Remote sensing of sea surface glacial meltwater on the Antarctic Peninsula shelf

Glacial meltwater is an important environmental variable for ecosystem dynamics along the biologically productive Western Antarctic Peninsula (WAP) shelf. This region is experiencing rapid change, including increasing glacial meltwater discharge associated with the melting of land ice. To better understand the WAP environment and aid ecosystem forecasting, additional methods are needed for monitoring and quantifying glacial meltwater for this remote, sparsely sampled location. Prior studies showed that sea surface glacial meltwater (SSGM) has unique optical characteristics which may allow remote sensing detection via ocean color data. In this study, we develop a first-generation model for quantifying SSGM that can be applied to both spaceborne (MODIS-Aqua) and airborne (PRISM) ocean color platforms. In addition, the model was prepared and verified with one of the more comprehensive in-situ stable oxygen isotope datasets compiled for the WAP region. The SSGM model appears robust and provides accurate predictions of the fractional contribution of glacial meltwater to seawater when compared with in-situ data (r = 0.82, median absolute percent difference = 6.38%, median bias = −0.04), thus offering an additional novel method for quantifying and studying glacial meltwater in the WAP region

Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño

The 2015–2016 El Niño led to historically high temperatures and low precipitation over the tropics, while the growth rate of atmospheric carbon dioxide (CO_2) was the largest on record. Here we quantify the response of tropical net biosphere exchange, gross primary production, biomass burning, and respiration to these climate anomalies by assimilating column CO_2, solar-induced chlorophyll fluorescence, and carbon monoxide observations from multiple satellites. Relative to the 2011 La Niña, the pantropical biosphere released 2.5 ± 0.34 gigatons more carbon into the atmosphere in 2015, consisting of approximately even contributions from three tropical continents but dominated by diverse carbon exchange processes. The heterogeneity of the carbon-exchange processes indicated here challenges previous studies that suggested that a single dominant process determines carbon cycle interannual variability

A unified approach to estimate land and water reflectances with uncertainties for coastal imaging spectroscopy

Coastal ecosystem studies using remote visible/infrared spectroscopy typically invert an atmospheric model to estimate the water-leaving reflectance signal. This inversion is challenging due to the confounding effects of turbid backscatter, atmospheric aerosols, and sun glint. Simultaneous estimation of the surface and atmosphere can resolve the ambiguity enabling spectral reflectance maps with rigorous uncertainty quantification. We demonstrate a simultaneous retrieval method that adapts the Optimal Estimation (OE) formalism of Rodgers (2000) to the coastal domain. We compare two surface representations: a parametric bio-optical model based on Inherent Optical Properties (IOPs); and an expressive statistical model that estimates reflectance in every instrument channel. The latter is suited to both land and water reflectance, enabling a unified analysis of terrestrial and aquatic domains. We test these models with both vector and scalar Radiative Transfer Models (RTMs). We report field experiments by two airborne instruments: NASA's Portable Remote Imaging SpectroMeter (PRISM) in an overflight of Santa Monica, California; and NASA's Next Generation Airborne Visible Infrared Imaging Spectrometer (AVIRIS-NG) in an overflight of the Wax Lake Delta and lower Atchafalaya River, Louisiana. In both cases, in situ validation measurements match remote water-leaving reflectance estimates to high accuracy. Posterior error predictions demonstrate a closed account of uncertainty in these coastal observations

Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño

The 2015–2016 El Niño led to historically high temperatures and low precipitation over the tropics, while the growth rate of atmospheric carbon dioxide (CO_2) was the largest on record. Here we quantify the response of tropical net biosphere exchange, gross primary production, biomass burning, and respiration to these climate anomalies by assimilating column CO_2, solar-induced chlorophyll fluorescence, and carbon monoxide observations from multiple satellites. Relative to the 2011 La Niña, the pantropical biosphere released 2.5 ± 0.34 gigatons more carbon into the atmosphere in 2015, consisting of approximately even contributions from three tropical continents but dominated by diverse carbon exchange processes. The heterogeneity of the carbon-exchange processes indicated here challenges previous studies that suggested that a single dominant process determines carbon cycle interannual variability

Hurricane-driven alteration in plankton community size structure in the Gulf of Mexico: A modeling study

