Enhancing the Satellite View of the Atmosphere

#2059 "Singleton Sunset Reflection" Pixels Link

An important digression before we return to the dry conveyor belt story which is written in the invisible ink of dry  air... it is important to appreciate the importance of satellite imagery and water vapour in particular in understanding the conveyor belts conceptual model and the atmosphere around us.

Historically I preferred using simple grey scale enhancements in satellite imagery. A particulart shade of grey can be related to the brightness or energy returned from every point in the image. A smart enhancement only spends those grey shades over the energy levels that one should expect to observe. That was the premise for those early days when I created special enhancements for the sunrise and sunset periods in order to glean every last bit of information from the visible satellite imagery. The relativity between the brightness of every picture element or pixel in the scene was preserved but greatly enhanced. The resulting pattern could be better interpreted as to what it meant meteorologically just in time for the early morning forecasts.

Enhanced Visible Imagery from 1981 and 1982

The human eye can really only see 30 shades of grey depending on the lighting. In the early days of satellite and computer technology I would struggle to see more than 15 different shades of grey . The images and their messages got fuzzy. If seeing the pattern is a challenge then that shape and the meteorology it represents are probably not worth finding anyway. The analysis and diagnosis of iffy  pixels was not justifiable.

On a colourful note, the human eye is capable of detecting around 10 million unique colours. Of course these colours need to be selected prudently to display the brightness temperatures from the satellite. The use of an excessive number of colours can result in an abstract work of art and science. Meteorologists can get as easily confused as anyone else. The use of these colours can highlight specific meteorologically important quantities and processes that might otherwise be missed in the world and whorls of black and white. I employed a lot of colours in my work with infra-red satellite imagery in those early days.

The water vapour enhancements used by UCAR are suitably linear and simple. They are as good as it gets for use in diagnosing the atmospheric conveyor belts. The subtle patterns and shapes in the water vapour pixel topography are greatly enhanced. The rising surfaces of the warm conveyor belt comprised of high and cold water vapour are displayed in cool shades of purple and green. The sinking dry and warm conveyor belt is witnessed in hot shades of orange and red - artistic earth tones. A linear grey scale is used to exhibit the water vapour surfaces between these cold and hot extremes. This three way use of colour and grey shades reveal to the human eye the very important physical processes that create the weather in our atmosphere. Water vapour imagery taught me about the importance of one’s frame of reference and swirls. The natural patterns are really quite beautiful as well. The science in the art was unmistakable.

Not everyone sees things the same way though. I used a lot of arm waving and right hand thumbs while in the Atmospheric Environment Service Training Branch, in an attempt to explain what the water vapour imagery was saying. Some of that material is included in these Blog Journals. At that time the message of the satellite imagery was competing with the very seductive numerical presentations of the weather. The numerical weather prediction (NWP) was getting much better and prettier by the month. Remote sensing depicted the real atmosphere but there were concerns and deciphering the messages in the satellite data could be challenging.

Two of the several geostationary satellites above the equator

The geostationary satellites parked above the equator provide terrific imagery in terms of time and space continuity. The drawback with this singular view is that layers of high water vapour in the lower latitudes can obscure important meteorological features below. The graphic will explain this concern.

High Level Moisture Obscures Lower Level Processes

In addition, it can be a challenge to "see" the water vapour imagery in the three dimensions that the atmosphere moves in. One needs imagination to envision what is not painted in the picture.

Looking northeast across North America

One day in 2012 during a break with my COMET friends in Boulder, I expressed a dream to make the three dimensionality of the water vapour (WV) more obvious. If we could only use the WV brightness temperature as the vertical axis and turn the water vapour into a 3-dimensional image... wouldn't that be instructive! It maybe took a day for the creative folks at COMET to achieve that dream. Here are the first examples of what the water vapour can reveal in 3-dimensions. The water vapour topographical surfaces could be turned and twisted into any orientation on the computer screen. The atmospheric secrets were obvious when you enhanced for them. The images can still not reveal what is hidden under higher level obscurations but the three dimensional flows of the conveyor belts were recognizable. This imagery could be produced in real time to aid the meteorologist. I was disappointed when few others were as excited as I was about this development. Sadly, it reminded me of my experience with enhanced visible imagery from the early eighties.

Looking southeast across North America

Those same co-workers are not yet retired and are working on interactive displays to allow the curious to walk through the conveyor belt conceptual model (coming in a future blog) among other meteorological concepts. These same approaches will also allow people to stroll through the weather forecast in four-dimensions including time ... imagine!

The natural world is a terrific and fascinating place. Technology may help us to understand and appreciate it before it is too late! This reminds me of Joni Mitchell's “Big Yellow Taxi”.

"They paved paradise And put up a parking lot With a pink hotel, a boutique 

And a swinging hot spot 

Don't it always seem to go 

That you don't know what you've got Till it's gone 

They paved paradise..."

In any event, weather satellites and our understanding of the atmosphere continue to improve. The movement of dry air is every bit as important as the circulations of clouds. Here is a weather information site created and maintained by my friends in Boulder, Colorado. I think you will find it very useful.

http://weather.rap.ucar.edu/satellite/ and select  Water Vapor (mid)

That's enough for today... much more to come. 

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick