Airfall volume of the 15 January 2022 eruption of Hunga volcano estimated from ocean color changes
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Liam J. Kelly↗
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Watching the Blue Planet from Space over Recent Decades: What's up for Science and Society?
Since the first photographs of “Earth Rise” taken by the Apollo astronauts in the 1960s galvanized the environmental movement, imaging of our planet from low Earth orbit has grown more sophisticated and diverse. Satellite and astronaut observations and imagery of the changing ocean still have the power to galvanize oceanographers and society. So what are some of the key ideas for oceanography and society that come out of out recent decades of ocean observation from space? Satellite oceanography has made fundamental contributions to our understanding and estimation of changing sea level, winds and storminess over the oceans, primary productivity of the seas, the role of the ocean in the water cycle, and the changes in the ocean known as ocean acidification. Some of these phenomena interact in complex ways and Mother Nature hides the future well. However, some things are clear. Sea level rise has been monitored from space for more than 20 years and now we have a more nuanced understanding of regional variation in sea level rise and the contributions of ocean thermal expansion and the melting of glaciers and ice sheets. Wind vectors at the ocean surface have been measured for more than 2 decades and provide evidence for shifts in wind patterns that help, for example, explain some of the regional variations in sea level rise. Chlorophyll-a has been estimated in a multi-decadal record of observations and is being used to describe the shifts and trends in ocean primary productivity. Sea surface temperature estimation from space has records going back to the 1970s and provides critical information for the interaction of the ocean with the atmosphere. Sea surface salinity has been measured from space only within the last decade and provides a novel new view of regional, seasonal, and inter-annual changes in the ocean related to precipitation, river run-off, and eddy transport. Potential changes in the Earth’s water cycle have a huge societal impact.
Blue Planet from Space↗
Role of the ocean in climate changes
The present program aimed at the study of ocean climate change is prepared by a group of scientists from State Oceanographic Institute, Academy of Science of Russia, Academy of Science of Ukraine and Moscow State University. It appears to be a natural evolution of ideas and achievements that have been developed under national and international ocean research projects such as SECTIONS, WOCE, TOGA, JGOFS and others. The two primary goals are set in the program ROCC. (1) Quantitative description of the global interoceanic 'conveyor' and it's role in formation of the large scale anomalies in the North Atlantic. The objectives on the way to this goal are: to get the reliable estimates of year-to-year variations of heat and water exchange between the Atlantic Ocean and the atmosphere; to establish and understand the physics of long period variations in meridianal heat and fresh water transport (MHT and MFWT) in the Atlantic Ocean; to analyze the general mechanisms, that form the MHT and MFWT in low latitudes (Ekman flux), middle latitudes (western boundary currents) and high latitudes (deep convection) of the North Atlantic; to establish and to give quantitative description of the realization of global changes in SST, surface salinity, sea level and sea ice data. (2) Development of the observational system pointed at tracing the climate changes in the North Atlantic. This goal merges the following objectives: to find the proper sites that form the inter annual variations of MHT; to study the deep circulation in the 'key' points; to develop the circulation models reflecting the principle features of interoceanic circulation; and to define global and local response of the atmosphere circulation to large scale processes in the Atlantic Ocean.
Gulev, Sergey K.↗
NeMO-Net – The Neural Multi-Modal Observation & Training Network for Global Coral Reef Assessment
We present NeMO-Net, the Srst open-source deep convolutional neural network (CNN) and interactive learning and training software aimed at assessing the present and past dynamics of coral reef ecosystems through habitat mapping into 10 biological and physical classes. Shallow marine systems, particularly coral reefs, are under significant pressures due to climate change, ocean acidification, and other anthropogenic pressures, leading to rapid, often devastating changes, in these fragile and diverse ecosystems. Historically, remote sensing of shallow marine habitats has been limited to meter-scale imagery due to the optical effects of ocean wave distortion, refraction, and optical attenuation. NeMO-Net combines 3D cm-scale distortion-free imagery captured using NASA FluidCam and Fluid lensing remote sensing technology with low resolution airborne and spaceborne datasets of varying spatial resolutions, spectral spaces, calibrations, and temporal cadence in a supercomputer-based machine learning framework. NeMO-Net augments and improves the benthic habitat classification accuracy of low-resolution datasets across large geographic ad temporal scales using high-resolution training data from FluidCam.NeMO-Net uses fully convolutional networks based upon ResNet and ReSneNet to perform semantic segmentation of remote sensing imagery of shallow marine systems captured by drones, aircraft, and satellites, including WorldView and Sentinel. Deep Laplacian Pyramid Super-Resolution Networks (LapSRN) alongside Domain Adversarial Neural Networks (DANNs) are used to reconstruct high resolution information from low resolution imagery, and to recognize domain-invariant features across datasets from multiple platforms to achieve high classification accuracies, overcoming inter-sensor spatial, spectral and temporal variations.Finally, we share our online active learning and citizen science platform, which allows users to provide interactive training data for NeMO-Net in 2D and 3D, integrated within a deep learning framework. We present results from the PaciSc Islands including Fiji, Guam and Peros Banhos 1 1 2 1 3 1 where 24-class classification accuracy exceeds 91%.
