The Longyearbyen Optical Station is the only ground station in the Northern Hemisphere with regularly scheduled airline service, which permits 24-hour observation of the aurora and airglow. The EISCAT radar polar cap extension will be built a few miles from the observatory site. This proposal seeks funding for maintenance of Longyearbyen in support of the Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) and Geospace Environmental Monitoring (GEM) programs so that it will provide a ready location for continued high-latitude optical studies. The station has supported investigations of dayside and nightside aurora, ionospheric currents, high-latitude dynamics of the thermosphere and mesosphere and also measurements of stratospheric minor constituents connected with the ozone cycle. In collaboration with the University of Tromsø, the University of Alaska has developed the station into a modern research facility complete with a set of first-class optical and magnetic instruments, individual observation bays for visitors, areas for setup and repairs, and comfortable living conditions. The PI plans the continuation of this work with centrally supported maintenance of the station and its instrument complement.
The Polar Cap Observatory (PCO) is considered essential for continued progress in understanding the Sun's influence on the structure and dynamics of our planet's atmosphere. An essential first step in the establishment of the PCO is the development of infrastructure in Resolute Bay, Northwest Territories, Canada, in which to conduct preliminary scientific investigations. The PI proposes to provide the necessary infrastructure with which to begin the Early PCO (EPCO) phase. This includes a building with laboratory space, optical domes and living quarters, along with road construction and installation of power lines. The PI will also provide a spaced-receiver scintillation detector and ionospheric drift monitor, as well as a frequency-agile radar for preliminary scientific investigations. These investigations will focus on polar cap E fields, plasma structure, polar cap auroral arcs and polar mesospheric echoes. In addition, the proposed infrastructure would be capable of supporting instruments proposed by other researchers that might include a spectrometer, interferometer, photometer, magnetometer, digisonde, riometer, medium frequency (MF) radar, ST radar and more.
This award is for joint radar and optical investigations of the interactions between the atmospheric constituents in the polar thermosphere and precipitating auroral electrons. The latter dissipate most of their energy through a combination of processes involving dissociation, excitation and ionization of some of the upper atmospheric constituents. In turn, the by-products of these processes interact with ambient air particles to modify polar thermospheric composition and thermodynamics. All these upper atmospheric auroral processes can be investigated by combining ground-based remote-sensing measurements of auroral ionization profiles using incoherent scatter radar (ISR) sounding of the auroral region, and concurrent bore-sighted spectroscopic and interferometric observations of the optical signatures of the auroral electron excitation of N2, O2, O and N. The database for these studies will be constructed from the (ISR) and spectro-interferometric observations of auroral displays occurring over Sondre Stromfjord, Greenland.
This proposal is a request for funds for the next three years (remainder of the (GEM) Boundary Layer Campaign) to analyze the data that is being received from an induction magnetometer operating at Iqaluit, Northwest Territories, Canada, which is nominally magnetically conjugate to South Pole, Antarctica. The magnetometer was built and installed at Iqaluit in June 1993 with funds provided under the (GEM) program and Grant # ATM-9111929. The major objective of the (GEM) Boundary Layer Campaign is to understand the interaction of the solar wind with the Earth's magnetic field and the transport of energy across dayside boundaries. Waves are an important mediator of this transport of energy due to the collisionless nature of the medium in which the boundaries are imbedded. Induction magnetometers measure the high-frequency component (greater than 0.1 Hz) of naturally occurring ultra-low-frequency (ULF) waves in the Earth's magnetosphere and in the solar wind, which cannot be done with conventional magnetometers. Ground measurement and the study of these waves in the magnetosphere is important because they are of sufficiently short wavelengths to propagate as wave packers in the Earth's magnetic field. In such a mode of propagation the Pc 1 and Pc 2 waves can be used as probes of the topology of the geomagnetic field and its boundaries. Their resonant generation by ions and the modification of their propagation by cold plasma populations indirectly provides a study of these particles. The location at Iqaluit is vital because this site permits a global study of ULF waves by using several sites in Antarctica, as well as at the Sondre Stromfjord site in Greenland. Repetitive structure in the wave form at two opposite hemisphere sites 180 degrees out of phase can be an indication of closed magnetic field lines. A time delay between sites at different longitudes in either hemisphere can give scale size and/or motion of the source creating the waves. Spacecraft making single point measurements are hard-pressed to define boundaries, but done in correlation with multiple ground measurements, as proposed here, one can begin to build a global picture of the important dayside magnetospheric boundaries. As a result of this correlative work in providing "space-truth," ground measurements in the future can monitor these boundaries and their dependence upon solar wind and, ultimately, solar conditions.
It is proposed to continue to operate and analyze data from the recently installed (MACCS) array of fluxgate magnetometers located at cusp/cleft latitudes (75° to 80°) in arctic Canada in a joint effort with Augsburg College. During the summers of 1992 and 1993, eight magnetometers were deployed at small communities in the eastern arctic. These eight observatories span nearly five hours in magnetic local time in the latitude region most valuable for ground-based observations of the magnetospheric boundary layer, and also serve to connect existing magnetometer sites in Alaska and western Canada to the west and to sites on Greenland and Baffin Island to the east. In addition, it is proposed here to add data loggers at three standard Canadian observatories (Resolute, Cambridge Bay and Baker Lake). This would allow researchers to obtain one-second data from these sites and routinely combine this data with the (MACCS) database, effectively extending the MACCS array another hour to the west. The purpose of the (MACCS) array is to study ionospheric currents, plasma flows and waves associated with the magnetospheric cusp and neighboring regions. In association with the radar systems beginning to operate in this same area, these magnetometers will provide high resolution, two-dimensional data on the electrodynamics of cusp convection. The MACCS data also contain numerous high-latitude substorm signatures. As the GEM program begins its substorm campaign, it is proposed to use (MACCS) data to study the small, contracted oval substorms associated with northward interplanetary magnetic field (IMF), and also to study the recovery phase of regular substorms during which the activity moves poleward over the (MACCS) array.
