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Articles 1 - 30 of 51
Full-Text Articles in Oceanography
A Copula-Based Framework For Multivariate Count Time Series With Mixed Marginal Distributions, Dimuthu Fernando, Yuxin Wen, Wimarsha Jayanetti
A Copula-Based Framework For Multivariate Count Time Series With Mixed Marginal Distributions, Dimuthu Fernando, Yuxin Wen, Wimarsha Jayanetti
Engineering Faculty Articles and Research
We developed a class of multivariate integer-valued time series models using copula theory. Each count time series is modeled as a Markov chain, with serial dependence characterized through copula-based transition probabilities for Poisson and negative binomial marginals. Cross-sectional dependence is modeled via a trivariate Gaussian or a “t-copula”, allowing for both positive and negative correlations and providing a flexible dependence structure. Model parameters are estimated using likelihood-based inference, where the trivariate Gaussian or t-copula integrals are evaluated through standard randomized Monte Carlo methods. Simulation results, along with an analysis of annual counts of major hurricanes (Category 3+) across the North …
Changes In Land, Ocean, Atmospheric Parameters Associated With The 2025 Myanmar (Mw 7.7) Earthquake, Feng Jing, Akshansa Chauhan, Ashwani Raju, Ramesh P. Singh
Changes In Land, Ocean, Atmospheric Parameters Associated With The 2025 Myanmar (Mw 7.7) Earthquake, Feng Jing, Akshansa Chauhan, Ashwani Raju, Ramesh P. Singh
Mathematics, Physics, and Computer Science Faculty Articles and Research
Multiple parameters associated with the land, atmosphere, and ocean were analyzed to study short-term and immediate pre-earthquake changes associated with the 28 March 2025 Myanmar earthquake (Mw 7.7). Anomalous clear-sky outgoing longwave radiation (ClrOLR) and trace gases (CH₄, CO, and O₃) were detected within two months prior to the mainshock. Vertical changes at different pressure levels suggest a possible underground source. High-temporal-resolution observations of the infrared brightness temperature and surface air pressure revealed short-lived fluctuations shortly before the earthquake, which may reflect localized stress adjustments and surface latent heat flux release during the final stage of earthquake preparation. In the …
A Probabilistic Deep Learning Framework For Retrieving Chlorophyll-A From Hyperspectral Imagery: Integrating Channel Attention And Mixture Density Networks, Wenzhao Li, Surendra Maharjan, Rejoice Thomas, Junde Chen, Hesham Morgan, Michael J. Garay, Olga V. Kalashnikova, Shahryar Fazli, Charles Ichoku, Hesham El-Askary
A Probabilistic Deep Learning Framework For Retrieving Chlorophyll-A From Hyperspectral Imagery: Integrating Channel Attention And Mixture Density Networks, Wenzhao Li, Surendra Maharjan, Rejoice Thomas, Junde Chen, Hesham Morgan, Michael J. Garay, Olga V. Kalashnikova, Shahryar Fazli, Charles Ichoku, Hesham El-Askary
Mathematics, Physics, and Computer Science Faculty Articles and Research
Accurate monitoring of Chlorophyll-a (Chla) is critical for assessing aquatic ecosystem health, yet ecological complexity often leads to ambiguous spectral signatures in satellite data. Traditional deterministic models assume a one-to-one mapping between spectra and pigments, often failing to capture these high-dimensional analytical challenges. In this study, we propose a novel deep learning architecture, the Channel Attention-Mixture Density Network (CA-MDN), to retrieve Chla from the National Aeronautics and Space Administration (NASA) Earth Surface Mineral Dust Source Investigation (EMIT) hyperspectral mission. The CA-MDN integrates an attention mechanism to dynamically select ecologically relevant spectral bands and employs a probabilistic output layer to quantify …
Multi-Satellite Image Matching And Deep Learning Segmentation For Detection Of Daytime Sea Fog Using Gk2a Ami And Gk2b Goci-Ii, Jonggu Kang, Hiroyuki Miyazaki, Seung Hee Kim, Menas Kafatos, Daesun Kim, Jinsoo Kim, Yangwon Lee
Multi-Satellite Image Matching And Deep Learning Segmentation For Detection Of Daytime Sea Fog Using Gk2a Ami And Gk2b Goci-Ii, Jonggu Kang, Hiroyuki Miyazaki, Seung Hee Kim, Menas Kafatos, Daesun Kim, Jinsoo Kim, Yangwon Lee
Institute for ECHO Articles and Research
Traditionally, sea fog detection technologies have relied primarily on in situ observations. However, point-based observations suffer from limitations in extensive monitoring in marine environments due to the scarcity of observation stations and the limited nature of measurement data. Satellites effectively address these issues by covering vast areas and operating across multiple spectral channels, enabling precise detection and monitoring of sea fog. Despite the increasing adoption of deep learning in this field, achieving further improvements in accuracy and reliability necessitates the simultaneous use of multiple satellite datasets rather than relying on a single source. Therefore, this study aims to achieve higher …
