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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Test and Analyses of a Composite Multi-Bay Fuselage Panel Under Uni-Axial Compression

A composite panel containing three stringers and two frames cut from a vacuum-assisted resin transfer molded (VaRTM) stitched fuselage article was tested under uni-axial compression loading. The stringers and frames divided the panel into six bays with two columns of three bays each along the compressive loading direction. The two frames were supported at the ends with pins to restrict the out-of-plane translation. The free edges of the panel were constrained by knife-edges. The panel was modeled with shell finite elements and analyzed with ABAQUS nonlinear solver. The nonlinear predictions were compared with the test results in out-of-plane displacements, back-to-back surface strains on stringer flanges and back-to-back surface strains at the centers of the skin-bays. The analysis predictions were in good agreement with the test data up to post-buckling.

Li, Jian↗
NASA NTRS2004

Experimental Results From Stitched Composite Multi-Bay Fuselage Panels Tested Under Uni-Axial Compression

The experimental results from two stitched VARTM composite panels tested under uni-axial compression loading are presented. The curved panels are divided by frames and stringers into five or six bays with a column of three bays along the compressive loading direction. The frames are supported at the ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field measurement technique that utilizes a camera-based-stero-vision system was used to record displacements. The panels were loaded in increments to determine the first bay to buckle. Loading was discontinued at limit load and the panels were removed from the test machine for impact testing. After impacting at 20 ft-lbs to 25 ft-lbs of energy with a spherical indenter, the panels were loaded in compression until failure. Impact testing reduced the axial stiffness 4 percent and less than 1 percent. Postbuckled axial panel stiffness was 52 percent and 70 percent of the pre-buckled stiffness.

Baker, Donald J.↗
NASA NTRS1956

Dynamic Investigation of Release Characteristics of a Streamlined Internal Store from a Simulated Bomb Bay of the Republic F-105 Airplane at Mach Numbers of 0.8, 1.4, and 1.98, Coord. No. AF-222

An investigation has been conducted in the 27- by 27-inch preflight jet of the Langley Pilotless Aircraft Research Station at Wallops Island, Va., of the release characteristics of a dynamically scaled streamlined-type internally carried store from a simulated bomb bay at Mach numbers M(sub o) of 0.8, 1.4, and 1.98. A l/17-scale model of the Republic F-105 half-fuselage and bomb-bay configuration was used with a streamlined store shape of a fineness ratio of 6.00. Simulated altitudes were 3,400 feet at M(sub o) = 0.8, 3,400, and 29,000 feet at M(sub o) = 1.4, and 29,000 feet at M(sub o) = 1.98. At supersonic speeds, high pitching moments are induced on the store in the vicinity of the bomb bay at high dynamic pressures. Successful ejections could not be made with the original configuration at supersonic speeds at near sea-level conditions. The pitching moments caused by unsymmetrical pressures on the store in a disturbed flow field were overcome by replacing the high-aspect-ratio fin with a low-aspect-ratio fin that had a 30-percent area increase which was less subject to aeroelastic effects. Release characteristics of the store were improved by orienting the fins so that they were in a more uniform flow field at the point of store release. The store pitching moments were shown to be reduced by increasing the simulated altitude. Favorable ejections were made at subsonic speeds at near sea-level conditions.

Lee, John B.↗
NASA NTRS2006

Remote Sensing Reflectance and Inherent Optical Properties in the Mid-mesohaline Chesapeake Bay

