Coloration determination of spectral darkening occurring on a broadband Earth observing radiometer: application to Clouds and the Earth's Radiant Energy System (CERES)

Matthews, Grant; Priestley, Kory J.; Loeb, Norman G.; Loukachine, K.; Thomas, Susan; Walikainen, Dale R.; Wielicki, Bruce A.

doi:10.1117/12.680884

Cited by 6 publications

(9 citation statements)

References 12 publications

(5 reference statements)

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“…Significant drifts in the FM-1 and FM-4 SW gains were found after processing of these editions began ). Matthews et al (2005) developed a set of scaling factors to account for the gain changes due to sensor degradation (additional information is available online at http:// eosweb.larc.nasa.gov/PRODOCS/ceres/SSF/Quality_ Summaries/CER_SSF_Terra_Edition2A.html and at http://eosweb.larc.nasa.gov/PRODOCS/ceres/SSF/ Quality_Summaries/CER_SSF_Aqua_Edition2A. html).…”

Section: Ceres Broadband Sw Radiancesmentioning

confidence: 99%

“…Corrections have been developed to eliminate trends due to shortwave sensor degradation on the Aqua and Terra scanners Matthews et al 2005) resulting in a very stable climate record of broadband radiance and flux data. Monitoring and adjusting the calibrations of the 490 detectors used for the 36 MODIS narrowband channels on Terra and Aqua (e.g., W. L. Barnes et al 2004) and the five VIRS channels is in itself a daunting task.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of the Visible Channel Calibrations of the VIRS on TRMM and MODIS on Aqua and Terra

Minnis

Doelling

Nguyen

et al. 2008

Journal of Atmospheric and Oceanic Technology

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Several recent research satellites carry self-calibrating multispectral imagers that can be used for calibrating operational imagers lacking complete self-calibrating capabilities. In particular, the visible (VIS, 0.65 m) channels on operational meteorological satellites are generally calibrated before launch, but require vicarious calibration techniques to monitor the gains and offsets once they are in orbit. To ensure that the self-calibrating instruments are performing as expected, this paper examines the consistencies between the VIS channel (channel 1) reflectances of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites and the version 5a and 6 reflectances of the Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission using a variety of techniques. These include comparisons of Terra and Aqua VIS radiances with coincident broadband shortwave radiances from the well-calibrated Clouds and the Earth's Radiant Energy System (CERES), time series of deep convective cloud (DCC) albedos, and ray-matching intercalibrations between each of the three satellites. Time series of matched Terra and VIRS data, Aqua and VIRS data, and DCC reflected fluxes reveal that an older version (version 5a, ending in early 2004) of the VIRS calibration produced a highly stable record, while the latest version (version 6) appears to overestimate the sensor gain change by ϳ1% yr Ϫ1 as the result of a manually induced gain adjustment. Comparisons with the CERES shortwave radiances unearthed a sudden change in the Terra MODIS calibration that caused a 1.17% decrease in the gain on 19 November 2003 that can be easily reversed. After correction for these manual adjustments, the trends in the VIRS and Terra channels are no greater than 0.1% yr Ϫ1 . Although the results were more ambiguous, no statistically significant trends were found in the Aqua MODIS channel 1 gain. The Aqua radiances are 1% greater, on average, than their Terra counterparts, and after normalization are 4.6% greater than VIRS radiances, in agreement with theoretical calculations. The discrepancy between the two MODIS instruments should be taken into account to ensure consistency between parameters derived from them. With the adjustments, any of the three instruments can serve as references for calibrating other satellites. Monitoring of the calibrations continues in near-real time and the results are available via the World Wide Web.

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Section: Ceres Broadband Sw Radiancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessment of the Visible Channel Calibrations of the VIRS on TRMM and MODIS on Aqua and Terra

Minnis

Doelling

Nguyen

et al. 2008

Journal of Atmospheric and Oceanic Technology

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“…r j sw (λ, k) is the SW channel fractional spectral response that is updated in month 'k' using the spectral darkening model. 4 …”

Section: Gain and Spectral Response Balancing Of Sw Channels On The Smentioning

confidence: 97%

“…The filtered equivalent of this metric is used to provide stability as part of the spectral darkening model. 4 Clearly Fig. 5(a) implies mission life lowering of Terra and Aqua DCC albedo measurements even after Edition 2 calibration adjustments are made.…”

Section: Gain and Spectral Response Balancing Of Sw Channels On The Smentioning

confidence: 98%

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Transfer of radiometric standards between multiple low earth orbit climate observing broadband radiometers: application to CERES

