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NASA NTRS2015

Characterization of Aerosol Episodes in the Greater Mediterranean Sea Area from Satellite Observations (2000-2007)

An algorithm able to identify and characterize episodes of different aerosol types above sea surfaces of the greater Mediterranean basin (GMB), including the Black Sea and the Atlantic Ocean off the coasts of Iberia and northwest Africa, is presented in this study. Based on this algorithm, five types of intense (strong and extreme) aerosol episodes in the GMB are identified and characterized using daily aerosol optical properties from satellite measurements, namely MODIS-Terra, Earth Probe (EP)-TOMS and OMIAura. These aerosol episodes are: (i) biomass-burning/urban-industrial (BU), (ii) desert dust (DD), (iii) dust/sea-salt (DSS), (iv) mixed (MX) and (v) undetermined (UN). The identification and characterization is made with our algorithm using a variety of aerosol properties, namely aerosol optical depth (AOD), Angstrom exponent (a), fine fraction (FF), effective radius (reff) and Aerosol Index (AI). During the study period (2000e2007), the most frequent aerosol episodes are DD, observed primarily in the western and central Mediterranean Sea, and off the northern African coasts, 7 times/year for strong episodes and 4 times/year for extreme ones, on average. The DD episodes yield 40% of all types of strong aerosol episodes in the study region, while they account for 71.5% of all extreme episodes. The frequency of occurrence of strong episodes exhibits specific geographical patterns, for example the BU are mostly observed along the coasts of southern Europe and off the Atlantic coasts of Portugal, the MX episodes off the Spanish Mediterranean coast and over the Adriatic and northern Aegean Sea, while the DSS ones over the western and central Mediterranean Sea. On the other hand, the extreme episodes for all but DD aerosol display more patchy spatial patterns. The strong episodes exhibit AOD at 550 nm as high as 1.6 in the southernmost parts of central and eastern Mediterranean Sea, which rise up to 5 for the extreme, mainly DD and DSS, episodes. Although more than 90% of all aerosol episodes last 1 day, there are few cases, mainly extreme DD episodes, which last up to 4 days. Independently of their type, the Mediterranean aerosol episodes occur more frequently in spring (strong and extreme episodes) and summer (strong episodes) and most rarely during winter. A significant year by year variability of Mediterranean aerosol episodes has been identified, more in terms of their frequency than intensity. An analysis of 5-day back trajectories for the most extreme episodes provides confidence on the obtained results of the algorithm, based on the revealed origin and track of air masses causing the episodes. The 25 and 6% of all strong and extreme episodes, respectively, are MX, thus highlighting the co-existence of different aerosol types in the greater Mediterranean. The intensity of both MX and DSS episodes exhibits similar patterns to those of DD strong ones, indicating that desert dust is a determinant factor for the intensity of aerosol episodes in the Mediterranean, including DSS and MX episodes.

Atmospheric Chemistry↗

NASA NTRS2012

Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure taps. Several areas of improvement have been indentified and are currently being developed.

Watkins, A. Neal↗

NASA NTRS2003

Loading Configurations and Ground Reaction Forces During Treadmill Running in Weightlessness

Studies have shown losses in bone mineral density of 1-2% per month in critical weight bearing areas such as the proximal femur during long-term space flight (Grigoriev, 1998). The astronauts currently onboard the International Space Station (ISS) use a treadmill as an exercise countermeasure to bone loss that occurs as a result of prolonged exposure to weightlessness. A crewmember exercising on the treadmill is attached by a harness and loading device. Ground reaction forces are obtained through the loading device that pulls the crewn1ember towards the treadmill surface during locomotion. McCrory et al. (2002) found that the magnitude of the peak ground reaction force (pGRF) during horizontal suspension running, or simulated weightlessness, was directly related to the load applied to the subject. It is thought that strain magnitude and strain rate affects osteogenesis, and is a function of the magnitude and rate of change of the ground reaction force. While it is not known if a minimum stimulus exists for osteogenesis, it has been hypothesized that in order to replicate the bone formation occurring in normal gravity (1 G), the exercise in weightlessness should mimic the forces that occur on earth. Specifically, the pGRF obtained in weightlessness should be comparable to that achieved in 1 G.

