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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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298 records · Page 17
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NASA NTRS2022

Atmospheric Lunar Tide in the Low Latitude Thermosphere-Ionosphere

We present simultaneous, independent measurements of the atmospheric semidiurnal lunar tide in neutral winds and plasma velocities from NASA's Ionospheric Connection Explorer, and in atomic oxygen 135.6 nm airglow measured by the Global-scale Observations of the Limb and Disk. Westward tidal winds near 115 km at the magnetic equator occur during part of the upward phase of the in-situ plasma drift. Vertical motions associated with the field-aligned plasma velocity occur away from the magnetic equator. The morphology of the lunar tide, and the phasing between the airglow and plasma velocities are consistent with E × B drift as a mechanism for linking neutral wind and plasma perturbations. This work provides the first observational quantification of global-scale E- and F-region coupling through E × B and field-aligned vertical drifts. Plain Language Summary: Tidal winds propagating upward from the neutral atmosphere influence ionospheric dynamo electric fields and vertical plasma drifts. However, these mechanisms have never been fully identified in comprehensive and simultaneous measurements spanning the ionosphere-thermosphere-mesosphere (ITM) system. The atmospheric lunar tide is an effective marker of ITM coupling because it originates at Earth's surface, propagates vertically, and is fully sampled in daytime-only and post-sunset satellite measurements. We utilize measurements from two new NASA missions to track the lunar tide in neutral and plasma velocities, and in an electron density proxy. Our work provides observational confirmation, and quantitative estimates of F-region vertical plasma motions driven by neutral winds and electrodynamical forces

Ruth S. Lieberman↗
NASA NTRSDate not supplied

The Orbital Drift Impact on the Monthly Regional TOA Flux Assuming Constant Meteorology

The NASA Clouds and the Earth's Radiant Energy System (CERES) gridded Single Scanner Footprint (SSF1deg) product provides TOA SW and LW monthly 1° regional all-sky fluxes, which are used to monitor the Earth’s energy balance. The CERES long-term climate data record relies on Terra and Aqua satellite sun-synchronous orbits that are maintained at 10:30 and 1:30 local equator crossing times (LECT), respectively. The Terra and Aqua satellites are expected to drift outside of their respective LECT during mid 2022. Both Terra and Aqua will drift over several years towards sunrise and sunset, respectively, and eventually will be deorbited. The CERES SSF1deg product monthly regional fluxes are based on the well calibrated and stable CERES observed fluxes and are temporally interpolated assuming constant meteorology between measurements to resolve the regional diurnal flux cycle to obtain a daily averaged flux. The drifting orbits may impact the monthly regional TOA flux over regions with systematic diurnal cycles, because the observations will shift in local time. The CERES project would like to determine the maximum Terra and Aqua LECT time shift before the monthly regional fluxes are diurnally impacted and become unreliable for long-term climate monitoring. To determine the impact of the drifting orbits on the SSF1deg monthly regional fluxes,15-minute Geostationary Earth Radiation Budget (GERB) broadband observed fluxes over the Meteosat geostationary satellite domain (±60° in longitude and latitude) are used as proxy CERES observations. The drifting orbit sampling pattern is achieved by simply incrementing the observation time by steps of 15 minutes from the CERES footprint time. For each 15-minute time interval, the CERES observed fluxes are replaced by the GERB observed fluxes. The-15 minute incremented monthly regional fluxes based on constant meteorology are compared to the reference 10:30 and 1:30 LECT fluxes. Regions with systematic diurnal cycles, include morning maritime stratus, where the clouds dissipate during the morning, and land afternoon convection, where clouds increase in the afternoon will impact the regional flux differences. Based on January and July 2010 GERB data, even a 15-minute LECT change caused regional monthly flux differences that would impact long term regional trend analysis. Results will be shown at the conference.

D R Doelling↗
NASA NTRSDate not supplied

What Can We Learn From The Skies Of Alien Planets? Astrophysicists Tell All.

