Mystery on satellite image - Eastern Arkansas

Interesting thread... I fowarded this to my major advisor (Dr. Mote -UGA), who is currently teaching satellite meteorology and thought he could show this to the class. Here's what he had to say about it:

This is interesting. I can't post on this site, but you may want to
refer people
to the near-real time MODIS imagery.

Look at the following web site:

http://rapidfire.sci.gsfc.nasa.gov/realtim...0192000.1km.jpg

You can zoom in to 250m resolution (this is 1km). Try the 7-2-1 "false
color"
composite. What you're looking at by default is a 1-4-3 "true color"
composite.
Then look at the NDVI.

This is an area of agricultural lands that is surrounded by mostly
forested lands.
The forested lands are darker than the exposed soil ascrops haven't yet
produced
much biomass while deciduous trees are greening and pines plus also mixed
in the surrounding forests. Note that the bare soil also heats more quickly
(warmer in IR) due to lack of latent heat flux meaning higher sensible
heat over
bare soil.

To see the difference in forest density, look at the following map:

http://forestry.about.com/library/graphics/ustype.pdf

or for lower resolution maps:

http://forestry.about.com/library/weekly/aa012102a.htm

Once you see these maps (especially the higher res pdf), the pattern is
obvious. Feel
free to forward/post this message to the group. [/b]
Click to expand...
 
Okay I just looked on satellite and I see it this morning, too. So it's obviously not weather-related as it is not moving. It also follows the topographical countours of Arkansas:

arkansas-nc.gif


That ridge in eastern and northeastern Arkansas of slightly higher elevation shows up nicely on satellite this morning - it is "white-free". So whatever this is, it seems to be confined to the lowest topographic elevations of Arkansas.

What the hell IS this? ;)

K.
 
So far the best explaination I have heard is sitting ground water which may be reflecting back into space...which would fit in to Karen's "lowest topography" observations. Anyone know the rainfall totals for this area over the last month?
 
Although I'm not sure exactly what causes it, it is definitely an agricultural phenomena. And it has been visible on high res vis satellite images for many years now.
 
I would think that region is pretty close to normal rainfall ... they were slipping into abnormally dry a few months ago but have recovered some since ... as much water as gets irrigated into rice fields you wouldn't have to have a lot of rain to have a lot of standing water. They flood those things so much that, quite often, a former rice field will get turned into a catfish farm instead (and there's a lot of stress on the undergound aquifer from overuse).

The soil types vary. Seems like I recall that it is more of sandy soil west of Crowley's Ridge (the small line of hills through the middle) transitioning to more of loamy soil east of the ridge. Lemme see if I can find something more definitive on that. I should know more, as my dad was involved in the rice milling industry for more than 30 years.
 
I'm heading to E Arkansas now. I'll report back in an hour or two with pics.

Still believe it's the flooded rice fields. As Kevin mentioned, farmers flood these fields when growing rice, and this is about time they should be seeding the fields.

Stay tuned.
 
I'm heading to E Arkansas now. I'll report back in an hour or two with pics.

Still believe it's the flooded rice fields. As Kevin mentioned, farmers flood these fields when growing rice, and this is about time they should be seeding the fields.

Stay tuned.
[/b]
Click to expand...

You go girl! :lol:

Say hi to Wynne for me...... B)

K.
 
Major Soil Types in the area;
Vertisols:
Clayey soils that shrink and develop cracks when they dry and swell when they become moist. The shrinking and swelling can damage buildings and roads. Technical definition: Mineral soils that have 30% or more clay, deep wide cracks when dry, and either gilgai microrelief, intersecting slickensides, or wedge-shaped structural aggregates tilted at an angle from the horizon.

Alfisols:
Soils in semiarid to humid areas that have a clay and nutrient-enriched subsoil. They commonly have a mixed vegatative cover and are productive for most crops. Technical definition: Mineral soils that have umbric or ochric epipedons, argillic horizons, and that hold water at < 1.5 MPa tension during at least 90 days when the soil is warm enough for plants to grow outdoors. Source: natural Resources Conservation Service[/b]
Click to expand...
Mike
 
I have the answer. It's dirt :)

It definitely is not anything blooming. And it's not flooded rice fields like I thought either. It looks like the farmers are out getting the fields ready to irrigate, but it's extremely dry out there.

pic1.jpg

pic2.jpg

pic3.jpg


I could post more pictures, but they all look the same. I drove to Brinkley, then north and east on some farm roads for several miles. Everything looks just like these pics. Farmers are out in full force. Maybe what we are seeing is a big ol' dust cloud from all these farmers hard at work.

