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DOE OSTI2017

Intermittency in Precipitation: Duration, Frequency, Intensity, and Amounts Using Hourly Data

Abstract Intermittency is a core characteristic of precipitation, not well described by data and very poorly modeled. Detailed analyses are made of near-global gridded (about 1°) hourly or 3-hourly precipitation rates from two updated observational datasets [3-hourly TRMM 3B42, version 7, and hourly CMORPH, version 1.0, bias corrected (CRT)] and from special runs of CESM from January 1998 to December 2013 to obtain hourly values. The analyses explore the intermittency of precipitation: the frequency, intensity, duration, and amounts. A comparison is made for all products using several metrics with a focus on the duration of events, and a new metric is proposed based on the ratio of the frequency of precipitation at certain rates (0.2–2 mm h−1) for hourly versus 3-hourly versus daily data. For all seasons and rain rates, TRMM values are similar in pattern to CMORPH, but durations are about 80%–85%. It is mainly over land in the monsoons that CMORPH exceeds TRMM rain durations. Observed duration of precipitation events in CMORPH over oceans are 12–15 h in the tropics and subtropics, much less than the ~20 h for CESM. Hence, the observational results differ somewhat but both are considerably different from the model, which has too much precipitation overall, and it precipitates far too often at low rates and not enough for intense rates, with the divide about 1–2 mm h−1. There is a need to properly represent precipitation phenomena and processes either explicitly or implicitly (parameterized).

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2019

Frontiers in the Economics of Widespread, Long-Duration Power Interruptions: Proceedings from an Expert Workshop

The costs to electric utility customers from short-term, limited geographic-scale power disruptions have been studied for many years. However, there is increasing interest among regulators, policy-makers, and utilities in developing and implementing methods for analyzing interruptions that are of longer duration (days, weeks, or longer) and of a larger geographic scope (entire metropolitan areas or regions which may extend across multiple service territories). A 2017 report from the U.S. National Academies of Sciences, Engineering, and Medicine indicated the importance of “develop[ing] comprehensive studies to assess the value to customers of improved reliability and resilience…during large-area, long-duration blackouts.” As a contribution toward fulfilling this recommendation, the U.S. Department of Energy’s (DOE) Office of Electricity’s Transmission Permitting and Technical Assistance Division, in partnership with Lawrence Berkeley National Laboratory (LBNL), convened a workshop to identify research needs and discuss potential avenues for methodological advances in the economics of widespread, long-duration power interruptions. The workshop was organized around six key themes in the economics of widespread, long-duration interruptions. LBNL conducted a competitive solicitation for white papers on these themes, and the authors selected were leading experts in academia, industry, and the non-profit sector. They were tasked with assessing the state of knowledge on particular topics, and identifying research needs and promising directions to expand it. These topics included definitions of resilience and reliability; regional economic modeling approaches; uncertainty quantification; data challenges and opportunities; contingent valuation survey techniques; and reduced-form analytical tools for assessing the impacts of power interruptions of this scale. The authors of the six white papers presented their findings at the workshop, titled “Frontiers in the Economics of Widespread, Long-Duration Power Interruptions,” and held in Washington, D.C., on March 6, 2018. Each paper was the subject of its own session, with the presentations followed by comments by assigned discussants, and in turn a general discussion of the papers, their findings, and the issues they raised. In addition to the authors, discussants, and LBNL and DOE staff, the workshop participants comprised government, industry, and academic thought leaders from across the country.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

NASA NTRS1990

Size, duration, and rate of growth of nocturnal lightning events appearing on space shuttle video tapes

