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Aerosol observations for climate studies

The Stratospheric Aerosol Measurement II and Stratospheric Aerosol and Gas Experiment satellite systems have provided to date more than five years and almost three years, respectively, of data on atmospheric aerosol profiles on a near-global scale. Studies with these unique data sets are developing a global aerosol climatology for the first time and have shown the existence and quantification of polar stratospheric clouds and tropical stratospheric cirrus. In addition, a tropospheric cirrus climatology is evolving. Since these two experiments were launched, a series of large volcanic eruptions have occurred which have greatly impacted the stratospheric aerosol loading. The aerosol layer produced by the eruption of El Chichon, for example, increased the 30 mb temperatures in the northern tropics by as much as 4 C for six months after the eruption. This paper describes in detail, from a climate perspective, the evolving aerosol and cloud climatologies as a function of space and time, and shows the stratospheric dynamics of volcanic injections and their enhancements on stratospheric optical depth and mass loading.

Mccormick, M. P.↗

Floor-fractured craters on the moon and Mars

Impact craters on the moon provided primary pathways for volcanic eruptions through shock-induced fractures that immediately or subsequently tap magma reservoirs. Evidence for this process includes unbreached lava-filled craters and fractured crater floors with associated eruptives. Over 200 craters with floor fractures have been identified on the moon. They commonly occur along the margins of irregular maria, thereby suggesting a link to this important phase of lunar volcanism. Topographic data reveal small elevation differences between the summit of the remnant central peaks and crater rim, and in many cases suggest that floor fracturing resulted from a tabular intrusion localized beneath the crater with uplift of the crater floor. A comparison of lunar and Martian crater photographs shows that some Martian craters also exhibit similar highly localized endogenic modifications.

Schultz, P. H.↗

Analysis of active volcanoes from the Earth Observing System

The Earth Observing System (EOS) scheduled for launch in 1997 and 1999 is briefly described, and the EOS volcanology investigation objectives are discussed. The volcanology investigation will include long- and short-term monitoring of selected volcanoes, the detection of precursor activity associated with unanticipated eruptions, and a detailed study of on-going eruptions. A variety of instruments on the EOS platforms will enable the study of local- and regional-scale thermal and deformational features of volcanoes, and the chemical and structural features of volcanic eruption plumes and aerosols.

Mouginis-Mark, Peter↗

Mid-infrared extinction by sulfate aerosols from the Mt. Pinatubo eruption

Quantitative measurements of the wavelength dependence of aerosol extinction in the 750-3400/cm spectral region have been derived from 0.01/cm resolution stratospheric solar occultation spectra recorded by the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer about 9 1/2 months after the Mt Pinatubo volcanic eruption. Strong, broad aerosol features have been identified near 900, 1060, 1190, 1720, and 2900/cm below a tangent height of approximately 30 km. Aerosol extinction measurements derived from approximately 0.05/cm wide microwindows nearly free of telluric line absorption in the ATMOS spectra are compared with transmission calculations derived from aerosol size distribution profiles retrieved from correlative SAGE (Stratospheric Aerosol and Gas Experiment) II visible and near i.r. extinction measurements, seasonal and zonally averaged H2SO4 aerosol weight percentage profiles, and published sulfuric acid optical constants derived from room temperature laboratory measurements. The calculated shapes and positions of the aerosol features are generally consistent with the observations, thereby confirming that the aerosols are predominantly concentrated H2SO4-H2O droplets, but there are significant differences between the measured and calculated wavelength dependences of the aerosol extinction. We attribute these differences as primarily the result of errors in the calculated low temperature H2SO4-H2O optical constants. Errors in both the published room temperature optical constants and the limitations of the Lorentz-Lorenz relation are likely to be important.

Rinsland, C. P.↗

Terrestrial Analog Field Investigations to Enable Science and Exploration Studies of Impacts and Volcanism on the Moon, NEAs, and Moons of Mars

