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Overview: I was adding Widgets to my iGoogle one day and found a cool little deal that displayed NOAA weather satellite images taken by the geosynchronous GEOS series. There are nine different views, with three different "spectra" available to each: Visible, Infrared and Water Vapor. Visible of course means half the pictures would be dark. IR is pretty much continuous, but looks like what you would expect clouds would look like from orbit. Pretty boring now days. But the Water Vapor channel... Wow! These looked like black & white images of Jupiter’s cloud tops!
Actually, the WV Channel is simply a narrow band IR view, from 8 km in the atmosphere, "tuned" to water vapor’s frequency. I understand the basics, but not the details. As a visual artist, I’m interested in the images. As an animator, I have always loved those nightly weather report loops. But they never went longer than 24 hours! And they never showed the Water Vapor channel.
After a bit of left & and right clicking on the NOAA images, I eventually found myself at a good old fashioned online directory listing! A true antique, as most servers no longer offer this. What was listed was line after line of .GIF images in sequence. All nine views with their three spectral channels.
The archives only go back 30 days, so for lengthy or on-going work multiple visits are required. The images are taken every 30 minutes, there are about 48 "frames" per day. The filenames are coded to reveal which camera, spectra, time and date each image was taken.
Actually, the WV Channel is simply a narrow band IR view, from 8 km in the atmosphere, "tuned" to water vapor’s frequency. I understand the basics, but not the details. As a visual artist, I’m interested in the images. As an animator, I have always loved those nightly weather report loops. But they never went longer than 24 hours! And they never showed the Water Vapor channel.
After a bit of left & and right clicking on the NOAA images, I eventually found myself at a good old fashioned online directory listing! A true antique, as most servers no longer offer this. What was listed was line after line of .GIF images in sequence. All nine views with their three spectral channels.
The archives only go back 30 days, so for lengthy or on-going work multiple visits are required. The images are taken every 30 minutes, there are about 48 "frames" per day. The filenames are coded to reveal which camera, spectra, time and date each image was taken.
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Signing UpStep 1Download Images
In theory all I need do is right-click on any image I want and download it to my local computer. But being a lazy human, I figured that there must be a easier way, since I wanted thousands. A short search of the Web turned up “Adsen Image Grab” which as its name would imply, was just the tool I was looking for! Best of all, it was freeware.
You start the program, enter in the Web site, then click whether to download displayed or linked images. However, I soon realized a serious drawback to this approach. If I went to the NOAA directory listing page, I would have to slog through the entire directory listing of a month’s worth of images: 48 per day; times 30 days; times 9 different views; times 3 three differential spectral channels equals a whopping 38,880 .GIF images at 160k per file! And I really only want just the water vapor, and only from the West Coast view, (I live in Oregon).
So I decided the simplest solution would be to create my own temporary Webpage listing of just the images I want. Then have Image Grab go there instead. In the FireFox browser, when you press the CTRL and U keys at the same time, the HTML code of the page you are viewing opens up in a new window. Called “Reveal Codes” the view shows the raw HTML code that makes up the directory listing. Depending on your connection speed, this may take awhile, as there is more than 38,880 lines of code.
Once the listing loads, I select the block of images I want, choose COPY (CTRL / C), then open up my HTML editor, and PASTE in the text, (CTRL / V). One can also choose SELECT ALL (CTRL / A) to copy the entire listing, then edit that down. Your choice.
In the original code, all the links to the images are of course local, or “relative links” as we say in the HTML editing field. This is because the images are on the same server as the Webpage. Once the modified listing is posted on my server, I need to change all those local links to “Absolute” links. A global search and replace editing action does this pretty quick. We need to add the full path to the image name, for example:
"ALIR092950030.GIF" becomes: "http://www.goes-arch.noaa.gov/ALIR092950030.GIF"
The code, generated by the Web server, also displays a generic image icon graphic next to the linked filename. I remove this line at the same time with one process. The result is a new Webpage, with just those images I want to download linked diercetly back to the NOAA server. I load the URL of that page into Adsen Image Grab. First you will need to wait for Image Grab to identify all the linked images. After that you select them all, and start the download process. then wait for the images to download into the pre-configured folder on my local machine. Depending on how many of the images are chosen, the wait can vary quite a bit. I often start these things before I leave for the evening or before I go to bed. But keeping in mind that the archives only go back 30 days, if you wait too long to start the process, older images may no longer be available.
You start the program, enter in the Web site, then click whether to download displayed or linked images. However, I soon realized a serious drawback to this approach. If I went to the NOAA directory listing page, I would have to slog through the entire directory listing of a month’s worth of images: 48 per day; times 30 days; times 9 different views; times 3 three differential spectral channels equals a whopping 38,880 .GIF images at 160k per file! And I really only want just the water vapor, and only from the West Coast view, (I live in Oregon).
So I decided the simplest solution would be to create my own temporary Webpage listing of just the images I want. Then have Image Grab go there instead. In the FireFox browser, when you press the CTRL and U keys at the same time, the HTML code of the page you are viewing opens up in a new window. Called “Reveal Codes” the view shows the raw HTML code that makes up the directory listing. Depending on your connection speed, this may take awhile, as there is more than 38,880 lines of code.
Once the listing loads, I select the block of images I want, choose COPY (CTRL / C), then open up my HTML editor, and PASTE in the text, (CTRL / V). One can also choose SELECT ALL (CTRL / A) to copy the entire listing, then edit that down. Your choice.
In the original code, all the links to the images are of course local, or “relative links” as we say in the HTML editing field. This is because the images are on the same server as the Webpage. Once the modified listing is posted on my server, I need to change all those local links to “Absolute” links. A global search and replace editing action does this pretty quick. We need to add the full path to the image name, for example:
"ALIR092950030.GIF" becomes: "http://www.goes-arch.noaa.gov/ALIR092950030.GIF"
The code, generated by the Web server, also displays a generic image icon graphic next to the linked filename. I remove this line at the same time with one process. The result is a new Webpage, with just those images I want to download linked diercetly back to the NOAA server. I load the URL of that page into Adsen Image Grab. First you will need to wait for Image Grab to identify all the linked images. After that you select them all, and start the download process. then wait for the images to download into the pre-configured folder on my local machine. Depending on how many of the images are chosen, the wait can vary quite a bit. I often start these things before I leave for the evening or before I go to bed. But keeping in mind that the archives only go back 30 days, if you wait too long to start the process, older images may no longer be available.
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