Atmospheric Teleconnection Patterns And Hydrological Whiplashes In The Western U.S., Wenzhao Li, Surendra Maharjan, Hesham El-Askary
Atmospheric Teleconnection Patterns And Hydrological Whiplashes In The Western U.S., Wenzhao Li, Surendra Maharjan, Hesham El-Askary
Mathematics, Physics, and Computer Science Faculty Articles and Research
The Western U.S. is undergoing notable transformations in its hydrological patterns, distinguished by rising variability and recurrent “whiplash” shifts between extreme wet and dry phases. Our comprehensive analysis of 469 streamflow stations from 1981 to 2023 reveals a substantial increase in hydrological whiplash events, with a peak of 206 stations experiencing dry-to-wet whiplash in the early 1990s. We establish strong links between these streamflow extremes and sub-seasonal to seasonal teleconnection factors, particularly the Western Pacific Oscillation (WP) and Eastern Pacific/North Pacific Oscillation (EPO). Additionally, we demonstrate the combined impacts of the El Niño-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO), …
Land Instability Compounds The Risk Of Sea Level Rise In Alexandria, Egypt, Rejoice Thomas, Sara Zouriq, Shahryar Fazli, Amr Fawzy, Nikolay Grisel Todorov, Surendra Maharjan, Wenzhao Li, Erik Linstead, Daniele Struppa, Hesham El-Askary
Land Instability Compounds The Risk Of Sea Level Rise In Alexandria, Egypt, Rejoice Thomas, Sara Zouriq, Shahryar Fazli, Amr Fawzy, Nikolay Grisel Todorov, Surendra Maharjan, Wenzhao Li, Erik Linstead, Daniele Struppa, Hesham El-Askary
Mathematics, Physics, and Computer Science Faculty Articles and Research
The coastal region of Alexandria Governorate in Egypt holds significant strategic importance for trade while being susceptible to extreme weather events. It confronts a dual challenge of the rising sea levels and, as found in this study, land instability. While much attention has been rightly directed towards sea level rise (SLR), the stability of the land warrants equal consideration. Here, a comprehensive analysis of land stability is conducted in Alexandria by measuring Line of Sight (LOS) displacements and assessing their topographical, hydrological, and coastal impacts. Persistent Scatterer Interferometry technique is used to measure the LOS displacements in association with land …
A Generalized Machine Learning Model For Long-Term Coral Reef Monitoring In The Red Sea, Justin J. Gapper, Surendra Maharjan, Wenzhao Li, Erik Linstead, Surya Prakash Tiwari, Mohamed A. Qurban, Hesham El-Askary
A Generalized Machine Learning Model For Long-Term Coral Reef Monitoring In The Red Sea, Justin J. Gapper, Surendra Maharjan, Wenzhao Li, Erik Linstead, Surya Prakash Tiwari, Mohamed A. Qurban, Hesham El-Askary
Mathematics, Physics, and Computer Science Faculty Articles and Research
Coral reefs, despite covering less than 0.2 % of the ocean floor, harbor approximately 35 % of all known marine species, making their conservation critical. However, coral bleaching, exacerbated by climate change and phenomena such as El Niño, poses a significant threat to these ecosystems. This study focuses on the Red Sea, proposing a generalized machine learning approach to detect and monitor changes in coral reef cover over an 18-year period (2000–2018). Using Landsat 7 and 8 data, a Support Vector Machine (SVM) classifier was trained on depth-invariant indices (DII) derived from the Gulf of Aqaba and validated against ground …
Linkages Of The 2022 Unprecedented Global Heatwave Events To Triple-Dip La Niña, Sachi Perera, Joshua B. Fisher, Mohamed Allali, Hesham El-Askary
Linkages Of The 2022 Unprecedented Global Heatwave Events To Triple-Dip La Niña, Sachi Perera, Joshua B. Fisher, Mohamed Allali, Hesham El-Askary
Mathematics, Physics, and Computer Science Faculty Articles and Research
Heatwaves are influenced significantly by El Niño-Southern Oscillation (ENSO), which alters temperature and precipitation patterns throughout the world. Since 2020, we have witnessed a "triple dip" La Niña conditions persisting for three consecutive years resulting in severe weather and climate driven events globally. In this study, we identified the dominant frequency of Niño 3.4 Sea Surface Temperature (SST) signals and correlated them with regions experiencing unprecedented heat waves in 2022, namely, the Indian Ocean, the North Atlantic around England and Spain, and the Mediterranean Sea. The signal's power spectrum and its three highest power components are determined based on the …
Sulfate Enhances The Adsorption And Retention Of Cu(Ii) And Zn(Ii) To Dispersed And Aggregated Iron Oxyhydroxide Nanoparticles, Emma M. Kocik, Abigail Kim, Miranda L. Aiken, Lauren Smith, Christopher S. Kim
