High-flying Aircraft Research Articles

Spatially coordinated airborne data and complementary products for aerosol, gas, cloud, and meteorological studies: the NASA ACTIVATE dataset

Abstract. The NASA Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) produced a unique dataset for research into aerosol–cloud–meteorology interactions, with applications extending from process-based studies to multi-scale model intercomparison and improvement as well as to remote-sensing algorithm assessments and advancements. ACTIVATE used two NASA Langley Research Center aircraft, a HU-25 Falcon and King Air, to conduct systematic and spatially coordinated flights over the northwest Atlantic Ocean, resulting in 162 joint flights and 17 other single-aircraft flights between 2020 and 2022 across all seasons. Data cover 574 and 592 cumulative flights hours for the HU-25 Falcon and King Air, respectively. The HU-25 Falcon conducted profiling at different level legs below, in, and just above boundary layer clouds (< 3 km) and obtained in situ measurements of trace gases, aerosol particles, clouds, and atmospheric state parameters. Under cloud-free conditions, the HU-25 Falcon similarly conducted profiling at different level legs within and immediately above the boundary layer. The King Air (the high-flying aircraft) flew at approximately ∼ 9 km and conducted remote sensing with a lidar and polarimeter while also launching dropsondes (785 in total). Collectively, simultaneous data from both aircraft help to characterize the same vertical column of the atmosphere. In addition to individual instrument files, data from the HU-25 Falcon aircraft are combined into “merge files” on the publicly available data archive that are created at different time resolutions of interest (e.g., 1, 5, 10, 15, 30, 60 s, or matching an individual data product's start and stop times). This paper describes the ACTIVATE flight strategy, instrument and complementary dataset products, data access and usage details, and data application notes. The data are publicly accessible through https://doi.org/10.5067/SUBORBITAL/ACTIVATE/DATA001 (ACTIVATE Science Team, 2020).

Quantification and mitigation of the instrument effects and uncertainties of the airborne limb imaging FTIR GLORIA

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an infrared imaging FTS (Fourier transform spectrometer) with a 2-D infrared detector that is operated on two high-flying research aircraft. It has flown on eight campaigns and measured along more than 300 000 km of flight track. This paper details our instrument calibration and characterization efforts, which, in particular, almost exclusively leverage in-flight data. First, we present the framework of our new calibration scheme, which uses information from all three available calibration sources (two blackbodies and upward-pointing “deep space” measurements). Part of this scheme is a new algorithm for correcting the erratically changing nonlinearity of a subset of detector pixels and the identification of the remaining bad pixels. Using this new calibration, we derive a 1σ bound of 1 % on the instrument gain error and a bound of 30 nW cm−2 sr−1 cm on the instrument offset error. We show how we can examine the noise and spectral accuracy for all measured atmospheric spectra and derive a spectral accuracy of 5 ppm on average. All these errors are compliant with the initial instrument requirements. We also discuss, for the first time, the pointing system of the GLORIA instrument. Combining laboratory calibration efforts with the measurement of astronomical bodies during the flight, we can achieve a pointing accuracy of 0.032∘, which corresponds to one detector pixel. The paper concludes with a brief study of how these newly characterized instrument parameters affect temperature and ozone retrievals. We find that the pointing uncertainty and, to a lesser extent, the instrument gain uncertainty are the main contributors to the error in the result.