This award will support the deployment of a resonance lidar at the Poker Flat Research Range near Fairbanks, Alaska. The lidar will provide measurements of the arctic middle atmosphere from the upper troposphere to the lower thermosphere. The lidar uses scattering from molecules, aerosols and metal atoms to yield measurements of density, temperature, aerosol backscatter ratio and metal density in the stratosphere and mesosphere. The measurements will be used to address several topics of current research interest: the role of aerosols in the chemistry of the high-latitude stratosphere, the occurrence of aerosols in the polar mesosphere, the temperature structure of the lower mesosphere and stratosphere, the structure of the mesospheric metal layers and the characteristics of waves and tides in the mesopause region.
This proposal is directed toward the continued operation of an array of unattended, automatic magnetic data collection platforms on the Greenland ice cap and the reduction, distribution and analysis of these data. The (MAGIC) array complements the magnetic stations on the coasts of Greenland. The (MAGIC) magnetic stations form a two-dimensional array with station separation of about 150 km. The scientific objective of these magnetic measurements is to investigate, in conjunction with the coastal stations, small-scale propagating magnetic disturbances which appear to result from moving filamentary field-aligned currents interacting with the ionosphere. Different classes of these systems now have been identified, and the origin of the field-aligned currents appears to be near the dayside magnetopause within the magnetospheric boundary layer. It is particularly important to have a dense two-dimensional array in order to resolve the motion and structural evolution of these current systems. The Greenland stations, in combination with the other (GEM) funded stations deployed in Canada, permit us to observe these phenomena over a sufficient region so as to identify their generational location and resolve their motion and spatial evolution as they propagate. These data and the proposed research are important in understanding the physics of the processes which couple energy and momentum from the solar wind to the magnetosphere and ionosphere, the physics of the magnetospheric boundary layer and the mapping of boundary layer phenomena to the high-latitude ionosphere.
This project involves the operation and maintenance of radar at Goose Bay, Labrador, Canada. Over the past several years, a global-scale network of high-latitude, high-frequency (HF) radars has been developed to probe some of the critical questions in solar-terrestrial research. The network is known by the acronym SuperDARN and the radars within it are based upon the design and operation of the radar located at Goose Bay. These HF radars sense ionospheric plasma motions from Doppler measurements of signals backscattered from small-scale ionospheric irregularities. The new radars are funded by Britain, Canada, Finland, France and Antarctica; four remain to be completed within the next 16 months. In addition to operation and maintenance, the PIs will ensure that the software that controls the radars is maintained and updated, and that data from all of the radars are collected onto common databases that are available to interested scientists from all participating countries, including the United States. They also will assist U.S. scientists in the acquisition and use of HF radar data, and continue their own research activities that are associated with the SuperDARN data. These include studies of the global-scale structure and dynamics of high-latitude convection under changing interplanetary magnetic field and solar-wind pressure, studies of transient magnetospheric boundary processes as imaged in the high-latitude ionosphere, studies of the detailed relationships that exist in the high-latitude E-region between electric fields, currents and conductivities, studies of large-scale MH resonances and studies of small-scale irregularity generation in the high-latitude ionosphere.
The PI will study the phenomenon of mesospheric clouds, their atmospheric environment and their role in middle atmospheric global change. The PI will combine (1) analysis of existing data gathered by spacecraft, rockets and ground-based radar; and (2) theoretical modeling of the microphysics of mesospheric ice particle evolution and of the atmospheric environment, including coupled dynamics, radiation and photochemistry of the mesosphere and lower thermosphere. The research will increase the understanding of physical processes that occur in the upper mesosphere, an atmospheric region which is still poorly understood because of its complexity and inaccessibility.
The PI will continue studying auroral arcs from Godhavn, Greenland. Simultaneously, incoherent scatter radar and optical instruments at the Sondrestrom facility will view the same aurora. Overlapping fields from these two sites will provide a database for two-dimensional measurement and tomographic description of auroral arcs in the magnetic meridian. The PI also will study auroral arcs and their thermospheric effects. The PI plans to operate a dedicated "aeronomy" campaign each winter. Finally, he will analyze and publish results in the third year.
This project will undertake analysis of data to increase our understanding of the possible signatures of magnetopause and magnetospheric boundary layer processes that are observed in the ionosphere and on the ground. The study will focus specifically on a search for simultaneous observations of two different geomagnetic perturbation phenomena whose possible sources may be either the magnetopause or the upstream solar wind. The phenomena that will be studied are Pc 3 micropulsations and high-latitude magnetic impulse events known as traveling convection vortices (TCVs). Pc 3 micropulsations are quasi-periodic pertubations of the Earth's magnetic field with periods between 10 and 45 seconds. One source of these pulsations is believed to be the upstream solar wind. High-latitude magnetic impulse events are large amplitude (100 nt), often monopolar, pulsations of the geomagnetic field of 10-20 minute durations. Interest in these pulsations was stimulated by the hypothesis that they constituted the ionospheric signature of sporadic reconnectionthough this speculation has become very controversial. Recent work suggests that they may occur on closed field lines. The possible connection between Pc 3 and TCVs has not been undertaken. There have, however, been some observations to indicate that Pc 3 events can occur simultaneously with TCV events and propagate with the same horizontal speed. This suggests that they may occur on the same field lines and share a common source. A detailed study is needed to develop a conclusive determination of a possible relationship between the two phenomena using data from the (MACCS) in northern Canada.