Sulfate Enhances The Adsorption And Retention Of Cu(Ii) And Zn(Ii) To Dispersed And Aggregated Iron Oxyhydroxide Nanoparticles, Emma M. Kocik, Abigail Kim, Miranda L. Aiken, Lauren Smith, Christopher S. Kim
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
The adsorption and retention of metal ions to nanoscale iron (hydr)oxides in aqueous systems is significantly influenced by prevailing environmental conditions. We examined the influence of sulfate, the second most common anion in seawater that is present in many other natural aquatic systems, on the adsorption and retention of Cu(II) and Zn(II) to synthetic iron oxyhydroxide nanoparticles (NPs) and their aggregates. Batch uptake experiments with monodisperse NPs and NPs aggregated by changes in pH, ionic strength, and temperature were conducted over sulfate concentrations ranging from 0 to 0.30 M. The introduction of 0.03 M sulfate significantly increased the initial adsorption …
Symbiotic Ucyn-A Strains Co-Occurred With El Niño, Relaxed Upwelling, And Varied Eukaryotes Over 10 Years Off Southern California, Colette Fletcher-Hoppe, Yi-Chun Yeh, Yubin Raut, J. L. Weissman, Jed A. Fuhrman
Symbiotic Ucyn-A Strains Co-Occurred With El Niño, Relaxed Upwelling, And Varied Eukaryotes Over 10 Years Off Southern California, Colette Fletcher-Hoppe, Yi-Chun Yeh, Yubin Raut, J. L. Weissman, Jed A. Fuhrman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Biological nitrogen fixation, the conversion of N2 gas into a bioavailable form, is vital to sustaining marine primary production. Studies have shifted beyond traditionally studied tropical diazotrophs. Candidatus Atelocyanobacterium thalassa (or UCYN-A) has emerged as a focal point due to its streamlined metabolism, intimate partnership with a haptophyte host, and broad distribution. Here, we explore the environmental parameters that govern UCYN-A’s presence at the San Pedro Ocean Time-series (SPOT), its host specificity, and statistically significant interactions with non-host eukaryotes from 2008-2018. 16S and 18S rRNA gene sequences were amplified by “universal primers” from monthly samples and resolved into Amplicon …
Dynamic And Thermodynamic Influences On Precipitation In Northeast Mexico On Orbital To Millennial Timescales, Kevin T. Wright, Kathleen R. Johnson, Gabriela Serrato Marks, David Mcgee, Tripti Bhattacharya, Gregory R. Goldsmith, Clay R. Tabor, Jean-Louis Lacaille-Muzquiz, Gianna Lum, Laura Beramendi-Orosco
Dynamic And Thermodynamic Influences On Precipitation In Northeast Mexico On Orbital To Millennial Timescales, Kevin T. Wright, Kathleen R. Johnson, Gabriela Serrato Marks, David Mcgee, Tripti Bhattacharya, Gregory R. Goldsmith, Clay R. Tabor, Jean-Louis Lacaille-Muzquiz, Gianna Lum, Laura Beramendi-Orosco
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
The timing and mechanisms of past hydroclimate change in northeast Mexico are poorly constrained, limiting our ability to evaluate climate model performance. To address this, we present a multiproxy speleothem record of past hydroclimate variability spanning 62.5 to 5.1 ka from Tamaulipas, Mexico. Here we show a strong influence of Atlantic and Pacific sea surface temperatures on orbital and millennial scale precipitation changes in the region. Multiple proxies show no clear response to insolation forcing, but strong evidence for dry conditions during Heinrich Stadials. While these trends are consistent with other records from across Mesoamerica and the Caribbean, the relative …
Murphy Scale: A Locational Equivalent Intensity Scale For Hazard Events, Yi Victor Wang, Antonia Sebastian
Murphy Scale: A Locational Equivalent Intensity Scale For Hazard Events, Yi Victor Wang, Antonia Sebastian
Institute for ECHO Articles and Research
Empirical cross-hazard analysis and prediction of disaster vulnerability, resilience, and risk requires a common metric of hazard strengths across hazard types. In this paper, the authors propose an equivalent intensity scale for cross-hazard evaluation of hazard strengths of events for entire durations at locations. The proposed scale is called the Murphy Scale, after Professor Colleen Murphy. A systematic review and typology of hazard strength metrics is presented to facilitate the delineation of the defining dimensions of the proposed scale. An empirical methodology is introduced to derive equivalent intensities of hazard events on a Murphy Scale. Using historical data on …
