Observations:
Atmosphere and
Surface – part I
Jón Egill Kristjánsson
Contents
• Changes in Atmospheric Composition
• Changes in Radiation Budgets
• Changes in Temperature
CHANGES IN
ATMOSPHERIC COMPOSITION
- Well-mixed (Long-lived) greenhouse gases
- Short-lived climate forcers
- Aerosols
WELL-MIXED GREENHOUSE GASES
The CO2 observational record
In 1750
(Pre-industrial):
278 ±2 ppm
Why the
wiggles?
Increase since
1750: 40%
CO2 contributes
80% of the
increase in
Radiative
Forcing from
greenhouse
gases in 20052011
Current growth rate: 2.0
ppm yr-1 (0.72% yr-1)
Assuming continued
0.72% yr-1 growth rate,
how long will it take to
reach a doubling
compared to preindustrial?
Main net
sources of CO2?
RF of CO2 doubling?
The CH4 observational record
In 1750
(Pre-industrial):
722 ±25 ppb
Increase since
1750: 150%
Main sources of
methane?
The N2O observational record
In 1750
(Pre-industrial):
270 ±7 ppb
Increase since
1750: 20%
Main sources of
nitrous oxide?
The observational record of halogens
Ozone-depleting substances
“Replacement” gases etc.
SHORT-LIVED CLIMATE FORCERS
Stratospheric Water Vapor
Where does it
come from?
In what way is
it important?
Stratospheric Ozone
Stratospheric Ozone
The
Ozone
Hole
Tropospheric Ozone
Main sources?
Precursor of O3
Lifetime: hours
Tropospheric NO2
Aerosol Optical Depth
• What does ‘Aerosol’
mean?
• What is AOD?
• What units does it
have?
• Why no retrievals at
high latitudes?
• Sources?
Aerosol Optical Depth - seasonal
- Positive trends in SE Asia
- Negative trends Europe, N-America
- Why?
SO2 emissions and visibility
Why is there a strong positive correlation
between [SO2] and visibility?
‘Black Triangle’, Europe
Stjern et al. (2011: J.Geophys.Res.)
China
Qian et al. (2009: J.Geophys.Res.)
Trends in particulate matter
Reductions in Europe, N-America
Trends in particulate matter - Sulfate
- Reductions in Europe, N-America
- Most pronounced trends before 2000
CHANGES IN
RADIATION BUDGETS
The Energy Budget
Energy Balance ≈ Radiative Balance for (1), (2), (3)?
(1) TOA
(2)
Atmos
phere
(3)
Surface
Where did the excess heat go?
Why is there a correlation between ocean heat storage and ENSO?
La Niña
(cold
event)
El Niño
(warm
event)
A strong El Niño brewing in the
tropical Pacific?
Surface Solar Radiation at Stockholm
What does this
figure tell us?
CHANGES IN
TEMPERATURE
‘SURFACE’ TEMPERATURE
Land Surface Air Temperature
What are the likely causes of the variations in the figure?
Homogenization
of this time series
(p.187)
Low
confidence
prior to 1880!
LAND
OCEAN
GLOBAL
Diurnal Temperature Range
• Is the nighttime temperature rising faster than
the daytime temperature?
• Is that to be expected?
• If so, why?
Sea Surface Temperature from
ICOADS: Measurement Techniques
Sea Surface Temperature and
Nighttime Marine Air Temperature
Cold bias prior
to 1941 due to
use of canvas or
wooden
buckets
Sea Surface Temperature – Satellite Estimates
(red) and in-situ measurements (black)
What
happened
here?
Sea Surface Temperature and Night
Marine Air Temperature
Has global
warming
stopped
(‘hiatus’)?
Decadal global surface temperature
anomalies
All of the 10 warmest
years have occurred
over the last 15 years
(1998-2012)
Discrepancies between
the three data sets
Where is the ‘hiatus’?
Global (land + ocean) Surface
Temperature
• 1901-1940: Warming
(+0.4 K)
• 1941-1975: Slight
cooling (- 0.1 K)
• 1976-2012: Warming
(+0.6 K)
• Possible causes?
Trends in Surface
Temperature
(3 different data sets)
- Why is the warming largest over
land?
- Why is the warming largest at
high latitudes?
- Why is there a minimum in
warming south of Greenland?
Trends in Surface
Temperature
(3 different time
periods)
- Why
cooling
only in
NH?
TEMPERATURE IN THE ATMOSPHERE
- How would we expect it to change if we increase [CO2],
keeping everything else unchanged?
- How about aerosols?
Vertical weighting functions in
microwave satellite retrievals
Trends in atmospheric temperature from satellite retrievals
Where
is this?
Where
is this?
Where
is this?
Why
negative
trend?
Upper atmosphere temperature
evolution
What’s causing this?
Temperature trends in Lower Stratosphere
and Lower Troposphere – Satellite Data
Trends in upper air temperature from
Radiosonde Data
Consistent with the satellite
retrievals?
Trends in upper air temperature from
Radiosonde and Satellite Data
Summary
• Atmospheric Composition: …. greenhouse
gases …. aerosols …..
• Energy Budget: … TOA imbalance … ocean
heat storage …
• Temperature: …. surface temperature ….
tropospheric temperature … stratospheric
temperature …..
• …. 1941-1976 ….
• …. continents …. high latitudes ….