This panel will explore the exciting and often speculative topic of what the skies of other worlds might look like. The discussion will delve into both the scientific research that informs our understanding of exoplanet atmospheres and the creative and imaginative ways that artists and writers have depicted alien skies in popular culture. The panel will bring together experts across stellar and planetary astronomy to discuss the latest scientific findings about exoplanet atmospheres and what they might reveal about the potential habitability of these worlds. They will explore questions such as: what gases might be present in the atmosphere of an exoplanet, and how might they affect the appearance of the sky? How might the presence of multiple stars in a planetary system impact the sky's appearance? And what implications might these findings have for the search for life beyond our solar system? The panel will also discuss the imaginative ways that artists and writers have depicted alien skies in popular culture, from the twin sunsets of Tatooine to the red, dusty sky of Mars in The Martian. They will explore how these depictions have influenced public perceptions of alien words, bridging the gap between science and the imagination.

Elisa Victoria Quintana↗
NASA NTRSDate not supplied

Validation of OMPS LP Ozone Profile Retrievals Using Solar Occultation Satellite Measurements

The OMPS Limb Profiler (OMPS LP) satellite instrument, launched in October 2011, performs limb measurements of scattered solar radiation in the ultraviolet and visible wavelengths, which allow for the retrieval of ozone profiles from the top of clouds up to 55km. In this study we utilize ozone retrievals from two solar occultation satellite instruments, SAGE III/ISS and ACE-FTS, to validate OMPS LP profile measurements processed with the new NASA GSFC version 2.6 retrieval algorithm. OMPS LP started operational observations in April 2012, whereas ACE-FTS observations started in February 2004, therefore, there are currently 12 years of data overlap to exploit for validation. SAGE III/ISS observations started in June 2017, which provides 7 years of data overlap with OMPS LP. The OMPS LP is a solar scattering instrument that makes observations in the sunlit portion of the Earth, whilst ACE-FTS and SAGE III/ISS are solar occultation instruments that measure ozone only at sunrise and sunset. To account for these differences in measurement times we use the Goddard Diurnal Ozone Climatology (GDOC). Diurnal adjustments using this climatology have been shown to help reduce biases above 30 km. Our analysis shows that biases between OMPS LP v2.6, ACE-FTS, and SAGE III/ISS are <10% between 18 and 45 km, and increase above and below these altitudes, which are comparable to the previous version of OMPS LP ozone retrievals (v2.5). The vertical patterns of the differences are similar across different latitudes and seasons, with larger seasonal variations observed in the Northern Hemisphere.

Atmospheric Science↗
NASA NTRSDate not supplied

Monthly Mean DNI and GTI Derived from Monthly Mean GHI and DHI Using Two Methods: Comparisons with the BSRN Data and the Results Derived from the CERES Hourly Data

Monthly mean Global Horizontal Irradiances (GHI) and Diffuse Horizontal Irradiances (DHI) are more widely available than monthly mean Direct Normal Irradiances (DNI) and Global Tilted Irradiances (GTI). Empirical methods have been developed to derive monthly mean DNI and GTI from monthly mean GHI or from GHI and DHI. In this paper, we evaluate two such methods. The first one was the Whitlock Method developed by Charles H. Whitlock (2005) for the NASA POWER project by means of regression of the BSRN data. The method expresses the monthly mean DHI-to-GHI ratio as polynomial functions of monthly mean clearness index, sunset hour angle and noon solar elevation angle on the monthly-average-day. The monthly mean DNI is calculated by dividing the monthly mean GHI-DHI difference, or DirHI, by the cosine of the solar zenith angle at the mid-time between sunrise and solar noon on the monthly-average-day. The second method is the LJCR Method developed by Liu and Jorden (1960) and Collares-Pereira and Rabl (1979), and this method empirically splits monthly mean GHI and DHI into hourly means on the monthly-average-day, and the resulting hourly mean GHI and DHI and their difference, DirHI, can then be used to compute the monthly mean DNI, GTI and the global solar tracker irradiance (GTrI). This method is also used by RETScreen. We recently produced a set of hourly DNI and DHI by bias-correcting the CERES hourly DNI and DHI, and computed hourly GTI and GTrI as well. The data span twenty plus years from March 2000 to near present on a 1 by 1 grid system. The monthly mean CERES GHI and the corrected DHI are used as inputs to the above two methods to compute monthly mean DNI, GTI and GTrI. Through comparisons with the BSRN data, it is found that the Whitlock Method, with slight modification, and the LJCR Method can produce results that are nearly as good as the results derived from the CERES hourly data.

