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NASA NTRS1976

Remote sensing of St. Augustine Decline (SAD) disease

Laboratory and field spectral reflectance measurements of healthy and infected St. Augustine grass were made using several different instruments. Spectral differences between healthy and infected grass occured in the visible and near infrared regions. Multiband and color infrared photographs were taken of healthy and diseased turf from ground-based platforms and low altitude aircraft. Qualitative (density slicing) and quantitative (transmission densitometry) analyses revealed distinct tonal differences between healthy and St. Augustine disease (SAD) infected grass. Similar experiments are described for determining if healthy and diseased grass can be distinguished from waterstressed grass and grass deficient in either nitrogen or iron.

Odle, W. C.↗

NASA NTRS1976

Lidar measurement of stratospheric dust from St. Augustine Volcano

The detection of a stratospheric dust layer of probable volcanic origin over Hampton, Va., on the evening of Jan. 28, 1976, with a 20-inch lidar system is reported. A digitized cathode-ray-tube trace of a return signal from altitudes of 12 to 24 km on January 28 is provided, and it is shown that 38% of the return was due to stratospheric aerosol. Noting that measurements on January 22 and February 2 showed no traces of this stratospheric dust layer, trajectories of dust-laden air parcels are followed from initiation at 0000 GMT on January 24 at the St. Augustine Volcano on Augustine Island, Alaska (59 deg N, 153 deg W). Analysis of the trajectories indicates that dust injected into the stratosphere at 59 deg N, 153 deg W could have been transported to Virginia in about 4 days. It is concluded that if the St. Augustine Volcano was the source of the dust, at least 23 deg of meridional transport from polar latitudes was observed.

Remsberg, E. E.↗

NASA NTRS1977

Thermal surveillance of active volcanoes using the LANDSAT-1 data collection system. Part 3: Heat discharge from Mount St. Helens, Washington

The author has identified the following significant results. Two thermal anomalies, A at 2740 m altitude on the north slope, and B between 2650 and 2750 m altitude on the southwest slope at the contact of the dacite summit dome of Mount St. Helens, Washington were confirmed by aerial infrared scanner surveys between 1971 and 1973. LANDSAT 1 data collection platform 6166, emplaced at site B anomaly, transmitted 482 sets of temperature values in 1973 and 1974, suitable for estimating the differential radiatin emission as 84 W/sq m, approximately equivalent to the Fourier conductive flux of 89 W/sq m in the upper 15 cm below the surface. The differential geothermal flux, including heat loss via evaporation and convection, was estimated at 376 W/sq m. Total energy yield of Mount St. Helens probably ranges between 0.1 and 0.4 x 10 to the 6th power W.

Friedman, J. D.↗

NASA NTRS1979

Petrology of impactites from Lake St. Martin structure, Manitoba

The 23-km Lake St. Martin crater was produced 200 to 250 million years ago in Archean granitic to amphibolic gneiss, overlain by 400 to 500 m of Ordovician to Devonian limestone and dolomite. In the present paper, a schematic model of the field geology, petrology, and geochemistry is presented. The scenario is built in part on the calculations of Kieffer and Simonds and observations made on the Lake St. Martin structure.

Simonds, C. H.↗

NASA NTRS1981

Approach to forecasting daily maximum ozone levels in St. Louis

Measurements taken in 1976 from the St. Louis Regional Air Pollution Study (RAPS) data base, conducted by EPA, were analyzed to determine an optimum set of air-quality and meteorological variables for predicting maximum ozone levels for each day in 1976. A 'leaps and bounds' regression analysis was used to identify the best subset of variables. Three particular variables, the 9 a.m. ozone level, the forecasted maximum temperature, and the 6-9 a.m. averaged wind speed, have useful forecasting utility. The trajectory history of air masses entering St. Louis was studied, and it was concluded that transport-related variables contribute to the appearance of very high ozone levels. The final empirical forecast model predicts the daily maximum ozone over 341 days with a standard deviation of 11 ppb, which approaches the estimated error.

Prior, E. J.↗

NASA NTRS1982

A preliminary study of the application of HCMM satellite data to define initial and boundary conditions for numerical models: A case study in St. Louis, Missouri

Infrared and visible HCMM data were used to examine the potential application of these data to define initial and boundary conditions for mesoscale numerical models. Various boundary layer models were used to calculate the distribution of the surface heat flux, specific humidity depression (the difference between the specific humidity in the air at approxmately the 10 m level and the specific humidity at the ground), and the eddy vicosity in a 72 km by 72 km area centered about St. Louis, Missouri. Various aspects of the implications of the results on the meteorology of St. Louis are discussed. Overall, the results indicated that a reasonable estimate of the surface heat flux, urban albedo, ground temperature, and specific humidity depression can be obtained using HCMM satellite data. Values of the ground-specific humidity can be obtained if the distribution of the air-specific humidity is available. More research is required in estimating the absolute magnitude of the specific humidity depression because calculations may be sensitive to model parameters.