This project is an airborne study of arctic stratus clouds with the objective of obtaining several comprehensive sets of simultaneous measurements of their microstructure and spectral radiative properties. Such concurrent measurements are basic to the improvement of current models of radiative properties of stratus clouds. These models, in turn, are a crucial component of global circulation models, which form an important basis for global change studies. The development of optimized radiative forcing algorithms is the objective of a major research effort. Additional objectives of this project are to measure the spectral reflective properties of various arctic surfaces such as tundra, open ocean and melting and refreezing sea ice, and to test a new approach for distinguishing water clouds from snow and ice surfaces. The observations will be made from a Convair C-131A aircraft configured specifically for airborne research.
This project uses high-frequency coherent back-scatter radars to study ionospheric structures of auroral origin and to determine the magnetospheric activity responsible for the radar echoes. The existing radars are at Goose Bay, Labrador, Canada, and the British Antarctic Survey station at Halley Bay, Antarctica. This pair is called the Polar Anglo-American Conjugate Experiment, and they are located such that their fields of view are magnetically conjugate. A new radar, called the Southern Hemisphere Auroral Experiment, will be installed at the new South African Sanae Station in Antarctica when it is built. Though not officially part of this consortium, the new radar at the Japanese Antarctic Station, Syowa, will contribute complementary data. The project is a joint venture of Johns Hopkins University Applied Physics Laboratory (JHU/APL), British Antarctic Survey and the South African National Antarctic Expedition. The Japanese National Institute of Polar Research is cooperating closely with the PACE/SHARE collaboration. JHU/APL developed the use of HF coherent radars for auroral research, based on their extensive experience with Over-The-Horizon radars, which are used for defense purposes.
The concentration of ozone in the lower stratosphere is sensitive to interaction of part-per-trillion abundances of radical species in the NOx, HOx, ClOx and BrOx families. While NOx and NOx and HOx are predominantly of natural origin, concentrations of the halogen oxides in the stratosphere are thought to be increasing due to anthropogenic uses of organic halides, mainly the chlorofluorocarbons (CFCs), halons, and methyl bromide. The inherent non-linear coupling of these radical families complicates interpretations of stratospheric photochemistry that rely either on isolated measurements of a single species in the atmosphere or on measurements using a single detection technique. This research project will focus on the design and deployment of a new instrument for in situ measurements of reactive chlorine (ClO and Cl2O2) and reactive bromine (BrO), one of which is based on the technique of chemical-conversion resonance fluorescence and the other one of which has flown successfully on aircraft and balloons. This instrument will be sufficiently lightweight that it could be deployed easily in conjunction with existing balloon- or aircraft-borne payloads, especially those to be flown on a new class of unmanned aircraft. Two major objectives will direct this project. First, these researchers will work closely with investigators who measure the halogen oxides with remote techniques from the ground, balloons and space to provide a critical intercomparison of the available techniques and an evaluation of the uncertainties of the measurements over the altitude range from 12 to 35 km. The PIs are also interested in interactions with members of both the Network for Detection of Stratospheric Change (NDSC) and the Upper Atmospheric Research Satellite (UARS). Second, the project scientists will seek collaborative investigations of the chemical and dynamical processes that determine the abundance of ozone-destroying radicals in the lower stratosphere. Their main interest will be the influence of aerosols on the balance of NOx, ClOx and BrOx chemistries, especially near the tropical tropopause and at mid-latitudes.
This project will serve as a bridge between global climate modeling and regionally focused hydrologic studies of northern high-latitudes. It will mesh with both the Global Energy and Water Cycle Experiment (GEWEX) and the Atmospheric Model Intercomparison Project (AMIP). The first task will be the compilation of a climatological database, including monthly fields as well as spatial and temporal variances, for use in: (1) validating climate model simulations of the high-latitude hydrologic cycle and its variability, and (2) quantifying the low-frequency variability in high-latitude hydrologic quantities. The database compilation will focus on precipitation and runoff fields, supplemented by computations of atmospheric moisture flux convergence, which will be used to estimate the net P E (precipitation minus evapotranspiration) on a regional basis. The second task will be to diagnose quantitatively the high-latitude hydrologic cycle of the AMIP simulations in order to determine the reasons for the model overestimation of arctic precipitation. The last task involves the use of a regional atmospheric model to determine what resolution is required to realistically simulate the spatial and temporal variability of precipitation over topographically complex areas in high-latitudes.
This research project is aimed at addressing key issues in stratospheric and tropospheric chemistry. For the stratosphere: (1) field observations will be used to test and refine our understanding of the role of heterogenous processes on the chemistry of the lower stratosphere; (2) diagnostic models will be developed and applied to elucidate the chemical and dynamical mechanisms responsible for long-term trends in the ozone, with particular attention given to global effects of volcanic aerosols; and (3) denitrification will be examined as the controlling influence on loss of ozone in polar regions, as part of a strategy to clarify differences between ozone loss in the Arctic and Antarctic. For the troposphere, the PI proposes to: (1) use data for short-lived species from recent field expeditions to test and improve photochemical mechanisms; (2) test the distribution of the hydroxyl radical in a global three-dimensional Chemical Tracer Model (CTM) by observations of carbon-14, labeled carbon monoxide; (3) by use of the CTM, test inventory of sources for carbon monoxide, a key species regulating hydroxyl radical concentrations, taking advantage of new data for carbon-13 labeled carbon monoxide and carbon-18, labeled carbon monoxide and including additional studies of ethylene and acetylene; and (4) by use of the CTM, investigate changes in the oxidizing power of the troposphere from 1950 to the present.