An analysis of video tapes of nocturnal lightning events, taken aboard space shuttle flights STS-8, STS-9, STS-41D, and STS-51J, shows flashes with dimensions ranging from approximately 1 km by 1 km to 440 km by 110 km. Of particular interest are the flashes whose dimensions exceeded 100 km, as flashes of this size are seldom reported. In general, larger flashes were found to have longer durations, take longer to reach their maximum extent, and reach their maximum extent at a smaller percent of their total duration than smaller flashes. Sixty four percent of the flashes occurred with one to five other events appearing in the same video frame. These simultaneous events were an average of 60 km apart from each other. If a breakdown process is propagating between the simultaneous flashes, it would be travelling at a rate of 10(exp 5)m/sec. Plots of the area of an event over its duration show peaks in the area curve which may be indicative if lightning strokes. There was an average of 3.6 peaks per flash. In general, the longer the flash duration, the more peaks there were in the area curve. The area curves of the lightning events fall into one of five shape categories. It is suggested that the shape of the area curve may indicate whether an event is an intracloud or cloud to ground lightning flash. Some of the lightning events had a persistent bright spot. These events had an average duration which was greater than that of events without the bright spot. On average, the bright spot events had a maximum area which was larger than that of the flashes without the bright spot.

Breslawski, Christine↗

NASA NTRS1992

Diurnal variation of overdense meteor echo duration and ozone

The diurnal variation of the median duration of overdense sporadic radar meteor echoes is examined. The meteors recorded in August, December, and January by the Ondrejov meteor radar during the period 1958-1990 were used for the analysis. A maximum median echo duration 1-3 hours after the time of local sunrise in the meteor region confirms the already known sunrise effect. Minimum echo duration occurring at the time of sunset seems to be the most important point of diurnal variation of the echo duration, when ozone is no longer dissociated by solar UV radiation. The effect of diurnal changes of the echo duration should be considered when the mass distribution of meteor showers is analyzed.

Simek, Milos↗

NASA NTRS1994

Subjective response to sonic booms having different shapes, rise times, and durations

Two laboratory experiments were conducted to quantify the subjective response of people to simulated outdoor sonic booms having different pressure signatures. The specific objectives of the experiments were to compare subjective response to sonic booms when described in terms of 'loudness' and 'annoyance'; to determine the ability of various noise metrics to predict subjective response to sonic booms; to determine the effects on subjective response of rise time, duration, and level; and to compare the subjective response to 'N-wave' sonic boom signatures with the subjective response to 'minimized' sonic boom signatures. The experiments were conducted in a computer-controlled, man-rated sonic boom simulator capable of reproducing user-specified pressure signatures for a wide range of sonic boom parameters. One hundred and fifty sonic booms representing different combinations of two wave shapes, four rise times, seven durations, and three peak overpressures were presented to 36 test subjects in each experiment. The test subjects in the first experiment made judgments of 'loudness' while the test subjects in the second experiment judged 'annoyance.' Subjective response to sonic booms was the same whether expressed in terms of loudness or in terms of annoyance. Analyses of several different noise metrics indicated that A-weighted sound exposure level and Perceived Level were the best predictors of subjective response. Further analyses indicated that, of these two noise metrics, only Perceived Level completely accounted for the effects of wave shape, rise time, and peak overpressure. Neither metric fully accounted for the effect of duration. However, the magnitude of the duration effect was small over the very wide range of durations considered.

Mccurdy, David A.↗

NASA NTRS1995

Duration distributions of bright and dim BATSE gamma-ray bursts

We have measured the T(sub 90) and T(sub 50) durations of bright and dim gamma-ray bursts detected by the Compton Gamma-Ray Observatory's (CGRO) Burst and Transient Source Experiment (BASTE). The T(sub 90) T(sub 50) duration is defined as the interval over which 5% (25%) to 95% (75%) of the burst counts accumulate. Out of 775 bursts observed by BATSE 159 bursts were analyzed; bursts with durations shorter than 1.5 s were excluded. A Kolmogorov-Smirnov test yields a probability of 6 x 10(exp -5) that the T(sub 50) durations of the dim and bright samples are drawn from the same parent population. We find that the centroid and extent of the duration distribution for the dim sample are scaled by approximately a factor of 2 relative to those of the bright sample. The measured time-dilation factor is not sensitive to choice of energy band. These results are quantitatively consistent with previous tests for time dilation in a smaller sample of BATSE bursts. The sources of dimmer bursts, if cosmological, would lie at redshifts of order 2.