Impact of COVID-19 on Environmental Issues- First Impressions

COVID-19 has generated an unprecedented impact in almost all countries of the world. As on 20 July 2020, there have been 14,043,176 confirmed cases of COVID-19, including 597,583 deaths, reported to WHO. Most countries have tried to fight the spread of the virus with lockdown and policies of social distancing along with COVID-19 screening tests and isolating the affected by institutional or home quarantine for protecting people's health.Satellite images confirm dramatic improvements in every country affected by the pandemic in air quality, as industry and transport shut down. Shipping has declined worldwide and reduced impacts on marine systems might be expected. This year will very likely see a global decline in greenhouse gas emissions, as well as large reductions in other drivers of global warming, such as the contrail cirrus from high-flying aircraft. These may be short-term improvements, but they dramatically underline the pervasiveness and severity of anthropogenic impacts worldwide. Protected areas appear to be safe at this point. Biodiversity is benefitting due to reduced human activities.The first studies estimated an increased organic waste from home, Increase in Medical waste and Reduction in waste recycling also. Noise, air, and water pollution, greenhouse gas emissions, and the many other adverse human impacts on wild nature will rebound. Society's priorities must be containment of the pandemic and human health. However, we need to have resumption of conservation practice and education. Reduction on funding and other support for conservation are likely, as they will have to compete with a wide range of new priorities for financial resources.This paper uses secondary data sources and observations of researchers.

EUropean Heliospheric FORecasting Information Asset 2.0

Aims: This paper presents a H2020 project aimed at developing an advanced space weather forecasting tool, combining the MagnetoHydroDynamic (MHD) solar wind and coronal mass ejection (CME) evolution modelling with solar energetic particle (SEP) transport and acceleration model(s). The EUHFORIA 2.0 project will address the geoeffectiveness of impacts and mitigation to avoid (part of the) damage, including that of extreme events, related to solar eruptions, solar wind streams, and SEPs, with particular emphasis on its application to forecast geomagnetically induced currents (GICs) and radiation on geospace.Methods: We will apply innovative methods and state-of-the-art numerical techniques to extend the recent heliospheric solar wind and CME propagation model EUHFORIA with two integrated key facilities that are crucial for improving its predictive power and reliability, namely (1) data-driven flux-rope CME models, and (2) physics-based, self-consistent SEP models for the acceleration and transport of particles along and across the magnetic field lines. This involves the novel coupling of advanced space weather models. In addition, after validating the upgraded EUHFORIA/SEP model, it will be coupled to existing models for GICs and atmospheric radiation transport models. This will result in a reliable prediction tool for radiation hazards from SEP events, affecting astronauts, passengers and crew in high-flying aircraft, and the impact of space weather events on power grid infrastructure, telecommunication, and navigation satellites. Finally, this innovative tool will be integrated into both the Virtual Space Weather Modeling Centre (VSWMC, ESA) and the space weather forecasting procedures at the ESA SSCC in Ukkel (Belgium), so that it will be available to the space weather community and effectively used for improved predictions and forecasts of the evolution of CME magnetic structures and their impact on Earth.Results: The results of the first six months of the EU H2020 project are presented here. These concern alternative coronal models, the application of adaptive mesh refinement techniques in the heliospheric part of EUHFORIA, alternative flux-rope CME models, evaluation of data-assimilation based on Karman filtering for the solar wind modelling, and a feasibility study of the integration of SEP models.

Laser reflection method for vegetation monitoring at eye-safe sensing wavelengths in the NIR spectral band

The paper analyses capabilities of a laser reflection method for remote vegetation monitoring at eye-safe sensing wavelengths in the NIR spectral band and provides a statistical simulation of correct detection and false alarm probabilities to solve the tasks of vegetation monitoring. Shows that at the wavelengths of 1.54 и 2.03 μm, for example, the laser reflection method of sensing allows us to detect vegetation under adverse conditions with a probability of correct detection close to one and a probability of false alarm ∼ second decimal places. The laser reflection method using two sensing wavelengths in the NIR spectral band can be accepted as a basis of the vegetation monitoring method using a high-flying aircraft.

Vertically Propagating Mountain Waves—A Hazard for High-Flying Aircraft?

AbstractStall warnings at flight level 410 (12.5 km) occurred unexpectedly during a research flight of the High Altitude and Long Range Research Aircraft (HALO) over Italy on 12 January 2016. The dangerous flight situation was mitigated by pilot intervention. At the incident location, the stratosphere was characterized by large horizontal variations in the along-track wind speed and temperature. On this particular day, strong northwesterly winds in the lower troposphere in concert with an aligned polar front jet favored the excitation and vertical propagation of large-amplitude mountain waves at and above the Apennines in Italy. These mountain waves carried large vertical energy fluxes of 8 W m−2 and propagated without significant dissipation from the troposphere into the stratosphere. While turbulence is a well-acknowledged hazard to aviation, this case study reveals that nonbreaking, vertically propagating mountain waves also pose a potential hazard, especially to high-flying aircraft. It is the wave-induced modulation of the ambient along-track wind speed that may decrease the aircraft speed toward the minimum needed stall speed.

