Calibration Adjustments to the MODIS Aqua Ocean Color Bands

After the end of the SeaWiFS mission in 2010 and the MERIS mission in 2012, the ocean color products of the MODIS on Aqua are the only remaining source to continue the ocean color climate data record until the VIIRS ocean color products become operational (expected for summer 2013). The MODIS on Aqua is well beyond its expected lifetime, and the calibration accuracy of the short wavelengths (412nm and 443nm) has deteriorated in recent years_ Initially, SeaWiFS data were used to improve the MODIS Aqua calibration, but this solution was not applicable after the end of the SeaWiFS mission_ In 2012, a new calibration methodology was applied by the MODIS calibration and support team using desert sites to improve the degradation trending_ This presentation presents further improvements to this new approach. The 2012 reprocessing of the MODIS Aqua ocean color products is based on the new methodology

Calibration Program for the Ocean Color Instrument (OCI) on the Plankton, Aerosol, and Cloud Ocean Ecosystem (PACE) Mission

No abstract availabl

MODIS Solar Diffuser Degradation Determination and Its Spectral Dependency

This study presents a modeling approach to improve solar diffuser (SD) degradation determination from SD stability monitor (SDSM) measurements. The MODIS instrument uses a SDto calibrate its reflective solar bands (RSBs) on-orbit. Due to the imperfectly designed SDSM sun view screen, the SD reflectance tracked by SDSM has large noise. The SDSM measurements noise is spectrally coherent and can be minimized by normalizing measurements to the least degradeddetector 9 (936 nm). In this study, a SD degradation model is used to determine the SDdegradation's wavelength dependency and the detector 9 degradation is estimated by the model solution.The results show the SD degradations measured at 6 SDSM detectors (554 _ 936 nm) have stable relationships, where the degradation is inversely proportion to 1/wavelength^4. The model estimated SD degradation at SDSM detector 9 wavelength (936 nm) is ~0.9% from 2002 to 2018.Based on the SD degradation model solution, the SD degradation at short/mid wave bands are estimated to improve short/mid wave bands calibration. The model can also be used to improve interpolating SD degradation at SDSM detectors to RSB wavelengths. Compared to linear interpolation, bands 9 and 10 show the largest differences of up to 0.3 and 0.4% respectively. These differences directly impact the calibration coefficients of these bands

Adjustments to the MODIS Terra Radiometric Calibration and Polarization Sensitivity in the 2010 Reprocessing

The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA s Earth Observing System (EOS) satellite Terra provides global coverage of top-of-atmosphere (TOA) radiances that have been successfully used for terrestrial and atmospheric research. The MODIS Terra ocean color products, however, have been compromised by an inadequate radiometric calibration at the short wavelengths. The Ocean Biology Processing Group (OBPG) at NASA has derived radiometric corrections using ocean color products from the SeaWiFS sensor as truth fields. In the R2010.0 reprocessing, these corrections have been applied to the whole mission life span of 10 years. This paper presents the corrections to the radiometric gains and to the instrument polarization sensitivity, demonstrates the improvement to the Terra ocean color products, and discusses issues that need further investigation. Although the global averages of MODIS Terra ocean color products are now in excellent agreement with those of SeaWiFS and MODIS Aqua, and image quality has been significantly improved, the large corrections applied to the radiometric calibration and polarization sensitivity require additional caution when using the data

Corrections to the MODIS Aqua Calibration Derived From MODIS Aqua Ocean Color Products

Ocean color products such as, e.g., chlorophyll-a concentration, can be derived from the top-of-atmosphere radiances measured by imaging sensors on earth-orbiting satellites. There are currently three National Aeronautics and Space Administration sensors in orbit capable of providing ocean color products. One of these sensors is the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, whose ocean color products are currently the most widely used of the three. A recent improvement to the MODIS calibration methodology has used land targets to improve the calibration accuracy. This study evaluates the new calibration methodology and describes further calibration improvements that are built upon the new methodology by including ocean measurements in the form of global temporally averaged water-leaving reflectance measurements. The calibration improvements presented here mainly modify the calibration at the scan edges, taking advantage of the good performance of the land target trending in the center of the scan