Norris, J. P.↗

NASA NTRS1995

Earth-space links and fade-duration statistics

In recent years, fade-duration statistics have been the subject of several experimental investigations. A good knowledge of the fade-duration distribution is important for the assessment of a satellite communication system's channel dynamics: What is a typical link outage duration? How often do link outages exceeding a given duration occur? Unfortunately there is yet no model that can universally answer the above questions. The available field measurements mainly come from temperate climatic zones and only from a few sites. Furthermore, the available statistics are also limited in the choice of frequency and path elevation angle. Yet, much can be learned from the available information. For example, we now know that the fade-duration distribution is approximately lognormal. Under certain conditions, we can even determine the median and other percentiles of the distribution. This paper reviews the available data obtained by several experimenters in different parts of the world. Areas of emphasis are mobile and fixed satellite links. Fades in mobile links are due to roadside-tree shadowing, whereas fades in fixed links are due to rain attenuation.

Davarian, Faramaz↗

NASA NTRS1996

On Determining the Rise, Size, and Duration Classes of a Sunspot Cycle

The behavior of ascent duration, maximum amplitude, and period for cycles 1 to 21 suggests that they are not mutually independent. Analysis of the resultant three-dimensional contingency table for cycles divided according to rise time (ascent duration), size (maximum amplitude), and duration (period) yields a chi-square statistic (= 18.59) that is larger than the test statistic (= 9.49 for 4 degrees-of-freedom at the 5-percent level of significance), thereby, inferring that the null hypothesis (mutual independence) can be rejected. Analysis of individual 2 by 2 contingency tables (based on Fisher's exact test) for these parameters shows that, while ascent duration is strongly related to maximum amplitude in the negative sense (inverse correlation) - the Waldmeier effect, it also is related (marginally) to period, but in the positive sense (direct correlation). No significant (or marginally significant) correlation is found between period and maximum amplitude. Using cycle 22 as a test case, we show that by the 12th month following conventional onset, cycle 22 appeared highly likely to be a fast-rising, larger-than-average-size cycle. Because of the inferred correlation between ascent duration and period, it also seems likely that it will have a period shorter than average length.

Wilson, Robert M.↗

NASA NTRS1996

Earth-Space Links and Fade-Duration Statistics

Davarian, Faramaz↗

NASA NTRS1999

Demonstration of a Low Cost Cryocooler on a Long Duration Balloon Mission

NASA/GSFC has been evaluating the use of low cost Stirling cycle cryocoolers for aerospace applications since 1994. These include the M77B and M77C cryocoolers built by Sunpower Corporation. To date NASA has tested eight M77B and two M77C cryocoolers, with 8 additional M77C units now under construction. The intent of this work is to determine the flight worthiness of these cryocoolers. The Sunpower M77 coolers are candidate for use on the Ultra Long Duration Balloons presently under development by NASA. The flight on the Long Duration Balloon (LDB) in July 1998 represented an opportunity to test the cryocooler in the high altitude balloon environment in order to gain experience to prepare for possible opportunities on the Ultra Long Duration Balloon (ULDB) missions. The Long Duration Balloon is typically a 10 to 15 day mission. Typical ULDB missions might be as long as 100 days or more, and it is this duration which now forces many science groups to consider the use of cryocoolers in place of stored cryogens. This paper will present the basic design of the cryocooler experiment, and data acquired during the flight. The paper will also include a general perspective on the use of cryocoolers on future ULDB flights.