Possible climatic implications of high-altitude black carbon emissions

Abstract. On account of its strong absorption of solar and terrestrial radiation, black carbon (BC) aerosol is known to impact large-scale systems, such as the Asian monsoon and the Himalayan glaciers, in addition to affecting the thermal structure of the lower atmosphere. While most studies focus on the near-surface abundance and impacts of BC, our study examines the implications of sharp and confined layers of high BC concentration (called elevated BC layers) at altitudes more than 4 km over the Indian region using the online regional chemistry transport model (WRF-Chem) simulations. These elevated BC layers were revealed in the recent in situ measurements using high-altitude balloons carried out on 17 March 2010, 8 January 2011 and 25 April 2011. Our study demonstrates that high-flying aircraft (with emissions from the regionally fine-tuned MACCity inventory) are the most likely cause of these elevated BC layers. Furthermore, we show that such aircraft-emitted BC can be transported to upper tropospheric or lower stratospheric heights ( ∼ 17 km) aided by the strong monsoonal convection occurring over the region, which is known to overshoot the tropical tropopause, leading to the injection of tropospheric air mass (along with its constituent aerosols) into the stratosphere. We show observational evidence for such an intrusion of tropospheric BC into the stratosphere over the Indian region using extinction coefficient and particle depolarisation ratio data from CALIOP Lidar on-board the CALIPSO satellite. We hypothesise that such intrusions of BC into the lower stratosphere and its consequent longer residence time in the stratosphere have significant implications for stratospheric ozone, especially considering the already reported ozone-depleting potential of BC.

Cosmic Dust: Finding a Needle in a Haystack

Collecting cosmic dust is a tricky business! Despite Earth's surface being showered by thousands of tons of comic dust every year, such dust is quickly lost in a sea of terrestrial particles. Finding the tiny cosmic treasures requires collecting dust from the cleanest environments where the terrestrial particle background is low. The stratosphere can be sampled via high-flying aircraft, whereas sampling cosmic dust from polar regions and the deep sea requires techniques that concentrate the particles. Collection efforts are worth it. Cosmic dust derives from every dust-producing object in the Solar System, including ancient Solar System materials, possibly even interstellar materials, of a type not found in meteorites.

Cirrus and the Earth system

Cirrus and the Earth system

ChemInform Abstract: Cosmic Dust in the Earth′s Atmosphere

AbstractReview: 100 refs.

CRISTA-NF measurements with unprecedented vertical resolution during the RECONCILE aircraft campaign

Abstract. The Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF), an airborne infrared limb-sounder, was operated aboard the high-flying Russian research aircraft M55-Geophysica during the Arctic RECONCILE campaign from January to March 2010. This paper describes the calibration process of the instrument and the retrieval algorithm employed and then proceeds to present retrieved trace gas volume mixing ratio cross-sections for one specific flight in this campaign. We are able to resolve the uppermost troposphere/lower stratosphere for several trace gas species for several kilometres below the flight altitude (16 to 19 km) with an unprecedented vertical resolution of 400 to 500 m for the limb-sounding technique. The instrument points sideways with respect to the flight direction. Therefore, the observations are also characterised by a rather high horizontal sampling along the flight track, which provides a full vertical profile every ≈15 km. Assembling the vertical trace gas profiles derived from CRISTA-NF measurements to cross-sections shows filaments of vortex and extra-vortex air masses in the vicinity of the polar vortex. During this campaign, the M55-Geophysica carried further instruments enabling trace gas volume mixing ratios derived from CRISTA-NF to be validated by comparing them with measurements by the in situ instruments HAGAR and FOZAN and observations by MIPAS-STR. This validation suggests that the retrieved trace gas volume mixing ratios are both qualitatively and quantitatively reliable.

