Both continuous and discrete realization techniques are provided. For the continuous techniques (e.g., contouring, imaging), the data are gridded to a uniform, regular grid via weighted averaging. The discrete techniques (e.g., scatter plots) may be overlaid with the continuous ones. Optionally, the elevation of each rainfall station may be used to create a topographic surface, that is overlaid with a pseudo-color representation of the rainfall. The daily distribution of the rainfall at an individual station may be shown as a time history plot.
The data for one day are shown as pseudo-colored deformed surface, where the height of the surface corresponds to local topography. A time history of the rainfall for a single station is shown as a plot.
Gridding Options Control Panel: The weighted averaging of the gridding process of the scattered data may be adjusted. The number of stations used to compute a value at each grid point may be selected. The radius of influence for each grid point may be selected.
Rainfall Time History Plots Control Panel: Optionally, a daily time history plot for the entire 11/1/82 - 6/30/83 period may be shown for a specific station, which is selected by name. The data are shown as a green line. In addition, the location of the station may shown on the map. The plot may be augmented with the daily mean (in yellow) and/or the daily maximum (in blue) for all reporting rainfall stations.
Ordinarily, this region is a desert. During the large-scale thunderstorms that occur as a result of El Nino, several centimeters of rain will fall each day, washing away everything in its path. This can be seen as deep blue regions in the various realizations. The storms are clearly affected by the local topography. The storms originate in the Pacific Ocean. As they reach the foothills of the Andes, they are diverted off to the northwest. A daily animation of these data illustrate this effect. The Sequencer is tied to Julian day for this purpose. The default period is during a major storm that took place in January 1983.
The rainfall realizations are registered with a base map in magenta showing the Pacific coast and part of the Peru-Ecuador border.
The data are available courtesy of the National Space Science Data Center, NASA/Goddard Space Flight Center.
A portion of the visual program that is the implementation of this application is shown.
Cartography Control Panel: One of five geographic map projections may be selected (Cylindrical Equidistant, Mollweide, Mercator, South Pole Orthographic and spherical). The orthographic projection is most appropriate for viewing the auroral oval and the evolution of the substorm. An additional option is available for placing of fiducial lines on the coastline and national boundary map.
One auroral image is shown in a south pole orthographic projection as a pseudo-colored, deformed shaded surface that has been smoothed by a Gaussian filter.
Magnetic Field Magnitude (|B|) Plane Control Panel: The user can place an annulus showing |B|, whose normal is determined by the dial widgets. The annulus is psuedo-color mapped and contoured.
Magnetic Field (B) Lines Control Panel: The user may choose how the magnetic field lines are traced. The seed points are entered manually or are computed automatically (20 uniformly distributed in the volume). B, curl B or both may be chosen for the lines to be traced.
Altitude Slice Options Control Panel: Optionally, the user may select a slice of the model at a specific altitude (0 to 30000 km by 2000), and view it as pseudo-color image of |B| or contours (every 0.025) or deformed surface, or streamlines or vector arrows of B. In addition, cartographic projections may be applied with a coastline and political boundary overlay.
The B-field is shown as a translucent, pseudo-colored isosurface at a value of 0.4 Gauss and streamlines advected by a set of coordinates entered manually.
There are three data sets of ground-based magnetometer observations, which are located at the South Pole, McMurdo Bay and Siple. There are a set of in situ (point) observations (i.e., samplings) of the plasma originating from the solar wind by instruments on board NASA's International Sun-Earth Explorer-1 (ISEE-1). These measurements are of energetic protons (temperature in electron volts, number density and velocity) and the magnetic field. Each of these data sets originally were in different cartesian coordinate systems. All of the data are shown geographically via coordinate warping surrounding a topographically derived globe and are properly registered and converted. The data are at different time resolutions but were interpolated to a common time base of irregularly-spaced 38 steps corresponding to those of the auroral images external to Data Explorer.
The program supports user-specified field line tracing, examination of the field strength, etc. for the magnetic field data through a number of different realization techniques. The time-dependent magnetic field as measured on the ground is shown via color-mapped vector glyphs. The time-dependent ultraviolet emissions of aurorae are shown as color-mapped translucent surfaces warped onto a sphere. Alternatively, the images may be shown as psuedo-color glyphs corresponding to the location of the pixels. This technique is useful since some of the pixels on some images have not been properly geolocated. The radius of the sphere is scaled according the radial distance of the spacecraft from the earth's center. The user can control the relative amount of offset between these spherical surfaces and the globe. These data are quite noisy and regions of no data are visible as open patches. The ISEE-1 data are shown as glyphs. The size of sphere glyph corresponds to the proton density, while its color corresponds to the proton temperature. There are two arrow glyphs, one for the proton velocity and the other for the magnetic field. Both are scaled in size by their respective magnitudes. The proton velocity glyph is magenta, while the magnetic field glyph is pseudo-colored by the same scale as is used for the ground station observations and the static magnetic field model data. The key feature in these images is the auroral oval, a region of intense emissions corresponding to where charged particles follow magnetic field lines into the earth's atmosphere. The interaction of the particles and the atmosphere leads to the observed emissions. Through the time sequence, the pulsating of the aurorae are quite visible. In some images there may be some regions of high intensity independent of the auroral oval. Since the images are taken mostly at night, this is sunlight coming across the day-night terminator and contaminating the observations.
