Atmospheric Measurement

Question 1

Types of measurements

Answer 1

Ice core
modelling
Mass spectroscopy
Optical absorption spectroscopy
Gas Chromatography
ECD

Question 2

Electron Capture Detection

Answer 2

radioactivity material emits e
Halogen attracts the e
measure the amount of e that flow
give the amount of halogen

Question 3

Advantages of Optical absorption measurements

Answer 3

remote/no human contact
sample not altered or disrupted
no complex handling
highly selective and sensitive
different measurement geometries

Question 4

Disadvantages of Optical Absorption measurements

Answer 4

non-linear relationship between light intensity and concentration (no extrapolation)
instrument calibration affects the measured spectrum
Not flexible?

Question 5

Calibration of measurement instruments

Answer 5

calibrate to standard gas
use ideal gas law
calibrate near testing site

Question 6

reducing measurement errors

Answer 6

remove interference or make irrelevant
Assess and correct regularly
Matrix match sample and standard
make sample as close as possible to standard

Question 7

In situ measurement networks

Answer 7

good to measure variability
low density regions rely on modelling
automation to prevent human inaccuracies
robust to change and low funding periods
satellites cannot detect low concentrations

Question 8

Summary of ozone depletion

Answer 8

CFCs were most depleting
now nitrous oxides from aircraft
most depletion in polar spring cold but with UV radiation