A General Pattern Of Trade-Offs Between Ecosystem Resistance And Resilience To Tropical Cyclones, Christopher J. Patrick, John S. Kominoski, William H. Mcdowell, Benjamin Branoff, David Lagomasino, Miguel Leon, Enie Hensel, Marc J. S. Hensel, Bradley A. Strickland, T. Mitchell Aide, Anna Armitage, Marconi Campos-Cerqueira, Victoria M. Congdon, Todd A. Crowl, Donna J. Devlin, Sarah Douglas, Brad E. Erisman, Rusty A. Feagin, Simon J. Geist, Nathan S. Hall, Amber K. Hardison, Michael R. Heithaus, J. Aaron Hogan, J. Derek Hogan, Sean Kinard, Jeremy J. Kiszka, Teng-Chiu Lin, Kaijun Lu, Christopher J. Madden, Paul A. Montagna, Christine S. O'Connell, C. Edward Proffitt, Brandi Kiel Reese, Joseph W. Reustle, Kelly L. Robinson, Scott A. Rush, Rolando O. Santos, Astrid Schnetzer, Delbert L. Smee, Rachel S. Smith, Gregory Starr, Beth A. Stauffer, Lily M. Walker, Carolyn A. Weaver, Michael S. Wetz, Elizabeth R. Whitman, Sara S. Wilson, Jianhong Xue, Xiaoming Zou
A General Pattern Of Trade-Offs Between Ecosystem Resistance And Resilience To Tropical Cyclones, Christopher J. Patrick, John S. Kominoski, William H. Mcdowell, Benjamin Branoff, David Lagomasino, Miguel Leon, Enie Hensel, Marc J. S. Hensel, Bradley A. Strickland, T. Mitchell Aide, Anna Armitage, Marconi Campos-Cerqueira, Victoria M. Congdon, Todd A. Crowl, Donna J. Devlin, Sarah Douglas, Brad E. Erisman, Rusty A. Feagin, Simon J. Geist, Nathan S. Hall, Amber K. Hardison, Michael R. Heithaus, J. Aaron Hogan, J. Derek Hogan, Sean Kinard, Jeremy J. Kiszka, Teng-Chiu Lin, Kaijun Lu, Christopher J. Madden, Paul A. Montagna, Christine S. O'Connell, C. Edward Proffitt, Brandi Kiel Reese, Joseph W. Reustle, Kelly L. Robinson, Scott A. Rush, Rolando O. Santos, Astrid Schnetzer, Delbert L. Smee, Rachel S. Smith, Gregory Starr, Beth A. Stauffer, Lily M. Walker, Carolyn A. Weaver, Michael S. Wetz, Elizabeth R. Whitman, Sara S. Wilson, Jianhong Xue, Xiaoming Zou
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Tropical cyclones drive coastal ecosystem dynamics, and their frequency, intensity, and spatial distribution are predicted to shift with climate change. Patterns of resistance and resilience were synthesized for 4138 ecosystem time series from n = 26 storms occurring between 1985 and 2018 in the Northern Hemisphere to predict how coastal ecosystems will respond to future disturbance regimes. Data were grouped by ecosystems (fresh water, salt water, terrestrial, and wetland) and response categories (biogeochemistry, hydrography, mobile biota, sedentary fauna, and vascular plants). We observed a repeated pattern of trade-offs between resistance and resilience across analyses. These patterns are likely the outcomes …
The Source Detection Of 28 September 2018 Sulawesi Tsunami By Using Ionospheric Gnss Total Electron Content Disturbance, Jann-Yenq Liu, Chi-Yen Lin, Yuh-Ing Chen, Tso-Ren Wu, Meng-Ju Chung, Tien-Chi Liu, Yu-Lin Tsai, Loren C. Chang, Chi-Kuang Chao, Dimitar Ouzounov, Katsumi Hattori
The Source Detection Of 28 September 2018 Sulawesi Tsunami By Using Ionospheric Gnss Total Electron Content Disturbance, Jann-Yenq Liu, Chi-Yen Lin, Yuh-Ing Chen, Tso-Ren Wu, Meng-Ju Chung, Tien-Chi Liu, Yu-Lin Tsai, Loren C. Chang, Chi-Kuang Chao, Dimitar Ouzounov, Katsumi Hattori
Mathematics, Physics, and Computer Science Faculty Articles and Research
The 28 September 2018 magnitude Mw7.8 Palu, Indonesia earthquake (0.178° S, 119.840° E, depth 13 km) occurred at 10:02 UTC. The major earthquake triggered catastrophic liquefaction, landslides, and a near-field tsunami. The ionospheric total electron content (TEC) derived from records of 5 ground-based global navigation satellite system (GNSS) receivers is employed to detect tsunami traveling ionospheric disturbances (TTIDs). In total, 15 TTIDs have been detected. The ray-tracing and beamforming techniques are then used to find the TTID source location. The bootstrap method is applied in order to further explore the possible location of the tsunami source based on results of …
Global Atmospheric Budget Of Acetone: Air-Sea Exchange And The Contribution To Hydroxyl Radicals, Siyuan Wang, Eric C. Apel, Rebecca H. Schwantes, Kelvin H. Bates, Daniel J. Jacob, Emily V. Fischer, Rebecca S. Hornbrook, Alan J. Hills, Louisa K. Emmons, Laura L. Pan, Shawn Honomichl, Simone Tilmes, Jean‐François Lamarque, Mingxi Yang, Christa A. Marandino, E. S. Saltzman, Warren J. De Bruyn, Sohiko Kameyama, Hiroshi Tanimoto, Yuko Omori, Samuel R. Hall, Kirk Ullmann, Thomas B. Ryerson, Chelsea R. Thompson, Jeff Peischl, Bruce C. Daube, Róisín Commane, Kathryn Mckain, Colm Sweeney, Alexander B. Thames, David O. Miller, William H. Brune, Glenn S. Diskin, Joshua P. Digangi, Steven C. Wofsy
Global Atmospheric Budget Of Acetone: Air-Sea Exchange And The Contribution To Hydroxyl Radicals, Siyuan Wang, Eric C. Apel, Rebecca H. Schwantes, Kelvin H. Bates, Daniel J. Jacob, Emily V. Fischer, Rebecca S. Hornbrook, Alan J. Hills, Louisa K. Emmons, Laura L. Pan, Shawn Honomichl, Simone Tilmes, Jean‐François Lamarque, Mingxi Yang, Christa A. Marandino, E. S. Saltzman, Warren J. De Bruyn, Sohiko Kameyama, Hiroshi Tanimoto, Yuko Omori, Samuel R. Hall, Kirk Ullmann, Thomas B. Ryerson, Chelsea R. Thompson, Jeff Peischl, Bruce C. Daube, Róisín Commane, Kathryn Mckain, Colm Sweeney, Alexander B. Thames, David O. Miller, William H. Brune, Glenn S. Diskin, Joshua P. Digangi, Steven C. Wofsy