Vukovich, F. M.↗

NASA NTRS1982

Small particles in plumes of Mount St. Helens

Particles in the size range 0.1-25 microns were sampled by aircraft carrying a quartz crystal microcascade in the Mount St. Helens plume on three dates in August and September 1980. Two of the sampling dates represented 'typical' emissions of the volcano between plinian eruptions. One sampling flight was made 1-4 hours before the small plinian eruption of August 7, 1980 when the plume had become discontinuous and visibly darker. The plume sampled on August 7, before the eruption, contained mainly approximately 2-micron diameter silicic glass particles, fragments of the Mount St. Helens magma. The typical plumes sampled on September 22 and August 6 had much smaller concentrations of particles, trimodal size distributions with peaks at 10, 0.4, and 0.1 microns. The particles were largely nonsilicate and apparently represented Cu-Zn oxide (10 micron peak), Al sulfate, chloride, and oxide, and sulfuric acid (smallest size peak).

Rose, W. I.↗

NASA NTRS1982

Radio interferometric detection of a traveling ionospheric disturbance excited by the explosion of Mount St. Helens

A large-amplitude traveling ionospheric disturbance (TID) was detected over Owens Valley, California, on May 18, 1980, by a highly sensitive very long baseline interferometry (VLBI) radio astronomy experiment. This TID is interpreted as the response of the ionosphere to a gravity wave excited in the neutral atmosphere by the explosion of Mount St. Helens that took place at 1532 UT on that day. A model, invoking the point-excitation of internal gravity waves in an isothermal atmosphere, which fits observations of the TID at several other stations, leads to identification of the features observed in the VLBI data. Small-amplitude higher-frequency changes in the ionosphere were detected for several hours after the passage of the large-amplitude Mount St. Helens TID, but it is not clear whether these were excited by the passage of the gravity wave or were background fluctuations.

Roberts, D. H.↗

NASA NTRS1982

A comparison of constituents of Mount St. Helens eruption clouds with those of some other volcanoes

Gases from Mount St. Helens were collected from the eruption clouds using an airplane during the period April 2 to April 8, 1980, and were analyzed for CO2, H2, CH4, and COS. The results were of similar magnitude to those obtained from magmatic eruptions in Central America. Thus, although the eruptions were evidently largely phreatic, magmatic gases may have played a larger role in these early small eruptions than has generally been believed. Electron micrographs of ash particles collected from the Mount St. Helens eruption clouds showed that the particles were for the most part much larger than those from the Central American eruptions.

Cadle, R. D.↗

NASA NTRS1982

The mechanisms of fine particle generation and electrification during Mount St. Helens volcanic eruption

Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

Cheng, R. J.↗

NASA NTRS1982

Ambient airborne solids concentrations including volcanic ash at Hanford, Washington sampling sites subsequent to the Mount St. Helens eruption

Airborne solids concentrations were measured on a near daily basis at two Hanford, Washington sites after the eruption of Mount St. Helens on May 18, 1980. These sites are about 211 km east of Mount St. Helens. Collected airborne solids included resuspended volcanic ash plus normal ambient solids. Average airborne solids concentrations were greater at the Hanford meteorological station sampling site which is 24 km northwest of the Horn Rapids dam sampling site. These increased concentrations reflect the sampling site proximity to greater ash fallout depths. Both sites are in low ash fallout areas although the Hanford meteorological station site is closer to the greater ash fallout areas. Airborne solids concentrations were decreased by rain, but airborne solids concentrations rapidly increased as surfaces dried. Airborne concentrations tended to become nearly the same at both sampling sites only for July 12 and 13.

Sehmel, G. A.↗

NASA NTRS1981

Landsat observations of Mount St. Helens

The eruption of Mount St. Helens on May 18, 1980, and subsequent destruction of approximately 593 square kilometers (229 square miles) of vegetation, clearly provided a unique opportunity for earth-oriented satellite remote sensing systems. Landsat, a relatively high resolution Multispectral Scanner (MSS) system, imaged Mount St. Helens both before and after its major eruption. Digital data have been used to create a damage assessment map and a change detection image. Several classes of timber damage and land cover modification have been developed. Acreages for each class have been tabulated.