DeWitt, John↗

NASA NTRSDate not supplied

Assessing Sediment Inputs into the Shoshone River in Wyoming to Determine Areas for Protection and Restoration Practices

In 2016, a routine repair operation at the Willwood Dam released tons of built-up sediment into the Shoshone River, polluting the river and killing thousands of fish. This release greatly concerned the communities that rely on the river for farming, recreation, and tourism. In partnership with the Wyoming Department of Environmental Quality (WDEQ), Shoshone River Partners, and the United States Geological Survey (USGS) Wyoming-Montana Water Science Center, this multipart project illustrated the application of high-resolution satellite imagery and hydrological modeling techniques to identify major tributaries contributing to sediment influxes into the Shoshone River between the Buffalo Bill Dam and the Willwood Dam. The team used PlanetScope and Sentinel-2 Multi-Spectral Instrument (MSI) satellite images to assess changes in the surface reflectance of the river in response to precipitation events. To determine these storm events, the team selected dates of interest using Global Precipitation Measurement (GPM) Integrated Multi-Spectral Retrieval (IMERG) and gauge precipitation data from the Global Historical Climatology Network Daily (GHCNd). The continuation of this research further quantified sediment influx in the Shoshone River following snowfall and melt events using the Soil & Water Assessment Tool (SWAT). The precipitation analysis and sediment contribution maps helped the partner organizations prioritize their current decision making and best management practices to specific sites along the river. The results demonstrated the feasibility of using PlanetScope data for categorizing sediment in the Shoshone River.

Caroline Williams↗

NASA NTRSDate not supplied

Exploring the Geochemistry of Tholeiitic Basalts and Hyaloclastites Formed in Submarine Volcanoes for Comparison With Venus Lavas

Underwater basaltic lavas exhibit distinct rock textures, mineralogy and morphological differences compared to those formed on land, primarily due to rapid cooling caused by contact with cold seawater instead of air and to high pressures – similar to Venus. The geomorphological similarities between terrestrial submarine volcanoes and some morphological classes of Venusian volcanoes have been investigated, but a comprehensive comparison in geochemical terms has yet to be conducted. Only three missions to Venus (Venera-13, Venera-14, and Vega-2) were able to report bulk composition of Venusian rocks, while other four missions (Venera-8, Venera-9, Venera-10, and Vega-1) provided limited geochemical information. Using X-Ray fluorescent (XRF) analysis, we saw that rocks analyzed on the surface of Venus are tholeiitic and alkalic basalts. This study, as part of the “Analogs for VENus's GEologically Recent Surfaces” (AVENGERS) initiative, aims to examine the possibility of seamounts/submarine volcanoes lavas serving as analogues to Venus lava geochemistry and morphology/formational processes. By sampling and analyzing submarine lavas from three distinct tectonic settings on Earth - hot-spot, convergent margins, and divergent margins - we will assess in which tectonic context the analogy with Venus is most comparable. Fieldwork will be conducted in further detail for submarine volcanoes located in Sicily, Hawaiʻi, and the Southern Pacific (Fiji, Vanuatu, Tonga, Samoa); we will use previously collected samples where these submarine areas are not accessible. Sampling efforts will target areas likely to yield submarine tholeiitic lavas and/or hyaloclastites. Samples collected during fieldwork will undergo detailed whole-rock geochemical analysis, including XRF, X-Ray diffraction (XRD) and Inductively Coupled Plasma Mass Spectrometry (ICPMS). Thin sections will be used to constrain differences in morphology/textures. The obtained geochemical data will then be compared with existing data on Venusian lava geochemistry, allowing for a comprehensive evaluation of potential analogies between submarine lavas from Earth and volcanic rocks on Venus. By elucidating these similarities and pinpointing specific tectonic contexts, our study has the potential to enhance our understanding of Venusian geology and the possibility of ephemeral plate tectonics on the planet.