Viewing Control Panel: The user may choose between a smooth or Rubbersheet'd presentation of the globe.
General Realization Control Panel: The user may choose which data set is to be shown and in some cases how it is to be realized. The magnitude of the static B-field may be shown as a volume or via isosurfaces. If the latter, then the user can enter the desired isosurface values. The static B-field may be shown via streamlines or vector arrow glyphs. The UV auroral image may be shown as a smooth surface or the locations of each pixel may be indicated. Since some pixels are not properly geolocated, the latter may be useful. The image "surface" is on a sphere, whose radius corresponds to that of the radial distance of the spacecraft, Dynamics Explorer-1, from the earth and the time the data were taken. The radius may be reduced to allow the other data to be seen more clearly. The in situ B-field observed by ISEE-1 may be shown as a pseudo-colored arrow glyph. The same color map as with the B-field is employed. The in situ proton data from ISEE-1 may be shown. Velocity is indicated by magenta vector arrows. Temperature is indicated by the color of a sphere and the density is indicated by the size of that sphere. The magnetic field as observed from the ground may be shown via pseudo-color-mapped vector arrows.
Magnetic Field Magnitude (|B|) Plane Control Panel: A user can place an annulus showing |B|, whose normal is determined by the dial widgets. The annulus is pseudo-color mapped and contoured.
Magnetic Field (B) Lines Control Panel: The user may choose how the magnetic field lines are traced from a static data set. The seed points may be entered manually through the vector list widget, sampled from the positions of the auroral image of the current time step, or from the constant locations of the ground stations. B, curl B or both may be chosen for the lines to be traced.
All of the data sets are shown, with magnetic field lines from the static field and a pseudo-colored, translucent shell of auroral imagery surrounding the earth. The three ground magnetometers are shown as pseudo-colored arrows while the position of ISEE-1 is shown with a pseudo-colored sphere for proton temperature and density, thick arrow for proton velocity and thin arrow for in situ magnetic field.
The data are available courtesy of the National Space Science Data Center at NASA/Goddard Space Flight Center.
Temperature Realization Control Panel: The user may choose to view the stratospheric temperature as a pseudo-colored volume, isosurface or slice. For isosurfaces, specific value(s) may be entered. For a slice, a specific pressure level may be chosen. The data optionally may be smoothed prior to realization.
Geopotential Height Realization Control Panel: The user may choose to view the stratospheric geopotential height as a pseudo-colored volume, isosurface or slice. For isosurfaces, specific value(s) may be entered. For a slice, a specific pressure level may be chosen. The data optionally may be smoothed prior to realization.
Stratospheric Viewing Control Panel: The user can choose the view the northern hemisphere volume as a collection of concentric hemispherical shells or as a cylindrical stack of orthographic disks.
Temperature isosurfaces of 195 and 220 K, and geopotential height isosurfaces at 19400 and 23700 m are shown in a northern hemisphere orthographic cylinder.
The user may examine either the daily temperature and/or the wind data through a number of different realization techniques. The temperature data may be realized via direct volume rendering, surface extraction, pressure surface or cutting plane with contours, each of which is pseudo-color mapped. One or more values may be chosen for the isosurface. The specific pressure level may be selected, The cutting/mapping plane in this spherical, earth-centered coordinate system is an annulus. A probe is used to select the normal of the annulus, which is marked with an arrow. The wind data may be realized as glyphs, streamlines or ribbons or streaklines or ribbons, which are pseudo-color mapped by horizontal wind speed. The ribbons may be optionally twisted by the curl of the velocity field, which is proportional to the wind vorticity. The user may enter specific seed points for the lines or the number of seed points, which are uniformly distributed in the volume. For glyphs, their size is redundantly mapped to horizontal wind speed. Optionally, the user may choose to realize the three-dimensional horizontal wind speed as a volume, pressure surface or isosurfaces.