Cosmic dust in the earth's atmosphere

This review discusses the magnitude of the cosmic dust input into the earth's atmosphere, and the resulting impacts from around 100 km to the earth's surface. Zodiacal cloud observations and measurements made with a spaceborne dust detector indicate a daily mass input of interplanetary dust particles ranging from 100 to 300 tonnes, which is in agreement with the accumulation rates of cosmic-enriched elements (Ir, Pt, Os and super-paramagnetic Fe) in polar ice cores and deep-sea sediments. In contrast, measurements in the middle atmosphere - by radar, lidar, high-flying aircraft and satellite remote sensing - indicate that the input is between 5 and 50 tonnes per day. There are two reasons why this huge discrepancy matters. First, if the upper range of estimates is correct, then vertical transport in the middle atmosphere must be considerably faster than generally believed; whereas if the lower range is correct, then our understanding of dust evolution in the solar system, and transport from the middle atmosphere to the surface, will need substantial revision. Second, cosmic dust particles enter the atmosphere at high speeds and undergo significant ablation. The resulting metals injected into the atmosphere are involved in a diverse range of phenomena, including: the formation of layers of metal atoms and ions; the nucleation of noctilucent clouds, which are a sensitive marker of climate change; impacts on stratospheric aerosols and O(3) chemistry, which need to be considered against the background of a cooling stratosphere and geo-engineering plans to increase sulphate aerosol; and fertilization of the ocean with bio-available Fe, which has potential climate feedbacks.

CRISTA-NF measurements during the AMMA-SCOUT-O3 aircraft campaign

Abstract. The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere – New Frontiers (CRISTA-NF) instrument participated in the AMMA-SCOUT-O3 measurement campaign in July and August 2006. The instrument is mounted on the high-flying Russian research aircraft M55-Geophysica and measures limb-emissions in the mid-infrared region in the tangent altitude range of about 6 to 21 km. We present a new retrieval setup which is based on 9 integrated spectral windows allowing to retrieve an extended set of trace gases and temperature fields with high vertical resolution (up to 500 m). Retrieval results are shown for temperature, water vapor (H2O), ozone (O3), nitric acid (HNO3), peroxyacetyl nitrate (PAN), carbon tetrachloride (CCl4), and aerosol extinction. Comparisons of temperature, O3, and H2O observations with corresponding in situ measurements on-board M55-Geophysica show reasonable agreement. In particular, CRISTA-NF observations in the vicinity of the aircraft resemble horizontal variations found in the in situ measurements better than corresponding ECMWF fields.

A New Look at High-Altitude Turbulence

Reconnaissance by aircraft from high altitudes remains an important priority for the Department of Defense. Aircraft at these altitudes experience both traditional mechanical turbulence as well as oscillatory fluctuations of temperature and horizontal and vertical wind speeds, which are attributed to gravity (also called buoyancy) waves. This paper investigates the effects of wavelike behavior on high-flying aircraft, finding high aircraft loads at certain frequencies. Aircraft are most susceptible to problems at the upper range of altitudes. This analysis shows that autopilots based on maintaining a constant Mach number and an indicated airspeed are both susceptible to temperature fluctuations. In addition, temperature changes shift the flight envelope, creating potentially dangerous stall or overspeeding conditions. The absence of temperature variation requirements in current aviation continuous gust load specifications along with a possible deficiency in gust magnitude design requirements at high altitude lead to a recommendation for revisiting high-altitude turbulence requirements and investigating the vulnerabilities of high-altitude unmanned aircraft.

The role of remote sensing in finding hydrothermal mineral deposits on earth.