This project consists of a multi-investigator measurement campaign studying the springtime outflow of arctic air toward the North Atlantic. During winter and spring, levels of photochemically active pollutants are elevated in the remote arctic troposphere. Recent work indicates that transport through the Arctic provides a substantial flux of total reactive nitrogen (NOy) and non-methane hydrocarbons to the temperate North Atlantic region. This process may play a significant role in the tropospheric ozone budget of this and other remote regions. Current understanding of these effects is limited by an absence of measurements of the relevant compounds in southward-transported arctic air. The ground-based measurement campaign will take place during JanuaryApril 1996, at a site in Newfoundland, within the dominant pathway of springtime arctic air flow. Measurements will include ozone, nitric oxide, nitrogen dioxide, peroxyacetic nitric anhydride, peroxypropionic nitric anhydride, alkyl nitrates, total reactive nitrogen, non-methane hydrocarbons and carbon monoxide, in addition to standard meteorological parameters and radiometer-based nitrogen dioxide photodissociation rates. Real-time isentropic back-trajectory forecasts and meteorological analyses will be used to guide the sampling frequency to ensure adequate coverage during outflow events. An archive of back-trajectories will assist in data interpretation. The results of this study will be used to assess the impact of the winterspring arctic reservoir on the levels and speciation of NOx, NOy and non-methane hydrocarbons at lower latitudes. Impacts on the local ozone formation/destruction rate and budget will be estimated by using a photochemical box model.
This project will explore heterogeneous reactions of bromine, which are potentially important to polar ozone depletion and ozone loss in the tropospheric Arctic boundary layer. The role of HBr (hydrogen bromide) conversion into photochemically active bromine on ice surfaces will be explored. The results of this study will lead to a better mechanistic understanding of uptake and heterogeneous reactions involved in ozone depletion. The initial focus will be on uptake of HBr and the formation mechanism of HBr hydrates on ice film surfaces. The phase diagram of HBr-ice, along with other thermodynamic properties will be determined from this study. The uptake of the hydrogen halides HF, HCl, HBr and HI on ice surfaces will be compared and the trends interpreted in terms of acidity and the interactions of the hydrogen halides with the ice surfaces. The reaction probabilities and mechanism of gaseous HOCl and HOBr with HBr on ice surfaces will be determined under simulated atmospheric conditions. This project will use a glass flow reactor, together with pulsed molecular beam sampling, quadruple mass spectrometry and phase sensitive detection methods. Formation processes for HBr hydrates will be examined by using specula reflection-absorbance IR spectroscopy. The effect of the ice film surface morphology on HBr uptake will be investigated by using scanning electron microscopic and isotherm adsorption methods. Models will be developed to interpret the results.
This Small Grant for Exploratory Research (SGER) is being awarded for the testing and deployment of a prototype instrument for detecting halogen oxides in the troposphere. An existing and proven instrument that has made measurements of chlorine monoxide and bromine monoxide in the stratosphere has been modified to perform under the higher total pressure and larger water vapor partial pressure conditions characteristic of the troposphere. Bromine species are believed to play a dominant role in the observed sudden depletions of ozone over the arctic region during springtime. Bromine monoxide has been detected in large abundance during these events. The PI will participate in the ARCTOC 1996 campaign, which is being sponsored by the European Community during MarchMay 1996. During this campaign, bromine monoxide will be measured using other techniques as well, thereby providing an opportunity to test the modified instrument. If this instrument works as anticipated, halogen oxide measurements will be provided with a faster time response and a lower detection limit than other techniques currently in use.
This project is an experimental and theoretical study of ice crystals in the Antarctic atmosphere and the halos that they produce. For reasons that currently are not known, the Antarctic interior experiences more frequent and better developed halos than any other location on Earth. The objectives of the project are to observe natural halos at South Pole Station and to sample ice crystals in order to validate computer models of light refraction and reflection in ice crystals. Such models have the potential for the remote sensing of atmospheric conditions. Controlled experiments, such as seeding the atmosphere with dry ice, will produce artificially generated but simple and well-formed single-species crystals. The project provides a unique mechanism for examining the crystal growth and evolution process in the natural atmosphere. The observation of halos through polarizing filters will also allow an examination of the atmospheric ice crystal orientation, shape and size. It will advance our understanding of the reasons for the growth of well-formed ice crystals, which is a characteristic of the Antarctic atmosphere, but is not generally observed elsewhere.
This award supports comprehensive study of relationships between atmospheric variability and fluctuations in the snow and sea-ice covers in the Northern Hemisphere. The primary thrust of the work is to provide a hemispheric synthesis of the sensitivity of the cryosphere to regional changes in the atmospheric circulation, and to diagnose this sensitivity with respect to associated interactions between precipitation, temperature, winds and the modes of large-scale teleconnection patterns. The PIs will identify those regions of the cryosphere warranting focused monitoring for potential climate change, and possible future responses of the cryosphere to changes in circulation regimes. As part of these efforts, they will perform a series of intercomparisons between observed snow-cover patterns and those simulated by different general circulation models (GCMs) under present and projected future climatic conditions. The study will address at least six basic questions: (1) What are the relationships between variations in northern hemisphere sea ice extent and terrestrial snow cover? (2) What areas of the cryosphere exhibit strong or weak responses to atmospheric circulation changes and why? (3) Which areas contribute most strongly to northern hemisphere cryosphere variability? (4) What are the responses of the cryosphere to the modes of large-scale teleconnections patterns, and how do these compare with parallel anomalies in synoptic activity, temperature and precipitation? (5) How well do different GCMs depict the present day distribution and variability of snow cover, and are changes in the cryosphere projected by GCMs in response to enhanced CO2 warming reasonable from the viewpoint of modeled circulation changes? (6) Can the cryosphere be used as a robust indicator of climate change? For the snow and sea-ice analyses, gridded National Oceanic and Atmospheric Administration (NOAA) charts of Northern Hemisphere snow extent and Navy/NOAA ice concentration data will be combined with available station records of snow depth, snowfall, precipitation and surface temperature.