We used an extensive set of bio-optical data and radiative transfer (RT) model simulations of radiation fields to investigate relationships between inherent optical properties and remotely sensed quantities in the optically complex, mid-mesohaline Chesapeake Bay waters. Field observations showed that the chlorophyll algorithms used by the MODIS (MODerate resolution Imaging Spectroradiometer) ocean color sensor (i.e. Chlor_a, chlor_MODIS, chlor_a_3 products) do not perform accurately in these Case 2 waters. This is because, when applied to waters with high concentrations of chlorophyll, all MODIS algorithms are based on empirical relationships between chlorophyll concentration and blue-green wavelength remote sensing reflectance (Rrs) ratios that do not account for the typically strong blue-wavelength absorption by non-covarying, dissolved and non-algal particulate components. Stronger correlation was observed between chlorophyll concentration and Rrs ratios in the red (i.e. Rrs(677)/Rrs(554)) where dissolved and non-algal particulate absorption become exponentially smaller. Regionally-specific algorithms that are based on the phytoplankton optical properties in the red wavelength region provide a better basis for satellite monitoring of phytoplankton blooms in these Case 2 waters. Good optical closure was obtained between independently measured Rrs spectra and the optical properties of backscattering, b(sub b), and absorption, a, over the wide range of in-water conditions observed in the Chesapeake Bay. Observed variability in the quantity f/Q (proportionality factor in the relationship between Rrs and the water inherent optical properties ratio b(sub b)/(a+b(sub b)) was consistent with RT model calculations for the specific measurement geometry and water bio-optical characteristics. Data and model results showed that f/Q values in these Case 2 coastal waters are not considerably different from those estimated in previous studies for Case 1 waters. Variation in surface backscattering significantly affected Rrs magnitude across the visible spectrum and was most strongly correlated (R(sup 2)=0.88) with observed variability in Rrs at 670 nm. Surface values of particulate backscattering were strongly correlated with non-algal particulate absorption, a(sub nap), in the blue wavelengths (R(sup 2)=0.83). These results, along with the measured values of backscattering fraction magnitude and non-algal particulate absorption spectral slope, suggest that suspended non-algal particles with high inorganic content are the major water constituents regulating b(sub b) variability in the mid-mesohaline Chesapeake Bay. Remote retrieval of surface b(sub b) and (a(sub nap), from Rrs(670) can be used in regionally-specific satellite algorithms to separate contribution by non-algal particles and dissolved organic matter to total light absorption in the blue, and monitor non-algal suspended particle concentration and distribution in these Case 2 waters.

Tzortziou, Maria↗
NASA NTRS2007

Investigation of MMOD Impact on Shuttle Payload Bay Door Radiator

Post flight inspections on the Space Shuttle Atlantis conducted after the STS-115 mission revealed a 0.11 inch (2.8 mm) hole in the outer facesheet of the starboard payload bay door radiator panel #4. This hole is the possible result of micrometeoroid/orbiting debris (MMOD) impact. The payload bay door radiators in this region are 0.5 inch (12.7 mm) thick aluminum honeycomb with 0.011 in (0.279 mm) thick aluminum facesheets topped with 0.005 in (0.127 mm) silver-Teflon tape. Inner facesheet damage included a 0.267 in (6.78 mm) long through crack with measurable deformation in the area of 0.2 in (5.1 mm). There was also a 0.031 in (0.787 mm) diameter hole in the rear facesheet. A large approximately 1 in (25 mm) diameter region of honeycomb was also destroyed. Since the radiators are located on the inside of the shuttle payload bay doors which are closed during ascent and reentry, the damage could only have occurred during the on-orbit portion of the mission. This paper will document the data collected from the impact site and will include results of the SEM/EDX analysis. Evidence will be presented that suggests a source of the impact as well as an analysis of the impact site features that indicate projectile directionality. Results of hypervelocity impact testing on representative samples in an attempt to simulate the impact event will be presented and discussed. Finally, the results of a study showing the regions of the orbiter vehicle that would be vulnerable to an equivalent projectile will be given.

Hyde, J. L.↗
NASA NTRS2006

Baseline HSR Inlet and Engine Bay Cowl Seal Requirements

The two dimensinal bifurcated inlet, down selected for the HSR program, and the engine bay cowling consist of many sealing interfaces. The variable geometry characteristics of this inlet and the size of the propulsion system impose new sealing requirements for commercial transport aircraft. Major inlet systems requiring seal development and testing include the ramp system, the bypass/take-off system, and the inlet/engine interface. Engine bay cowling seal interfaces include the inlet/cowling interface, the keel split line, the hinge beam/engine bay cowling, and the nozzle/cowling interface. These seals have to withstand supersonic flight operating temperatures and pressures with typical commercial aircraft reliability and lives. The operating conditions and expected seal lives will be identified for the various interfaces. Boeing's SST seal development program will also be discussed.