Terrestrial analog studies are a critical component for furthering our understanding of geologic processes on the Moon, near-Earth asteroids (NEAs), and the moons of Mars. Carefully chosen analog sites provide a unique natural laboratory with high relevance to the associated science on these solar system target bodies. Volcanism and impact cratering are fundamental processes on the Moon, NEAs, and Phobos and Deimos. The terrestrial volcanic and impact records remain invaluable for our understanding of these processes throughout our solar system, since these are our primary source of firsthand knowledge on volcanic landform formation and modification as well as the three-dimensional structural and lithological character of impact craters. Regarding impact cratering, terrestrial fieldwork can help us to understand the origin and emplacement of impactites, the history of impact bombardment in the inner Solar System, the formation of complex impact craters, and the effects of shock on planetary materials. Volcanism is another dominant geologic process that has significantly shaped the surface of planetary bodies and many asteroids. Through terrestrial field investigations we can study the processes, geomorphic features and rock types related to fissure eruptions, volcanic constructs, lava tubes, flows and pyroclastic deposits. Also, terrestrial analog studies have the advantage of enabling simultaneous robotic and/or human exploration testing in a low cost, low risk, high fidelity environment to test technologies and concepts of operations for future missions to the target bodies. Of particular interest is the importance and role of robotic precursor missions prior to human operations for which there is little to no actual mission experience to draw upon. Also critical to understanding new worlds is sample return, and analog studies enable us to develop the appropriate procedures for collecting samples in a manner that will best achieve the science objectives.

complex impact craters↗

Fluid dynamics of multiphase flow in volcanic environments on the Earth, Io, and other planets

Data was compiled on H2O, CO2, S, and SO2 and it was analyzed by various techniques to prepare phase diagrams relevant to conditions on the Earth, Io, Mars, and other planets. The use of Cray models for volcanic eruptions was examined. Attempts are being made to develop equations of state of the compounds listed above to be compatible with the Cray code so that they can be called as subroutines for the volcanic models. This is a major project, as the current code uses only the equation of state for a perfect gas, and requires that the atmosphere be the same composition as the volcanic gas. The analysis of the thermodynamic data is time consuming, and was complicated by changes from a VAX/VMS system to Macintosh's, Crays using CTSS, Crays using Unicos, and Sun workstations.

Kieffer, Susan Werner↗

CALIPSO Detection of an Asian Tropopause Aerosol Layer

The first four years of the CALIPSO lidar measurements have revealed the existence of an aerosol layer at the tropopause level associated with the Asian monsoon season in June, July and August. This Asian Tropopause Aerosol Layer (ATAL) extends geographically from Eastern Mediterranean (down to North Africa) to Western China (down to Thailand), and vertically from 13 to 18 km. The Scattering Ratio inferred from CALIPSO shows values between 1.10. 1.15 on average with associated depolarization ratio of less than 5%. The Gaussian distribution of the points indicates that the mean value is statistically driven by an enhancement of the background aerosol level and not by episodic events such as a volcanic eruption or cloud contamination. Further satellite observations of aerosols and gases as well as field campaigns are urgently needed to characterize this layer, which is likely to be a significant source of non-volcanic aerosols for the global upper troposphere with a potential impact on its radiative and chemical balance

Vemier, J.-P.↗

MISR Radiance Anomalies Induced by Stratospheric Volcanic Aerosols

The 16-year MISR monthly radiances are analyzed in this study, showing significant enhancements of anisotropic scattering at high latitudes after several major volcanic eruptions with injection heights greater than 14 km. The anomaly of deseasonalized radiance anisotropy between MISR’s DF and DA views (70.5° forward and aft) is largest in the blue band with amplitudes amounting to 5–15% of the mean radiance. The anomalous radiance anisotropy is a manifestation of the stronger forward scattering of reflected sunlight due to the direct and indirect effects of stratospheric volcanic aerosols (SVAs). The perturbations of MISR radiance anisotropy from the Kasatochi (August 2008), Sarychev (June 2009), Nabro (June 2011) and Calbuco (April 2015) eruptions are consistent with the poleward transported SVAs observed by CALIOP and OMPS-LP. In a particular scene over the Arctic Ocean, the stratospheric aerosol mid-visible optical depth can reach as high as 0.2–0.5. The enhanced global forward scattering by SVAs has important implications for the shortwave radiation budget

radiance anisotropy; volcanic aerosol direct and i↗

Solar Mesosphere Explorer observations of stratospheric and mesospheric water vapor

It is noted that while the SME (Solar Mesosphere Explorer) data is consistent with the earlier LIMS (Limb Infrared Monitor of the Stratosphere) results, its interpretation is complicated by aerosol contamination, particularly at altitudes below 35 km. This contamination arose from several volcanic eruptions, including that of El Chichon. Analyses are reported of a subset of data from the SME satellite, concentrating primarily on the period January through March 1982 so as to avoid contamination from the El Chichon volcanic aerosol. The SME observations of water vapor between 20 and 60 km were inverted for the first three months of 1982 as well as for selected additional periods. Reasonable results are obtained at locations where no contamination by aerosol is suspected.

