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Tornado producing thunderstorms using conventional surface and upper air data combined with ATS-III data, discussing mesoscale disturbances and momentum exchange
Computed error bars are added to the upper-air density measurements of January 31, 1969, at Wallops Island, Virginia, reported by Faucher and Morrissey. A triaxial accelerometer-instrumented inflated falling sphere was used for the measurements. Bases for the computation are presented. The conclusions of Faucher and Morrissey are substantiated to about 100 km if comparable uncertainty in each of the five soundings reported is assumed.
There are no author-identified significant results in this report. This investigation is directed towards determining the meteorological information content of ERTS-1 MSS bulk data at 0.6 - 0.7 microns as a function of resolution. To accomplish this, the resolution of the MSS data is degraded incrementally to 0.5 min. Subsequent analysis of the processed photographs in conjunction with surface and upper air observations will then determine to what extent significant meteorological information has been lost in the degradation process.
A brief history is reported of the first San Marco project, a joint program of the United States and Italy. The Project was a three phase effort to investigate upper air density and associated ionosphere phenomena. The initial phase included the design and development of the spacecraft, the experiments, the launch complex, and a series of suborbital flights, from Wallops Island. The second phase, consisting of designing, fabricating, and testing a spacecraft for the first orbital mission, culminated in an orbital launch also from Wallops Island. The third phase consisted of further refining the experiments and spacecraft instrumentation and of establishing a full-bore scout complex in Kenya. The launch of San Marco B, in April 1967, from this complex into an equatorial orbit, concluded the initial San Marco effort.
The author has identified the following significant results. Photographic data received from the ERTS-1 satellite over the Lesser Antilles Islands shows distinct ocean features on the leeward side of each island. Attempts to relate these features to ocean eddy formations with the aid of ground truth data proved unsuccessful. However, analysis of surface and upper air wind data correlate extremely well with the size, shape, and downwind extent of the ocean features. Studies to date indicate strongly that these features result from horizontal differences in sea surface roughness due to the wind shadow effect of the islands. The results suggest that horizontal variations in the reflectance of the sea surface will make remote sensing of the ocean mixed layer more difficult than previously anticipated. The surface reflection seems to be large enough to mask the smaller variations in backscattered energy from the mixed layer. Efforts to limit the effect of surface reflectance by photographic differencing of two MSS bands were unsuccessful. A supplementary study to enhance the energy reflected from the mixed layer through numerical differencing of ERTS-1 digital data is planned.
The author has identified the following significant results. Photographic data received from the ERTS-1 satellite over the Lesser Antilles Islands show distinct ocean features on the leeward side of each island. Attempts to relate these features to ocean eddy formations with the aid of ground truth data proved unsuccessful. However, surface and upper air wind data indicate a good correlation with the size, shape, and downwind extent of the ocean features. Studies to date indicate strongly that these features result from horizontal differences in sea surface roughness due to the wind shadow effect of the islands. The results suggest that horizontal variations in the reflectance of the sea surface will make remote sensing of the ocean mixed layer more difficult than previously anticipated. The surface reflection seems to be large enough to mask the smaller horizontal variations in backscattered energy from the mixed layer.
Illustrations of high sferics content Omega data are presented and techniques for recovering the true Omega phase data are discussed. A description is given of the design and the operation of the hardware preprocessor developed to extract the true Omega phase data from the received signals. The software developed to compute upper-air winds from high sferics content data is discussed together with the program conducted to establish the validity of the system.
Horizontal wind components, potential temperature, and mixing ratio fields associated with a severe storm environment in the south central U.S. were analyzed from synoptic upper air observations with a nonhomogeneous, anisotropic weighting function. Each data field was filtered with variational optimization analysis techniques. Variational optimization analysis was also performed on the vertical motion field and was used to produce advective forecasts of the potential temperature and mixing ratio fields. Results show that the dry intrusion is characterized by warm air, the advection of which produces a well-defined upward motion pattern. A corresponding downward motion pattern comprising a deep vertical circulation in the warm air sector of the low pressure system was detected. The axes alignment of maximum dry and warm advection with the axis of the tornado-producing squall line also resulted.
Photographic data received from the ERTS-1 satellite over the Lesser Antilles Islands show distinct ocean features on the leeward side of each island. Attempts to relate these features to ocean eddy formations with the aid of ground truth data proved unsuccessful. However, surface and upper air wind data indicate a good correlation with the size, shape, and downwind extent of the ocean features. Studies to date indicate strongly that these features result from horizontal differences in a sea surface roughness due to the wind-shadow effect of the islands. The results suggest that horizontal variations in the reflectance of the sea surface will make remote sensing of the ocean mixed layer more difficult than previously anticipated. The surface reflection seems to be large enough to mask the smaller variations in backscattered energy from the mixed layer. Efforts to limit the effect of surface reflectance by photographic differencing of two multi-spectral scanner bands were unsuccessful.