Volumetric Temperature Realization Control Panel: The user can choose to realize the temperature data as an annulus, volume, pressure surface or isosurfaces. For the annulus, a probe is used to select the normal and it is pseudo-color mapped and contoured. For an isosurface, the user may enter one or may values for which to extract the surfaces.
Pressure Slice Viewing Options Control Panel: The user may choose which pressure level in the atmosphere to study with two-dimensional techniques. The temperature data are realized as a pseudo-color image overlaid with similarly pseudo-color mapped contours. The user may select the upper and lower bounds for the color scale and contouring as well as the contour increment. The contouring may be line or filled. In addition, numeric labels may be overlaid on the temperature data. The user may choose between cell-based pseudo-color imaging and smoothed images. The horizontal wind data are realized as vector (arrow) glyphs, whose length corresponds to wind speed and direction corresponds to wind direction. The glyphs may be a constant color or pseudo-color mapped to the wind speed. The glyphs are rendered on a reduced resolution grid, where the user can control the degree of reduction. Alternatively, the wind data may be realized as streamlines, where each time step is considered steady-state. The streamlines may be a constant color or pseudo-color mapped to the wind speed. The program supports five different cartographic map projections, which are implemented without interpolation via coordinate warping. The projections are Cylindrical Equidistant, Mollweide, Mercator and northern and southern hemisphere orthographic, and spherical. The data are overlaid with conventional maps of world coastlines and political boundaries as well as fiducial lines. The user may choose the particular style of map that is employed for realization. These options, include the map projection, the use of and style of fiducial lines, and the map color.
This program provides analysis of daily total column global ozone for the period September 1, 1987 through November 30, 1987, which are available courtesy of the National Space Science Data Center at NASA/Goddard Space Flight Center. It supports conventional two-dimensional geographic mapping, for which the data are realized as a pseudo-color image optionally overlaid with similarly pseudo-color mapped contours. The user has the ability to adjust the boundaries of a pseudo-color map, which defaults to a non-linear RGB color map and contouring range as well as the increment of the contour lines. The program supports five different cartographic map projections, which are implemented without interpolation via coordinate warping. The projections are Cylindrical Equidistant, Mollweide, Mercator, northern and southern hemisphere orthographic and spherical. The data are overlaid with conventional maps of world coastlines and political boundaries as well as fiduical lines.
From the choice of two-dimensional projection each day of data may be realized as a deformed surface, which is redundantly represented by both the pseudo-color spectrum and height. The height mapping clearly dramatizes the concept of a hole or depression in the ozone layer while the color enhances this perception as color would enhance the topographic map. The daily sequencing of the data showing the (super)rotation of the ozone hole surrounded by the ozone ridge region, which is consistent with the formation of the polar vortex that some believe help to trap ozone-destroying chemicals in the stratosphere and thus, aid in the creation of the Antarctic ozone hole. Such rotation usually has a period of several days. Below each translucent surface is a world coastline map in magenta with political boundaries corresponding to each hemisphere. The map is from a data base of lines, which has been transformed in a manner similar to that of the ozone data.
Independent of the specific realization techniques, the user can examine the daily data, the difference from one day to the next, a running difference from a base day, or the deviation of the daily data from the corresponding monthly mean. On any of these choices of data, the user has the option of applying histogram equalization, various signal processing techniques (e.g., edge detection) or select a longitude value for viewing a zonal profile plot of the ozone.
As one sequences through September, coming out of Antarctic winter, the availability of polar ozone data is apparent as well as the formation of the hole. Precursor and correlative signatures are visible in the temperature data and the wind patterns evoke a cyclonic pattern corresponding to the polar vortex. The 100 mb data are derived from the spacecraft, balloon and aircraft observations, which have been modelled and gridded. The 100 mb are on a 2.5 degree grid, originally 144 x 73 cells (longitude x latitude). The program supports four different cartographic map projections, which are implemented without interpolation via coordinate warping. The projections are Cylindrical Equidistant, Mollweide, Mercator and northern and southern hemisphere orthographic. If the south pole orthographic projection is selected this correlation corresponding to the vortex is quite clear in each data set.
Viewing Control Panel: The user has the ability to select which of five data sets to display, total column ozone, 100 mb temperature, 100 mb horizontal winds, topography and a map of coastlines and national boundaries. The user can choose the geographic map projection to use. The ozone, temperature and wind may be stacked and registered with the maps or may be viewed separately in separate windows with the coastlines map.
Realization Control Panel: The user has the ability to select the display and options associated with each realization function that may be mapped to a specific data set. For pseudo-color imagery the data may be smoothed and/or histogram equalized. For contours, the contour increment can be chosen and the lines may either be black or pseudo-colored.