Sandquist, David↗
NASA NTRS2010

Use of Land Use Land Cover Change Mapping Products in Aiding Coastal Habitat Conservation and Restoration Efforts of the Mobile Bay NEP

The Mobile Bay region has undergone significant land use land cover change (LULC) over the last 35 years, much of which is associated with urbanization. These changes have impacted the region s water quality and wildlife habitat availability. In addition, much of the region is low-lying and close to the Gulf, which makes the region vulnerable to hurricanes, climate change (e.g., sea level rise), and sometimes man-made disasters such as the Deepwater Horizon (DWH) oil spill. Land use land cover change information is needed to help coastal zone managers and planners to understand and mitigate the impacts of environmental change on the region. This presentation discusses selective results of a current NASA-funded project in which Landsat data over a 34-year period (1974-2008) is used to produce, validate, refine, and apply land use land cover change products to aid coastal habitat conservation and restoration needs of the Mobile Bay National Estuary Program (MB NEP). The project employed a user defined classification scheme to compute LULC change mapping products for the entire region, which includes the majority of Mobile and Baldwin counties. Additional LULC change products have been computed for select coastal HUC-12 sub-watersheds adjacent to either Mobile Bay or the Gulf of Mexico, as part of the MB NEP watershed profile assessments. This presentation will include results of additional analyses of LULC change for sub-watersheds that are currently high priority areas, as defined by MB NEP. Such priority sub-watersheds include those that are vulnerable to impacts from the DWH oil spill, as well as sub-watersheds undergoing urbanization. Results demonstrating the nature and permanence of LULC change trends for these higher priority sub-watersheds and results characterizing change for the entire 34-year period and at approximate 10-year intervals across this period will also be presented. Future work will include development of value-added coastal habitat quality assessment products that will be used by the MB NEP and its partners in the planning of coastal conservation and restoration activities.

Spruce, Joseph P.↗
NASA NTRS2010

Using Remote Sensing Data to Evaluate Habitat Loss in the Mobile, Galveston, and Tampa Bay Watersheds

The Gulf of Mexico has experienced dramatic wetland habitat area losses over the last two centuries. These losses not only damage species diversity, but contribute to water quality, flood control, and aspects of the Gulf coast economy. Overall wetland losses since the 1950s were examined using land cover/land use (LCLU) change analysis in three Gulf coast watershed regions: Mobile Bay, Galveston Bay, and Tampa Bay. Two primary causes of this loss, LCLU change and climate change, were then assessed using LCLU maps, U.S. census population data, and available current and historical climate data from NOAA. Sea level rise, precipitation, and temperature effects were addressed, with emphasis on analysis of the effects of sea level rise on salt marsh degradation. Ecological impacts of wetland loss, including fishery depletion, eutrophication, and hypoxia were addressed using existing literature and data available from NOAA. These ecological consequences in turn have had an affect on the Gulf coast economy, which was analyzed using fishery data and addressing public health impacts of changes in the environment caused by wetland habitat loss. While recent federal and state efforts to reduce wetland habitat loss have been relatively successful, this study implies a need for more aggressive action in the Gulf coast area, as the effects of wetland loss reach far beyond individual wetland systems themselves to the Gulf of Mexico as a whole.

Steffen, Morgan↗
NASA NTRS2010

Evaluation of Shortwave Infrared Atmospheric Correction for Ocean Color Remote Sensing of Chesapeake Bay

The NASA Moderate Resolution Imaging Spectroradiometer onboard the Aqua platform (MODIS-Aqua) provides a viable data stream for operational water quality monitoring of Chesapeake Bay. Marine geophysical products from MODIS-Aqua depend on the efficacy of the atmospheric correction process, which can be problematic in coastal environments. The operational atmospheric correction algorithm for MODIS-Aqua requires an assumption of negligible near-infrared water-leaving radiance, nL(sub w)(NIR). This assumption progressively degrades with increasing turbidity and, as such, methods exist to account for non-negligible nL(sub w)(NIR) within the atmospheric correction process or to use alternate radiometric bands where the assumption is satisfied, such as those positioned within shortwave infrared (SWIR) region of the spectrum. We evaluated a decade-long time-series of nL(sub w)(lambda) from MODIS-Aqua in Chesapeake Bay derived using NIR and SWIR bands for atmospheric correction. Low signal-to-noise ratios (SNR) for the SWIR bands of MODIS-Aqua added noise errors to the derived radiances, which produced broad, flat frequency distributions of nL(sub w)(lambda) relative to those produced using the NIR bands. The SWIR approach produced an increased number of negative nL(sub w)(lambda) and decreased sample size relative to the NIR approach. Revised vicarious calibration and regional tuning of the scheme to switch between the NIR and SWIR approaches may improve retrievals in Chesapeake Bay, however, poor SNR values for the MODIS-Aqua SWIR bands remain the primary deficiency of the SWIR-based atmospheric correction approach.