The objective of this project is to investigate the decade- to century-scale affects of ocean heat transports in numerical climate change simulations. The project uses the Goddard Institute for Space Studies (GISS) atmospheric general circulation model (GCM), coupled with an ocean model that includes meridional transport of heat by the oceans, to test directly whether changes in ocean heat transport could enhance or ameliorate the effects of trace-gas-induced global warming. The project is designed as a three-year, two-phase study. In the first phase, surface heat flux diagnostics from GCM experiments will be used to calculate the potential ocean heat transport associated with historical (20th century) anomalies in sea surface temperatures (SST) and sea-ice extent. The SST and sea-ice anomalies will be acquired from the most comprehensive data sets available. In addition, ocean heat transports will be calculated from GCM simulations and proxy data from the Little Ice Age (ca. 1700 AD) and Last Glacial Maximum (ca. 18-2lky BP) in order to obtain larger variations of heat fluxes that may be closer to the potential variability of the system. The second phase of the project focuses on simulations of the climatic effects of altered ocean heat transports in conjunction with transient trace gas increase scenarios. Ten 100-year simulations are planned in which the ocean heat values, calculated in phase one, will be used to perturb the normal pattern of climate change associated with the atmospheric trace gas increase. The simulations in phase two will take approximately two years to complete, based on estimates of the current computational efficiency of the GISS GCM running on an IBM RS/6000-580 workstation. Individual transient experiments will be completed and analyzed at the rate of one every three months. The primary objective of this project is to identify patterns of climate change that are associated with variability in the air/sea/ice system and to estimate the potential ocean energy feedback that may accompany climate changes induced by atmospheric trace gas increase. Fingerprinting of such climate patterns will improve our ability to detect the signs of ocean-induced climate change and can improve our ability to distinguish between natural variability and anthropogenic climate change. Furthermore, it will provide us with a quantitative assessment of the oceans ability, through energy transport feedback, to alter the climate sensitivity and GCM predictions of future climate change. In lieu of fully coupled atmosphere-ocean-ice models, which are unlikely to reach a reliable predictive capacity in the near future, these experiments provide a realistic alternative for gauging the ability of the oceans to alter GCM future climate diagnoses. This project is funded under the U.S. Global Change Research Program (USGCRP) NSF Climate Modeling, Analysis and Prediction program.
This award supports dendroclimatic research at the Tree-Ring Laboratory (TRL) at the LamontDoherty Earth Observatory. Analysis of growth rings of old-aged trees provides an almost unique tool for determining seasonal and year-by-year variations of past climate to evaluate recent climatic changes. Large-scale reconstructions and local studies show unusual warming in the past century, occasional abrupt climatic changes and more prevalent extremes in dry and wet events. The current effort will update and improve the coverage of climatically-sensitive forest-ecotone sites with the addition of sampling for moisture stress variations and inclusion of subfossil material to extend the tree-ring record farther into the past. This extension is crucial for comparison of the present, possibly anthropogenic, warmer period to natural warmer periods of the more distant past.
This project will assemble a team of senior researchers with expertise in the areas of climate, hydrological cycles, biogeochemical cycles, geological processes and human interventions. This team will outline, in a conference format, the state of our knowledge of Nunavut and similar high-latitude regions, and will then propose, in round table discussions, the designs for long-term experiments aimed at identifying and measuring change in these systems, and the collection and compilation of other data and observations of change which will be the focus of the proposal to be submitted to IAI Start-Up Grants Phase II. Phase I of the (IAI) Start-Up Grants will aim to produce a volume of review papers on the environment of Nunavut. Invited delegates will be obligated to produce summaries of the understanding of the land, sea, air and biology of Nunavut, and these summaries would be used to establish baseline data and guidelines for future endeavors in Phase II of the (IAI) Start-Up Grants. Logistically, platforms for this research may be centered on the National Park reserves on Baffin, Bylot and Ellesmere Islands. These three islands delineate a transect from below the Arctic Circle to near the North Pole. The application developed for Phase II will identify the relevance of this work to regional and global interests. From a scientific perspective, understanding environmental change is an important contribution towards understanding the earth system. By predicting changes to Nunavut, government land-use policy can be modified to accommodate future developments, and to contribute to increasing the state of knowledge of similar high-latitude regions of the Americas. It is likely that the Phase II proposal will reopen the Arctic Research Establishment, a field station in Pond Inlet, and its training component for local technicians and university students. In addition, this proposal will link universities in Canada and the United States with the (IAI) Network. These countries are members of the (IAI), an initiative to stimulate global change research among the scientific institutions of the Americas.
This grant will promote the diagnosis and understanding of the behavior of global climate models in polar regions. The diagnostic tasks will complement upcoming Arctic field programs (Surface Heat Budget of the Arctic Ocean and Atmospheric Radiation Measurements programs), driven by the need to narrow the uncertainties in model simulations of climate change. Research will draw upon daily output of a set of global climate models to: (1) assess the Arctic cloud-radiation-temperature associations in the model simulations, permitting direct comparisons with results of the field measurements, (2) determine the frequency and spatial distribution of extreme events in the atmospheric model simulations and (3) determine the contribution of surface winds to apparent biases in simulated evapotranspiration over polar surfaces. In addition, the PI will compose a review paper synthesizing many recent sea-ice sensitivity experiments with global climate models to identify priorities for improving the treatment of sea ice in climate models. The research will increase understanding of climate processes in polar regions, as well as improve our ability to simulate these processes with mathematical/physical models.