N Mari↗

NASA NTRS2013

Orbiting Rainbows: Optical Manipulation of Aerosols and the Beginnings of Future Space Construction

Our objective is to investigate the conditions to manipulate and maintain the shape of an orbiting cloud of dust-like matter so that it can function as an ultra-lightweight surface with useful and adaptable electromagnetic characteristics, for instance, in the optical, RF, or microwave bands. Inspired by the light scattering and focusing properties of distributed optical assemblies in Nature, such as rainbows and aerosols, and by recent laboratory successes in optical trapping and manipulation, we propose a unique combination of space optics and autonomous robotic system technology, to enable a new vision of space system architecture with applications to ultra-lightweight space optics and, ultimately, in-situ space system fabrication. Typically, the cost of an optical system is driven by the size and mass of the primary aperture. The ideal system is a cloud of spatially disordered dust-like objects that can be optically manipulated: it is highly reconfigurable, fault-tolerant, and allows very large aperture sizes at low cost. See Figure 1 for a scenario of application of this concept. The solution that we propose is to construct an optical system in space in which the nonlinear optical properties of a cloud of micron-sized particles are shaped into a specific surface by light pressure, allowing it to form a very large and lightweight aperture of an optical system, hence reducing overall mass and cost. Other potential advantages offered by the cloud properties as optical system involve possible combination of properties (combined transmit/receive), variable focal length, combined refractive and reflective lens designs, and hyper-spectral imaging. A cloud of highly reflective particles of micron-size acting coherently in a specific electromagnetic band, just like an aerosol in suspension in the atmosphere, would reflect the Sun's light much like a rainbow. The only difference with an atmospheric or industrial aerosol is the absence of the supporting fluid medium. This new concept is based on recent understandings in the physics of optical manipulation of small particles in the laboratory and the engineering of distributed ensembles of spacecraft clouds to shape an orbiting cloud of micron-sized objects. In the same way that optical tweezers have revolutionized micro- and nano-manipulation of objects, our breakthrough concept will enable new large scale NASA mission applications and develop new technology in the areas of Astrophysical Imaging Systems and Remote Sensing because the cloud can operate as an adaptive optical imaging sensor. While achieving the feasibility of constructing one single aperture out of the cloud is the main topic of this work, it is clear that multiple orbiting aerosol lenses could also combine their power to synthesize a much larger aperture in space to enable challenging goals such as exoplanet detection. Furthermore, this effort could establish feasibility of key issues related to material properties, remote manipulation, and autonomy characteristics of cloud in orbit. There are several types of endeavors (science missions) that could be enabled by this type of approach, i.e. it can enable new astrophysical imaging systems, exoplanet search, large apertures allow for unprecedented high resolution to discern continents and important features of other planets, hyperspectral imaging, adaptive systems, spectroscopy imaging through limb, and stable optical systems from Lagrange-points. Future micro-miniaturization might hold promise of a further extension of our dust aperture concept to other more exciting smart dust concepts with other associated capabilities.