This was the first study to analyze phytoplankton and zooplankton community size structure during hurricane passage. A three-dimensional biophysical model was used to assess ecosystem dynamics, plankton biomass, and plankton distribution in the Gulf of Mexico during Hurricane Katrina (2005). Model simulations revealed that large phytoplankton were most responsive to hurricane-induced turbulent mixing and nutrient injection, with increases in biomass along the hurricane track. Small phytoplankton, microzooplankton, and mesozooplankton biomass primarily shifted in location and increased in spatial extent as a result of Hurricane Katrina. Hurricane passage disrupted the distribution of plankton biomass associated with mesoscale eddies. Biomass minimums and maximums that resided in the center of warm- and cold-core eddies and along eddy peripheries prior to hurricane passage were displaced during Hurricane Katrina

Palliative Care Knowledge Following an Interdisciplinary Palliative Care Seminar

Background: The COVID-19 pandemic created a unique opportunity to evolve an interdisciplinary palliative care seminar (IPC) into a virtual platform. This seminar provides foundational palliative and hospice concepts, introductions into palliative care disciplines, integration of teamwork, and incorporates interdisciplinary student led patient encounters. Traditionally, this experience had been in person, however during the COVID-19 pandemic, healthcare restrictions transitioned the educational delivery to a virtual platform. Methods: To assess the knowledge gained from this novel experience, the Palliative Care Knowledge Test (PCKT) was administered before and after the IPC Seminar. A 1-year follow up survey was also administered to evaluate how the IPC Seminar was applicable to the students’ clinical experiences and practice. Results: The virtual didactics and virtual student led patient encounters significantly improved learners understanding of palliative and hospice care. This gain of knowledge was noted across undergraduate and graduate programs, which highlights the need for and benefit from foundational concepts. Furthermore, a 1-year follow up survey noted the IPC seminar was applicable to their practices and suggests that this experience will impact future patients. Discussion: Many of the students practice in rural areas where access to palliative care services is limited or non-existent. This experience exponentially impacts the growth of palliative and hospice care understanding and access to care across the region. Conclusion: Evolving our IPC Seminar has shown to significantly improve knowledge, foster collaboration of student led interdisciplinary teams, and increases capacity to meet the needs of more learners

Physical and Biological Responses to Hurricane Katrina (2005) in a 1/25 Degrees Nested Gulf of Mexico HYCOM

Recent studies indicated sea surface temperature (SST) cooling of 6-7 degrees C and a phytoplankton bloom of 3 mg chlorophyll-a m(-3) during the passage of Hurricane Katrina (23-30 August 2005) in a region from 23.5 degrees to 25.5 degrees N and 85 degrees to 83 degrees W in the Gulf of Mexico (GoM). Employing a 20-layer. 1/25 degrees horizontal resolution nested CoM HYbrid Coordinate Ocean Model (HYCOM), the evolving three-dimensional ocean response to Hurricane Katrina in the GoM was examined. During the passage of Hurricane Katrina, analysis of model surface and subsurface dynamics in this region revealed strong upwelling/downwelling of 1.5-2 x 10(-4) m s(-1), wind-driven currents dominating the surface circulation, and near-inertial oscillations following Hurricane Katrina. Associated with the storm, the 26 degrees C isotherm was raised by 28 m, generating SST cooling of 3-4 degrees C and salinity freshening of 0.1-0.2 in less than 24 h. Comparison of model-simulated SSTs with in situ buoy data and satellite observations revealed that model SSTs were cooler by 1-2 degrees C and had a greater spatial extent of cooling. Analysis of heat budget terms in the mixed layer (20 m) indicated that surface heat flux accounted for pre-storm temperature changes, and wind-driven mixing (-3375 W m(-2)) dominated net upper-ocean cooling (-2464 W m(-2)) during Hurricane Katrina. At 50 m depth, temperature changes were largely due to vertical advection associated with upwelling and downwelling processes. A temperature-nitrate relationship was derived to illustrate the potential contribution that nitrate influx had upon the satellite-observed phytoplankton bloom associated with Hurricane Katrina. Comparison of calculated nitrate agreed reasonably well with in situ nitrate profiles in the interest region. Nitrate concentrations of 3.7 mu M were entrained from 30 m depth during hurricane passage. An approximate nitrate to chlorophyll-a ratio provided a chlorophyll-a value of 3 mg m(-3), which was consistent with that derived from satellite. Thus, the elevated chlorophyll-a concentration following the passage of Katrina was greatly influenced by nitrate entrainment into the surface layer through vertical mixing and Ekman divergence. (C) 2009 Elsevier B.V. All rights reserved