Werdell, P. Jeremy↗
NASA NTRS2013

Evidence for Smectite Clays from MSL SAM Analyses of Mudstone at Yellowknife Bay, Gale Crater, Mars

Drilled samples of mudstone from the Sheepbed unit at Yellowknife Bay were analyzed by MSL instruments including the Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments in MSL's Analytical Laboratory. CheMin analyses revealed the first in situ X-ray diffraction based evidence of clay minerals on Mars, which are likely trioctahedral smectites (e.g., saponite) and comprise approx 20% of the mudstone sample (e.g., Bristow et al., this meeting). SAM analyses, which heated the mudstone samples to 1000 C and monitored volatiles evolved to perform in situ evolved gas analysis mass spectrometry (EGA-MS), resulted in a H2O trace exhibiting a wide evolution at temperatures < 500 C, and an evolution peak at higher temperatures near approx 750 C. The low temperature H2O evolution has many potential contributors, including adsorbed H2O, smectite interlayer H2O, and structural H2O/OH from bassanite and akaganeite (identified by CheMin) and H2O/OH from amorphous phases in the sample. The high temperature H2O is consistent with the evolution of H2O from the dehydroxylation of the smectite clay mineral. Comparison to EGA-MS data collected under SAM-like conditions on a variety of clay mineral reference materials indicate that a trioctahedral smectite, such as saponite, is most consistent with the high temperature H2O evolution observed. There may also be SAM EGA-MS evidence for a small high temperature H2O evolution from scoop samples from the Yellowknife Bay Rocknest sand shadow bedform. As in the mudstone samples, this evolution may indicate the detection of smectite clays, and the idea that minor clays may be present in Rocknest materials that could be expected to be at least partially derived from local sources is reasonable. But, because smectite clays were not definitively observed in CheMin analyses of Rocknest materials, they must be present at much lower abundances than the approx 20% observed in the mudstone samples. This potential detection underscores the complementary nature of the MSL CheMin and SAM instruments for investigations of martian sample mineralogy. Information on the nature of Yellowknife Bay clay minerals may also be available from the detection of H2 evolved during SAM EGA-MS at high temperature. A likely source of at least some of this H2 is H2O evolved from the smectite clays at high temperature, and it is possible these evolutions can be used in a similar fashion to high temperature H2O releases to provide constraints on the clay minerals in a sample. In addition, the D/H of this high temperature H2, as well as the H2O, can be derived from SAM MS and Tunable Laser Spectrometer (TLS) data, respectively. These D/H values may help to inform the provenance of high and low temperature water evolved from martian samples

McAdam, Amy↗
NASA NTRS2015

Effect of Sulfur Concentration and PH Conditions on Akaganeite Formation: Understanding Akaganeite Formation Conditions in Yellowknife Bay, Gale Crater, Mars

The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of akaganeite have revealed that akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.

Fox, A.↗
NASA NTRS2016

Synthesis of Akaganeite in the Presence of Sulfate: Implications for Akaganeite Formation in Yellowknife Bay, Gale Crater, Mars

Akaganeite (beta-FeOOH) is an Fe(III) (hydr)oxide with a tunnel structure usually occupied by chloride. Akaganeite has been recently discovered in a mudstone on the surface of Mars by the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments onboard the Mars Science Laboratory (MSL) Curiosity Rover in Gale crater [1, 2]. Akaganeite was detected together with sulfate minerals [anhydrite (CaSO4) and basanite (2CaSO4·2H2O)] in the drilled Cumberland and John Clein mudstone samples at Yellowknife Bay [2]. Discovery of akaganeite and sulfates in the same samples suggests that sulfate ions could be present in aqueous solution during akaganeite formation. However, mechanism and aqueous environmental conditions of akaganeite formation (e.g., pH and range of sulfate concentration) in Yellowknife Bay remain unknown. The objective of our work was to perform synthesis of akaganeite without or with sulfate addition at variable pHs in order to constrain formation conditions of akaganeite in Yellowknife Bay, Gale crater on Mars.