Space Construction↗

NASA NTRSDate not supplied

UAM Decision Making

NASA, in collaboration with the industry and FAA, is conducting research on Urban Air Mobility (UAM). UAM introduces unique and evolving operational characteristics unaccounted for within current transportation planning tools. This evolving modality requires a unique and comprehensive tool that integrates new and existing planning methodologies to provide a holistic solution for decision makers. NASA has identified a number of barriers and research areas related to aircraft, airspace, and communities as well as infrastructure requirements. The research will identify requirements related to urban capable aircraft and airspace technologies. While civil aviation authorities are responsible for safety and structure of operations through the air, the local and regional authorities are responsible for decisions related to location of vertiports, helipads, and airports. The implementation of UAM vertiports will consider diverse regional system categories such as weather, airspace restrictions, noise acceptability, surface traffic, availability of power, vertipad locations, routes, impact on surface traffic, safety and risks, economic impact, ingress/egress for electric/hybrid VTOL aircraft, applicable fire codes, evacuation strategy, zoning requirements, emergency preparedness, interactions with surface traffic, and community acceptance. Therefore, regional implementation bodies need a decision making tool to assess systemic dependencies in preparation for UAM impact on the region. We are developing a simulation and modeling tool that allows regional authorities to consider many factors while deciding the location of vertiport and UAM operations. The objective of this paper is to present the conceptual design of a comprehensive decision making tool to assist planning bodies in developing UAM infrastructure. Specifically, the UAM planning tool will simultaneously consider all relevant local/regional considerations to identify for vertiport locations and UAM operations for a region.

Parimal Kopardekar↗

NASA NTRSDate not supplied

Results from Two Full-Scale Hawker 4000 Fuselage Drop Tests

In the spring of 2022, NASA Langley Research Center (LaRC) conducted two full-scale drop tests on a Hawker 4000 partial fuselage structure for the evaluation of composite material response under dynamic impact loading conditions. The specific objectives of the tests were to induce dynamic composite damage initiation and progression and in primary structure and to understand the nature of the failure modes. The tests were conducted via dividing the fuselage hardware into three smaller sections. Dynamic drop tests were conducted on the forward and aft portions of the fuselage under different dynamic loading conditions, while the middle section was reserved for materials testing. Both tests were conducted by dropping the test articles from a height of 14 feet with significant amounts of pitch, which was added to initiate damage in specific regions of the structure. The test articles were ballasted then instrumented with accelerometers at various locations and speckle-coated on both exterior sides with a black and white stochastic pattern for use with three-dimensional digital image correlation (3D-DIC). In addition, the interior belly portion of the forward section test article was also speckle-coated, which was intended to capture deformations on the belly of the test article from the interior at impact. The interior of the aft section test article was not speckle-coated. Prior to testing, bow-tie markers were applied at various locations for use in marker tracking, to measure impact conditions such as vertical impact velocity and pitch. In this report, a partial summary of the data collected from the tests is presented. The data was primarily in the form of accelerometers to measure impact acceleration and 3D-DIC to measure deformation and failure onset and propagation. Post-test inspections revealed the primary damage mechanism was fiber cracking and delamination primarily in and around the area that contacted the impact surface. Acceleration pulse shapesin the ballast locations were trapezoidal in nature and ranged between 10 g and 40 g, depending on the location and test.

full scale testing↗

NASA NTRSDate not supplied

Results from Two Full-Scale Hawker 4000 Fuselage Drop Tests

full scale testing↗

NASA NTRSDate not supplied

SIBatt-3D: In-Space/On-Surface 3D Printing of Sodium Ion Batteries from ISRU Materials