Radiometric Quality of the MODIS Bands at 667 and 678nm

The MODIS instruments on Terra and Aqua were designed to allow the measurement of chlorophyll fluorescence effects over ocean. The retrieval algorithm is based on the difference between the water-leaving radiances at 667nm and 678nm. The water-leaving radiances at these wavelengths are usually very low relative to the top- of-atmosphere radiances. The high radiometric accuracy needed to retrieve the small fluorescence signal lead to a dual gain design for the 667 and 678nm bands. This paper discusses the benefits obtained from this design choice and provides justification for the use of only one set of gains for global processing of ocean color products. Noise characteristics of the two bands and their related products are compared to other products of bands from 412nm to 2130nm. The impact of polarization on the two bands is discussed. In addition, the impact of stray light on the two bands is compared to other MODIS bands

The Media Pedagogy Futurelab: Quality Development – Professionalisation – Standards. Thesis Paper on the 2017 GMK Forum on Communication Culture

Das Forum Kommunikationskultur der Gesellschaft für Medienpädagogik und Kommunikationskultur (GMK) steht im Jahr 2017 unter dem Anspruch, sich mit Fragen der Qualitätsentwicklung medienpädagogischen Handelns in Wissenschaft und Praxis auseinanderzusetzen. Dabei soll besonderes Augenmerk auf Fragen der Professionalisierung und der Entwicklung von Standards gelegt werden. Zu diesen Fragen stellen wir im Folgenden ausgewählte Thesen mit ergänzenden und erweiternden Erläuterungen im Sinne eines programmatischen Textes zur Diskussion. Die mit diesem Papier anzustossende Diskussion soll zunächst einer konstruktiv-weiterführenden internen Klärung wichtiger Fragen medienpädagogischer Praxis und Forschung dienen und dabei auch anzeigen, welche Positionen in der Community konsensfähig sind und welche möglicherweise strittig erscheinen. Zugleich sollen die Thesen und die Diskussion zu einer Positionsbestimmung der GMK bezüglich praktischer und wissenschaftlicher medienpädagogischer Arbeit nach aussen beitragen. Mit der Diskussion ist das Ziel verbunden, künftige Bedarfe für Handlungs- und Forschungsfelder der Medienpädagogik – jedoch ohne Anspruch auf Vollständigkeit – zu identifizieren. Um der Prägnanz und Kürze willen, wird der zu jeder These gehörende Hintergrund nur knapp angedeutet, ohne die damit verbundenen (teils sehr umfassenden) Diskurse im Detail nachzuzeichnen. Angegebene Literaturbezüge sollen jeweils beispielhaft auf differenzierende und tiefergehende Ausführungen verweisen. Die Thesenfolge beginnt mit Überlegungen zum technikinduzierten gesellschaftlichen Wandel („Digitalisierung“) und seiner Bedeutung für die Medienbildung. Dies vorausschickend, gehen wir auf Fragen der Qualifizierung und Professionalisierung für praktisches Handeln sowie auf die Rolle der Medienpädagogik als Wissenschaft und schliessend auf den Stellenwert von Standards zur Orientierung und Reflexion ein.The 2017 Forum on Communication Culture hosted by the Society for Media Pedagogy and Communication Culture (GMK – Gesellschaft für Medienpädagogik und Kommunikations­kultur) is devoted to quality development in media pedagogy in both research and practice. Particular focus is placed on issues of professionalisation and the development of standards. The following document contains selected theses with supplementary and explanatory notes and is intended to serve as a programmatic text for discussion. The discussion ensuing from this paper is intended first and foremost to serve the ongoing internal clarification of important issues related to media pedagogy in research and practice. Consequently, it seeks to identify those positions the community can agree on, and those which might transpire to be more contentious. At the same time, the theses and the accompanying discussion aim to assist the GMK in formally determining where it stands on practical and scholarly work being undertaken in media pedagogy, thereby enabling it to formulate an official position which it can represent externally. Inherent within the discussion is the goal of pinpointing any future requirements in the respective fields of practice and research in media pedagogy – albeit without claiming to be exhaustive in this respect. In the interests of concision and brevity, the accompanying background to each thesis is dealt with only briefly, without detailed scrutiny of its (often very comprehensive) associated discourse. Accompanying literature references are intended to provide examples of more finely grained and in-depth explanations. The theses begin with considerations on technology-driven social change («digitisation») and its significance for media education. Following on from this, we then discuss issues related to qualifications and the professionalisation of media pedagogy in practice; we also examine the role of media pedagogy as a scholarly activity, and conclude with the importance of standards as points of orientation and initiators of debate