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Acetone is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere. The oceans impose a strong control on atmospheric acetone, yet the oceanic fluxes of acetone remain poorly constrained. In this work, the global budget of acetone is evaluated using two global models: CAM‐chem and GEOS‐Chem. CAM‐chem uses an online air‐sea exchange framework to calculate the bidirectional oceanic acetone fluxes, which is coupled to a data‐oriented machine‐learning approach. The machine‐learning algorithm is trained using a global suite of seawater acetone measurements. GEOS‐Chem uses a fixed surface seawater concentration of acetone to calculate the oceanic fluxes. Both …
Long-Term Ndvi And Recent Vegetation Cover Profiles Of Major Offshore Island Nesting Sites Of Sea Turtles In Saudi Waters Of The Northern Arabian Gulf, Rommel H. Maneja, Jeffrey D. Miller, Wenzhao Li, Hesham El-Askary, Ace Vincent B. Flandez, Joshua J. Dagoy, Joselito Francis A. Alcaria, Abdullajid U. Basali, Khaled A. Al-Abdulkader, Ronald A. Loughland, Mohamed A. Qurban
Long-Term Ndvi And Recent Vegetation Cover Profiles Of Major Offshore Island Nesting Sites Of Sea Turtles In Saudi Waters Of The Northern Arabian Gulf, Rommel H. Maneja, Jeffrey D. Miller, Wenzhao Li, Hesham El-Askary, Ace Vincent B. Flandez, Joshua J. Dagoy, Joselito Francis A. Alcaria, Abdullajid U. Basali, Khaled A. Al-Abdulkader, Ronald A. Loughland, Mohamed A. Qurban
Mathematics, Physics, and Computer Science Faculty Articles and Research
Vegetation is an important ecological component of offshore islands in the Arabian Gulf (AG), which maintains long-term resilience of these islands. This is achieved by influencing sediment retention and moisture acquisition via condensation during periods of high humidity and by providing a variety of microhabitats for island fauna. The resilience of offshore islands’ ecosystems in the Saudi waters is important because they host the largest number of nesting hawksbill and green turtles in the AG. This study defines the characteristics and the long-term trends in vegetation cover of the offshore islands used by sea turtles as nesting grounds in the …
Synergistic Use Of Remote Sensing And Modeling For Estimating Net Primary Productivity In The Red Sea With Vgpm, Eppley-Vgpm, And Cbpm Models Intercomparison, Wenzhao Li, Surya Prakash Tiwari, Hesham El-Askary, Mohamed Ali Qurban, Vassilis Amiridis, K. P. Manikandan, Michael J. Garay, Olga V. Kalashnikova, Thomas C. Piechota, Daniele C. Struppa
Synergistic Use Of Remote Sensing And Modeling For Estimating Net Primary Productivity In The Red Sea With Vgpm, Eppley-Vgpm, And Cbpm Models Intercomparison, Wenzhao Li, Surya Prakash Tiwari, Hesham El-Askary, Mohamed Ali Qurban, Vassilis Amiridis, K. P. Manikandan, Michael J. Garay, Olga V. Kalashnikova, Thomas C. Piechota, Daniele C. Struppa
Mathematics, Physics, and Computer Science Faculty Articles and Research
Primary productivity (PP) has been recently investigated using remote sensing-based models over quite limited geographical areas of the Red Sea. This work sheds light on how phytoplankton and primary production would react to the effects of global warming in the extreme environment of the Red Sea and, hence, illuminates how similar regions may behave in the context of climate variability. study focuses on using satellite observations to conduct an intercomparison of three net primary production (NPP) models--the vertically generalized production model (VGPM), the Eppley-VGPM, and the carbon-based production model (CbPM)--produced over the Red Sea domain for the 1998-2018 time period. …
Changes In Atmospheric, Meteorological, And Ocean Parameters Associated With The 12 January 2020 Taal Volcanic Eruption, Feng Jing, Akshansa Chauhan, Ramesh P. Singh, Prasanjit Dash
Changes In Atmospheric, Meteorological, And Ocean Parameters Associated With The 12 January 2020 Taal Volcanic Eruption, Feng Jing, Akshansa Chauhan, Ramesh P. Singh, Prasanjit Dash
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
The Taal volcano erupted on 12 January 2020, the first time since 1977. About 35 mild earthquakes (magnitude greater than 4.0) were observed on 12 January 2020 induced from the eruption. In the present paper, we analyzed optical properties of volcanic aerosols, volcanic gas emission, ocean parameters using multi-satellite sensors, namely, MODIS (Moderate Resolution Imaging Spectroradiometer), AIRS (Atmospheric Infrared Sounder), OMI (Ozone Monitoring Instrument), TROPOMI (TROPOspheric Monitoring Instrument) and ground observations, namely, Argo, and AERONET (AErosol RObotic NETwork) data. Our detailed analysis shows pronounced changes in all the parameters, which mainly occurred in the western and south-western regions because the …