In the Northern Hemisphere, large and rapid shifts in environmental conditions have occurred repeatedly over the last glacial-interglacial cycle. Indications are that climate change occurs on two characteristic time scales, roughly 13,000 years and 510,000 years. Evidence for millennial-scale climate variability has been found in ice cores drilled through the Greenland Ice Sheet, sediment cores from the North Atlantic Ocean, pollen records from both North America and Europe, and glacial deposits in North America. Paleoclimate records from the Southern Hemisphere also show climatic variability on millennial time scales. While interhemispheric synchrony has been observed for the last termination, the record of alpine glaciers and lake sediments in the Andes and New Zealand now suggest that these higher frequency changes may also be synchronous with the climatic fluctuations of the Northern Hemisphere. This award supports a project designed to model the higher frequency variations of climate. One of the challenges of developing such a theory for millennial-scale climate change will be to account for interhemispheric connections within the context of a global environmental system. While changes in the thermohaline circulation of the ocean have been postulated as a cause for rapid climate change on millennial time scales in and around the North Atlantic, interhemispheric synchrony would implicate the atmosphere as a key factor in global climate change on this time scale.
The proposed project examines physical processes that affect the manner in which heat, vapor and chemical species in air are incorporated into snow and polar firn. The processes include diffusion and advection, the transport of heat, vapor and chemical species by air flow within snow and firn. An understanding of these processes is important because they control grain growth, snow metamorphism, and the rate at which chemical species in the atmosphere become incorporated into the snow and firn, and thus will affect interpretation of polar ice core data. The objectives of the project are to define the magnitude and extent, both in space and time, of these transfer processes, and to develop a process-level understanding and modeling capability of the phenomena within the snow and firn. The approach is to conduct field studies at sites where shallow cores and meteorological data are being obtained on the Greenland Ice Sheet to determine the spatial and temporal extent for key parameters, and boundary conditions needed to model the conduction and advection of heat, mass and chemical species within the firn. An existing multidimensional numerical model is being expanded to simulate the processes and serve as the basis for ongoing and future work in transport and distribution of chemical species. Currently, interpretation of the polar ice core data assumes that diffusion controls the rate at which chemical species are incorporated into the firn. The proposed project will determine the site-specific extent of ventilation in the firn, and will provide a model for multidimensional diffusion and ventilation on grain growth, sublimation rates and chemical species transport.
Rising concentrations of carbon dioxide and other gases in the atmosphere are expected to cause global warming. The effects of warming are expected to be amplified and observable first in high-latitudes. Current models predict that rapid warming will combine with increases in summer rainfall and winter snowfall in northwestern North America-conditions that may result in rapid degradation of permafrost throughout large parts of Alaska and northwestern Canada. Similar conditions may also persist in northern Eurasia. Although permafrost is not in direct contact with the atmosphere, seasonal snow cover, surface vegetation and an organic mat serve as an active layer that buffers heat transfer. Energy passes through this active layer through convection and through non-convective processes (including evaporation and condensation, freezing and melting and volatilization and sublimation), which consume or release latent energy. High-frequency measurements of temperature and water-ionic concentrations in soils conducted by the PI in discontinuous permafrost regions covered by boreal forests in Alaska have indicated that the non-conductive processes can, under some circumstances, dominate heat transfers in freezing and thawing soils. This project will continue this line of research in both areas of discontinuous permafrost and expand it into Arctic areas where permafrost is continuous. Data will be collected at two different scales, with high-frequency monitoring of near-surface processes conducted at three sites. Measurements also will be taken in the upper levels of permafrost at the same sites in order to refine methods for observing changes in crucial variables in this critical zone. This research will make contributions from both substantive and methodological perspectives. It will add to general knowledge about the role of non-conductive processes within the buffering active layer above permafrost, especially as that layer responds to changes in temperature and precipitation. Expansion of this line of research into the upper layers of permafrost will increase understanding of processes in this zone and will provide tests of the feasibility of new monitoring procedures for use in many similar locales.
The PI will study, through remote sensing, various disturbances in the polar upper atmosphere over the Cusp Auroral Observatory in Longyearbyen, Svalbard. This research will address two aeronomic problems: (1) the effects of charged particles on thermospheric composition and thermodynamics, and (2) the effects of planetary, tidal and gravity waves on the middle atmosphere and lower thermosphere density and temperature. The unique location of Longyearbyen permits monitoring optical signatures of upper atmospheric disturbances triggered by the magnetospheric particles precipitating in the cusp and poleward boundary of the night sector of the auroral oval, as well as in the polar cap region. Large differences in the average energy of the particles precipitating in these regions lead to optical emissions from distinctly different heights. Absolute intensities of the emissions will provide the necessary database for quantitative assessment of upper atmospheric disturbances. Such data constitute the input needed for detailed numerical auroral model calculations to derive thermospheric temperatures and constituent densities at different heights. Finally, the proposed measurements can determine the dynamical and chemical processes that convert the effects of zonally symmetric non-migrating tides in the polar middle atmosphere and lower thermosphere.
