Google Maps and GHCN adjustmentsA fortnight ago I posted a Google Maps gadget for viewing GHCN stations colored according to the effect on them of GHCN adjustments. I've been doing some improvements, and rewriting the code in the process. This simplifies the logic, and I'm hoping to produce a generic application to operate on any supplied data.
For the moment, the main improvement is that it displays a count of whatever is colored on the screen. So you can quickly show how many have been adjusted up, or down, with selection criteria specified. The other improvement is that the popup data includes a link to the GHCN display page, giving extensive history and graphs of observations and adjustments.
I have also updated the data to Jan 2015.
The plot is below. And below that, some details about the usage logic. The field Trend_Adj is the trend difference over whole of life made by adjustment, in °C/cen. It is set to NaN for stations with less than 360 months of adjusted data in total (maybe with gaps).
The green box on the right has a collection of selection criteria. Some are comparisons, some are logical. The second small button toggles between the relation options (>,==,T/F etc), and for comparison, the third is a text box in which you enter the reference value. Only one selection can be live at a time, determined by the left radio button.
When you have a live selection, you can click a radio button in the top orange section (Pink,Cyan etc). Any stations that fulfill your requirement will change to that color. In the middle column, the numbers in each color are shown, and updated with each choice. Invisibles are still in the totals.
The right column shows the most recent logical operation that was implemented for that color. It does not show the status of all markers in that color. If the color is eg pink, then the expression will not include markers that were pink before the latest selection, and the other logicals don't change. I could make a logical expression for the state, but it would quickly get very complicated.
The All button, when F does nothing, but when T and live changes everything to one color. You may want to start with everything invisible. I'd make this the default, except that it is a bit discouraging when you are first trying to make something happen.
You can enter NaN into the text fields, which will have the effect of changing any NaN to that color. Usually used to make them invisible. For Trend_Adj, there is the option of equality ("=="), mainly used to test for zero. I should warn that it tests to rounding level, which is 0.01. Very few stations totally escape adjustment (eg MMTS), but it is often very small.
I've included Lat and Lon; it doesn't mean much when you have a map. but is useful for counting, eg Arctic. I have given Urban and Rural as separate options, because there is also Mixed. So if you color Urban T, that is what you see, but Rural F gives Urban and Mixed.
You'll find negative logic useful. The advice on how to sculpt an elephant is, take a very big rock and chip away anything that doesn't look like an elephant. Same here. If you want pink to show urban stations that have trend increased on adjustment, then pink all uptrended, then go to Urban F, and make that invisible. That will affect other colors too (if any).