Chirayath, Ved↗
Sensitivity of the Tropical Atmospheric Energy Balance to ENSO-Related SST Changes: Comparison of Climate Model Simulations to Observed Responses
This paper focuses on how fresh water and radiative fluxes over the tropical oceans change during ENSO warm and cold events and how these changes affect the tropical energy balance. At present, ENSO remains the most prominent known mode of natural variability at interannual time scales. While this natural perturbation to climate is quite distinct from possible anthropogenic changes in climate, adjustments in the tropical water and energy budgets during ENSO may give insight into feedback processes involving water vapor and cloud feedbacks. Although great advances have been made in understanding this phenomenon and realizing prediction skill over the past decade, our ability to document the coupled water and energy changes observationally and to represent them in climate models seems far from settled (Soden, 2000 J Climate). In a companion paper we have presented observational analyses, based principally on space-based measurements which document systematic changes in rainfall, evaporation, and surface and top-of-atmosphere (TOA) radiative fluxes. Here we analyze several contemporary climate models run with observed SSTs over recent decades and compare SST-induced changes in radiation, precipitation, evaporation, and energy transport to observational results. Among these are the NASA / NCAR Finite Volume Model, the NCAR Community Climate Model, the NCEP Global Spectral Model, and the NASA NSIPP Model. Key disagreements between model and observational results noted in the recent literature are shown to be due predominantly to observational shortcomings. A reexamination of the Langley 8-Year Surface Radiation Budget data reveals errors in the SST surface longwave emission due to biased SSTs. Subsequent correction allows use of this data set along with ERBE TOA fluxes to infer net atmospheric radiative heating. Further analysis of recent rainfall algorithms provides new estimates for precipitation variability in line with interannual evaporation changes inferred from the da Silva, Young, Levitus COADS analysis. The overall results from our analysis suggest an increase (decrease) of the hydrologic cycle during ENSO warm (cold) events at the rate of about 5 W/sq m per K of SST change. Model results agree reasonably well with this estimate of sensitivity. This rate is slightly less than that which would be expected for constant relative humidity over the tropical oceans. There remain, however, significant quantitative uncertainties in cloud forcing changes in the models as compared to observations. These differences are examined in relationship to model convection and cloud parameterizations Analysis of the possible sampling and measurement errors compared to systematic model errors is also presented.
Robertson, Franklin R.↗
Recent Changes in Arctic Ocean Sea Ice Motion Associated with the North Atlantic Oscillation
Examination of a new ice motion dataset of the Arctic Ocean over a recent eighteen year period (1978-1996) reveals patterns of variability that can be linked directly to the North Atlantic Oscillation.
North Atlantic Oscillation sea ice Arctic Ocean cl↗
The future of spaceborne altimetry. Oceans and climate change: A long-term strategy
The ocean circulation and polar ice sheet volumes provide important memory and control functions in the global climate. Their long term variations are unknown and need to be understood before meaningful appraisals of climate change can be made. Satellite altimetry is the only method for providing global information on the ocean circulation and ice sheet volume. A robust altimeter measurement program is planned which will initiate global observations of the ocean circulation and polar ice sheets. In order to provide useful data about the climate, these measurements must be continued with unbroken coverage into the next century. Herein, past results of the role of the ocean in the climate system is summarized, near term goals are outlined, and requirements and options are presented for future altimeter missions. There are three basic scientific objectives for the program: ocean circulation; polar ice sheets; and mean sea level change. The greatest scientific benefit will be achieved with a series of dedicated high precision altimeter spacecraft, for which the choice of orbit parameters and system accuracy are unencumbered by requirements of companion instruments.
