Monitoring on-orbit calibration stability of the Terra MODIS and Landsat 7 ETM+ sensors using pseudo-invariant test sites

Chander, Gyanesh; Xiong, Xiaoxiong; Choi, Taeyoung; Angal, Amit

doi:10.1016/j.rse.2009.12.003

Cited by 121 publications

(80 citation statements)

References 29 publications

(24 reference statements)

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“…Pseudo-invariant Earth targets have been used extensively to monitor the post-launch radiometric stability of satellite sensors for over two decades [10][11][12][13][14][15][16][17][18][19][20]. These targets primarily include subtropical deserts, polar ice sheets, and deep convective clouds.…”

Section: Methodsologymentioning

confidence: 99%

“…Owing to its high surface reflectance, high spatial homogeneity, excellent radiometric stability (less than 2% in VIS and NIR [21]), low aerosol loading, and minimal cloud cover, Libya-4 is considered to be one of the best invariant targets on Earth for post-launch satellite calibration and validation purpose [20,21,24]. Libya-4 has been used for monitoring the temporal stability of many satellite sensors including Landsat Multispectral Scanner (MSS) [19], Thematic Mapper (TM) [16], and Enhanced Thematic Mapper plus (ETM+) [17], AVHRR [12], and Aqua and Terra MODIS [17,18]. This study also uses Libya-4 as a radiometrically invariant target to assess the calibration stability of the 8 VIIRS RSB listed in Table 1.…”

Section: Desert Approachmentioning

confidence: 99%

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Initial Stability Assessment of S-NPP VIIRS Reflective Solar Band Calibration Using Invariant Desert and Deep Convective Cloud Targets

Bhatt

Doelling

et al. 2014

Remote Sensing

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Abstract:The latest CERES FM-5 instrument launched onboard the S-NPP spacecraft will use the VIIRS visible radiances from the NASA Land Product Evaluation and Analysis Tool Elements (PEATE) product for retrieving the cloud properties associated with its TOA flux measurement. In order for CERES to provide climate quality TOA flux datasets, the retrieved cloud properties must be consistent throughout the record, which is dependent on the calibration stability of the VIIRS imager. This paper assesses the NASA calibration stability of the VIIRS reflective solar bands using the Libya-4 desert and deep convective clouds (DCC). The invariant targets are first evaluated for temporal natural variability. It is found for visible (VIS) bands that DCC targets have half of the variability of Libya-4. For the shortwave infrared (SWIR) bands, the desert has less variability. The brief VIIRS record and target variability inhibits high confidence in identifying any trends that are less than ±0.6%/yr for most VIS bands, and ±2.5%/yr for SWIR bands. None of the observed invariant target reflective solar band trends exceeded these trend thresholds. Initial assessment results show that the VIIRS data have been consistently OPEN ACCESSRemote Sens. 2014, 6 2810 calibrated and that the VIIRS instrument stability is similar to or better than the MODIS instrument.

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Section: Methodsologymentioning

confidence: 99%

Section: Desert Approachmentioning

confidence: 99%

Initial Stability Assessment of S-NPP VIIRS Reflective Solar Band Calibration Using Invariant Desert and Deep Convective Cloud Targets

Bhatt

Doelling

et al. 2014

Remote Sensing

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“…If unaccounted for, there would be a residual RVS error, which would lead to biases in L1B reflectance, leading to biases in aerosol or other products. This residual RVS error was identified by taking long-term measurements of "pseudo-invariant" ground sites such as remote deserts (Chander et al, 2010), and comparing instrument response at later dates with earlier measurements. It was in this way that MCST could confirm that there was a drift in the blue (0.47 µm) channel that was consistent with trend in retrieved AOD over land.…”

Section: Calibration Issues and Expected Impact On Terra Productsmentioning

confidence: 99%

The Collection 6 MODIS aerosol products over land and ocean

et al. 2013

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Abstract. The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. The C6 aerosol data set will be created from three separate retrieval algorithms that operate over different surface types. These are the two "Dark Target" (DT) algorithms for retrieving (1) over ocean (dark in visible and longer wavelengths) and (2) over vegetated/dark-soiled land (dark in the visible), plus the "Deep Blue" (DB) algorithm developed originally for retrieving (3) over desert/arid land (bright in the visible). Here, we focus on DT-ocean and DTland (#1 and #2). We have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H 2 O, O 3 , CO 2 , etc.) absorption corrections, while relaxing the solar zenith angle limit (up to ≤ 84 • ) to increase poleward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence on the surface reflectance, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information.At the same time, we quantified how "upstream" changes to instrument calibration, land/sea masking and cloud masking will also impact the statistics of global AOD, and affect Terra and Aqua differently. For Aqua, all changes will result in reduced global AOD (by 0.02) over ocean and increased AOD (by 0.02) over land, along with changes in spatial coverage. We compared preliminary data to surface-based sun photometer data, and show that C6 should improve upon C5. C6 will include a merged DT/DB product over semi-arid land surfaces for reduced-gap coverage and better visualization, and new information about clouds in the aerosol field. Responding to the needs of the air quality community, in addition to the standard 10 km product, C6 will include a global (DT-land and DT-ocean) aerosol product at 3 km resolution.

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“…Radiometric calibration trending using invariant sites on the Earth's surface has been used for more than a decade [1][2][3][4][5][6][12][13][14]. These sites are popularly known in the calibration validation fraternity as PICS.…”

Section: Libya 4 Pics and Satellite Observationsmentioning

confidence: 99%

“…The advantages of using these spatially uniform sites are their stable spectral characteristics over time, high reflectance, and minimal atmospheric effect on upward radiance. As a result, these sites have been used extensively by researchers to monitor the multi-temporal and multi-angular stability of satellite sensors using time series analysis and cross-calibration [1][2][3][4][5][6]. However, PICS alone have the potential to be used for absolute calibration.…”

Section: Introductionmentioning

confidence: 99%

Absolute Calibration of Optical Satellite Sensors Using Libya 4 Pseudo Invariant Calibration Site

et al. 2014

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Abstract:The objective of this paper is to report the improvements in an empirical absolute calibration model developed at South Dakota State University using Libya 4 (+28.55°, +23.39°) pseudo invariant calibration site (PICS). The approach was based on use of the Terra MODIS as the radiometer to develop an absolute calibration model for the spectral channels covered by this instrument from visible to shortwave infrared. Earth Observing One (EO-1) Hyperion, with a spectral resolution of 10 nm, was used to extend the model to cover visible and near-infrared regions. A simple Bidirectional Reflectance Distribution function (BRDF) model was generated using Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations over Libya 4 and the resulting model was validated with nadir data acquired from satellite sensors such as Aqua MODIS and Landsat 7 (L7) Enhanced Thematic Mapper (ETM+). The improvements in the absolute calibration model to account for the BRDF due to off-nadir measurements and annual variations in the atmosphere are summarized. BRDF models due to off-nadir viewing angles have been derived using the measurements from EO-1 Hyperion. In addition to L7

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Monitoring on-orbit calibration stability of the Terra MODIS and Landsat 7 ETM+ sensors using pseudo-invariant test sites

Cited by 121 publications

References 29 publications

Initial Stability Assessment of S-NPP VIIRS Reflective Solar Band Calibration Using Invariant Desert and Deep Convective Cloud Targets

Initial Stability Assessment of S-NPP VIIRS Reflective Solar Band Calibration Using Invariant Desert and Deep Convective Cloud Targets

The Collection 6 MODIS aerosol products over land and ocean

Absolute Calibration of Optical Satellite Sensors Using Libya 4 Pseudo Invariant Calibration Site

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