Constructed more than 20 years ago, the International Space Station’s primary power system originally used nickel-hydrogen batteries with a lifetime of 6.5 years, until NASA began the process of replacing them in 2016 with lithium-ion batteries with a lifetime of 10 years. The demanding and costly process was accomplished after four flights of the Japanese H-II Transfer Vehicle cargo spacecraft (with a cost of about $10,000 per pound of payload), and 13 different astronauts conducting 14 spacewalks. Besides utilization in the ISS, rechargeable batteries are present in many space applications: they are installed in exploration robots, life support systems and in portable communication devices, to mention some. In this context, this project is focused on the in-space manufacturing of shape-conformable batteries using in-situ resources, and aims to address the NASA’s gaps related to the development of next generation of energy storage devices (TX03), as well as in-space manufacturing and in-situ resource utilization (TX07). The proposed work also tackles the HEOMD’s objectives targeting the in-space additive manufacturing (AM) from Lunar/Martian materials (regolith as AM feedstock) to reinvigorate America’s Human Space Exploration Program (SPD-1). This project is in direct alignment with the STMD’s objectives to demonstrate in-space autonomous manufacturing and assembly of complete systems by 2030, and to enable humans to live and explore in space and on planetary surfaces by 2040 thanks to in-space habitation, infrastructure development and in-situ resource utilization (ST1 and ST5). Manufacturing of shape conformable batteries directly in-space and using in-situ resources would also contribute to reducing the payload weight and volume (TX12) for future missions, thus reducing risk for long term Mars missions where rapid resupply is logistically infeasible. Nowadays, commercial batteries consist of stacked two-dimensional (2D) sheets, which are only manufactured in restricted geometries (cylindrical and coin cell). Evolving from conventional 2D, complex 3D battery architectures have been proven to increase the electrochemical active surface area and ion diffusion path, leading to improved areal energy density and power performance. This tendency was illustrated in our recent in-depth modeling studies by simulating a classical Ragone plot exhibiting the energy-power relationship. Our team demonstrated through modeling that a complex gyroidal 3D printed battery architecture exhibits significantly improved power performances (>150% at the current density of 6C; full discharge in 10 minutes) in comparison to a traditional 3D printed planar geometry. Motivated by these results and as the fabrication of intricate 3D battery design is only possible experimentally thanks to the geometric freedom offered by additive manufacturing (AM), our team has already initiated leveraging thermoplastic material extrusion at the laboratory scale. While 3D printing of batteries is relatively recent (2013), it has witnessed a growing interest during the last recent years, as next-generation shape-conformable 3D batteries can be co-designed with the system. Consequently, dead-volume and mass brought from Earth are minimized, in addition to improved battery performance, in alignment with the aforementioned NASA’s objectives. Further, while this project is specifically dedicated to batteries, it lends itself towards the maturation of in-space manufacturing via 3D printing using in-situ resources, stated in HEOMD and STMD goals.

In-Space Manufacturing↗

NASA NTRS2011

Microwave Tissue Soldering for Immediate Wound Closure

A novel approach for the immediate sealing of traumatic wounds is under development. A portable microwave generator and handheld antenna are used to seal wounds, binding the edges of the wound together using a biodegradable protein sealant or solder. This method could be used for repairing wounds in emergency settings, by restoring the wound surface to its original strength within minutes. This technique could also be utilized for surgical purposes involving solid visceral organs (i.e., liver, spleen, and kidney) that currently do not respond well to ordinary surgical procedures. A miniaturized microwave generator and a handheld antenna are used to deliver microwave energy to the protein solder, which is applied to the wound. The antenna can be of several alternative designs optimized for placement either in contact with or proximity to the protein solder covering the wound. In either case, optimization of the design includes the matching of impedances to maximize the energy delivered to the protein solder and wound at a chosen frequency. For certain applications, an antenna could be designed that would emit power only when it is in direct contact with the wound. The optimum frequency or frequencies for a specific application would depend on the required depth of penetration of the microwave energy. In fact, a computational simulation for each specific application could be performed, which would then match the characteristics of the antenna with the protein solder and tissue to best effect wound closure. An additional area of interest with potential benefit that remains to be validated is whether microwave energy can effectively kill bacteria in and around the wound. Thus, this may be an efficient method for simultaneously sterilizing and closing wounds. Using microwave energy to seal wounds has a number of advantages over lasers, which are currently in experimental use in some hospitals. Laser tissue welding is unsuitable for emergency use because its large, bulky equipment cannot be easily moved between operating rooms, let alone relocated to field sites where emergencies often occur. In addition, this approach is highly dependent on the uniformity and thickness of the protein solder as well as the surgeon s skills. In contrast, the use of microwave energy is highly tolerant of the thickness of the protein solder, level of fluids in and around the wound, and other parameters that can adversely affect the outcome of laser welding. However, controlling the depth of penetration of the microwave energy into the wound is critical for achieving effective wound sealing without damaging the adjacent tissue. In addition, microspheres that encapsulate metallic cores could also be incorporated into the protein solder to further control the depth of penetration of the microwave energy.

Arndt, G. Dickey↗

NASA NTRS2011

Microwave Tissue Soldering for Immediate Wound Closure

Arndt, G. Dickey↗

NASA NTRS1985

Field Utilization and Analysis of AIS 128-channel Imagery Using Microcomputers: Application to Yerington, Nevada Field Area

Geologists in exploration need to be able to determine the mineral composition of a given outcrop, and then proceed to another in order to carry out the process of geologic mapping. Since April 1984 researchers have been developing a portable microcomputer-based imaging system (with a grey-scale of 16 shades of amber), which were demonstrated during the November 1984 GSA field trip in the field at Yerington, NV. A color-version of the same technology was recently demonstrated. The portable computer selected is a COLBY 10-Megabyte, hard disk-equipped repackaged-IBM/XT, which operates on either 110/220 VAC or on 12VDC from the cigarette lighter in a field vehicle. A COMPAQ PLUS or an IBM Portable will also work on modified software. The underlying concept is that the atmospheric transmission and surface albedo/slope terms are multiplicative, relating the spectral irradiance to the spectral color of the surface materials. Thus, the spectral color of a pixel remains after averaged log-albedo and log-irradiance have been estimated. All these steps can be carried out on the COLBY microcomputer, using 80 image lines of the 128-channel, 12-bit imagery. Results are shown for such an 80-line segment, showing the identification of an O-H bearing mineral group (of slightly varying specific characters) on the flight line.

Lyon, R. J. P.↗

NASA NTRS2000

The Test and Evaluation of a Non-Chromate Finishing Agent

This research is focused on the design, development and implementation of an industry, military and commercial standard testing cell for surface coatings, which focuses on advanced non-chromate materials technology and their commercialization. Currently, within both private and commercial sectors, chromates are used in the corrosion prevention. processes. However, there is a great demand for chromate-free systems that are able to provide equal protection. At the end of this effort, it is intended that a patented alternative to chromate conversion coatings would be tested and processed for commercialization. Thus far, research studies have been concerned primarily with current corrosion knowledge and testing methods. Corrosion can be classified into five categories: The first type is uniform corrosion which is dominated by a uniform thinning due to an even and regular loss of metal. The second type is called localized corrosion in which most of the loss occurs in discrete areas. The third type, metallurgically influenced corrosion is a form of attack where metallurgy plays a significant role. The fourth type, titled mechanically assisted degradation is a form of attack where velocity, abrasion, and hydrodynamics control the corrosion process. The last type of corrosion is defined as environmentally induced cracking which occurs when cracks are produced under specific, premeditated stress. Oddly enough, with these varying classifications, there are not as many standardized corrosion testing sites. Two of the most common testing methods for corrosion are salt spray testing and filiform. Although neither has proven to be absolute, in terms of the resulting observations, our research aims to help provide data that may be used to support the standardization for corrosion testing. We would acquire and use a Singleton Cyclic Corrosion Testing Chamber. Singleton test chambers perform a wide range of commonly used catalytic corrosion tests. They are used throughout the industry, some of which are - automotive, aerospace, electronic and many more. In addition to this, Singleton test chambers are fully expandable to accommodate cyclic corrosion testing needs. Singleton chambers are also designed for complete compliance and conformity with ASTM (American Society for Testing and Materials), military and commercial standards.