You go girl! :lol:

Say hi to Wynne for me...... B)

K.
[/b]
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Wynne says to please keep the tornadoes in OK for awhile. It and the surrounding areas are pretty stressed out right now and need a break ;)
 
That's pretty darn interesting... I wouldn't think that the dirt would be that reflective, but I suppose if the dirt is light enough and with how dry it is. Interesting feature and way to go out there and investigate!! :D
 
I have the answer. It's dirt :)

It definitely is not anything blooming. And it's not flooded rice fields like I thought either. It looks like the farmers are out getting the fields ready to irrigate, but it's extremely dry out there.

I could post more pictures, but they all look the same. I drove to Brinkley, then north and east on some farm roads for several miles. Everything looks just like these pics. Farmers are out in full force. Maybe what we are seeing is a big ol' dust cloud from all these farmers hard at work.
Wynne says to please keep the tornadoes in OK for awhile. It and the surrounding areas are pretty stressed out right now and need a break ;)
[/b]
Click to expand...

Whoa. Dirt. LOL j/k - thanks for going out there to investigate, Sheila! :D

This makes sense, and moreso if you do a little satellite tour of the U.S. just now too. It's not a dust cloud I don't think - as it's not moving and therefore it is not airborne. However - it stands to reason that vast areas of dirt fields will reflect a different "color" to the satellites than areas of forest, water or other kinds of vegitation.

Run a loop of this area of eastern AR and look at the color of this anomaly. Then, run a loop of, say, Nebraska, New Mexico, and the Carolinas for comparison.

Everywhere west and north of OK seems to have this light-appearing earth color (dry, semi-arid scrub farmland). Most places east and south of Oklahoma (especially the deep south, Louisiana, Mississippi etc.) are much darker in ground color (moist, tree-laden areas).

In particular, look at the loop of the Carolinas by the coast. Do you see what I see? An apparently similar-looking area of lighter-colored soil all the way along the coast to about halfway inshore of these states. Is this also a big agricultural area with much farmland being prepared for cultivation currently??

This would also explain why some have claimed this "white anomaly" is there sometimes and not there other times. At certain times of the year these areas are thick with crops and greenery as they are commercially farmed. Also - I would imagine that if the general area is very damp and has received a lot of rain (i.e. not like the present day's blowing dust era) the soil color would change and it may appear less light also.

K.
 
Thanks for the sleuthing, Sheila. Before the ground is tilled for spring planting, the soil often gets that white appearance because of deposits from fertilizers, etc. Really shows up if its dry. Even up here, where the soil is as dark as coffee you can see it this time of year. Down there it looks like the soil is a lot lighter in color ... more like coffee creamer. Put Missouri and Arkansas together and it's like living at Starbucks ... (I wish) ...

Anyway - that also explains the Google Earth imagery from that area - - - you can see the silt and sand deposits along the rivers and they are very light in color.
 
Water typically shows up as a dark color on visible images (though not much, if any, if it's surrounded by forests). In addition, as was noted earlier, much more of the insolation is converted to latent heating (e.g. evaporation) over lakes or bodies of water and less is used for sensible heating. In other words, think of it like this -- the sun's energy is used to evaporate water (raise Td) over a lake or whatnot moreso than the energy is used to raise the temperature of the air over the lake. When looking at IR satellite imagery, then, the lakes and other very wet areas tend to look 'brighter' than nearby areas. On the other hand, very dry land lends itself to more sensible heating than latent heating (dry land can get very hot during the summer months), since there just isn't a lot of moisture to evaporate. On IR imagery, then, we'd expect dry land to show up darker (hotter) than nearby areas. When looking at the IR imagery linked to on the 1st page (I think), the land areas that were white on visible are dark on IR. This is the same thing as was discussed in the email copied/pasted on the last page of this.

Thanks, Sheila, for checking this out!
 
Well you gotta have dirt before you can flood it for rice, so it make sense. Also explains why Karen's tornado at Wynne kicked up such a nice little dust debris cloud almost West Texas style. Thanks Sheila for taking a look. I visit the dirt, which should be sprouting a little green by then, in about 3 weeks ... primarily to see my folks and drop off my dog for "summer camp" while I go on a big chase trip later.... but I will chase anything chaseable if it happens in that area ...
 
I lived in Arkansas for years and one thing I remember is that there was a lot of quartz crystal in the soil. Almost every rock you would pick up would have these beautiful sparkling crystals in them. Could that also add to the reflectiveness of the soil?
 
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