ALPS prototypes of enhanced ensemble data functionality.

Aug 13 2008

http://www-sdd.fsl.noaa.gov/~ramer/alps/ensembles/ensembles.html

Link to material posted on June 9, 2008.

Outline of ensemble display capabilities prototyped in ALPS to date.

New features for Legend Management.

Here is a screen shot of a spaghetti plot of 500 heights from the 21 member SREF ensemble. Note that when the data is first loaded, all the legends are colapsed into a single legend, with a big plus sign on the left end of the legend. The plus sign is an indicator that the legends are collapsed. Also note that the part of the legend text that describes the particular ensemble member is replaced with ***.

Figure 1.



Here is what this looks like after clicking on the plus sign; note that the entire stack of legends is now displayed, with large minus signs on the left end of the legend. The minus signs are an indicator that the legends can be collapsed. Clicking on one of the minus signs with the left mouse button will recollapse all the legends from that load back to a single legend.

Figure 2.



Clicking on one of the minus signs with the middle button, however, will collapse just that group, in this case the group defined by the green set of legends.

Figure 3.



The rest of the legends after the plus or minus behave much as before; clicking on them with the left button will toggle the visibility of an individual legend, the middle button will toggle the visibility of all legends in a group, and clicking the third button will toggle the visibility of all legends from a single load. Holding the third button down still gives access to a popup for more controls. Furthermore, the activity of these controls is now sensitive to which overlays were last acted on together. That is, if a collection of overlays had its visibility all toggled together with a single mouse action, then using the third button pop-up density control on one of those overlays will change the density of all the overlays that were acted on together. If legends are collapsed into a single legend, that will also cause them to respond to pop-up controls in unison.

Figure 4.



All the pop-up options from Line Style through Density behave in this coordinated manner on multiple overlays. The Set Color pop-up has special behavior in the case where it is applied to a set of collapsed legends. Suppose one were to take the situation in the very first screen shot on the page and use the pop-up on the collapsed legend to change the color to cyan. Instead of changing all the colors to cyan, the color difference needed to change yellow to cyan is computed, and that change is applied to all overlays in the collapsed set of legends. Note that this computation is done in hue, saturation, and brightness space, not red, green and blue space.

Figure 5.



There are also some new accelator keys; the ones with the less than and greater than signs on them decrease and increase the density of the last overlay or set of overlays that were acted on together. The keys on the main keyboard with the plus and minus signs rotate the toggle state of all the overlays in an ensemble set upward and downward; this only does anything unless there is such a set that has different toggle states among the members.

Predefined function overlay invocations.

What follows is a screen shot of the updated function overlay menu. One will note that there are many new functions. Also note the last selector, highlighted at the bottom, entitled FireWx.

Figure 6.



If one loads that selector, here is what one sees:

Figure 7.



The legend indicates that this is data from the 21 member SREF, and that it incorporates data for surface temperature, wind speed, and 850MB relative humidity. Furthermore, the legends indicate that this is a plot of the sample relative frequency for where the following conditions are met; temperature greater than 80F, wind speed greater than 10 knots, and relative humidity less than 40 percent. Also note the small greyed out string "more" right above the far right end of the legend. This next screen shot shows what happens after we click on the "more", open the new Ensemble Controls GUI from the tools menu, and hit the Inherit from Display button in that GUI.

Figure 8.



So what does this all mean? First, this means that the Fire Wx product is actually a multi-load of temperature, wind speed, and 850MB relative humidity from the SREF, plus the Triplet EnsRF function overlay. EnsRF is a shorthand for ensemble relative frequency. Also, the SREF overlays were loaded with zero density, so their data is available for input to function overlays, but their graphics are not be visible and as such one can clearly read the `Fire Wx' overlay. Because these overlays had zero density, we refer to them as empty overlays; the greyed out "more" is present whenever there are suppressed empty overlays, and one can click on it to show the legends for the empty overlays. Overlays that are toggled off are also considered empty, but do not make their data available for input to function overlays.

This multiload had a predefined set of valid range parameters associated with it (80 to infinity, 10 to infinity, and -infinity to 40), and we can pull that set of parameters into the GUI with the Inherit from Display button. If one then goes into the minimum: entry field in the GUI, replaces the text with `90', hits return, and then double clicks on the legend for the Fire Wx overlay, this is what happens:

Figure 9.



A double click on any function overlay legend tells it to recompute itself. If some of the overlays that were input to the function were toggled off, then the toggled off overlays will no longer contribute data to the computation. If the function overlay is one that requires parameters from the Ensemble Controls GUI, then the current set of parameters entered into the GUI will be used. If one updates the parameters in this manner and stores the display as a bundle, that set of parameters will be remembered.

Some additional new function overlay features.

Another example of a new function overlay is Value of Ens Rel Freq. Let's load up the SREF-21 surface temperature, make its density zero with its pop-up, enter the number 25 into the minimum: entry field in the Ensemble Controls GUI, and load the Value of Ens Rel Freq function overlay. Here is what we get:

Figure 10.



In this graphic, the value is that temperature where 25% of the members have a lower temperature and 75% of the members have a higher temperature. If we had instead typed 50 into the GUI, then this would have been the same as the Median function overlay.

One final new function overlay we want to demonstrate here is the Color Histogram function. Here we load up the SREF-21 500MB heights, load the Color Histogram function overlay and start sampling:

Figure 11.



As the name implies, this function overlay allows one to see a histogram, which is computed from data interpolated to the cursor location from each member. Each symbol in the histogram representing a member's contribution is colored the same as that overlay. Changing the color of an overlay causes the histogram to dynamically reflect that change.

As with all function overlays in the past, except for the image versions, all these functions work on top of line graphs and cross section displays as well. Furthermore, if one loads up a whole bunch of overlays that are the same field from many different models, that can function as a virtual ensemble set as far as function overlays are concerned.