The Advanced Baseline Imager (ABI) is a passive imaging radiometer on-board National Oceanic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellites-R (GOES-R) series. Its bands 7 to 16 are categorized as infrared (IR) bands, sampling within a spectral range of 3.9 to 13.3 μm in mid-wave infrared (MWIR) and long-wave infrared (LWIR) regions. ABI provides variable area imagery and radiometric information of Earth’s surface, atmosphere, and cloud cover. All of the IR bands are calibrated on-orbit in reference to an internal blackbody. While the ABI aboard the GOES-16 satellite has been working properly, an anomaly with GOES-17 ABI’s cooling system, specifically its loop heat pipe (LHP) subsystem, prevents heat from being efficiently transferred from the ABI electronics to the radiator to be dissipated into space. As a consequence, the heat accumulates inside the instrument, so the temperatures of its key components for IR calibration, including the focal plane modules (FPMs), scan mirrors, and blackbody, cannot be maintained at their designed operational levels. As an example, the temperatures of MWIR and LWIR FPMs, where IR detectors are located, are currently operated at a baseline temperature of ∼20 K warmer than the design and vary by as many as 27 K diurnally. This causes severe degradation to the data quality of ABI IR Level 1b radiance and subsequent Level 2+ products during the hot period of the day. Significant progress has been made to mitigate the effects of the LHP anomaly to optimize the IR performance of GOES-17 ABI. We summarize the efforts made by NOAA’s GOES-R Calibration Working Group, working collaboratively with other teams, to evaluate and alleviate the negative impacts of warmer and floating FPM temperatures on ABI IR calibration, and assess the IR performance accordingly.
The GOES-17 Advanced Baseline Imager (ABI) has an anomaly with its on-board cooling system that prevents it from maintaining its Focal Plane Modules (FPMs) at cold, optimal temperatures. Because of this, during certain times of the year the FPMs and their detectors warm and cool throughout the day. Changing the detectors’ temperature changes their response to incoming radiance, which leads to calibration errors over time and degrades the imagery. Numerous mitigation strategies have been implemented to reduce the solar insolation on the instrument and to mitigate image degradation, including semi-annual yaw flips and changing the integration time of the detectors twice daily. These and other mitigations all work with the baseline calibration algorithms currently in place on the GOES-R Ground System. In an attempt to reduce the image degradation even further, the ABI vendor designed a new calibration scheme that predicts key parameters forward in time to account for the drifting FPM temperatures. These parameters, the linear gain term and dark current scene, are nominally updated on orbit every 5 minutes and 30 seconds, respectively. However, even at these relatively short cadences the detectors can change temperature, thereby rendering the parameters invalid for accurate calibration. By projecting these parameters forward in time the radiometric bias is reduced and image quality improves. This Predictive Calibration modification was deployed to operations on July 25, 2019, following several months of extensive testing and optimization by the GOES-R science teams. During this time several parameters and thresholds were tuned to ensure Predictive Calibration was turning on and off at the optimal times. Since going into operations users have seen noticeable improvement to the imagery and its calibration. This paper will discuss the fundamental assumptions behind the baseline equations and highlight the changes introduced by Predictive Calibration. Results will show the improvements to the calibration of the operational L1b products and reduction in image degradation.
Two flight models of the Advanced Baseline Imager (ABI) are in-orbit on the GOES-16 and GOES-17 geostationary satellites, with two more planned to be launched on GOES-T (2021) and GOES-U (2024). The ABI is the primary Earthviewing weather imaging instrument on the GOES-R Series, producing Level 1b (L1b) radiances and Cloud and Moisture Imagery (CMI) data products. The ABI L1b product is the source for all the ABI Level 2+ (L2+) products, including CMI, which makes the maturity process for these two products important. CMI is the only key performance parameter (KPP) of the GOES-R Series mission and thus CMI takes precedence over other ABI L2+ products. As the only KPP, CMI follows the same maturity schedule as the ABI L1b product. For the ABI L1b and CMI data products to be declared operational, they must pass through a series of calibration and validation tests and analyses, with the peerreviewed results showing that the instruments and products have achieved each level of maturity consistent with mission success. This paper describes the assessment process, the definitions of the product validation maturity levels, and an overview of the product performance for each instrument at each validation level. Additionally, this paper will describe planned programmatic changes aimed at streamlining the maturity process for the upcoming GOES-T and GOES-U satellites.
The first satellite of the Geostationary Operational Environmental Satellite-R series (GOES-R), the next generation of NOAA geostationary environmental satellites, was launched November 19, 2016. This satellite, GOES-16, carries six instruments dedicated to the study of the Earth’s weather (ABI), lightning mapping (GLM), solar observations (EXIS and SUVI), and space weather monitoring (SEISS and MAG). Each of these six instruments are in the process of going through a series of specialized calibration plans to achieve their product quality requirements. In this review paper we will describe the overall status of the on-orbit calibration program, the path forward to Full product validation status, and any changes that may occur for the cal/val plans for GOES-S, which is planned for launch in early 2018.
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