James, Edward F.↗

NASA NTRS1999

Circadian Entrainment, Sleep-Wake Regulation and Neurobehavioral Performance During Extended Duration Space Flight

Long-duration manned space flight requires crew members to maintain a high level of cognitive performance and vigilance while operating and monitoring sophisticated instrumentation. However, the reduction in the strength of environmental synchronizers in the space environment leads to misalignment of circadian phase among crew members, coupled with restricted time available to sleep, results in sleep deprivation and consequent deterioration of neurobehavioral function. Crew members are provided, and presently use, long-acting benzodiazepine hypnotics on board the current, relatively brief space shuttle missions to counteract such sleep disruption, a situation that is only likely to worsen during extended duration missions. Given the known carry-over effects of such compounds on daytime performance, together with the reduction in emergency readiness associated with their use at night, NASA has recognized the need to develop effective but safe countermeasures to allow crew members to obtain an adequate amount of sleep. Over the past eight years, we have successfully implemented a new technology for shuttle crew members involving bright light exposure during the pre-launch period to facilitate adaptation of the circadian timing system to the inversions of the sleep-wake schedule often required during dual shift missions. However for long duration space station missions it will be necessary to develop effective and attainable countermeasures that can be used chronically to optimize circadian entrainment. Our current research effort is to study the effects of light-dark cycles with reduced zeitgeber strength, such as are anticipated during long-duration space flight, on the entrainment of the endogenous circadian timing system and to study the effects of a countermeasure that consists of scheduled brief exposures to bright light on the human circadian timing system. The proposed studies are designed to address the following Specific Aims: (1) test the hypothesis that synchronization of the human circadian pacemaker will be disturbed in men and women by the reduction in LD cycle strength. (2) test the hypothesis that this disturbed circadian synchronization will result in the secretion of the sleep-promoting hormone melatonin during the waking day, disturbed sleep, reduced growth hormone secretion, and impaired performance and daytime alertness; (3) as a countermeasure, test the hypothesis that brief daily exposures to bright light (10,000 lux) will reestablish normal entrained circadian phase, resulting in improved sleep consolidation, normalized sleep structure and endogenous growth hormone secretion and enhanced daytime performance. To date, we have carried out twelve experiments to address Hypotheses I and 2 and data analyses are in progress. The results of the current research may have important implications for the treatment of circadian rhythm sleep disorders, such as delayed sleep phase syndrome and shift-work dyssomnia, which are anticipated to have a high incidence and prevalence during extended duration space flight such as planned for the International Space Station and manned missions to Mars.

Czeisler, Charles A.↗

NASA NTRS1992

Effectiveness and duration of intramuscular antimotion sickness medications

Motion sickness inhibits gastric motility, making the oral route ineffective for medications. The intramuscular route is an effective alternative. The rotating chair was used to produce the M 111 level of motion sickness on the Graybiel Symptom Scale. The intramuscular medications given 30 minutes before rotation were compared with placebo (saline, 1 mL) for effectiveness and duration in increasing the number of tolerated head movements. Average placebo number of head movements was 294. Promethazine 25 mg increased head movements by 78% (P < .05), with a duration of 12 hours. Scopolamine 0.2 mg increased head movements by 91% (P < .05), with a duration of 4 hours. The effect of caffeine 250 mg and ephedrine 25 mg was not significant. When combined with scopolamine, ephedrine produced an 32% additive effect. Scopolamine 0.08 mg, 0.1 mg, and 0.2 mg and also promethazine 12.5 mg and 25 mg were significant (P < .05). Promethazine appears to be the drug of choice for intramuscular use because of a longer duration and a high level of effectiveness. Scopolamine was of high effectiveness, but had a duration of 4 hours. It was eight times as potent by the intramuscular as by the oral route.