Koblinsky, C. J.↗
Neural Network Reflectance Prediction Model for Both Open Ocean and Coastal Waters
Remote sensing of global ocean color is a valuable tool for understanding the ecology and biogeochemistry of the worlds oceans, and provides critical input to our knowledge of the global carbon cycle and the impacts of climate change. Ocean polarized reflectance contains information about the constituents of the upper ocean euphotic zone, such as colored dissolved organic matter (CDOM), sediments, phytoplankton, and pollutants. In order to retrieve the information on these constituents, remote sensing algorithms typically rely on radiative transfer models to interpret water color or remote-sensing reflectance; however, this can be resource-prohibitive for operational use due to the extensive CPU time involved in radiative transfer solutions. In this work, we report a fast model based on machine learning techniques, called Neural Network Reflectance Prediction Model (NNRPM), which can be used to predict ocean bidirectional polarized reflectance given inherent optical properties of ocean waters. This supervised model is trained using a large volume of data derived from radiative transfer simulations for coupled atmosphere and ocean systems using the successive order of scattering technique (SOS-CAOS). The performance of the model is validated against another large independent test dataset generated from SOS-CAOS. The model is able to predict both polarized and unpolarized reflectances with an absolute error (AE) less than 0.004 for 99% of test cases. We have also shown that the degree of linear polarization (DoLP) for unpolarized incident light can be predicted with an AE less than 0.002 for 99% of test cases. In general, the simulation time of SOS-CAOS depends on optical depth, and required accuracy. When comparing the average speeds of the NNRPM against the SOS-CAOS model for the same parameters, we see that the NNRPM is able to predict the Ocean BRDF 6000 times faster than SOS-CAOS. Both ultraviolet and visible wavelengths are included in the model to help differentiate between dissolved organic material and chlorophyll in the study of the open ocean and the coastal zone. The incorporation of this model into the retrieval algorithm will make the retrieval process more efficient, and thus applicable for operational use with global satellite observations.
radiative transfer↗
El Nino, La Nina and VLBI Measured LOD
VLBI is one of the most important techniques for measuring Earth orientation parameters (EOP), and is unique in its ability to make high accuracy measurements of UT1, and its time derivative, which is related to changes in the length of day, conventionally called LOD. These measurements of EOP give constraints on geophysical models of the solid-Earth, atmosphere and oceans. Changes in EOP are due either to external torques from gravitational forces, or to the exchange of angular momentum between the Earth, atmosphere and oceans. The effect of the external torques is strictly harmonic and nature, and is therefore easy to remove. We analyze an LOD time series derived from VLBI measurements with the goal of comparing this to predictions from AAM, and various ENSO indices. Previous work by ourselves and other investigators demonstrated a high degree of coherence between atmospheric angular momentum (AAM) and EOP. We continue to see this. As the angular momentum of the atmosphere increases, the rate of rotation of the Earth decreases, and vice versa. The signature of the ENSO is particularly strong. At the peak of the 1982-83 El Nino increased LOD by almost 1 ms. This was subsequently followed by a reduction in LOD of 0.75 ms. At its peak, in February of 1998, the 1997-98 El Nino increased LOD by 0.8 msec. As predicted at the 1998 Spring AGU, this has been followed by an abrupt decrease in LOD which is currently -0.4 ms. At this time (August, 1998) the current ENSO continues to develop in new and unexpected ways. We plan to update our analysis with all data available prior to the Fall AGU.
Clark, Thomas A.↗
A Unique Perspective from Space on our Planet: Science, Technologies and Applications
The study of Planet earth is a very complex problem. It has many non-linear and chaotic systems operating in parallel and have interdependencies. In reality, these systems/phenomena s are not well understood or mathematically modeled because of our lack of knowledge of such intricate processes. However, in order to further the subject of Earth as an integrated system, space provides excellent vantage points to look at these processes in multidimensional framework. For example, we can make strives to understand the global water cycle, carbon cycle, atmospheric chemistry, biomass changes, oceans and solid Earth variations by making multitude of global measurements such as soil moisture, precipitation, tropospheric and stratospheric gases, aerosols, tropospheric winds, ocean salinity, ocean color, vegetation cover, crustal dynamics and many more. Such suites of measurements derive the coupled models so we may predict the changes due to natural and anthropogenic forcing. NASA along with other international space agencies have made tremendous investments in recent years in developing and flying remote sensing space borne sensors to enable these measurements. These science measurements and products are further used to address pressing issues such as coastal zone erosion, air quality, severe weather, water availability and quality, public health, fires, earthquakes, land slides and others for societal benefits. This presentation provides a comprehensive overview of NASA s science investigations, related technologies and satellites/sensors and applications.