The identification of surface mineralogical composition using hyperspectral sensors is now the major remote sensing opportunity for exploration geologists seeking refined vectors to potential ore-bearing hydrothermal systems. This involves no less than remote, visible and infrared spectroscopy of the molecular composition of geological materials from remote platforms using a large number of calibrated spectral bands. From field-portable systems to those flying in high-flying aircraft on the edges of space, it is now possible to define a long list of minerals and their weathering products detectable at these wavelengths. These include hydroxyl-bearing minerals such as hydrothermal clays, sulfates, ammonium-bearing minerals, phyllosilicates, iron oxides, carbonates, and a wide range of silicates. Indeed, even the chemical composition of micas and chlorites has been mapped remotely using subtle wavelength shifts in their diagnostic reflectance spectra, indicating varying degrees of Na, K, Al, Mg and Fe substitution. Spatial zones, relative abundances and assemblages of these minerals allow geologists to reconstruct the mineralogical, chemical and sometimes thermal disposition of ancient hydrothermal systems in their search for optimal drilling targets. Such minerals not only result directly from the hydrothermal processes involved but may also 'expose' older host rocks caught up in the process and brought to the surface. New microwave radar systems are also shedding new light on landscape processes, textures and structure and occasionally penetrating dry surface layers to reveal buried structures.

Astronomy from Antarctica

Astronomers have always sought the very best locations for their telescopes. From observatories in city centres, astronomers moved first to nearby mountain tops, then to remote sites in distant countries, to aircraft, and into space. In the past decade we have come to realize that the best astronomical observing conditions on the surface of the earth are to be found on the Antarctic plateau. The combination of high altitude, low temperature, low absolute humidity, low wind and extremely stable atmosphere offers astronomers gains in sensitivity and measurement precision that can exceed two orders of magnitude over even the best temperate sites. In addition, spectral windows are opened up – particularly in the far-infrared and terahertz regions – that are otherwise only accessible from high-flying aircraft or from space. Established and highly successful telescopes at the South Pole are soon to be joined by a new generation of facilities at Concordia Station, including large telescopes and interferometers. It has even been suggested that the largest optical telescopes currently proposed, with diameters of up to 100 m, might achieve their science goals at a lower overall cost if they are built on the Antarctic plateau rather than at a temperate site. Such telescopes offer the possibility of not only detecting earth-like planets in other star systems, but also of analysing their atmospheres spectroscopically.

Meteorological benefits from atmospheric nuclear tests.

The presence in the atmosphere of radioactive debris from nuclear tests provided a unique opportunity to study atmospheric motions and transfers of trace substances. Measurements of the concentrations in air of radionuclides were used to verify trajectories derived solely from weather data. The profiles of radioactive concentration along the aircraft tracks were non-Gaussian. High-flying aircraft and balloons collected air and particulate samples to approximately 30,000 m from Alaska to South America. The measurements from these samples were used in verifying stratospheric motions on a hemispheric and global scale. Other benefits to the atmospheric sciences gained during the nuclear testing era are briefly described.

