Model ◽

Regional Climate ◽

Radiant Energy ◽

Energy System ◽

Radiation Budget ◽

Shortwave Radiation ◽

Monsoon Region ◽

Clear Sky ◽

Sky Conditions

The regional climate model RegCM version 4.6, developed by the European Centre for Medium-Range Weather Forecasts Reanalysis, was used to simulate the radiation budget over China. Clouds and the Earth’s Radiant Energy System (CERES) satellite data were utilized to evaluate the simulation results based on 4 radiative components: net shortwave (NSW) radiation at the surface of the earth and top of the atmosphere (TOA) under all-sky and clear-sky conditions. The performance of the model for low-value areas of NSW was superior to that for high-value areas. NSW at the surface and TOA under all-sky conditions was significantly underestimated; the spatial distribution of the bias was negative in the north and positive in the south, bounded by 25°N for the annual and seasonal averaged difference maps. Compared with the all-sky condition, the simulation effect under clear-sky conditions was significantly better, which indicates that the cloud fraction is the key factor affecting the accuracy of the simulation. In particular, the bias of the TOA NSW under the clear-sky condition was <±10 W m-2 in the eastern areas. The performance of the model was better over the eastern monsoon region in winter and autumn for surface NSW under clear-sky conditions, which may be related to different levels of air pollution during each season. Among the 3 areas, the regional average biases overall were largest (negative) over the Qinghai-Tibet alpine region and smallest over the eastern monsoon region.

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