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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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NASA NTRS2021

The PMIP4 Last Glacial Maximum experiments: preliminary results and comparison with the PMIP3 simulations

The Last Glacial Maximum (LGM, ∼ 21 000 years ago) has been a major focus for evaluating how well state-of-the-art climate models simulate climate changes as large as those expected in the future using paleoclimate reconstructions. A new generation of climate models has been used to generate LGM simulations as part of the Paleoclimate Modelling Intercomparison Project (PMIP) contribution to the Coupled Model Intercomparison Project (CMIP). Here, we provide a preliminary analysis and evaluation of the results of these LGM experiments (PMIP4, most of which are PMIP4-CMIP6) and compare them with the previous generation of simulations (PMIP3, most of which are PMIP3-CMIP5). We show that the global averages of the PMIP4 simulations span a larger range in terms of mean annual surface air temperature and mean annual precipitation compared to the PMIP3-CMIP5 simulations, with some PMIP4 simulations reaching a globally colder and drier state. However, the multi-model global cooling average is similar for the PMIP4 and PMIP3 ensembles, while the multi-model PMIP4 mean annual precipitation average is drier than the PMIP3 one. There are important differences in both atmospheric and oceanic circulations between the two sets of experiments, with the northern and southern jet streams being more poleward and the changes in the Atlantic Meridional Overturning Circulation being less pronounced in the PMIP4-CMIP6 simulations than in the PMIP3-CMIP5 simulations. Changes in simulated precipitation patterns are influenced by both temperature and circulation changes. Differences in simulated climate between individual models remain large. Therefore, although there are differences in the average behaviour across the two ensembles, the new simulation results are not fundamentally different from the PMIP3-CMIP5 results. Evaluation of large-scale climate features, such as land–sea contrast and polar amplification, confirms that the models capture these well and within the uncertainty of the paleoclimate reconstructions. Nevertheless, regional climate changes are less well simulated: the models underestimate extratropical cooling, particularly in winter, and precipitation changes. These results point to the utility of using paleoclimate simulations to understand the mechanisms of climate change and evaluate model performance.

Last Glacial Maximum↗
NASA NTRS2019

Widespread Increase of Boreal Summer Dry Season Length Over the Congo Rainforest

Dry season length strongly influences tropical rainforest vegetation and is largely determined by precipitation patterns. Over the Amazon, the dry season length has increased since 1979 and severe short-term droughts have occurred. However, similar changes have not been investigated for the world’s second largest rainforest, the Congo Basin, where long-term drying and large-scale declines in forest greenness and canopy water content were reported. Here we present observational evidence for widespread increases in the boreal summer (June–August) dry season length over the Congo Basin since the 1980s, from both hydrological and ecological perspectives. We analyzed both dry season onset and dry season end via multiple independent precipitation and satellite derived vegetation datasets for the period 1979–2015. The dry season length increased by 6.4–10.4 days per decade in the period 1988–2013, primarily attributed to an earlier dry season onset and a delayed dry season end. The earlier dry season onset was caused by long-term droughts due to decreased rainfall in the pre-dry season (April–June). The delayed dry season end resulted from insufficiently replenished soil moisture, which postpones the start of the next wet season and hinders vegetation regrowth. If such changes continue, the enhanced water stress in a warming climate may affect the carbon cycle and alter the composition and structure of evergreen rainforest.

Congo rainforest growing season NDVI SIF↗
NASA NTRS1993

Relationship between Birkeland current regions, particle precipitation, and electric fields

The relationship of the large-scale dayside Birkeland currents to large-scale particle precipitation patterns, currents, and convection is examined using DMSP and Sondrestrom radar observations. It is found that the local time of the mantle currents is not limited to the longitude of the cusp proper, but covers a larger local time extent. The mantle currents flow entirely on open field lines. About half of region 1 currents flow on open field lines, consistent with the assumption that the region 1 currents are generated by the solar wind dynamo and flow within the surface that separates open and closed field lines. More than 80 percent of the Birkeland current boundaries do not correspond to particle precipitation boundaries. Region 2 currents extend beyond the plasma sheet poleward boundary; region 1 currents flow in part on open field lines; mantle currents and mantle particles are not coincident. On most passes when a triple current sheet is observed, the convection reversal is located on closed field lines.