Dynamics of Droplets

1R36. Dynamics of Droplets. - A Frohn and N Roth (Inst fur Thermodynamik, Univ of Stuttgart, Pfaffenwaldring 31, Stuttgart, 70550, Germany). Springer-Verlag, Berlin. 2000. 292 pp. ISBN 3- 540-65887-4. $82.00.Reviewed by Y Chisti (Inst of Tech and Eng, Massey Univ, Private Bag 11 222, Palmerston N, New Zealand).Many natural and technical processes depend on generation of droplets and interaction among droplets and other phases. Droplet dynamics influence processes as diverse as cloud formation, rain, spray painting, and dispersal of aerosols. Because of its wide-ranging significance, substantial research literature has accumulated on droplet dynamics, but not many books treat this subject. This book provides a useful discussion of droplet dynamics in a compact volume. Some of the theoretical aspects relevant to drop dynamics are covered in an extensive first chapter. The major topics discussed include surface tension and internal pressure; liquid-liquid and solid-liquid interfaces; charged droplets; small-amplitude droplet oscillations; internal circulation; instability of droplets; instability of jets; relaxation phenomena; thermodynamics; phase transition processes; droplet evaporation; and interaction of light with droplets. Topics, such as internal circulation and how it is affected by droplet dimensions and the presence of surfactants, are addressed quite poorly despite the importance of these topics in many processing scenarios. A chapter is devoted to droplet generation. This subject is discussed in less depth than some of the other topics in the book. Much practical information exists on design, selection, and operation of spray nozzles and other droplet generation devices, but the book does not reflect this knowledge. Pressure atomizers, rotary atomizers, and ultrasonic atomizers are barely mentioned. A chapter entitled “Droplet systems” addresses topics such as sprays, streams and arrays of droplets, and single droplets suspended by various means. An extensive chapter deals with the relevant measurement techniques such as the photographic methods, techniques of measuring velocity and size, measurement of optical properties, temperature, and surface tension. Not all available methods are discussed sufficiently or thoroughly. In most practical droplet systems, droplets interact among themselves with the suspending gas and with the suspended solids. Methods for the study of such physical interactions in flow systems are devoted a chapter. Many droplet-related processes involve phase transitions. Examples are condensation of water vapor into clouds, evaporation of fuel droplets during combustion, and spray-drying of droplets to powders. Some of the experimental methods for study of phase transition in droplet systems are discussed in an extensive chapter devoted entirely to this subject. Combustion related phase transition phenomena are discussed in particular depth. Some of the applications of droplet dynamics are outlined briefly, perhaps superficially, in a chapter entitled “Miscellaneous applications.” The applications mentioned include everything from ink jet printing to gaining an understanding of development of condensation trails of high-flying aircraft. The book covers many topics, but also leaves out a great deal. Nevertheless, this book should prove useful to anyone working on droplet dynamics and related fields such as spray technology and aerosol science. The book’s emphasis on experimental methods is one of its strong points. The book cites more than 500 references and is illustrated with more than 200 figures of generally good quality. On the negative side, the writing is needlessly verbose and sometime irritatingly so. The book’s short index is not especially useful, but this shortcoming is partly compensated for by a detailed table of contents. The text is hardbound, of good quality, and is reasonably priced ($82.00) for a specialist monograph. Dynamics of Droplets is a recommended acquisition for research libraries and individuals working on droplet dynamics.

Tracking Africa’s Inferno

This article focuses on instruments aboard an orbiting satellite and high-flying aircraft study grass fires that straddle a continent. NASA designed its $1.3 billion Terra to be the flagship in a new series of Earth-observing satellites that will study phenomena affecting the climate. The instruments carried by Terra that were most active during the Safari 2000 field experiment were Moderate-Resolution Imaging Spectro-Radiometer (MODIS), Multi-Angle Imaging Spectro-Radiometer (MISR), and Measurements of Pollution in the Troposphere (MOPITT). MOPITT accomplishes its mission by using gas correlation spectroscopy to measure rising and reflected infrared radiance in three absorption bands of carbon monoxide and methane. The Terra’s Safari 2000 observations were augmented by measurements taken by instruments aboard several aircraft, including the high-altitude Lockheed-Martin ER-2 that NASA flew from Pietersburg, South Africa, as part of the African field experiment. The South African Weather Bureau contributed two Aerocommander 690A aircraft to Safari 2000. One of the twin-engine, turboprop planes was used for aerosol research, while the other one helped validate the carbon monoxide measurements obtained by MOPITT.

CF4 and the Age of Mesospheric and Polar Vortex Air

A chronology of tropospheric CF4 mixing ratios is reported for the northern hemisphere. A decline of global emissions of CF4 from 16,000 to 11,000 metric tons yr−1 is found for the periods 1978–1990 and 1992–1998, respectively. The atmospheric chronology of CF4 is applied to determine the age of air of cryogenic air samples collected on rocket and balloon platforms. Age values of 7 years are found inside the polar vortex between 25–44 km altitude and of 11 years between 56 and 61 km altitude, which is significantly higher than predicted by most models currently used to assess the effects of high‐flying aircraft. The results suggest that the mesosphere is more isolated from below than previously believed. A comparison of age values derived from CF4 and SF6 relative to predicted deviations constrains the atmospheric lifetime of SF6 to >5,000 years.