Introduction to Upper Air Data

1
Introduction to Upper Air Data

• Mandatory and Significant Levels
• General Vertical Profiles of the Atmosphere
• Upper Air Maps
• TTAAs, TTBBs, PPBBs

2
Mandatory vs. Significant Levels

• Mandatory levels are those that will always
  appear in upper air analysis gathered from
  radiosonde data
• Significant levels are levels where there is
  significant data to present (usually not
  represented with a map but just incorporated on
  soundings)

3
Mandatory Levels and Heights

• Surface - obviously
• 1000mb - varies on station elevation
• 925mb - varies on station elevation
• 850mb - 1500m
• 700mb - 3000m
• 500mb - 5500m
• 400mb - 7000m
• 300mb - 9500m
• 250mb - 11000m
• 200mb - 12000m
• 150mb - 14000m
• 100mb - 16000m

4
Upper Air Maps

• This is why knowing heights is important
• Dew point vs. Dew point depression
• Normally temperature decreases with height until
  200mb where it becomes isothermal then increases
  with height in the stratosphere
• Wind increasing with height until the jet stream
  (250mb)
• There are troughs and ridges like sfc maps
• http//weather.unisys.com/upper_air/mandatory.html
  
• Details

5
TTAAs and TTBBs

• TTAAs are mandatory level data, temperature, dew
  point depression, height of p level, wind speed
  and direction is given
• TTBBs are significant level data, temperature,
  dew point depression, and p level is given
• PPBBs are the corresponding wind data with
  heights of the significant levels

6
Decoding all that data

• See http//www.ems.psu.edu/Courses/Meteo200/lesson
  5/decode.htm
• This link shows how to decode all this data and
  all the tricks
• There are little tests on this page to help
• All this data is displayed in thermodynamic
  charts, such as Skew T Log P diagrams
• In this class well focus just on TTAA

7
850 mb Maps

• How to decode station models for this level
• Temp plotted upper left in Celsius
• Dewpoint DEPRESSION plotted
• Circle shaded if T-D is 5 or less
• Height plotted in meters without first 1
• Height change over 12 hours given in decameters.
• Winds plotted same as surface maps

8
850 mb Maps

• What is the significance of 850 mb maps?
• Temperature and moisture advection
• Rain/snow detection
• Forecast of high and low temperature
• Low level jet
• Tilting of pressure systems
• Height contour intervals are every 30m and
  isotherms are every 5 degrees

9
700 mb Maps

• Interpretation is the same as 850mb except
  heights are plotted without the first digit,
  which is a 2 or 3.
• Contour intervals are every 30m and isotherms are
  every 5 degrees.
• Used to find
• Short waves
• Advections
• Steering flow for storms

10
500 mb Maps

• Contours are every 60 meters
• Stations are plotted as on 850 700mb maps, but
  height is given without the last digit, which is
  a 0.
• Used to find areas of vorticity advection.

11
1000-500 mb Thickness plots

• This plot gives the thickness of the layer of the
  atmosphere between 1000mb and 500mb.
• Related to mean temperature of the atmosphere.
• Can determine motion of organized convection
  (Mesoscale convective complexes)
• Rain vs. Snow

12
300/250/200 mb Maps

• Contour interval is 120 m, isotachs are every 20
  knots
• Heights coded just like in TTAA
• Used to find jet streams and jet streaks
• Useful to find areas of convergence/divergence
  aloft.
• Cyclogenesis can be enhanced
• Boundary between cold and warm air

13
Combining the Upper-Air Maps

• So how can using all these maps help us
  understand the state of the atmosphere.
• Atmosphere is 3-D
• Can help aid in forecasting development/decay of
  weather systems
• Developing cyclones tilt left as you look higher
  in the atmosphere
• Dying cyclones tend to be stacked or tilt right

14
Combining the upper air maps

• Impacts for air travel?
• Jet streams/streaks
• Wind speed and direction aloft
• Temperatures aloft
• Moisture aloft
• Next Plotting and diagnosing data on a Skew-T,
  stability, severe wx signatures etc.