Gulley, H.↗

NASA NTRS2026

Multi-Agent Swarm State of the Art Report

The Next-Generation Multi-Agent Swarm (NGS) Study conducted by NASA’s Ames Research Center for NASA’s Space Technology Mission Directorate (STMD) will develop a comprehensive understanding of emerging multi-agent swarm capabilities. The study aims to identify existing swarm capabilities and asses their potential for persistent lunar space situational awareness, surface monitoring, and distributed autonomy demonstrations. A key objective is to inform the design of a next-generation multi-agent swarm that can perform autonomous distributed remote sensing, position, navigation, and timing (PNT) services, automated deployment that leverages autonomy, edge computing, and interoperable networking to enable cooperative operations without the need for immediate human operation. This study will address specific shortfalls identified by STMD, including intelligent multi-agent constellations, autonomy, edge computation, position, navigation, and timing for small spacecraft, small spacecraft propulsion, and space situational awareness (1625, 1438, 1433, 1557, 1431, 1430, 1589). The NASA Ames Mission Design Center (MDC) will provide subject matter expertise to support systems engineering trades, while experts in autonomy and spacecraft swarms in NASA’s Intelligent Systems Division will lead the study and focus on identifying emerging next-generation swarm capabilities. The study objectives include: capturing the current state-of-the-art for multi-agent swarm capabilities, evaluating technologies and creating technology roadmaps, and developing at least one new technology demonstration mission concept. This initial NGS study report surveys the current state of the art in technology areas relevant for the next-generation multi-agent swarm design. Our primary focus is on surveying relevant deployed space systems1, supplemented with selective analysis of relevant proposed missions and technology developments that have yet to fly.

agent↗

NASA NTRS2011

Passive Microwave Remote Sensing of Falling Snow and Associated GPM Field Campaigns

Retrievals of falling snow from space represent one of the next important challenges for the atmospheric, hydrological, and energy budget scientific communities. Historically, retrievals of falling snow have been difficult due to the relative insensitivity of satellite rain-based channels as used in the past. We emphasize the use of high frequency passive microwave channels (85-200 GHz) since these are more sensitive to the ice in clouds and have been used to estimate falling snow from space. While satellite-based remote sensing provides global coverage of falling snow events and the science is relatively new, retrievals are still undergoing development with challenges remaining. There are several current satellite sensors, though not specifically designed for estimating falling snow, are capable of measuring snow from space. These include NOAA's AMSU-B, the MHS sensors, and CloudSat radar. They use high frequency (greater than 85 GHz) passive and active microwave and millimeter-wave channels that are sensitive to the scattering from ice and snow particles in the atmosphere. Sensors with water vapor channels near 183 GHz center line provide opaqueness to the Earth's surface features that can contaminate the falling snow signatures, especially over snow covered surface. In addition, the Global Precipitation Measurement (GPM) mission scheduled for launch in 2013 is specifically designed to measure both liquid rain and frozen snow precipitation. Since falling snow from space is the next precipitation measurement challenge from space, information must be determined in order to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, snow event system characteristics, and surface types. For example, can a lake effect snow system with low cloud tops having an ice water content (IWC) at the surface of 1.0 gram per cubic meter be detected? If this information is known, we can focus retrieval efforts on detectable storms and concentrate advances on achievable results. In this work, the focus is to determine thresholds of detection for falling snow for various snow conditions over land and lake surfaces. The results rely on simulated Weather Research Forecasting (WRF) simulations of falling snow cases [9] since simulations provide all the information to determine the measurements from space and the ground truth. This analysis relies on data from the Canadian CloudSat/CALIPSO Validation Program (C3VP) field campaign held from October 31, 2006 through March 1, 2007. In January 2012 GPM will return to the C3VP area for the GPM Cold Precipitation Experiment (GCPEx). This presentation will describe the thresholds-of-detection procedure and results, as well as the field campaign details.