Jakosky, Bruce M.↗

Vertical Profiles of Aerosol Volume from High Spectral Resolution Infrared Transmission Measurements: Results

The high-resolution infrared absorption spectra of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are utilized to derive vertical profiles of sulfate aerosol volume density and extinction coefficient. Following the eruption of Mt. Pinatubo in June 1991, the ATMOS spectra obtained on three Space Shuttle missions (1992, 1993, and 1994) provide a unique opportunity to study the global stratospheric sulfate aerosol layer shortly after a major volcanic eruption and periodically during the decay phase. Synthetic sulfate aerosol spectra are fit to the observed spectra, and a global fitting inversion routine is used to derive vertical profiles of sulfate aerosol volume density. Vertical profiles of sulfate aerosol volume density for the three missions over portions of the globe are presented, with the peak in aerosol volume density occurring from as low as 10 km (polar latitudes) to as high as 20 km (subtropical latitudes). Derived aerosol volume density is as high as 2-3.5 (mu)m(exp 3) per cubic centimeter +/-10% in 1992, decreasing to 0.2-0.5 (mu)m(exp 3) per cubic centimeter +/-20% in 1994, in agreement with other experiments. Vertical extinction profiles derived from ATMOS are compared with profiles from Improved Stratospheric And Mesospheric Sounder (ISAMS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) that coincide in space and time and show good general agreement. The uncertainty of the ATMOS vertical profiles is similar to CLAES and consistently smaller than ISAMS at similar altitudes.

stratospheric aerosol↗

Volcanoes and global catastrophes

The search for a single explanation for global mass extinctions has let to polarization and the controversies that are often fueled by widespread media attention. The historic record shows a roughly linear log-log relation between the frequency of explosive volcanic eruptions and the volume of their products. Eruptions such as Mt. St. Helens 1980 produce on the order of 1 cu km of tephra, destroying life over areas in the 10 to 100 sq km range, and take place, on the average, once or twice a decade. Eruptions producing 10 cu km take place several times a century and, like Krakatau 1883, destroy life over 100 to 1000 sq km areas while producing clear global atmospheric effects. Eruptions producting 10,000 cu km are known from the Quaternary record, and extrapolation from the historic record suggests that they occur perhaps once in 20,000 years, but none has occurred in historic time and little is known of their biologic effects. Even larger eruptions must also exist in the geologic record, but documentation of their volume becomes increasingly difficult as their age increases. The conclusion is inescapable that prehistoric eruptions have produced catastrophes on a global scale: only the magnitude of the associated mortality is in question. Differentiation of large magma chambers is on a time scale of thousands to millions of years, and explosive volcanoes are clearly concentrated in narrow belts near converging plate margins. Volcanism cannot be dismissed as a producer of global catastrophes. Its role in major extinctions is likely to be at least contributory and may well be large. More attention should be paid to global effects of the many huge eruptions in the geologic record that dwarf those known in historic time.