The Atmospheric Variability Experiment (AVE II) was conducted in May 1974. Rawinsonde releases were made at 54 upper-air stations in two thirds of the eastern U.S. at 3-hr intervals for a 24-hr period. Radar data were obtained from 11 stations located near the center of the observational area, and as many data as possible were collected from the Nimbus 5, NOAA 2, ATS-3, and DMSP satellites. The present paper provides an overview of the experiment and describes how the user community can obtain copies of the data.
The meteorological data for the 33-hour period prior to the Centaur (Titan III E) launch from Kennedy Space Center at 0948 EDT on February 11, 1974, are archived in this report. These data were collected in support of the NASA rocket exhaust effluent prediction and monitoring program. This is a rather unique data set in that a high temporal resolution of upper air soundings is provided. All supporting data, such as synoptic charts and wind tower data, are also included. This is the second in a series of seven data reports.
As part of the SEASAT program, two sets of analysis programs were developed. One set of programs produce 63 x 63 horizontal mesh analyses on a polar stereographic grid. The other set produces 187 x 187 third mesh analyses. The parameters analyzed include sea surface temperature, sea level pressure and twelve levels of upper air temperature, height and wind analyses. Both sets use operational data provided by a weather bureau. The analysis output is used to initialize the primitive equation forecast models also included.
Upper air sounding are used to examine a cold front of average intensity. Vertical cross sections of potential temperature and wind, and horizontal analyses were compared and adjusted for consistency. These analyses were then used to study the evolution of the front, found to consist of a complex system of fronts occurring at all levels of the troposphere. Low level fronts were strongest at the surface and rapidly weakened with height. Fronts in the midddle troposphere were much more intense. The warm air ahead of the fronts was nearly barotropic, while the cold air behind was baroclinic through deep layers. A deep mixed layer was observed to grow in this cold air.
As part of the SEASAT program of NASA, two sets of analysis programs were developed for the Jet Propulsion Laboratory. One set of programs produce 63 x 63 horizontal mesh analyses on a polar stereographic grid. The other set produces 187 x 187 third mesh analyses. The parameters analyzed include sea surface temperature, sea level pressure and twelve levels of upper air temperature, height and wind analyses. The analysis output is used to initialize the primitive equation forecast models.
Horizontal wind components, potential temperature, and mixing ratio fields associated with a severe storm environment in the south central United States were objectively analyzed from synoptic upper air observations with a nonhomogeneous anisotropic weighting function. The particular case study discussed here is the tornado producting squall line which moved through eastern Oklahoma 26 May 1973. The synoptic situation which preceded squall line development was cyclogenesis and frontogenesis in the lee-of-mountain trough, which produced a well-defined surface dry line (or dew point front) and a pronounced mid-level dry air intrusion. It is shown that the intrusion was also characterized by warm air, with a lapse rate approaching the dry adiabatic.
Results are presented from numerical simulations performed with the general circulation model (GCM) for winter and summer. The monthly mean simulated fields for each integration are compared with observed geographical distributions and zonal averages. In general, the simulated sea level pressure and upper level geopotential height field agree well with the observations. Well simulated features are the winter Aleutian and Icelandic lows, the summer southwestern U.S. low, the summer and winter oceanic subtropical highs in both hemispheres, and the summer upper level Tibetan high and Atlantic ridge. The surface and upper air wind fields in the low latitudes are in good agreement with the observations. The geographical distirbutions of the Earth-atmosphere radiation balance and of the precipitation rates over the oceans are well simulated, but not all of the intensities of these features are correct. Other comparisons are shown for precipitation along the ITCZ, rediation balance, zonally averaged temperatures and zonal winds, and poleward transports of momentum and sensible heat.
The heavy lift launch vehicles (HLLV) proposed for use in constructing satellite power systems (SPS) would deposit various contaminants in the middle atmosphere, contaminants that would conceivable have adverse effects on climate and upper air structure. These contaminants consist of the major constitutents of water vapor, hydrogen, carbon dioxide, and carbon monoxide, and the minor constituents of sulfur dioxide and nitric oxide in the rocket effluent, as well as nitric oxide formed during reentry. To assess the magnitudes of the effects, new models or modified existing models were constructed.
Results from a test to determine the effectiveness of satellite data for helping airlines avoid heavy concentrations of ozone are reported. Information from the Total Ozone Mapping Spectrometer, aboard the Nimbus-7 was transmitted, for use in meteorological forecast activities. The results show: (1) Total Ozone Mapping Spectrometer profile of total ozone in the atmosphere accurately represents upper air patterns and can be used to locate meteorological activity; (2) route forecasting of highly concentrated ozone is feasible; (3) five research aircraft flights were flown in jet stream regions located by the Total Ozone Mapping Spectrometer to determine winds, temperatures, and air composition. It is shown that the jet stream is coincides with the area of highest total ozone gradient, and low total ozone amounts are found where tropospheric air has been carried along above the tropopause on the anticyclonic side of the subtropical jet stream.