Non-NASA Center↗

NASA NTRS2010

Maximum Oxygen Uptake During and After Long-Duration Space Flight

Decreased maximum oxygen consumption (VO2max) during and after space flight may impair a crewmember s ability to perform mission-critical work that is high intensity and/or long duration in nature (Human Research Program Integrated Research Plan Risk 2.1.2: Risk of Reduced Physical Performance Capabilities Due to Reduced Aerobic Capacity). When VO2max was measured in Space Shuttle experiments, investigators reported that it did not change during short-duration space flight but decreased immediately after flight. Similar conclusions, based on the heart rate (HR) response of Skylab crewmembers, were made previously concerning long-duration space flight. Specifically, no change in the in-flight exercise HR response in 8 of 9 Skylab crewmembers indicated that VO2max was maintained during flight, but the elevated exercise HR after flight indicated that VO2max was decreased after landing. More recently, a different pattern of in-flight exercise HR response, and assumed changes in VO2max, emerged from routine testing of International Space Station (ISS) crewmembers. Most ISS crewmembers experience an elevated in-flight exercise HR response early in their mission, with a gradual return toward preflight levels as the mission progresses. Similar to previous reports, exercise HR is elevated after ISS missions and returns to preflight levels by 30 days after landing. VO2max has not been measured either during or after long-duration space flight. The purposes of the ISS VO2max experiment are (1) to measure VO2max during and after long-duration spaceflight, and (2) to determine if submaximal exercise test results can be used to accurately estimate VO 2max.

Moore, Alan D., Jr.↗

NASA NTRS2011

Building a Shared Definitional Model of Long Duration Human Spaceflight

In 1956, on the eve of human space travel Strughold first proposed a simple classification of the present and future stages of manned flight that identified key factors, risks and developmental stages for the evolutionary journey ahead. As we look to optimize the potential of the ISS as a gateway to new destinations, we need a current shared working definitional model of long duration human space flight to help guide our path. Initial search of formal and grey literature augmented by liaison with subject matter experts. Search strategy focused on both the use of term long duration mission and long duration spaceflight, and also broader related current and historical definitions and classification models of spaceflight. The related sea and air travel literature was also subsequently explored with a view to identifying analogous models or classification systems. There are multiple different definitions and classification systems for spaceflight including phase and type of mission, craft and payload and related risk management models. However the frequently used concepts of long duration mission and long duration spaceflight are infrequently operationally defined by authors, and no commonly referenced classical or gold standard definition or model of these terms emerged from the search. The categorization (Cat) system for sailing was found to be of potential analogous utility, with its focus on understanding the need for crew and craft autonomy at various levels of potential adversity and inability to gain outside support or return to a safe location, due to factors of time, distance and location.

Orr, M.↗

NASA NTRS2017

The Effects of Long-Duration Spaceflight on Training Retention and Transfer

Training our crew members for long duration, exploration-class missions will have to maximize long-term retention and transfer of the trained skills. The expected duration of the missions, our inability to predict all the possible tasks the crew will be called upon to perform, and the low training-to-mission time ratio require that the training be maximally effective such that the skills acquired during training will be retained and will be transferrable across a wide range of specific tasks that are different from the particular tasks used during training. However, to be able to design training that can achieve these ambitious goals, we must first understand the ways in which long-duration spaceflight affects training retention and transfer. Current theories of training retention and transfer are largely based on experimental studies conducted at university laboratories using undergraduate students as participants. Furthermore, all such studies have been conducted on Earth. We do not know how well the results of these studies predict the performance of crew members. More specifically, we do not know how well the results of these studies predict the performance of crew members in space and especially during long-duration missions. To address this gap in our knowledge, the current on-going study seeks to test the null hypothesis that performance of university undergraduate students on Earth on training retention and transfer tests do in fact predict accurately the performance of crew members during long-duration spaceflights. To test this hypothesis, the study employs a single 16-month long experimental protocol with 3 different participant groups: undergraduate university students, crew members on the ground, and crew members in space. Results from this study will be presented upon its completion. This poster presents results of study trials of the two tasks used in this study: a data entry task and a mapping task. By researching established training principles, by examining future needs, and by using current practices in spaceflight training as test beds, this research project is mitigating program risks and generating templates and requirements to meet future training needs.