De La Beaujardiere, O.↗
NASA NTRS2019

Climates of Warm Earth-like Planets. II. Rotational "Goldilocks" Zones for Fractional Habitability and Silicate Weathering

Planetary rotation rate has a significant effect on atmospheric circulation, where the strength of the Coriolis effect in part determines the efficiency of latitudinal heat transport, altering cloud distributions, surface temperatures, and precipitation patterns. In this study, we use the ROCKE-3D dynamic ocean general circulation model to study the effects of slow rotations and increased insolations on the "fractional habitability" and silicate weathering rate of an Earth-like world. Defining the fractional habitability f (h) to be the percentage of a planet's surface that falls in the 0 ≤ T ≤ 100 °C temperature regime, we find a moderate increase in f (h) with a 10% and 20% increase in insolation and a possible maximum in f (h) at sidereal day lengths between 8 and 32 times that of the modern Earth. By tracking precipitation and runoff, we further determine that there is a rotational regime centered on a 4 day period in which the silicate weathering rate is maximized and is particularly strongly peaked at higher overall insolations. Because of weathering's integral role in the long-term carbonate–silicate cycle, we suggest that climate stability may be strongly affected by the anticipated rotational evolution of temperate terrestrial-type worlds and should be considered a major factor in their study. In light of our results, we argue that planetary rotation period is an important factor to consider when determining the habitability of terrestrial worlds.

atmospheric effects↗
NASA NTRS2019

Climates of Warm Earth-like Planets. II. Rotational "Goldilocks" Zones for Fractional Habitability and Silicate Weathering

Planetary rotation rate has a significant effect on atmospheric circulation, where the strength of the Coriolis effect in part determines the efficiency of latitudinal heat transport, altering cloud distributions, surface temperatures, and precipitation patterns. In this study, we use the ROCKE-3D dynamic ocean general circulation model to study the effects of slow rotations and increased insolations on the "fractional habitability" and silicate weathering rate of an Earth-like world. Defining the fractional habitability f(sub h) to be the percentage of a planet's surface that falls in the 0 ≤ T ≤ 100 °C temperature regime, we find a moderate increase in f(sub h) with a 10% and 20% increase in insolation and a possible maximum in f(sub h) at sidereal day lengths between 8 and 32 times that of the modern Earth. By tracking precipitation and runoff, we further determine that there is a rotational regime centered on a 4 day period in which the silicate weathering rate is maximized and is particularly strongly peaked at higher overall insolations. Because of weathering's integral role in the long-term carbonate–silicate cycle, we suggest that climate stability may be strongly affected by the anticipated rotational evolution of temperate terrestrial-type worlds and should be considered a major factor in their study. In light of our results, we argue that planetary rotation period is an important factor to consider when determining the habitability of terrestrial worlds.

Atmospheric effects↗
NASA NTRSDate not supplied

Feasibility Study to Interactive Workshop: Building End-user Capacity to Integrate Earth Observation Data into Federally Endangered Atlantic Salmon (Salmo salar) Habitat Monitoring in Main

Changes in temperature and precipitation patterns, along with alterations in land cover threaten ongoing conservation efforts for Federally Endangered Atlantic salmon (Salmo salar) in Maine. Earth observation data offers a unique perspective for habitat monitoring that can complement habitat restoration and conservation activity on the ground. As a dual capacity building program, the NASA DEVELOP National Program strives to build the capacity of program participants by leveraging Earth observation data to address environmental concerns across the globe, while also building capacity in partner organizations to integrate Earth observation data into their decision making practices. Between September 2021 and August 2022, three NASA DEVELOP teams demonstrated the feasibility of utilizing NASA Earth observations including Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), Terra MODIS, Landsat 5 Thematic Mapper (TM), Landsat 8 Operation Land Imager (OLI), and Shuttle Radar Topography Mission (SRTM) in conjunction with Sentinel-2 MultiSpectral Instrument (MSI) to assess temperature, precipitation, and land use land cover (LULC) over time throughout salmon habitat in Maine. While the first two teams completed projects that were categorized as NASA DEVELOP’s traditional feasibility projects, the third and final project team generated resources and planned an interactive workshop to transfer project methods to end-user organizations. Ultimately, the goal of this work was to not only inform the partner’s ongoing salmon population recovery and habitat restoration initiatives but provide tools that allow partner organizations to continue integrating Earth observation data into their work beyond their partnership with the program. This project serves as a case study within the NASA DEVELOP Program and provides lessons learned for moving beyond traditional feasibility studies to more interactive partner engagement and knowledge transfer practices.

Nicole Ramberg-Pihl↗
NASA NTRS2024

How Can Future Climate Change Affect the Corn Production System in Nebraska, USA?