Habib, Shaid↗
The Ocean Colour Climate Change Initiative: I. A Methodology for Assessing Atmospheric Correction Processors Based on In-Situ Measurements
The Ocean Colour Climate Change Initiative intends to provide a long-term time series of ocean colour data and investigate the detectable climate impact. A reliable and stable atmospheric correction procedure is the basis for ocean colour products of the necessary high quality. In order to guarantee an objective selection from a set of four atmospheric correction processors, the common validation strategy of comparisons between in-situ and satellite derived water leaving reflectance spectra, is extended by a ranking system. In principle, the statistical parameters such as root mean square error, bias, etc. and measures of goodness of fit, are transformed into relative scores, which evaluate the relationship of quality dependent on the algorithms under study. The sensitivity of these scores to the selected database has been assessed by a bootstrapping exercise, which allows identification of the uncertainty in the scoring results. Although the presented methodology is intended to be used in an algorithm selection process, this paper focusses on the scope of the methodology rather than the properties of the individual processors.
Climate Change↗
Analyzing the Effects of Climate Change on Sea Surface Temperature in Monitoring Coral Reef Health in the Florida Keys Using Sea Surface Temperature Data
This presentation discusses use of 4 kilometer satellite-based sea surface temperature (SST) data to monitor and assess coral reef areas of the Florida Keys. There are growing concerns about the impacts of climate change on coral reef systems throughout the world. Satellite remote sensing technology is being used for monitoring coral reef areas with the goal of understanding the climatic and oceanic changes that can lead to coral bleaching events. Elevated SST is a well-documented cause of coral bleaching events. Some coral monitoring studies have used 50 km data from the Advanced Very High Resolution Radiometer (AVHRR) to study the relationships of sea surface temperature anomalies to bleaching events. In partnership with NOAA's Office of National Marine Sanctuaries and the University of South Florida's Institute for Marine Remote Sensing, this project utilized higher resolution SST data from the Terra's Moderate Resolution Imaging Spectroradiometer (MODIS) and AVHRR. SST data for 2000-2010 was employed to compute sea surface temperature anomalies within the study area. The 4 km SST anomaly products enabled visualization of SST levels for known coral bleaching events from 2000-2010.
Jones, Jason↗
Decadal Changes in Global Ocean Annual Primary Production
The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence of how the Earth's climate may be changing and how ocean biota respond. Furthermore, the results have implications for the ocean carbon cycle.
Gregg, Watson↗
Exploring the southern ocean response to climate change
The purpose of this project was to couple a regional (Southern Ocean) ocean/sea ice model to the existing Goddard Institute for Space Science (GISS) atmospheric general circulation model (GCM). This modification recognizes: the relative isolation of the Southern Ocean; the need to account, prognostically, for the significant air/sea/ice interaction through all involved components; and the advantage of translating the atmospheric lower boundary (typically the rapidly changing ocean surface) to a level that is consistent with the physical response times governing the system evolution (that is, to the base of the fast responding ocean surface layer). The deeper ocean beneath this layer varies on time scales several orders of magnitude slower than the atmosphere and surface ocean, and therefore the boundary between the upper and deep ocean represents a more reasonable fixed boundary condition.
Martinson, Douglas G.↗
The orbital record in stratigraphy
Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity, and (2) presence of abundant microfossils yields close ties to geochronology. A tantalizing possibility that stratigraphy may yield a record of orbital signals unrelated to climate has turned up in magnetic studies of our Cretaceous core. Magnetic secular variations here carry a strong 39 ka periodicity, corresponding to the theoretical obliquity period of that time - Does the obliquity cycle perhaps have some direct influence on the magnetic field?