The PIs intend to test their prediction abilities of the location and timing of ionospheric irregularities in the high-latitude F region. Much of the high-latitude F-region weather is caused by small-scale (irregularities) and large-scale (polar cap patches, polar cap arcs, boundary blobs, subauroral blobs, auroral blobs and auroral ionospheric cavities) electron density structures. There is an intimate cause and effect relationship between these small- and large-scale irregularities. The PIs will use the Global Theoretical Ionospheric Model (GTIM) to determine the requirements for accurately forecasting patches and blobs, and, in turn, by using expressions for instability growth rates, forecast the appearance of electron density irregularities. In sum, this three-year project will: (1) test current understanding of large-scale F-region structures and their ability to produce small-scale irregularities, (2) confirm the role of two instability processes in generating small-scale irregularities, (3) test current capability to specify and forecast conditions in the high-latitudes that impact satellite communications, (4) help establish what processes need to be included in any physics-based ionospheric weather model and (5) establish the level of detail required in the high-latitude electric field in order to specify and forecast ionospheric weather.
This grant supports the continued operation and analysis of the data produced by induction magnetometers at South Pole and McMurdo Stations in Antarctica and Sondre Stromfjord, Greenland. These high geomagnetic latitude sites are ideally suited for the study of plasm physics processes which occur near the boundary of the Earth's magnetosphere, at the poleward edge of the auroral oval and in the polar cap. The data from this three station network, plus data from additional new magnetometers operated by the same group but supported by other programs, will make possible research which almost certainly will result in new insight into the various phenomena which produce magnetic micropulsations.
This is a project to investigate how energy from the solar wind enters Earth's magnetosphere. The rate of energy transfer is controlled by the electric field along the separatrix, which is the boundary between open and closed magnetic field lines at the surface of the magnetosphere. For this study, ground-based observations will be used to measure the rate of reconnection of magnetic field lines across the separatrix. Both the motion of the separatrix and the flow of plasma across it must be measured simultaneously. The investigators will measure these quantities using radar and optical techniques with a time resolution sufficient to resolve changes associated with the growth and expansion phases of auroral substorms. The results will be used to test models of plasma convection in the magnetosphere and to evaluate the accuracy of reconnection theories. The variation in reconnection rate associated with auroral substorms and dayside transient effects also will be studied.
This award will enable the operation of a two-station array of cosmic ray neutron monitors in Canada to continue for two years. They are scheduled to be terminated very soon by the Canadian National Research Council (NRC), which owns and operates them. The PI has reached an agreement with the NRC to run them and eventually to obtain their ownership. This award allows time for the arrangements of transfer to occur, as well as to determine the relative priority of various such facilities. These instruments, along with other high-latitude monitors, are especially important contributors to cosmic ray studies because their fields of view are well defined and also because they are much more sensitive to low-energy cosmic rays, compared to mid-latitude monitors.
The University of Maryland will continue studies of the high-magnetic latitude ionosphere and magnetosphere using galactic radio noise absorption techniques (riometry). Several years ago, they developed a new imaging riometer which allows the study of auroral morphology during daylight and through clouds. These imaging riometers are now being operated at Iqaluit, Canada; Sonde Stromfjord, Greenland; and South Pole, Antarctica. Additionally, they are operating broad beam riometers at Iqaluit, McMurdo and South Pole as well as auroral photometers at McMurdo and South Pole. In the next few years they will provide part of the hardware necessary to build imaging riometers at the British Halley Bay and the Australian Davis stations, both in Antarctica, thus considerably extending coverage. The riometers work synergistically with a number of other instruments which are operated at these sites by other investigators. A major focus of investigations over the next few years will be the characterization of drifting polar auroral patches and their relationship to polar cap convection.
This award will provide continued support for the Sondrestrom incoherent scatter radar and lidar facility at Kangerlussuaq, Greenland (formerly Sondre Stromfjord, Greenland). SRI International will use the funds to continue operating, maintaining and upgrading the facility and for the scientific research efforts of its professional staff. The Sondrestrom facility is the poleward mainstay of the four-radar chain that extends to the magnetic equator. The requested funding will be used to accomplish the following tasks involving both the radar and lidar systems: (1) schedule and operate the radar approximately 1200 hours per year, and assist in operating collocated instruments; (2) assist users in planning, designing and interpreting results from radar and lidar experiments; coordinate their visits, including obtaining U.S. Air Force and diplomatic approval and providing logistics support; (3) maintain and upgrade the radar and lidar facility, and assist in maintaining other collocated facilities; (4) develop and maintain system software for acquiring, reducing and interpreting data; (5) carry out World Day observations and specific research programs; (6) provide World Day data to the National Center for Atmospheric Research database and its users, and maintain a comprehensive data library at Menlo Park; (7) collaborate with scientists throughout the world in scientific pursuits concerning the geospace environment; and (8) be the liaison between the Greenland Home Rule Government, Danish Commission for Scientific Research in Greenland and the National Science Foundation on issues related to the Sondrestrom facility.
The first part of this project will be studying the physical and chemical processes associated with formation of thin metallic-ion structures in the very-high-latitude upper atmosphere. Experiments will be conducted at the Sondrestrom incoherent scatter radar facility at Kangerlussauq, Greenland. The PI will use a routine measurement program (currently underway) to establish a database that characterizes different structures, such as single versus double layers, and latitudinal and altitude distributions. He will also use a new experimental mode that simultaneously determines latitudinal variation of electric fields and high resolution density structures. In conjunction with a new numerical model, these data will investigate the relative roles of electric fields and neutral winds in layer formation, determine the effects of time-varying E-fields, and discover the effects of aeronomic parameters, such as the ion-neutral collision frequency. Secondly, the PI will further develop a new Eulerian 3-time-dependent model of the polar ionosphere. This approach is advantageous to the traditional Lagrangian method in permitting efficient high spatial resolution, in turn allowing time-dependent studies of polar plasma structures and better comparisons with data. Using a new electric field model, the PI will investigate time-dependent ionospheric effects, particularly for northward interplanetary magnetic field (IMF) conditions. This model can determine the continuous ionospheric response to a time-varying IMF. He can then predict "space weather" effects, if appropriate IMF and space-particle data inputs are available to the model.