Skofronick-Jackson, Gail↗

NASA NTRS2016

Comparing Potential Recharge Estimates From Three Land Surface Models Across the Western US

Groundwater is a major source of water in the western US. However, there are limited recharge estimates available in this region due to the complexity of recharge processes and the challenge of direct observations. Land surface Models (LSMs) could be a valuable tool for estimating current recharge and projecting changes due to future climate change. In this study, simulations of three LSMs (Noah, Mosaic and VIC) obtained from the North American Land Data Assimilation System (NLDAS-2) are used to estimate potential recharge in the western US Modeled recharge was compared with published recharge estimates for several aquifers in the region. Annual recharge to precipitation ratios across the study basins varied from 0.01-15% for Mosaic, 3.2-42% for Noah, and 6.7-31.8% for VIC simulations. Mosaic consistently underestimates recharge across all basins. Noah captures recharge reasonably well in wetter basins, but overestimates it in drier basins. VIC slightly overestimates recharge in drier basins and slightly underestimates it for wetter basins. While the average annual recharge values vary among the models, the models were consistent in identifying high and low recharge areas in the region. Models agree in seasonality of recharge occurring dominantly during the spring across the region. Overall, our results highlight that LSMs have the potential to capture the spatial and temporal patterns as well as seasonality of recharge at large scales. Therefore, LSMs (specifically VIC and Noah) can be used as a tool for estimating future recharge rates in data limited regions.

groundwater↗

NASA NTRS2001

Atmospheric Constraints on Landing Site Selection

The Martian atmosphere is a significant part of the environment that the Mars Exploration Rovers (MER) will encounter. As such, it imposes important constraints on where the rovers can and cannot land. Unfortunately, as there are no meteorological instruments on the rovers, there is little atmospheric science that can be accomplished, and no scientific preference for landing sites. The atmosphere constrains landing site selection in two main areas, the entry descent and landing (EDL) process and the survivability of the rovers on the surface. EDL is influenced by the density profile and boundary layer winds (up to altitudes of 5 to 10 km). Surface survivability involves atmospheric dust, temperatures and winds. During EDL, the atmosphere is used to slow the lander down, both ballistically and on the parachute. This limits the maximum elevation of the landing site to -1.3 km below the MOLA reference aeroid. The landers need to encounter a sufficiently dense atmosphere to be able to stop, and the deeper the landing site, the more column integrated atmosphere the lander can pass through before reaching the surface. The current limit was determined both by a desire to be able to reach the hematite region and by a set of atmosphere models we developed for EDL simulations. These are based on Thermal Emission Spectrometer (TES) atmospheric profile measurements, Ames Mars General Circulation Model (MGCM) results, and the 1-D Ames GCM radiative/convective model by J. Murphy. The latter is used for the near surface diurnal cycle. The current version of our model encompasses representative latitude bands, but we intend to make specific models for the final candidate landing sites to insure that they fall within the general envelope. The second constraint imposed on potential landing sites through the EDL process is the near surface wind. The wind in the lower approximately 5 km determines the horizontal velocity that the landers have when they land. Due to the mechanics of the landing process, the total velocity (including both the horizontal and vertical components) determines whether or not the landers are successful. Unfortunately, the landing system has no easy way to nullify any horizontal velocity imparted by the wind, so the landing sites selected need to have as little wind as possible. In addition to the mean wind velocity, the landing system is sensitive to vertical wind shear in the lowest kilometer or so. Wind shear can deflect the retro rockets (RADs) from their nominal vertical orientation producing unwanted horizontal spacecraft velocities. Both mean velocity and wind shear are dominated by the the local topography and other surface properties (in particular albedo and thermal inertia which control the surface temperature). This is seen even in simplified 2-D mesoscale models. The effects in a fully 3-D model are expected to he even more topographically dependent. In particular there is potential for wind channeling in canyons and other terrain features. Boundary layer winds and wind shear are currently being modeled based on terrestrial data and boundary layer scaling laws modified for Martian conditions. We hope to supplement this with mesoscale model results (from several sources) once the number of landing sites is reduced to a manageable number.

Kass, David M.↗