Peretyazhko, T. S.↗
NASA NTRS2015

Preparation for Testing a Multi-Bay Box Subjected to Combined Loads

The COmbined Loads Test System (COLTS) facility at NASA Langley Research Center provides a test capability to help develop validated structures technologies. The test machine was design to accommodate a range of fuselage structures and wing sections and subject them to both quasistatic and cyclic loading conditions. The COLTS facility is capable of testing fuselage barrels up to 4.6 m in diameter and 13.7 m long with combined mechanical, internal pressure, and thermal loads. The COLTS facility is currently being prepared to conduct a combined mechanical and pressure loading for a multi-bay pressure box to experimentally verify the structural performance of a composite structure which is 9.1 meters long and representative of a section of a hybrid wing body fuselage section in support of the Environmentally Responsible Aviation Project at NASA. This paper describes development of the multi-bay pressure box test using the COLTS facility. The multi-bay test article will be subjected to mechanical loads and internal pressure loads up to design ultimate load. Mechanical and pressure loads will be applied independently in some tests and simultaneously in others.

Rouse, Marshall↗
NASA NTRS2018

Prioritizing Aquatic Science and Applications Needs in the Chesapeake Bay for a Space-Borne Hyperspectral Mission

The Chesapeake Bay is the largest estuary in North America, benefiting a growing population through its ecosystem services, fishing, recreations, and transportation routes. Studies indicate the health of the Bay as seen some improvement in recent years, yet threats to its health persist (e.g. warming, pollution nutrient run-off). Increasing human activities in coastal regions requires constant vigilance by agencies managing water quality, to ensure the safety of the population. Since April 2018, an interagency working group has been meeting monthly and a daylong workshop was convened with science and applications stakeholders around the overall theme of monitoring water quality from space. Current ocean color images indicate bloom locations used to guide in situ sampling efforts, despite limited spatial, spectral and temporal resolution. High resolution hyperspectral remote sensing provides a potential opportunity to measure additional indicators of ecological health and water quality. Assessing the needs of the aquatic user community around the Chesapeake Bay will inform science and applications recommendations during the current architecture study for a Surface Biology and Geology (SBG) Mission, as well as future scoping studies of other coastal and inland water bodies.

Schollaert Uz, Stephanie↗
NASA NTRS2019

MLI Impact Phenomenology Observed on the HST Bay 5 MLI Panel

Multi-layer insulation (MLI) blankets covering the Hubble Space Telescope (HST) electronics bays were removed during HST Servicing Mission 4 and returned to Earth for analysis. The NASA Orbital Debris Program Office obtained HST Bay 5, 8, and 10 MLI blankets to characterize impact features and develop a flux estimate based on those features. This paper reports on the impact feature phenomenology observed during imaging campaigns in 2011 and 2018. Earlier conventions of measuring impacted features by recording the largest diameter to determine impacting particle size do not provide the best subsequent estimation of the impacting particle size. Instead of an impacted feature as a smooth-edged through-hole, a ‘petaling’ phenomenon along with multiple-layering composition in impacted features has been observed in both hypervelocity testing and in the Bay 5 MLI. A new methodology of characterization techniques used during research and analysis of the HST MLI is presented, which will provide greater understanding and a more accurate estimation of impacting particles and their parameters.

Ward, Melissa A.↗
NASA NTRS2020

Searching for Hyperspectral Optical Proxies to Aid Chesapeake Bay Resource Managers in the Detection of Poor Water Quality

Shellfish aquaculture is a growing industry in the Chesapeake Bay. As population grows near the coast, extreme weather events cause a greater volume of pollutant runoff from impervious surfaces and agricultural lands. Resource managers who monitor shellfish beds need reliable information on a variety of water quality indicators at higher frequency than is possible through field monitoring programs and at a higher level of detail than current satellite products can provide. Although many factors causing degraded water quality that can impact human health are not currently discernable by traditional multispectral techniques, hyperspectral imagery offers a new opportunity to detect phytoplankton communities associated with harmful algal blooms and biotoxin production. Together with resource managers in their routine monitoring of sites around the bay from small boats, we have been exploring remotely sensed optical proxies for the detection of harmful algal blooms and sewage. Early warning by remote sensing could guide sampling and improve the efficiency of shellfish bed closures, ultimately improving health outcomes for humans and animals. An extensive network of routine sampling by Chesapeake Bay Program managers makes this is an ideal location to develop and test future satellite data products to support management decisions. Next generation hyperspectral measurements from the future Plankton Aerosol Cloud ocean Ecosystem (PACE) mission at nearly daily frequency, combined with the potential of higher spatial resolution from the Surface Biology and Geology (SBG) observing system recommended in the recent Decadal Survey, along with high frequency observations from the newly selected Geostationary Littoral Imaging and Monitoring Radiometer (GLIMR) Earth Venture Instrument make this a critical time for defining the needs of the aquaculture and resource management community to save lives, time, and money.