Taiping Zhang↗
NASA NTRSDate not supplied

Comparisons of ozone profile retrievals from the OMPS Limb Profiler and ACE-FTS

The OMPS Limb Profiler (OMPS LP) was launched in October 2011, and has more than 10 years of overlap with ACE-FTS. Therefore, ACE-FTS offers an excellent opportunity to obtain independent ozone profile data with which to validate OMPS LP ozone retrievals. In this study we utilize ACE-FTS ozone retrievals to evaluate 10 years of OMPS LP profile measurements processed with the new NASA GSFC version 2.6 retrieval algorithm. The OMPS LP is a solar scattering instrument that makes observations in the sunlit portion of the Earth, whilst ACE-FTS is a solar occultation instrument that measures ozone only at sunrise and sunset. To account for these differences in measurement times we use the Goddard Diurnal Ozone Climatology (GDOC). Diurnal adjustments using this climatology have been shown to help reduce biases above 30 km. Our analysis shows that biases between OMPS LP v2.6 and ACE-FTS v5.2 are <10% between 18 and 45 km, and increase above and below these altitudes. The vertical patterns of the differences are similar across different latitudes and seasons, with larger seasonal variations observed in the Northern Hemisphere. We also analyze ozone time series from the two instruments.

Atmospheric Science, Stratospheric Ozone↗
NASA NTRS2024

The Diurnal Variation of Dust and Water Ice Aerosol Optical Depth at Jezero Crater Observed By MEDA/TIRS Over A Full Martian Year

The Thermal InfraRed Sensor (TIRS) on the Perseverance rover has provided nearly two full Mars years of systematic monitoring of the total aerosol optical depth above Jezero Crater. These observations span a wide range of timescales, capturing seasonal patterns, diurnal variations, and minute-to-minute fluctuations in aerosol loading. By combining TIRS retrievals with orbital observations, the relative contributions of dust and water ice aerosols can be estimated, revealing their different seasonal and diurnal behaviors. The TIRS record shows distinct periods of dust storm activity, including strong regional storms during the perihelion season as well as short lived but intense dust events outside the typical dust storm season. Water ice clouds exhibit pronounced seasonal and diurnal variability, with peak activity occurring during the aphelion season but with a presence throughout the year. The diurnal variation of clouds differs significantly between the aphelion and perihelion seasons, with clouds persisting throughout the night during the aphelion season, while largely absent outside of specific periods after sunrise and sunset during the perihelion season. These results provide new insights into the complex behavior of aerosols at Jezero Crater and their connections to atmospheric dynamics and the Martian dust and water cycles.

Michael D Smith↗
NASA NTRS2024

Iridescence Reveals the Formation and Growth of Ice Aerosols in Martian Noctilucent Clouds

Water and carbon dioxide each form mesospheric clouds on Mars. At such altitudes (40–100 km), clouds may remain sunlit for part of the night. We describe a previously unreported, visually spectacular season of iridescent, noctilucent clouds visible in early southern autumn from the Curiosity rover's site in Gale crater. Ice nucleation begins near sunset with a narrow range of particle sizes, and the ice aerosols grow and precipitate. The iridescence, visible through three-color imaging, arises from locally uniform particle sizes resulting from similar growth histories. Colorful fall streaks show the clouds evolving, and a scattering corona shows size uniformity over large areas. The terminator was observed on the clouds, allowing the determination of cloud altitudes and a likely CO2 composition. This is the first observation of particle size variations within individual Martian clouds, allowing a new probe of Martian cloud physics.

M T Lemmon↗