Methanethiol, Dimethyl Sulfide And Acetone Over Biologically Productive Waters In The Southwest Pacific Ocean, Sarah J. Lawson, Cliff S. Law, Mike J. Harvey, Thomas G. Bell, Carolyn F. Walker, Warren J. De Bruyn, Eric S. Saltzman
Methanethiol, Dimethyl Sulfide And Acetone Over Biologically Productive Waters In The Southwest Pacific Ocean, Sarah J. Lawson, Cliff S. Law, Mike J. Harvey, Thomas G. Bell, Carolyn F. Walker, Warren J. De Bruyn, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Atmospheric methanethiol (MeSHa), dimethyl sulfide (DMSa) and acetone (acetonea) were measured over biologically productive frontal waters in the remote southwest Pacific Ocean in summertime 2012 during the Surface Ocean Aerosol Production (SOAP) voyage. MeSHa mixing ratios varied from below the detection limit (< 10 ppt) up to 65 ppt and were 3 %–36 % of parallel DMSa mixing ratios. MeSHa and DMSa were correlated over the voyage (R2=0.3, slope = 0.07) with a stronger correlation over a coccolithophore-dominated phytoplankton bloom (R2=0.5, slope 0.13). The diurnal cycle for MeSHa shows similar behaviour to DMSa with mixing ratios …
Air/Sea Transfer Of Highly Soluble Gases Over Coastal Waters, J. G. Porter, Warren J. De Bruyn, S. D. Miller, E. S. Saltzman
Air/Sea Transfer Of Highly Soluble Gases Over Coastal Waters, J. G. Porter, Warren J. De Bruyn, S. D. Miller, E. S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
The deposition of soluble trace gases to the sea surface is not well studied due to a lack of flux measurements over the ocean. Here we report simultaneous air/sea eddy covariance flux measurements of water vapor, sulfur dioxide (SO2), and momentum from a coastal North Atlantic pier. Gas transfer velocities were on average about 20% lower for SO2 than for H2O. This difference is attributed to the difference in molecular diffusivity between the two molecules (D SO 2/D H 2O = 0.5), in reasonable agreement with bulk parameterizations in air/sea gas …
Bias Reduction In Machine Learning Classifiers For Spatiotemporal Analysis Of Coral Reefs Using Remote Sensing Images, Justin J. Gapper
Bias Reduction In Machine Learning Classifiers For Spatiotemporal Analysis Of Coral Reefs Using Remote Sensing Images, Justin J. Gapper
Computational and Data Sciences (PhD) Dissertations
This dissertation is an evaluation of the generalization characteristics of machine learning classifiers as applied to the detection of coral reefs using remote sensing images. Three scientific studies have been conducted as part of this research: 1) Evaluation of Spatial Generalization Characteristics of a Robust Classifier as Applied to Coral Reef Habitats in Remote Islands of the Pacific Ocean 2) Coral Reef Change Detection in Remote Pacific Islands using Support Vector Machine Classifiers 3) A Generalized Machine Learning Classifier for Spatiotemporal Analysis of Coral Reefs in the Red Sea. The aim of this dissertation is to propose and evaluate a …
Ecological Response Of Phytoplankton To The Oil Spills In The Oceans, Danling Tang, Jing Sun, Li Zhou, Sufen Wang, Ramesh P. Singh, Gang Pan
Ecological Response Of Phytoplankton To The Oil Spills In The Oceans, Danling Tang, Jing Sun, Li Zhou, Sufen Wang, Ramesh P. Singh, Gang Pan
Mathematics, Physics, and Computer Science Faculty Articles and Research
Oil spills in oceans have substantial influence on marine ecosystems. This study investigates 21 oil spills in the world. Analyzing Chlorophyll-a (Chl-a) from Moderate Resolution Imaging Spectroradiomerer (MODIS) data after Penglai oil spills on 4 June 2011, found a bloom with peak value of Chl-a (13.66 mg m−3) spread over an area of 800 km2 during 18–25 June 2011, and a pronounced increase in the monthly Chl-a concentration (6.40 mg m−3) on June 2012 in the Bohai Sea. Out of the 21 oil spills, 14 blooms were observed, while 11 …
Impacts Of Pacific Ssts On Atmospheric Circulations Leading To California Winter Precipitation Variability: A Diagnostic Modeling, Boksoon Myoung, Sang-Wook Yeh, Jinwon Kim, Menas Kafatos
Impacts Of Pacific Ssts On Atmospheric Circulations Leading To California Winter Precipitation Variability: A Diagnostic Modeling, Boksoon Myoung, Sang-Wook Yeh, Jinwon Kim, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