Bohn, C. G.↗

NASA NTRS1983

The economics of data acquisition computers for ST and MST radars

Some low cost options for data acquisition computers for ST (stratosphere, troposphere) and MST (mesosphere, stratosphere, troposphere) are presented. The particular equipment discussed reflects choices made by the University of Alaska group but of course many other options exist. The low cost microprocessor and array processor approach presented here has several advantages because of its modularity. An inexpensive system may be configured for a minimum performance ST radar, whereas a multiprocessor and/or a multiarray processor system may be used for a higher performance MST radar. This modularity is important for a network of radars because the initial cost is minimized while future upgrades will still be possible at minimal expense. This modularity also aids in lowering the cost of software development because system expansions should rquire little software changes. The functions of the radar computer will be to obtain Doppler spectra in near real time with some minor analysis such as vector wind determination.

Watkins, B. J.↗

NASA NTRS1984

Estimating vegetation coverage in St. Joseph Bay, Florida with an airborne multispectral scanner

A four-channel multispectral scanner (MSS) carried aboard an aircraft was used to collect data along several flight paths over St. Joseph Bay, FL. Various classifications of benthic features were defined from the results of ground-truth observations. The classes were statistically correlated with MSS channel signal intensity using multivariate methods. Application of the classification measures to the MSS data set allowed computer construction of a detailed map of benthic features of the bay. Various densities of segrasses, various bottom types, and algal coverage were distinguished from water of various depths. The areal vegetation coverage of St. Joseph Bay was not significantly different from the results of a survey conducted six years previously, suggesting that seagrasses are a very stable feature of the bay bottom.

Savastano, K. J.↗

NASA NTRS1985

Morphologic Evolution of the Mount St. Helens Crater Area, Washington

The large rockslide-avalanche that preceded the eruption of Mount St. Helens on 18 May 1980 removed approximately 2.8 cubic km of material from the summit and north flank of the volcano, forming a horseshoe-shaped crater 2.0 km wide and 3.9 km long. A variety of erosional and depositional processes, notably mass wasting and gully development, acted to modify the topographic configuration of the crater area. To document this morphologic evolution, a series of annual large-scale topographic maps is being produced as a base for comparitive geomorphic analysis. Four topographic maps of the Mount St. Helens crater area at a scale of 1:4000 were produced by the National Mapping Division of the U. S. Geological Survey. Stereo aerial photography for the maps was obtained on 23 October 1980, 10 September 1981, 1 September 1982, and 17 August 1983. To quantify topographic changes in the study area, each topographic map is being digitized and corresponding X, Y, and Z values from successive maps are being computer-compared.

Beach, G. L.↗

NASA NTRS1984

The Sondrestrom radar: Progress and proposed upgrades for ST work

The capabilities and limitations of the Sondrestrom Radar for stratosphere-troposphere ST observations were previously presented. Recent progress and proposed upgrades are summarized. During the first year of operation (April 1983 to April 1984) there was only one ST experiment, mainly with the objective of evaluating the site and determining that the hardare and software were still operational after the radar's move from Alaska. The Sondrestrom site has about the same degree of ground clutter as the former Chatanika site and the data appear to be similar. The radar's operation continues to be incoherent-scatter observations of the ionosphere. The main radar parameters are summarized.

Watkins, B. J.↗

NASA NTRS1984

Measurements of vertical velocity over flat terrain by ST radar and other related uses of the radar data set

The need to study vertical velocity measurements from an ST radar located on the plains, far from the mountains is pointed out, as all presently available clear-air radars are located in or near mountains. The construction and operation of a VHF Doppler (ST) radar in the midwestern part of the United States to make meteorological measurements is also discussed. While primary interest is in measuring the synoptic-scale vertical velocities in the troposphere and lower stratosphere, it should be stressed, however, that the radar data set generated during the radar experiment would have many other valuable uses of interest to us and others some of whom are listed below. The required radar parameters, approximate costs, and recommended mode of operation are also detailed.

Green, J. L.↗

NASA NTRS1986

The INSU and DMN network of ST radars

Due to their capabilities of measuring wind profiles with good time and height resolution, Stratosphere-Troposphere (ST) are well adapted to carry out atmospheric research. In France, a Very High Frequency (VHF) and an Ultrahigh Frequency (UHF) ST radar are working for research purposes. The INSU (Institut National des Sciences de l'Univers) and the DMN (Direction de la Meteorologie Nationale) networks are discussed.

Petitdidier, M.↗