Fischer, Alfred G.↗
Current Trends in Satellite Laser Ranging
Satellite Laser Ranging (SLR) techniques are used to accurately measure the distance from ground stations to retroreflectors on satellites and the moon. SLR is one of the fundamental techniques that define the international Terrestrial Reference Frame (iTRF), which is the basis upon which we measure many aspects of global change over space, time, and evolving technology. It is one of the fundamental techniques that define at a level of precision of a few mm the origin and scale of the ITRF. Laser Ranging provides precision orbit determination and instrument calibration/validation for satellite-borne altimeters for the better understanding of sea level change, ocean dynamics, ice budget, and terrestrial topography. Laser ranging is also a tool to study the dynamics of the Moon and fundamental constants. Many of the GNSS satellites now carry retro-reflectors for improved orbit determination, harmonization of reference frames, and in-orbit co-location and system performance validation. The GNSS Constellations will be the means of making the reference frame available to worldwide users. Data and products from these measurements support key aspects of the GEOSS 10-Year implementation Plan adopted on February 16, 2005, The ITRF has been identified as a key contribution of the JAG to GEOSS and the ILRS makes a major contribution for its development since its foundation. The ILRS delivers weekly additional realizations that are accumulated sequentially to extend the ITRF and the Earth Orientation Parameter (EOP) series with a daily resolution. Additional products are currently under development such as precise orbits of satellites, EOP with daily availability, low-degree gravitational harmonics for studies of Earth dynamics and kinematics, etc. SLR technology continues to evolve toward the next generation laser ranging systems as programmatic requirements become more stringent. Ranging accuracy is improving as higher repetition rate, narrower pulse lasers and faster detectors are implemented. Automation and pass interleaving at some stations is already expanding temporal coverage. Web-based safety keys are allowing the SLR network stations to range to optically vulnerable satellites. Some stations are experimenting with two-wavelength operation as a means of better understanding the atmospheric refraction and with very low power laser to improve eye-safety conditions. New retroreflector designs are improving the signal link and enable daylight ranging. Dramatic improvements have also been made with lunar ranging with the new APOLLO Site in New ?Mexico, USA and the upgraded lunar station "MEO" in Grasse,
Pearlman, M. R.↗
Interannual Variation in Phytoplankton Concentration and Community in the Pacific Ocean
Climate events such as El Nino have been shown to have an effect on the biology of our ocean. Because of the lack of data, we still have very little knowledge about the spatial and temporal effect these climate events may have on biological marine systems. In this study, we used the NASA Ocean Biogeochemical Model (NOBM) to assess the interannual variability in phytoplankton community in the Pacific Ocean between 1998 and 2005. In the North Central and Equatorial Pacific Ocean, changes in the Multivariate El Nino Index were associated with changes in phytoplankton composition. The model identified an increase in diatoms of approx.33 % in the equatorial Pacific in 1999 during a La Nina event. This increase in diatoms coincided with a decrease of approx.11 % in cyanobacteria concentration. The inverse relationship between cyanobacteria and diatoms concentration was significant (p<0.05) throughout the period of study. The use of a numerical model allows us to assess the impact climate variability has on key phytoplankton groups known to lead to contrasting food chain at a spatial and temporal resolution unachievable when relying solely on in-situ observations.
Rousseaux, C. S.↗
MISR Decadal Observations of Mineral Dust: Property Characterization and Climate Applications
The Multi-angle Imaging SpectroRadiometer (MISR) provides a unique, independent source of data for studying dust emission and transport. MISR's multiple view angles allow the retrieval of aerosol properties over bright surfaces, and such retrievals have been shown to be sensitive to the non-sphericity of dust aerosols over both land and water. MISR stereographic views of thick aerosol plumes allow height and instantaneous wind derivations at spatial resolutions of better than 1.1 km horizontally and ~200m vertically. We will discuss the radiometric and stereo-retrieval capabilities of MISR specifically for dust, and demonstrate the use of MISR data in conjunction with other available satellite observations for dust property characterization and climate studies.First, we will discuss MISR non-spherical (dust) fraction product over the global oceans. We will show that over the Atlantic Ocean, changes in the MISR-derived non-spherical AOD fraction illustrate the evolution of dust during transport. Next, we will present a MISR satellite perspective on dust climatology in major dust source regions with a particular emphasis on the West Africa and Middle East and discuss MISR's unique strengths as well as current product biases. Finally, we will discuss MISR dust plume product and climatological applications.
dust sources↗