One of the primary meteorological causes of the winter precipitation deficits and droughts in California (CA) is anomalous developments and maintenance of upper-tropospheric ridges over the northeastern Pacific. In order to understand and find the key factors controlling the winter precipitation variability in CA, the present study examines two dominant atmospheric modes of the 500 hPa geopotential height in the Northern Hemisphere using an Empirical Orthogonal Function (EOF) and their associated large-scale circulation patterns for the last 41 winters (1974/75–2014/15). Explaining 17.5% of variability, the second mode (EOF2) shows strong anti-cyclonic circulations in the North Pacific and cyclonic circulations in …
Evaluation Of Spatial Generalization Characteristics Of A Robust Classifier As Applied To Coral Reef Habitats In Remote Islands Of The Pacific Ocean, Justin J. Gapper, Hesham El-Askary, Erik J. Linstead, Thomas Piechota
Evaluation Of Spatial Generalization Characteristics Of A Robust Classifier As Applied To Coral Reef Habitats In Remote Islands Of The Pacific Ocean, Justin J. Gapper, Hesham El-Askary, Erik J. Linstead, Thomas Piechota
Mathematics, Physics, and Computer Science Faculty Articles and Research
This study was an evaluation of the spectral signature generalization properties of coral across four remote Pacific Ocean reefs. The sites under consideration have not been the subject of previous studies for coral classification using remote sensing data. Previous research regarding using remote sensing to identify reefs has been limited to in-situ assessment, with some researchers also performing temporal analysis of a selected area of interest. This study expanded the previous in-situ analyses by evaluating the ability of a basic predictor, Linear Discriminant Analysis (LDA), trained on Depth Invariant Indices calculated from the spectral signature of coral in one location …
Eddy Flux Measurements Of Sulfur Dioxide Deposition To The Sea Surface, Jack G. Porter, Warren J. De Bruyn, Eric S. Saltzman
Eddy Flux Measurements Of Sulfur Dioxide Deposition To The Sea Surface, Jack G. Porter, Warren J. De Bruyn, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Deposition to the sea surface is a major atmospheric loss pathway for many important trace gases, such as sulfur dioxide (SO2). The air–sea transfer of SO2 is controlled entirely on the atmospheric side of the air–sea interface due to high effective solubility and other physical– chemical properties. There have been few direct field measurements of such fluxes due to the challenges associated with making fast-response measurements of highly soluble trace gases at very low ambient levels. In this study, we report direct eddy covariance air–sea flux measurements of SO2, sensible heat, water vapor, and momentum. The measurements were made over …
Synergistic Use Of Remote Sensing And Modeling To Assess An Anomalously High Chlorophyll-A Event During Summer 2015 In The South Central Red Sea, Wenzhao Li, Hesham El-Askary, K. P. Manikandan, Mohamed A. Qurban, Michael J. Garay, Olga V. Kalishnikova
Synergistic Use Of Remote Sensing And Modeling To Assess An Anomalously High Chlorophyll-A Event During Summer 2015 In The South Central Red Sea, Wenzhao Li, Hesham El-Askary, K. P. Manikandan, Mohamed A. Qurban, Michael J. Garay, Olga V. Kalishnikova
Mathematics, Physics, and Computer Science Faculty Articles and Research
An anomalously high chlorophyll-a (Chl-a) event (>2 mg/m3) during June 2015 in the South Central Red Sea (17.5° to 22°N, 37° to 42°E) was observed using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Terra and Aqua satellite platforms. This differs from the low Chl-a values (<0.5 mg/m3) usually encountered over the same region during summertime. To assess this anomaly and possible causes, we used a wide range of oceanographical and meteorological datasets, including Chl-a concentrations, sea surface temperature (SST), sea surface height (SSH), mixed layer depth (MLD), ocean current velocity and aerosol optical depth (AOD) obtained from different sensors and models. Findings confirmed this anomalous behavior in the spatial domain using Hovmöller data analysis techniques, while a time series analysis addressed monthly and daily variability. Our analysis suggests that a combination of factors controlling nutrient supply contributed to the anomalous phytoplankton growth. These factors include horizontal transfer of upwelling water through eddy circulation and possible mineral fertilization from atmospheric dust deposition. Coral reefs might have provided extra nutrient supply, yet this is out of the scope of our analysis. We thought that dust deposition from a coastal dust jet event in late June, coinciding with the phytoplankton blooms in the area under investigation, might have also contributed as shown by our AOD findings. However, a lag cross correlation showed a two- month lag between strong dust outbreak and the high Chl-a anomaly. The high Chl-a concentration at the edge of the eddy emphasizes the importance of horizontal advection in fertilizing oligotrophic (nutrient poor) Red Sea waters.