Simkin, Tom↗

Assessing the Needs of NASA's Near Real-Time Earth Observation Products

"The 2017-2027 Decadal Survey for Earth Science and Applications from Space stated that NASA's Earth Science with planned implementation of applications provides sustained earth observations for societal benefits [1]. The Decadal Survey indicated that data latency is invaluable for time-sensitive applications including disaster risk reduction, wildland fire carbon emissions quantification, real-time measurements of the state of the hydrologic systems and many more. Data latency refers to the time between earth observation and data products available to users. During the past 13 years, NASA's Land, Atmosphere Near Real-Time Capability for Earth Observing Systems (LANCE) continues to provide free access to earth observation products that are made available much quicker than routine processing allows. The latency of most LANCE data products is Near Real-time (NRT) which is defined as less than three hours from satellite observations [2]. LANCE is managed by the Earth Science Data and Information System (ESDIS) Project at NASA Goddard Space Flight Center [3], and a User Working Group (UWG) is responsible for providing guidance to LANCE. LANCE data are used by direct users and brokers who add value to the data [4]. NASA Earth Applied Sciences Program (ASP) is one of the primary users of LANCE, which collaborates with partner organizations and provides support to scientists to solve problems in applications of earth observations. ASP promotes the use of LANCE NRT data products to demonstrate applications in decision making, facilitates end-user feedback to the science team to improve data products, and provides information on future demands for research. LANCE supports applications that need a rapid response including detecting wildland fires and volcanic eruptions, tracking smoke, ash and dust plumes, monitoring air quality and tracking extreme weather events such as hurricanes, landslides, and floods. To gather feedback regarding the availability, accessibility and actionability of NASA's NRT data products for societal benefit, three surveys and a few discussions with experts involved in the topic within ASP were conducted from the perspective of users. Feedback has been collected from users who are interested in using low latency NASA data within application communities of agriculture, disasters, water resources, health and air quality, ecological conservation, wildland fires and capacity building. Analysis-ready NRT data products in a variety of formats have been mentioned many times in the collected feedback, especially for applied users with little to no experience using research-grade earth observation products. Users prefer to have products that can be easily integrated into their existing workflows and take their analysis to the data. HDF5 is a commonly used data format for research, but typically requires some conversion to a more friendly format for applications and regular use in decision-making. Users prefer the GeoTIFF data format that can be directly ingested into a GIS mapping software and platform for data analysis and visualization. For example, LANCE’s fire, flood, SO2 and Black Marble Nighttime Blue/Yellow Composite data products have been integrated into NASA Disasters Mapping Portal, which is an GIS-based open data portal, for users in the disaster management community. There are 291 LANCE NRT layers available through GIBS and Worldview, where users can download a snapshot in GeoTIFF format. Operational users expect data to be processed as close to the user as possible. The collected feedback indicates that LANCE fire products within 3 hours latency would meet the needs of the wildland fire community. The ideal latency for volcanic application is 10-15 minutes. Users in Volcanic Ash Advisory Centers (VAAC) reported that the first forecast volcanic product should be issued within 75 minutes from the volcano eruption [5]. Overall, for disaster applications, data latency within 3 hours is useful while latency greater than 12 hours is not timely enough for operational use. Capacity building and training are critical for users to be able to access, interpret and use data products and tools for their decision making, especially for applied users with limited experience using earth observation products. LANCE data products have been used in a number of capacity building projects domestically and internationally [6]. As LANCE continues to bring new products into the system, users request training to utilize LANCE new and upcoming data products and capabilities in their applications. Due to the limitation of bandwidth and downstream flow paths, users in some developing countries need tools to select and download data for a specific area of interest instead of bulk downloads. The collected feedback also shows the lack of available SAR satellite low latency data products. The advantages of SAR to monitor conditions and changes on the ground through darkness, clouds, volcanic ash, and other atmospheric conditions, are appealing to low latency users. For example, terabytes of low latency but cloudy optical images are not helpful in rapidly identifying the extent of flood or fire impacts. LANCE could be complemented with low latency measurements via the upcoming NASA-ISRO Synthetic Aperture Radar (NISAR) mission [7]. Requests for higher spatial resolution products are expressed. A user from the wildland fire management community reported that products with 30-m spatial resolution could be used to detect small fires. The 30-m Landsat OLI fire data is now part of NASA’s Fire Information for Resource Management System (FIRMS) US/Canada [8]. Within the open and free NASA resources, LANCE disseminates NRT data products in a manner that allows them to be accessible and understandable to both scientific and applied users. In many application areas, latency plays an important or even decisive role where low latency earth observations help people to observe areas of interest, detect and track changes in the environment and make timely decisions. NASA’s Earth Applied Sciences Program promotes the use of LANCE NRT products and builds a bridge between application users and research teams. The collected feedback indicates data latency within 3 hours is useful for most of the applications, and shows the needs of user-friendly, analysis-ready products, and requests training on LANCE’s new and upcoming data products. User feedback has been provided to LANCE UWG for guidance and recommendations, and for translating findings into something actionable.

Tian Yao↗

Changes in stratospheric ozone and temperature due to the eruptions of Mt. Pinatubo

The paper investigates the impact of the Mt. Pinatubo eruptions on the total column ozone measured from the Nimbus 8 TOMS and the NOAA-11 SBUV/2 spectrometers. Within a few months after the eruptions, the total column ozone decreased by 5-6 percent in the tropics, 3-4 percent at midlatitudes, and 6-9 percent at high latitudes in the Northern Hemisphere. After the effects of quasi-biennial oscillations and interannual variability are taken into account, the decrease in the column ozone attributed to volcanic eruptions at these latitudes may not be more than 2-4 percent. The most noticeable effect on the Pinatubo eruptions, as observed during the El Chichon period, is the breakdown of the phase relation between ozone and temperature. This is attributed to additional heating in the lower stratosphere caused by volcanic aerosols.