This award will continue the operation of the AlaskaCanada meridian chain of magnetomers and riometers as a tool for the continued investigation of high-latitude geomagnetic phenomena and also as a remote sensing facility for the space physics community. The chain has provided a virtually continuous database for study since the 1950s. Data from various sites are returned in near real time to the NOAA Space Environment Laboratory where it is available for public use and distribution. The data are used to study magnetospheric processes, including substorms, convection patterns, ionospheric currents, geomagnetic pulsations and the polar cusp. The data are also used to support rocket and satellite experiments that require information about the overall conditions in the space environment. The investigators will continue to operate the chain, provide data to the data center and conduct scientific studies of geomagnetic processes. Three GOES satellite radio transmitters will be purchased to allow real-time transmission of data from the remote sites to the Space Environment Center in Boulder, Colorado.
This project will apply the capabilities of the existing SuperDARN (Dual Auroral Radar Network) high-frequency (HF) radar pairs in the Arctic and Antarctic to the data needs of the National Space Weather Program (NSWP). These radars are operated in large arrays in both polar regions by several nations. One of the principal ways in which solar activity influences the Earth is through the effect of the solar wind on the magnetosphere and the upper atmosphere. The SuperDARN radars measure the flow velocity of ionospheric structures in the upper atmosphere from which the driving magnetospheric electric fields can be deduced. Thus, in its present form, the radars can provide important data for the research component of the NSWP. Additionally, the project will implement real-time data links which will provide alerts of sudden disturbances in the near-Earth space environment.
This three-year program will quantify the individual energy streams that make up the arctic surface radiation budget, and will relate the observed radiation distribution to synoptic-scale wind, pressure and moisture patterns. It will be the first effort to produce a comprehensive radiation climatology for the Arctic. The arctic surface energy budget, particularly that of the Arctic Ocean, has been identified as a major component of the global climate system that is potentially sensitive to climate-scale perturbations due to feedback mechanisms involving the surface albedo, the stability of the lower troposphere and water vapor transport. The project includes four main tasks: (1) the analysis of solar and long-wave radiation data obtained directly at manned observation sites in the Arctic; (2) the calculation of radiative fluxes at the surface and at the top of the atmosphere using a satellite-based cloud data product from the International Satellite Cloud Climatology Project (ISCCP); (3) for selected months, the ISCCP-derived fluxes will be compared to the corresponding synoptic regime; and (4) a study to assess the effects of the sampling and analysis procedure on the radiation statistics and their temporal variability will be undertaken.
This research involves the application of two observational methods for the study of Polar Stratospheric Clouds (PSCs) and ozone in the Arctic winter vortex. The first method uses balloon-borne aerosol and particle instrumentation floating with a fixed air mass for many days as PSCs begin to form and evolve, while at the same time ozone concentrations will be measured. The second approach involves making normal balloon soundings with similar equipment at several Arctic stations which, in contrast to the first method, will provide information on the evolution of PSCs over a fixed location. This project is a continuation and refinement of an ongoing successful international (United States, Russia, Germany, Denmark and Finland) effort and represents a new approach to identifying and quantifying ozone loss in the Arctic Stratosphere.
Infrared observations of the atmosphere from two sites in the Arctic are proposed: Fairbanks, Alaska, and Eureka, Northwest Territories, Canada. The instrument at Fairbanks will be a very high-spectral-resolution solar absorption spectrometer. This instrument covers the range from 2.5 to 15°m. At least 30 chemical compounds have absorptions in the instrument bandpass. This permits the derivation of total atmospheric quantities of those gases. The very high spectral resolution permits recovery of altitude profile information for at least half a dozen gases, including ozone, HCI, HF, and N2O. This information will be used to study stratospheric chemistry and dynamics, and will be compared with data from McMurdo Station, Antarctica and other Northern Hemisphere sites. Fairbanks is usually outside of the stratospheric polar vortex, but is in the area where maximum leakage of vortex air occurs. This allows the study of filaments of materials with different temperature, sunlight and chemical conditioning. The Eureka (80°N, 86°W) instrument is a medium-spectral-resolution system designed to measure the infrared thermal emission of the atmosphere. This instrument covers the range from 6 to 15°m. The atmosphere is very cold, and the signal is small, but measurements can be made in the absence of sunlight. Eureka is usually on the edge of the polar vortex, allowing observations in and out of vortex conditions within a few days. The amounts of several gases can be determined from the observations, particularly HNO3, which is directly involved in the formation of polar stratospheric clouds (PSC), and the chemical processing that occurs in ozone destroying conditions. The spectral data also relate directly to the greenhouse effect, and will be used to study the effect of chemistry, clouds and snow on the radiation balance. Both instruments will be used for the study of chemical processes that occur in the Arctic during the winter. The multiyear data set will be important in the study of seasonal cycles, and in the study of global change.
This project provides funds to service ARGOs via the Office of Climatic and Atmospheric Research of NOAA for processing data obtained from a satellite system which provides global coverage every six hours. The ARGOs system was placed on Tiros and NOAA satellites launched since 1979. The ARGOs system provides a means of locating platforms and relaying environmental measurements from these platforms. The data are relayed from the platforms to the satellite and thence to a ground station in France where they are processed and sent to individual users. Scientific experiments sponsored by the NSF, which require the use of the ARGOs system, include the studies of ocean circulation patterns using fixed and drifting buoys, and the weather and climate of Antarctica.