Estimation Of Bubble-Mediated Air–Sea Gas Exchange From Concurrent Dms And Co2 Transfer Velocities At Intermediate–High Wind Speeds, Thomas G. Bell, Sebastian Landwehr, Scott D. Miller, Warren J. De Bruyn, Adrian H. Callaghan, Brian Scanlon, Brian Ward, Mingxi Yang, Eric S. Saltzman
Estimation Of Bubble-Mediated Air–Sea Gas Exchange From Concurrent Dms And Co2 Transfer Velocities At Intermediate–High Wind Speeds, Thomas G. Bell, Sebastian Landwehr, Scott D. Miller, Warren J. De Bruyn, Adrian H. Callaghan, Brian Scanlon, Brian Ward, Mingxi Yang, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Simultaneous air–sea fluxes and concentration differences of dimethylsulfide (DMS) and carbon dioxide (CO2/ were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the gas transfer velocities of these two gases (1kw/ over a range of wind speeds up to 21ms1. These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with 1kw, consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation …
Sea Surface Temperature Rises Shift Migration Patterns Due To Ecosystem Changes, Alexia Skrbic, Hesham El-Askary
Sea Surface Temperature Rises Shift Migration Patterns Due To Ecosystem Changes, Alexia Skrbic, Hesham El-Askary
Student Scholar Symposium Abstracts and Posters
The continuing climate change is negatively impacting ecosystems, specifically oceans which are declining and food webs are being altered by the increase of greenhouse gases. The increase of the carbon dioxide and other greenhouse gases is increasing sea surface temperature of the world’s oceans. Certain organisms lower on the food chain like phytoplankton and zooplankton are directly affected by the warming which alters how they process nutrients and their productivity. The limited amount of these primary producers in the oceans and specifically the location they inhabit directly affects all the organisms above them on the food chain. Several marine animals …
Temporal Variation In Optical Properties Of Chromophoric Dissolved Organic Matter (Cdom) In Southern California Coastal Waters With Nearshore Kelp And Seagrass, Catherine D. Clark, Warren J. De Bruyn, Paige Aiona
Temporal Variation In Optical Properties Of Chromophoric Dissolved Organic Matter (Cdom) In Southern California Coastal Waters With Nearshore Kelp And Seagrass, Catherine D. Clark, Warren J. De Bruyn, Paige Aiona
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Optical properties of chromophoric dissolved organic matter (CDOM) were measured in surf zone waters in diurnal field studies at a Southern California beach with nearshore kelp and seagrass beds and intertidal plant wrack. Absorption coefficients (aCDOM(300 nm)) ranged from 0.35 m21 to 3.7 m21 with short-term variability<1 h, increases at ebb and flood tides and higher values (6 m21) during an offshore storm event. Spectral slopes (S) ranged from 0.0028 nm21 to 0.017 nm21, with higher values after the storm; S was generally inversely correlated with aCDOM(300 nm). 3-D excitation–emission matrix spectra (EEMs) for samples with lower S values had humic-type peaks associated with terrestrial material (A, C), marine microbial material (M) and protein peaks, characteristic of freshly produced organic material. Samples with high S values had no or reduced protein peaks, consistent with aged material. Fluorescent indexes (f450/f500 >2.5, BIX>1.1) were consistent with microbial aquatic sources. Leachates of senescent kelp and seagrass had protein and humic-type EEM peaks. After solar simulator irradiation (4 h), protein peaks rapidly photochemically degraded, humic-type peak C increased in intensity and peak M disappeared. Optical characteristics of kelp leachates were most similar to field samples, …
Dimethylsulfide Gas Transfer Coefficients From Algal Blooms In The Southern Ocean, T. G. Bell, Warren J. De Bruyn, Christa A. Marandino, S. D. Miller, C. S. Law, Eric S. Saltzman
Dimethylsulfide Gas Transfer Coefficients From Algal Blooms In The Southern Ocean, T. G. Bell, Warren J. De Bruyn, Christa A. Marandino, S. D. Miller, C. S. Law, Eric S. Saltzman
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Air-sea dimethylsulfide (DMS) fluxes and bulk air-sea gradients were measured over the Southern Ocean in February-March 2012 during the Surface Ocean Aerosol Production (SOAP) study. The cruise encountered three distinct phytoplankton bloom regions, consisting of two blooms with moderate DMS levels, and a high biomass, dinoflagellate-dominated bloom with high seawater DMS levels (> 15 nM). Gas transfer coefficients were considerably scattered at wind speeds above 5 m s(-1). Bin averaging the data resulted in a linear relationship between wind speed and mean gas transfer velocity consistent with that previously observed. However, the wind-speed-binned gas transfer data distribution at all wind …