Chandra, S.↗

Recent Solar Measurements Results at the Parabolic Dish Test Site

After the Mexican volcanic eruptions of March 28, April 3 and 4, 1982, the question of its effect on insolation levels at the Parabolic Dish Test Site (PDTS) naturally arose. Clearly, the answer to the original question is that the Mexican volcanic explosion had a significant impact on energy and insolation levels at the PDTS and, furthermore, it has been quite long lasting. The first really significant decrease in energy and insolation levels occurred in June 1982 when the energy level decreased by 19.7% while the peak insolation levels went down by 4.0%. June of 1982 was also the first month (of 13 consecutive months) when peak insolation levels did not equal or exceed 1,000 W/sq m. Signs of a recovery from the effects of the volcanic explosion began to appear in May of 1983, when the energy level exceeded that of May 1981 as well as May 1982. It would appear that energy and insolation levels are improving at the PDTS, but have not quite reached normal or pre-volcanic levels. At this time the data would seem to suggest a return to normal energy and insolation levels will occur in the very near future.

Ross, D. L.↗

SAGE and SAM II measurements of global stratospheric aerosol optical depth and mass loading

Several volcanic eruptions between November 1979 and April 1981 have injected material into the stratosphere. The SAGE and SAM II satellite systems have measured, with global coverage, the 1-micron extinction produced by this material, and examples of the data product are shown in the form of global maps of stratospheric optical depth and altitude-latitude plots of zonal mean extinction. These data, and that for the volcanically quiet period in early 1979, have been used to determine the changes in the total stratospheric mass loading. Estimates have also been made of the contribution to the total aerosol mass from each eruption. It has been found that between 1979 and mid-1981, the total stratospheric aerosol mass increased from a background level of approximately 570,000 metric tons to a peak of approximately 1,300,000 metric tons.

Kent, G. S.↗

The great Tambora eruption in 1815 and its aftermath

The events consequent to the cataclysmic eruption of Mount Tambora, Indonesia, in April of 1815 are reconstructed by quantitative analytical methods which synthesize data and methods from the volcanological, oceanographic, glaciological, meteorological, climatological, astronomical and historical disciplines. This eruption is noteworthy in having been an order of magnitude greater in discharged pyroclastics volume than the Krakatau eruption of 1883, and further, in exceeding the size of any known eruption in the last 10,000 years. The mean temperature in the Northern Hemisphere dropped by 0.4 to 0.7 C in 1816 as a result of its dust veil. It is suggested that Tambora may be used as a calibrating standard in the investigation of other volcanic eruptions.

Stothers, R. B.↗

The E ring of Saturn and satellite Enceladus

Photographic imagery from Pioneer and Voyager flyby satellites has been used to study the microphysical properties of Saturn's outermost E-ring, and to determine the physical relationship between the E-ring and the satellite Enceladus. The optical and infrared characteristics of the E-ring are explained in terms of Mie scattering of ice spheres with an effective diameter of 2 to 2.25 microns and an effective variance of 0.1 to 1.5. It is suggested that the E-ring is continuously replenished by volcanic eruptions on Enceladus, and recent tectonic evidence is cited in support of this hypothesis. A number of similarities in the relationship between the E-ring and Enceladus and Io and its torus are discussed, within the framework of a general model of outer solar system volcanism and planetary ring interaction.

Pang, K. D.↗

A 3-D Model Analysis of The Impact of Asian Anthropogenic Emissions on the Sulfur Cycle Over the Pacific Ocean

The impact of anthropogenic activities on the SO2 and sulfate aerosol levels over the Pacific region is examined in the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model. We focus on the analysis of the data from the NASA Pacific Exploratory Missions (PEM) over the western North Pacific and the tropical Pacific. These missions include PEM-West A in September-October 1991, when the Asian outflow was at the minimum but the upper atmosphere was heavily influenced by the Pinatubo volcanic eruption, and PEM-West B in March-April 1994 when the Asian outflow was at the maximum, and PEM-Tropics A in August-September at a region relatively free of direct anthropogenic influences. Specifically, we will examine the relative importance of anthropogenic, volcanic and biogenic sources to the SO2 and sulfate concentrations over the Pacific, and quantify the processes controlling the distributions of SO2 and sulfate in both the boundary layer and the free troposphere. We will also assess the global impact of SO2 emission in Asia on the sulfate aerosol loading.

Chin, Mian↗