Geography 520: Climatology

1
Geography 520 Climatology
Intro Cont. Atmospheric Sounding

• Autumn Quarter, 2007
• J. Box and M. Davis

Lecture 02
2
Air Temperature (revised)
Easy, but less accurate TC0.5(TF-30) So, if TF
50, what is TC? less easy, accurate
TC(5/9)(TF-32)
Easy, less accurate TF2TC30 So, if TC 20,
what is TF? less easy, accurate TF(9/5)TC32
3
Comparison of temperature scales
4
In-Situ

• within

5
Remote Sensing

• Sensor is not in contact with observed entity
• Examples
• Infrared thermometer
• Satellite imager
• Digital camera

6
Phases

• Solid phase
• Liquid phase
• Gas (or vapor) phase

7
Humidity

• Humidity is the amount of water in the air.
• Water vapor pressure (e ) Pa
• A partial pressure is exerted by water vapor
• P Pd e
• Clausius-Clapeyron equation
• Saturation vapor pressure (es) as a f(T)
• e/es100 Relative Humidity

8
Plots of SVP Vs. T given linear (left) and
logarithmic (right) y-axes
Freezing point (0 C)
Freezing point (0 C)
9
es
10
Dewpoint

• Temperature at which air can no longer hold water
  vapor

11
Weather and Climate

• Weather is the instantaneous state of the
  atmosphere
• Climate is the average (or mean) state of the
  atmosphere
• Distinguished in temporal scales
• Weather is shorter term, that is, seconds,
  minutes, hours
• Climate is longer term, that is, hours, days,
  years
• Distinguished in spatial scales
• Weather is smaller-scale, that is, micro, local,
  regional
• Climate is larger-scale, that is , micro, local,
  regional, planetary

12
Scales of Atmospheric Motion and Weather Phenomena
Oke (1987)
13
Atmospheric Profiles
14
Sounding the Atmosphere

• Radiosonde
• In-situ (within)
• Vaisala
• since 1936
• Variables
• Temperature
• Pressure
• Height/altitude
• Humidity
• Wind Speed
• Wind Direction

Vaisala RS92
Vaisala RS80
15
A sounding
16
Radiosonde Launch Sites
Source Durre, I., R. S. Vose and D. B. Wuertz.
2006 Overview of the Integrated Global
Radiosonde Archive. Journal of Climate Vol. 19,
No. 1, pp. 53-68. The World Meteorological
Organization develops standards for
weather/climate observations
17
Climatology of Upper Air Soundings

• 1964-2005

N 30660
18
Upper AirTemperatureChanges1964-2005
Box J.E. and A.E. Cohen, 2006 Upper-air
temperatures around Greenland 19642005,
Geophys. Res. Lett., 33, L12706,
doi10.1029/2006GL025723
19
Humidity Changes 1980-2003
NOAA/ESRL Global Monitoring Division
20
Sounding the Atmosphere in the 21st century

• Remote sensing
• obtaining information about matter while not in
  contact with matter

AIRS, the Atmospheric Infrared Sounder
NASA Aqua Spacecraft, host to AIRS
21
AIRS, the Atmospheric Infrared Sounder

• Gridded data
• improved the accuracy of weather forecasts

Global Total Water Vapor, 500 millibar to
top-of-atmosphere, January 2003 - NASA
22
AIRS Specs

• 2378 spectral channels
• 100 times greater spectral resolution than
  previous IR sounders
• provides more accurate information on the
  vertical profiles of atmospheric temperature and
  moisture.
• AIRS also measures greenhouse gases
• Ozone (O3), carbon monoxide (CO), and methane
  (CH4), water vapor (H2O)

23
Earths Limb
24
Review Questions

• What is the meaning of in-situ?
• What is the meaning of remote sensing?
• Explain the difference between weather and
  climate or meteorology and climatology
• What is a radiosonde?