The increasing temperatures and changing precipitation patterns have affected both crop yields and water requirements challenging agricultural systems in sustaining high crop yields and ensuring water and food security. In the present study, we evaluated the impact of climate change on the corn production under irrigated and rainfed cropping systems in Nebraska considering four climate zones until 2100 as a case study for the US Corn Belt. Additionally, suggests ways to reduce the impact of climate change on corn yield and water resources. Five global circulation model datasets from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) interconnected to Shared Socioeconomic Pathways (SSPs), were selected. Three future periods: near (2020–2039), mid (2040–2069), and far future (2070–2100) under SSP226, SSP370, and SSP585 scenarios were used to predict the climate changes, crop cycle length, crop yield, and crop water requirement. Additionally, we input annual CO2 concentration scenarios for each SSP scenario to model changes from 2015 to 2100 using the CERES-Maize model. Temperatures are forecasted to rise, precipitation to decline, and crop cycle length to decrease, particularly for SSP370 (up to 49% yield decrease) and SSP585 (up to 67% yield decrease) by 2070–2100. Yields are expected to decline across all scenarios and periods for irrigated and rainfed fields due to the reduction in crop cycle length. Crop water demand is projected to increase, with rainfed systems facing heightened impact due to reduced precipitation. Addressing climate change in Nebraska requires actions like developing new corn varieties to longer the crop season, transitioning to efficient irrigation systems, improving irrigation management for water and food security, and reducing the risk of conflicts over its use. These results open possibilities for discussion about the actions that can be taken to cope with climate change and guarantee water and food security in the US Corn Belt.

CMIP6↗
NASA NTRS1972

Earth's magnetospheric processes; Proceedings of the Symposium, Cortina, Italy, August 30-September 10, 1971.

New data obtained by satellites, rockets, aircraft, and ground-based observations are interpreted in papers dealing with the magnetospheric structure and processes, particle distributions, magnetic and electric fields, plasma convection, particle acceleration and diffusion mechanisms, and substorm phenomena. Attention is given to particle populations in different magnetospheric regions, auroral particle precipitation patterns, effects of electric fields on plasma convection, VLF phenomena, a high-energy proton model for the inner radiation belt, substorm behavior of plasma sheet particles, and interpretations of magnetic field variations during substorms. Individual items are announced in this issue.

Mccormac, B. M.↗
NASA NTRS1973

The auroral oval - A reevaluation.

The auroral oval represents a region of auroral occurrence where particular spectral features have sufficient integrated intensity to exceed all-sky camera thresholds. It has been argued that this is not a good representation of the characteristics of particle precipitation or of energy deposition. Consequently, the auroral oval concept may not be a good one to use to order diverse auroral data on a 24-hour basis. Rather, the precipitation patterns for specific energy classes of protons and electrons should form the basis for the interpretation of high-latitude geophysical measurements.

Eather, R. H.↗
NASA NTRS1986

The dynamics of warm and cold climates

Changes occurring as a result of climatic warming or cooling are presently investigated by comparing the atmospheric dynamics of five different climate simulations encompassing two ice ages, current and doubled CO2 climates, and a simulation of the warm Cretaceous; a global average surface air temperature range of 13 C is covered by the models. It is noted that many zonally averaged processes do not change systematically as climate changes: the January Hadley cell, the jet stream, mean precipitation patterns, and total atmospheric transport, show very little variation among the different climate simulations. These features result from balances between competing factors; while individual processes differ in the cold and warm climates, there is considerable compensation.

Rind, D.↗
NASA NTRS1988

Annual cycle, quasi-biennial oscillation, and Southern Oscillation in global precipitation

Using 80 years (1901-1980) of global station rainfall data, the spatial and temporal variations in global precipitation associated with the annual cycle (AC), the tropospheric quasi-biennial oscillation (QBO), and southern oscillation (SO, defined as the background 3- to 7-year fluctuation in which the El Nino events are embedded) were investigated. It was found that the dominant global precipitation pattern fluctuates irregularly, with 2- to 5-year periods associated with the SO. The temporal variation shows, in addition to the SO time scale, a distinct QBO signal. The best correlation occurred during the El Nino SO, with an apparent phase locking between the QBO and SO. The role of the possible influence of the AC and other factors involved in the QBO interaction is discussed.

Lau, K.-M.↗
NASA NTRS1988

Rainfall index over oceans derived from SSM/I data

Ths Special Sensor Microwave/Imager radiometer on board the DMSP satellite measured microwave radiation at 19.35, 22.235, 37.0, and 85.5 GHz with a swath width of 1400 km, providing an opportunity to study global precipitation distributions. A monthly averaged rainfall index was derived using only the 19.35 GHz data. It covers the + or - 50 deg portion of the world with a 5 deg x 5 deg grid. The brightness temperature histogram is analyzed to derive the rainfall distribution. Estimates of the freezing level heights and the water vapor contents are utilized to understand the rainfall distribution better. Log normal and gamma distribution functions are fitted to the data and the derived monthly rainfall index compares favorably with historical precipitation patterns.

