the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Remote sensing of lower-middle thermosphere temperatures using the N2 Lyman-Birge-Hopfield (LBH) bands
Abstract. The scientific and societal importance of short-term changes in the thermosphere-ionosphere (T-I) system has highlighted the need to advance our understanding of short-term changes in the lower-middle thermosphere. This need has become increasingly important with the rapid increase in the number of low-earth-orbiting satellites. Geomagnetic activity can dramatically increase thermospheric temperatures and, almost equivalently, thermospheric densities and satellite drag. However, specification of drag during quiet periods may also be problematic when the number of satellites is large. While temperatures and densities at higher altitudes (>~250 km) have been extensively studied and modeled, there is a knowledge gap for densities at lower-middle thermosphere altitudes (< ~200 km). At these lower altitudes the primary sources of thermospheric density data, in situ and drag data from satellites, are rarely available. Remote sensing of temperatures and composition by NASA’s Global-scale Observations of the Limb and Disk (GOLD) mission can help fill this gap The GOLD mission produces disk images of neutral temperature, which is key parameter for understanding neutral density in the lower-middle thermosphere. However, since disk images of the temperature have become available only since the launch of GOLD, some researchers may be unfamiliar with the current observational capability that is relevant to the data interpretation. Also, other temperature retrieval techniques than GOLD’s have been published. Comparisons indicate that GOLD’s technique gives the most consistent results and yields the lowest uncertainties. This paper discusses both temperature retrieval techniques and issues in interpreting GOLD’s images of temperatures.
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Status: closed (peer review stopped)
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RC1: 'Comment on amt-2024-52', Anonymous Referee #1, 26 Aug 2024
The manuscript presents results of GOLD retrieved disk temperature (Tdisk) in the middle thermosphere near ~160km. The detailed information of the retrieval is not described, but referenced to a recent already published paper (Evans et al., 2024, https://doi.org/10.1029/2024JA032424), which is fine to me. The manuscript discusses Tdisk uncertainties, solar zenith angle dependence and solar cycle variation, which are important and valuable for the users to understand the data and correctly interpret the data when using the dataset. I do have some comments in the annotated pdf file for the authors to consider when they revise the manuscript.
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RC2: 'Comment on amt-2024-52', Anonymous Referee #2, 04 Sep 2024
This paper summarizes the GOLD multi-band LBH temperature retrieval approach described in a recent paper, briefly discusses recent version 5 improvements of the TDISK product, and compares results to two other approaches for retrieving thermospheric from FUV observations. The paper argues that the absence of artifacts in new GOLD temperatures, the physical behavior of retrieved temperatures, and the low uncertainties from high signal-to-noise from multi-band retrievals make the GOLD thermospheric temperatures reliable. The paper provides an overview of retrieved GOLD temperatures and uncertainties during the mission. Moreover, examples of challenges in an alternate single-band rotational temperature retrieval method and a vibrational band ratio temperature retrieval method indicate that these methods are not yet mature and require further analysis to resolve issues regarding biases and uncertainties compared to GOLD temperature retrievals.
The paper is well-organized and supports the major conclusions with examples, particularly as the intent appears to be to more widely disseminate GOLD temperature products to the community and provide a basic understanding of GOLD temperature behavior and limitations. This paper is not an exhaustive modeling or statistical study of the GOLD temperature product versus other approaches. The wording is not as economical as possible and the figures would benefit from minor tweaks. An attachment details minor suggestions.
Status: closed (peer review stopped)
-
RC1: 'Comment on amt-2024-52', Anonymous Referee #1, 26 Aug 2024
The manuscript presents results of GOLD retrieved disk temperature (Tdisk) in the middle thermosphere near ~160km. The detailed information of the retrieval is not described, but referenced to a recent already published paper (Evans et al., 2024, https://doi.org/10.1029/2024JA032424), which is fine to me. The manuscript discusses Tdisk uncertainties, solar zenith angle dependence and solar cycle variation, which are important and valuable for the users to understand the data and correctly interpret the data when using the dataset. I do have some comments in the annotated pdf file for the authors to consider when they revise the manuscript.
-
RC2: 'Comment on amt-2024-52', Anonymous Referee #2, 04 Sep 2024
This paper summarizes the GOLD multi-band LBH temperature retrieval approach described in a recent paper, briefly discusses recent version 5 improvements of the TDISK product, and compares results to two other approaches for retrieving thermospheric from FUV observations. The paper argues that the absence of artifacts in new GOLD temperatures, the physical behavior of retrieved temperatures, and the low uncertainties from high signal-to-noise from multi-band retrievals make the GOLD thermospheric temperatures reliable. The paper provides an overview of retrieved GOLD temperatures and uncertainties during the mission. Moreover, examples of challenges in an alternate single-band rotational temperature retrieval method and a vibrational band ratio temperature retrieval method indicate that these methods are not yet mature and require further analysis to resolve issues regarding biases and uncertainties compared to GOLD temperature retrievals.
The paper is well-organized and supports the major conclusions with examples, particularly as the intent appears to be to more widely disseminate GOLD temperature products to the community and provide a basic understanding of GOLD temperature behavior and limitations. This paper is not an exhaustive modeling or statistical study of the GOLD temperature product versus other approaches. The wording is not as economical as possible and the figures would benefit from minor tweaks. An attachment details minor suggestions.
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