Matthews

Priestley

Thomas

2007

Earth Observing Systems XII

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The Clouds and the Earth's Radiant Energy System (CERES) is the only project currently measuring the global Earth Radiation Budget (ERB) from space. Two CERES instruments are located on the EOS Terra platform and two more are placed on the EOS Aqua satellite. One more CERES unit provided 8 months of ERB data in 1998 from the TRMM platform. Each of the CERES devices uses three broadband radiometric scanning telescopes: the shortwave (SW 0.3 → 5µm), Total (0.3 → 100µm), and window (8 → 12µm) channels. Rigorous pre-launch ground calibration is performed on each CERES unit to achieve an accuracy goal of 1% for Short Wave (SW) and 0.5% for outgoing Long Wave (LW) radiance. Any ground to flight or in-flight changes in radiometer response is monitored using onboard calibration sources. For the total and window channels these take the form of concentric groove blackbodies, while the SW channels use stable tungsten lamps. Recent studies have shown that the SW response of space based broadband radiometers can change dramatically due to optical contamination. With these changes having most impact on optical response to blue-UV radiance, where tungsten lamps are largely devoid of output, such changes are hard to monitor accurately using existing on-board sources. This study details an attempt to use the vicarious stability metric of deep convective clouds (DCC), nighttime LW scenes and a newly developed SW optical darkening model to place all CERES instrument measurements on the same radiometric scale. The results show that scene dependant dispersion in nadir comparisons between instruments on the same satellite are significantly reduced. Also the suggestion is that the pre-flight contamination of the CERES instruments may require an increase in Terra and Aqua measured SW flux. A larger necessary increase in Aqua SW flux is believed to be due to greater pre-flight contamination of the CERES Aqua optics.

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NASA CERES Spurious Calibration Drifts Corrected by Lunar Scans to Show the Sun Is not Increasing Global Warming and Allow Immediate CRF Detection

Matthews¹

2021

Geophysical Research Letters

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There is still much uncertainty surrounding how the Earth will respond to the rapid recent warming that has been observed, due to significant anthropogenic greenhouse gas releases in the last 120 years. The resulting changes to clouds, often referred to as cloud radiative forcing/feedback or CRF (Bony et al., 2006), remains one of the largest unknowns. More specifically, it is unclear if the rapidly arriving warmer Earth will result in more, less, or simply different types of clouds, and whether changes to say their sunlight reflection will diminish or amplify warming (i.e., as a negative or positive climate feedback).The time averaged solar flux of 1,361 2Wm arriving at Earth is currently very stable on decadal length scales, with a slight negative trend of −0.029%/decade in the 2000-2015 timeframe, so cannot by itself be responsible for current rapid surface temperature rises (see Figure 1, LASP, 2021). This work is therefore not an analysis of effects of variation in solar output on climate change (Haigh, 1996), but instead its focus is on changes to remaining planetary solar input after reflection from Earth, defined here as "albedo solar warming" (at first assuming the Solar output flux is completely constant over time). Albedo changes have the potential to be a primary driver of climate change, as they would alter the energy entering Earth from the currently stable Sun. For example, the rise in atmospheric reflectivity due to particulate aerosols emitted from the 1991 Pinatubo volcanic eruption (Soden et al., 2002), led to a temporary global cooling of around half a degree Celsius.Climate scientists and economists estimated that the size of the CRF albedo solar warming/cooling climate signal trends being looked for, are no larger than just under 0.8 2Wm /decade in magnitude (Cooke et al., 2013;Wielicki et al., 2013). This is in terms of changes to fractional Earth reflectivity, multiplied with the incoming solar flux (that averages to 1,361 2Wm with an overhead Sun). Solar flux is measured daily Abstract Orbital Earth Radiation Budget measurement comparisons to models, are critical for climate prediction confidence. Satellite systems must reduce calibration drifts for this purpose. NASA Clouds and the Earth's Radiant Energy System (CERES) measures Earth albedo reductions that if correct, would increase solar forcing and suggest greater sunlight absorption is driving much of recent temperature increases. Such results are presented, alongside those from the Moon and Earth Radiation Budget Experiment (MERBE). MERBE uses constant lunar reflectivity for tracking and compensation of instrument telescope degradation, undetectable by CERES. MERBE finds Earth albedo constant compared to that of the Moon, because Arctic solar warming effects are balanced by solar cooling elsewhere, likely due to negative feedbacks. Contrary to NASA, this shows the Sun is not increasing warming and that CERES results are not as stable as claimed and assumed. Furthermore, MERBE can actually resolve Cloud Radiative Forcing (CRF) sign...

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Coloration determination of spectral darkening occurring on a broadband Earth observing radiometer: application to Clouds and the Earth's Radiant Energy System (CERES)

Cited by 6 publications

References 12 publications

Assessment of the Visible Channel Calibrations of the VIRS on TRMM and MODIS on Aqua and Terra

Assessment of the Visible Channel Calibrations of the VIRS on TRMM and MODIS on Aqua and Terra

Transfer of radiometric standards between multiple low earth orbit climate observing broadband radiometers: application to CERES

NASA CERES Spurious Calibration Drifts Corrected by Lunar Scans to Show the Sun Is not Increasing Global Warming and Allow Immediate CRF Detection

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