Schollaert Uz, Stephanie↗
NASA NTRS2020

Interannual Variability in the Thermal Habitat of Alexandrium catenella in the Bay of Fundy and the Implications of Climate Change

Globally, harmful algal blooms (HABs) are an increasing problem. In the Gulf of Maine and Bay of Fundy, blooms of the toxic dinoflagellate Alexandrium catenella are annually recurrent phenomena. As this region is one of the most rapidly warming areas of the global ocean, an improved understanding of the mechanisms driving the initiation of local A. catenella blooms, their interannual variability and the implications of future climate change is critical to local monitoring strategies and marine resources management. A 27-year (1988–2014) time series of weekly A. catenella cell counts from the Bay of Fundy and concurrent satellite-measured sea surface temperature, freshwater discharge from the St. John River and wind-driven turbulence are compared to assess their relationship to variability in bloom phenology metrics. The mean thermal habitat associated with early detection of A. catenella is 6.5 ± 1.6°C, whereas that of bloom initiation averages 9.2 ± 1.5°C. Both thermal habitats for A. catenella are trending earlier over the study period. Bloom initiations that precede the arrival of the thermal habitat mean (occur in colder water) are associated with higher spring freshwater discharge and are generally weaker blooms. Increased spring freshwater discharge is also associated with earlier bloom initiation and earlier maximum concentration dates. No significant relationship was observed with the strength of wind-driven mixing. Removal of the mean thermal seasonal cycle shows that surface temperature anomalies have a strong negative relationship to the bloom phenology metrics and arrival of thermal habitat: warmer years are linked to earlier arrival of thermal habitats (∼12 days °C–1) and earlier detection and bloom initiation dates (∼33 days °C–1). Using these relationships and present trends in Bay of Fundy surface temperature warming over the period 1982–2019, we project the arrival dates of bloom thermal habitat and bloom phenology metrics out to the middle of this century. Based on current rates of sea surface temperature change, bloom phenology metrics (e.g., bloom initiation, early detection), can be expected to shift 1–2 months earlier in the season by mid-century. Such changes in the phenology of A. catenella blooms will need to be incorporated into both monitoring strategies and forecasting models for the region.

Andre F. Bucci↗
NASA NTRS2021

Jobos Bay Water Resources: Using Earth Observations to Analyze Shoreline Changes and Understand the Effects of Sea Level Rise in Southern Puerto Rico

Jobos Bay is located on the southern coast of Puerto Rico, which is known for intense hurricane seasons and increased seasonal storm surge. Scientists at Jobos Bay National Estuarine Research Reserve (JBNERR) are concerned that sea level rise will exacerbate coastal damage from these weather events. Using NASA Earth observations, our team analyzed coastal change, land use land cover change (LULC), mangrove forest extent, and water quality of Jobos Bay. Using Google Earth Engine, we evaluated coastal change and mangrove forest habitat within the study region by classifying NASA Earth observation imagery. We created historic LULC composite images to observe how land use changes over time and improve understanding of urbanization in the watershed. Leveraging previous water quality studies, our team compared water quality datasets generated by the Optical Reef and Coastal Area Assessment (ORCAA) tool to in situ sensors provided by JBNERR partners to understand the overall quality of water in the study area with respect to turbidity, chlorophyll-a, sea surface temperature, and colored dissolved organic matter (CDOM) concentrations. We discovered that 17% of the reserve has shifted from land to water since 1997 and lost 4.85 square kilometers of mangrove habitat over the past decade. Results from this study will inform the scientists of JBNERR and community members of the regional impacts of sea level rise. Being the first comprehensive study done in the estuary in nearly a decade, this serves as a baseline for future conservation efforts and research in the estuary.

Olivia Spencer↗