Pre-launch characterization of spectral response functions for the Clouds and Earth's Radiant Energy System (CERES) instrument sensors

Shankar, Mohan; Thomas, Susan; Priestley, Kory J.

doi:10.1117/12.859927

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…To reduce noise, a 5-month running mean is used. Recently, Shankar et al (2010) re-evaluated the ground calibration data collected prior to CERES Terra and Aqua launches and derived new pre-launch calibration data. Thomas et al (2010) summarize results of a reanalysis of CERES gain changes through March 2010.…”

Section: Discussionmentioning

confidence: 99%

Advances in Understanding Top-of-Atmosphere Radiation Variability from Satellite Observations

et al. 2012

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This paper highlights how the emerging record of satellite observations from the Earth Observation System (EOS) and A-Train constellation are advancing our ability to more completely document and understand the underlying processes associated with variations in the Earth's top-of-atmosphere (TOA) radiation budget. Large-scale TOA radiation changes during the past decade are observed to be within 0.5 Wm

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Section: Discussionmentioning

confidence: 99%

Advances in Understanding Top-of-Atmosphere Radiation Variability from Satellite Observations

et al. 2012

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“…The unfiltering process involves applying an algorithm that relates unfiltered and filtered radiances based upon knowledge of the instrument SRF and a radiance spectral database representative of Earth scenes [6]. Shankar et al [7] re-evaluated the ground calibration data collected prior to the CERES Terra and Aqua launches and derived new pre-launch SRFs for each CERES instrument. Figure 1 provides CERES SRFs for the FM1 instrument.…”

Section: Instrument Calibrationmentioning

confidence: 99%

CERES Top-of-Atmosphere Earth Radiation Budget Climate Data Record: Accounting for in-Orbit Changes in Instrument Calibration

Loeb

Manalo‐Smith

et al. 2016

Remote Sensing

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Abstract:The Clouds and the Earth's Radiant Energy System (CERES) project provides observations of Earth's radiation budget using measurements from CERES instruments onboard the Terra, Aqua and Suomi National Polar-orbiting Partnership (S-NPP) satellites. As the objective is to create a long-term climate data record, it is necessary to periodically reprocess the data in order to incorporate the latest calibration changes and algorithm improvements. Here, we focus on the improvements and validation of CERES Terra and Aqua radiances in Edition 4, which are used to generate higher-level climate data products. Onboard sources indicate that the total (TOT) channel response to longwave (LW) radiation has increased relative to the start of the missions by 0.4% to 1%. In the shortwave (SW), the sensor response change ranges from´0.4% to 0.6%. To account for in-orbit changes in SW spectral response function (SRF), direct nadir radiance comparisons between instrument pairs on the same satellite are made and an improved wavelength dependent degradation model is used to adjust the SRF of the instrument operating in a rotating azimuth plane scan mode. After applying SRF corrections independently to CERES Terra and Aqua, monthly variations amongst these instruments are highly correlated and the standard deviation in the difference of monthly anomalies is 0.2 Wm´2 for ocean and 0.3 Wm´2 for land/desert. Additionally, trends in CERES Terra and Aqua monthly anomalies are consistent to 0.21 Wm´2 per decade for ocean and 0.31 Wm´2 per decade for land/desert. In the LW, adjustments to the TOT channel SRF are made to ensure that removal of the contribution from the SW portion of the TOT channel with SW channel radiance measurements during daytime is consistent throughout the mission. Accordingly, anomalies in day-night LW difference in Edition 4 are more consistent compared to Edition 3, particularly for the Aqua land/desert case.

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“…The spectral response determination in the longwave region uses multiple sources and beam-splitters to cover the entire longwave range along with a reference pyro-electric detector. The approach is discussed in detail by Shankar et al 10 . The shortwave calibration set up in the RCF with the 13 narrow band filters cover the measurements for the spectral shape of sensors in 0.3 to 3.0 μm region.…”

Section: Shortwave Calibrationmentioning

confidence: 99%

Pre-launch sensor characterization of the CERES Flight Model 5 (FM5) instrument on NPP mission

et al. 2011

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Clouds and the Earth's Radiant Energy System (CERES) instrument was designed to measure broadband radiances in reflected shortwave and emitted outgoing longwave energy. The 3-sensor CERES instrument measure radiances in 0.3 to 5.0 micron region with Shortwave sensor, 0.3 to >100 microns with Total sensor and 8 to 12 micron region with Window sensor. Flight Model 5 (FM5), the sixth of the CERES instruments is scheduled to launch aboard the NPP spacecraft on October 2011. An accurate determination of the radiometric gains and spectral responsivity of CERES FM5 sensors was accomplished through rigorous calibrations at Northrop Grumman Aerospace Systems' (NGAS) Radiometric Calibration Facility (RCF). The longwave calibration of the total and window sensors are achieved using the Narrow Field-of-View Blackbody (NFBB) source which is tied to International Scale of 1990 (ITS '90). A Shortwave Reference Source (SWRS) along with the Transfer Active Cavity radiometer (TACR) which acts as the transfer standard of NFBB source, is used to determine the radiometric responsivity and spectral response estimates of the SW sensor and shortwave portion of the Total sensor. The spectral responsivity in longwave region is determined using a Fourier Transform Spectrometer (FTS) system. CERES instrument also perform calibrations using on-board sources during pre-launch testing which serve as a traceability standard to carry the ground determined sensor radiometric gains to orbit. This paper covers the calibration philosophy and the results from ground calibration testing of FM5 sensors conducted in 2008. The sensor radiometric gain responses calculated using primary sources and performance of the sensors using on-board sources will be discussed.

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Pre-launch characterization of spectral response functions for the Clouds and Earth's Radiant Energy System (CERES) instrument sensors

Cited by 6 publications

References 7 publications

Advances in Understanding Top-of-Atmosphere Radiation Variability from Satellite Observations

Advances in Understanding Top-of-Atmosphere Radiation Variability from Satellite Observations

CERES Top-of-Atmosphere Earth Radiation Budget Climate Data Record: Accounting for in-Orbit Changes in Instrument Calibration

Pre-launch sensor characterization of the CERES Flight Model 5 (FM5) instrument on NPP mission

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