Chang, A. T. C.↗
NASA NTRS1989

Dynamics of super cloud clusters, westerly wind bursts, 30-60 day oscillations and ENSO - An unified view

Results are presented on numerical experiments that were carried out to investigate the mechanisms of the observed variabilities in wind and convection associated with supercloud clusters (SCCs), westerly wind bursts, and 30-60 day oscillations in the western Pacific region. It is shown that the generation of a 30-60 day eastward propagating precipitation pattern in the Lau and Peng (1987) model, which can be identified as SCC, is accompanied by convective clusters coming in opposite direction to that of the SCC itself. The results suggest that the westward propagating cloud clusters are produced at the initial stage of the 30-60 day disturbance due to mutual adjustment of the large-scale flow and heating.

Lau, K.-M.↗
NASA NTRS1989

Large-scale transport of a CO-enhanced air mass from Europe to the Middle East

On November 14, 1981, the shuttle-borne Measurement of Air Pollution from Satellites (MAPS) experiment observed a carbon monoxide (CO) enhanced air mass in the middle troposphere over the Middle East. The primary source of this polluted air was estimated by constructing adiabatic isentropic trajectories backwards from the MAPS measurement location over a 36 h period. The isentropic diagnostics indicate that CO-enhanced air was transported southeastward over the Mediterranean from an organized synoptic-scale weather regime, albeit of moderate intensity, influencing central Europe on November 12. Examination of the evolving synoptic scale vertical velocity and precipitation patterns during this period, in conjuction with Meteosat visible, infrared, and water vapor imagery, suggests that the presence of this disturbed weather system over Europe may have created upward transport of CO-enhanced air between the boundary-layer and midtropospheric levels, and subsequent entrainment in the large-scale northwesterly jet stream flow over Europe and the Mediterranean.

Connors, V. S.↗
NASA NTRS1992

Staircase ion signature in the polar cusp - A case study

On 15 October, 1981 Dynamics Explorer 2 crossed the polar cusp at 1015 MLT and observed three distinct ion populations as it was moving poleward. These three populations had peak-flux energy around 2.7 keV, 850 eV, and 360 eV. At the time of observation, the IMF was southward. The first step coincided with a rotation of the flow from westward to poleward and then eastward. The second and third steps showed a flow directed principally poleward. Furthermore, the magnetic and electric perturbations in the first step are well fitted by an elongated flux tube footprint model. These results suggest that three consecutive Flux Transfer Events (FTEs) have injected solar wind plasma into the ionosphere forming the polar cusp. The individual FTE signatures can only be identified by the jumps in the precipitation pattern. The newest reconnected FTE footprint was crossed near the edge of the event while the two oldest ones were crossed around the event center. The small latitudinal size of these FTE footprints (40 km) and their short recurrence rate (3, 6 min) is consistent with an intermittent reconnection taking place at the subsolar point on a short time scale.

Escoubet, C. P.↗
NASA NTRS1994

Diurnal heating and cloudiness in the NCAR Community Climate Model (CCM2)

In this paper, the authors assess the suitability of the heating fileds in the latest version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2) for modeling the thermal forcing of atmospheric tides. Accordingly, diurnal variations of the surface pressure, outgoing longwave radiation (OLR), cloudiness, and precipitation are examined in the CCM2. The fields of radiative, sensible, and latent heating are similarly analyzed. These results are subjectively compared with available data. Equatorial diurnal surface pressure tides are fairly well simulated by CCM2. The model successfully reproduces the semidiurnal surface pressure tides; however, this may result in part from reflection of wave energy at the upper boundary. The CCM2 large-scale diurnal OLR is generally consistent with observations. The moist-convective scheme in the model is able to reproduce the diurnally varying cloudiness and precipitation patterns associated with land-sea contrasts; however, the amplitudes of CCM2 diurnal continental convective cloudiness are weaker than observations. The CCM2 boundary-layer sensible heating is consistent with a very limited set of observations, and with estimates obtained from simple models of diffusive heating. Although the CCM2 tropospheric solar radiative heating is similar in magnitude to previous estimates, there are substantial differences in the vertical structures. A definitive assessment of the validity of the CCM2 diurnal cycle is precluded by the lack of detailed observations and the limitations of our CCM2 sample. Nevertheless, the authors conclude that the global-scale components of the CCM2 diurnal heating are useful proxies for the true diurnal forcing of the tides.

Lieberman, Ruth S.↗