Instrument Characterization for Ocean Color Remote Sensing

No abstract availabl

Satellite Ocean Color Sensor Design Concepts and Performance Requirements

In late 1978, the National Aeronautics and Space Administration (NASA) launched the Nimbus-7 satellite with the Coastal Zone Color Scanner (CZCS) and several other sensors, all of which provided major advances in Earth remote sensing. The inspiration for the CZCS is usually attributed to an article in Science by Clarke et al. who demonstrated that large changes in open ocean spectral reflectance are correlated to chlorophyll-a concentrations. Chlorophyll-a is the primary photosynthetic pigment in green plants (marine and terrestrial) and is used in estimating primary production, i.e., the amount of carbon fixed into organic matter during photosynthesis. Thus, accurate estimates of global and regional primary production are key to studies of the earth's carbon cycle. Because the investigators used an airborne radiometer, they were able to demonstrate the increased radiance contribution of the atmosphere with altitude that would be a major issue for spaceborne measurements. Since 1978, there has been much progress in satellite ocean color remote sensing such that the technique is well established and is used for climate change science and routine operational environmental monitoring. Also, the science objectives and accompanying methodologies have expanded and evolved through a succession of global missions, e.g., the Ocean Color and Temperature Sensor (OCTS), the Seaviewing Wide Field-of-view Sensor (SeaWiFS), the Moderate Resolution Imaging Spectroradiometer (MODIS), the Medium Resolution Imaging Spectrometer (MERIS), and the Global Imager (GLI). With each advance in science objectives, new and more stringent requirements for sensor capabilities (e.g., spectral coverage) and performance (e.g., signal-to-noise ratio, SNR) are established. The CZCS had four bands for chlorophyll and aerosol corrections. The Ocean Color Imager (OCI) recommended for the NASA Pre-Aerosol, Cloud, and Ocean Ecosystems (PACE) mission includes 5 nanometers hyperspectral coverage from 350 to 800 nanometers with three additional discrete near infrared (NIR) and shortwave infrared (SWIR) ocean aerosol correction bands. Also, to avoid drift in sensor sensitivity from being interpreted as environmental change, climate change research requires rigorous monitoring of sensor stability. For SeaWiFS, monthly lunar imaging accurately tracked stability at an accuracy of approximately 0.1% that allowed the data to be used for climate studies [2]. It is now acknowledged by the international community that future missions and sensor designs need to accommodate lunar calibrations. An overview of ocean color remote sensing and a review of the progress made in ocean color remote sensing and the variety of research applications derived from global satellite ocean color data are provided. The purpose of this chapter is to discuss the design options for ocean color satellite radiometers, performance and testing criteria, and sensor components (optics, detectors, electronics, etc.) that must be integrated into an instrument concept. These ultimately dictate the quality and quantity of data that can be delivered as a trade against mission cost. Historically, science and sensor technology have advanced in a "leap-frog" manner in that sensor design requirements for a mission are defined many years before a sensor is launched and by the end of the mission, perhaps 15-20 years later, science applications and requirements are well beyond the capabilities of the sensor. Section 3 provides a summary of historical mission science objectives and sensor requirements. This progression is expected to continue in the future as long as sensor costs can be constrained to affordable levels and still allow the incorporation of new technologies without incurring unacceptable risk to mission success. The IOCCG Report Number 13 discusses future ocean biology mission Level-1 requirements in depth

Corrections to MODIS Terra Calibration and Polarization Trending Derived from Ocean Color Products

Remotely sensed ocean color products require highly accurate top-of-atmosphere (TOA) radiances, on the order of 0.5% or better. Due to incidents both prelaunch and on-orbit, meeting this requirement has been a consistent problem for the MODIS instrument on the Terra satellite, especially in the later part of the mission. The NASA Ocean Biology Processing Group (OBPG) has developed an approach to correct the TOA radiances of MODIS Terra using spatially and temporally averaged ocean color products from other ocean color sensors (such as the SeaWiFS instrument on Orbview-2 or the MODIS instrument on the Aqua satellite). The latest results suggest that for MODIS Terra, both linear polarization parameters of the Mueller matrix are temporally evolving. A change to the functional form of the scan angle dependence improved the quality of the derived coefficients. Additionally, this paper demonstrates that simultaneously retrieving polarization and gain parameters improves the gain retrieval (versus retrieving the gain parameter only)