ISS↗

NASA NTRS2018

The Effects of Long-Duration Spaceflight on Training Retention and Transfer

training↗

NASA NTRS2017

Bone and Cartilage Degeneration in Mice Following Long-Duration Spaceflight: The Role of Bone Marrow Stem Cells

The detrimental effects of mechanical unloading in microgravity, including the musculo-skeletal system, are well documented. However, the effects of mechanical unloading on joint health and the interaction between bone and cartilage specifically, are less well known. Our ongoing studies with the mouse bone model have identified the failure of normal stem cell-based tissue regeneration, in addition to tissue degeneration, as a significant concern for long-duration spaceflight, especially in the mesenchymal and hematopoietic tissue lineages. Furthermore, we have identified the cell cycle arrest molecule, CDKN1ap21, as specifically up-regulated during spaceflight exposure and localized to osteoprecursors on the bone surface and chondroprogenitors in articular cartilage that are both required for normal tissue regeneration. The 30-day BionM1 and 37-day Rodent Research 1 (RR1) missions enabled the possibility of studying these effects in long-duration microgravity experiments. We hypothesized that the inhibition of stem cell-based tissue regeneration in short-duration spaceflight would continue during long-duration spaceflight resulting in significant tissue alterations and we specifically studied the hip joint (pelvis and proximal femur) to elucidate these effects. To test this hypothesis we analyzed bone and bone marrow stem cells using techniques including high-resolution Microcomputed Tomography (MicroCT), in-vivo differentiation and migration assays, and whole transcriptome expression profiling. We found that exposure to spaceflight for 30 days results in a significant decrease in bone volume fraction (-31), trabecular thickness (-14) and trabecular number (-20). Similar decrements in bone volume fraction (-27), trabecular number (-13) and trabecular thickness (-17) were found in female mice exposed to 37 days spaceflight. Furthermore, high-resolution MicroCT and immunohistochemical analysis of spaceflight tissues revealed a severe disruption of the epiphyseal boundary, resulting in endochondral ossification of the femoral head and perforation of articular cartilage by bone. This suggests that spaceflight in microgravity may cause rapid induction of an aging-like phenotype with signs of osteoarthritic disease in the hip joint. Microarray analysis also revealed that the top pathways altered during spaceflight include activation of matrix metalloproteinases, oxidative stress signaling and inflammation in both whole bone tissue and isolated bone marrow stem cells. In conclusion, the observed inhibition of stem cell-based tissue regeneration persists during long-duration spaceflight. Furthermore, spaceflight mice exhibit disruption of the epiphyseal boundary and endochondral ossification of the femoral head, and an inhibition of stem cell based tissue regeneration, which, taken together, may indicate onset of an accelerated aging phenotype with signs of osteoarthritic disease.

Cartilage↗

NASA NTRS2020

The Influence of Frequency and Duration Of Seismic Ground Motion On The Size Of Triggered Landslides—A Regional View

Observation, theory, and intuition all suggest that larger earthquakes should trigger larger landslides. Many factors could contribute to this, including depth-dependent shear strength or non-linearity of ground motion in soils and rock, but we hypothesize that the key characteristics of large earthquakes causing this phenomenon are (in addition to magnitude) the frequency and duration of the strong ground motion. Because of the paucity of site-specific data for detailed analysis, we take a regional approach to this question by analyzing strong-motion records and earthquake-induced landslide (EQIL) inventories from six well-documented earthquakes. Ground motion is characterized using earthquake magnitude and the median durations and frequencies (mean periods) of subsets of strong-motion records relevant to landslide triggering. EQIL inventories are characterized using the median landslide area of the entire inventory as well as the median areas of the largest 1% of the landslides and the largest 10 landslides. We then compare ground-motion characteristics with landslide size statistics to determine possible correlations. Comparisons of all earthquake- and landslide-size statistics show strong positive correlations between landslide size and (1) magnitude, (2) ground-motion duration, and (3) mean period. Although all the ground-motion measures yield highly correlated regressions, mean period appears to be the best overall predictor of landslide size. Landslide modeling using Newmark's sliding-block method also shows that longer mean periods and durations and larger magnitudes correlate strongly with increases in modeled displacements. These results support our hypothesis that increasing period and duration of seismic ground motion are the physical factors driving increased landslide sizes for larger earthquakes. Additional studies including data from a much larger set of earthquakes is needed to confirm the results of this initial study.

Hakan Tanyas↗