MICROCLIMATE EFFECTS ON ATMOSPHERIC

1
MICROCLIMATE EFFECTS ON ATMOSPHERIC CARBON
DIOXIDE GROUP WORK BASED ON THE PRAIRIE RIDGE
PROJECT MEA 760 BIOGEOCHEMISTRY WILFRED
AKAH September 21, 2006
2

• Climate and Climate Processes -
• Why climatology
• climate as a constraint for geological
  processes
• climate as a constraint for environmental/
  ecological/evolutionary processes
• climate as a constraint for human society
• understanding the climate system is a
  prerequisite for understanding the anthropogenic
  impact on environment and climate

3
Climate Climate is the set of weather
conditions typical of a given region together
with the frequency of these conditions and their
seasonal variations. (Monin 1986) Thus
climate denotes the mean weather and the
statistical weather distribution of a certain
area as determined over a certain number of years
(frequently 30 years reference climate
1931-1960).
4
Present-day climate is a result of the
interaction of various components and factors.
Climate conditions at a location is suitably
described by the parameters Solar
radiation Temperature Precipitation and
Air pressure
(Dommergues, 1979)
5

• Climate classification
• The generic climate classifications of Flohn
  (1950) regards
• Equatorial westerly zone constantly wet
• 2. Tropical zone, winter trades summer rain
• 3. Subtropical dry zone (trades or subtropical
  high)
• 4. Subtropical winter-rain zone winter rain
• 5. Extra-tropical westerly zone precipitation
  through the year
• 6. Subpolar zone less precipitation through the
  year
• 7. High polar zone sparse precipitation, summer
  rain, early
• winter snow

6

• Relevant climate parameters
• mean annual temperature (MAT)
• mean temperature of the coldest month (CMT)
• mean temperature of the warmest month (WMT)
• mean annual precipitation (MAP)
• mean precipitation of driest month

7
Spatial Scales of Climate

• Microclimate mm to 100 m
• Mesoclimate 100 m to 100km
• Macroclimate 100 km to 10,000 km
• Climate system
• Atmosphere, land, ocean, ice and biosphere
  together form the climate system. (IPCC 1995)
• The climate system is influenced by
  extraterrestrial factors, in particular by solar
  radiation.

8
(No Transcript)
9
Components of the Climate System and External
Factors External Factors The Sun
Geometry and Orbital Parameters of the
Earth Components of the Climate System
Atmosphere Land Ocean Ice Biosphere
10

• Average Composition of the Atmosphere (below 25
  km, dry air)
• Nitrogen, N2 78 vol. (dry air)
• Oxygen, O2 20.95
• Argon, Ar 0.93
• Carbon dioxide, CO2 0.035 350 ppm
• Neon, Ne 0.0018
• Krypton, Kr 0.0011
• Helium, He 0.0005
• Methane, CH4 0.00017 1700
  ppb
• Ozone, O3 0.00006

11
Greenhouse Gases (Data from 1991) Gas
Concentration Increase/a
CO2
355(280)ppm 0.5 CH4
1.7(0.8)ppm
0.9 CFM 0.3(0)ppb
4 N2O 0.31(0.29)ppb
0.25 O3 30(?)ppb
1(?)
12
Global Cycles of Atmospheric Greenhouse Gases
Carbon Reservoirs (pre-industrial/recent)
Atmosphere 600/750 Gt C Land Biota 610/550
Gt C Soil/Detritus 1560/1500 Gt C Marine
Biota 3/3 Gt C Ocean surface 1000/1020 Gt
C DOC 700/700 Gt C interm. deep
38000/38100
13
Humidity and precipitation Humidity Measurement
of the proportion of water vapor in the
atmosphere (relative and absolute). Humidity
depends on temperature. The higher air
temperature is, the more water vapor can be
incorporated. Important processes which can
change humidity Evaporation Energy supply
causes change from liquid water to water vapour
at temperatures below the boiling
point Condensation Occurs when relative
humidity is 100 and temperature
further decreases, leads then to condensation,
clouds and likewise to Precipitation Freezing
Temperature decrease below 0C in the atmosphere
14
Anthropogenic Concentration of greenhouse gases
since 250 years
15
Tropical forest Energy
Chemistry Agriculture
Destruction of forest Co2 and other trace gases
Air pollution CO2, NO2, Cox, CH4
Production, application CFC
Fertilization N2O, CH4
16
Estimated sources of CO2 and CO2 cycle
17

• CO2 in Relation to Plants
• At the photosynthesis level, there are three main
  plant groups
• C3, C4, and CAM (Craussulacean Acid Metabolism)
  plants.
• Examples of C3 plants Soybean, wheat, rice, and
  potato.
• The C4 pathway is found in tropical grass crops
  like corn, sugarcane, sorghum and some members of
  the families Chenopodia Ceae and Arnaranthaceae.
• The C4 plants are more efficient in
  photosynthesis than the C3 plants.
• In C3 plants, 20-50 of the carbon fixed is
  immediately lost by photorespiration.
• In contrast, C4 plants exhibit little
  photorespiration.

18
In comparison to these two plant types, the CAM
plants are a form of C4 except that the CO2 is
fixed at night and then processed via a C3
pathway during the day. CAM plants
include pineapple and succulent vegetation like
Cacti and stone crops they are highly efficient
users of water.
19
Temperature change in the Atmosphere
Mid-tropospheric (850-300mb) temperatures have
increased between the 1970s and 1990s, in
parallel with surface temperature. In the
upper troposphere (300-100mb) there has been a
steady decline in temperature of about 0.4C
since the 1960s. Temperatures in the lower
stratosphere (100-50mb) show the greatest change,
especially since 1980. It is mostly attributed to
changes over and around Antarctica, probably
related, in part, to the decrease in
springtime stratospheric ozone.
20
Precipitation, cloud cover and sea-level
change With globally increasing temperatures,
increases in global precipitation would be
expected due to the greater rates of evaporation
of sea surface water. Observations however,
show for the last few decades an increase in the
mid-latitudes, decrease in the Northern
Hemisphere subtropics and increase throughout the
Southern Hemisphere. Increased global
cloudiness also would be an expected consequence
of higher global temperatures. Over Europe,
Australia, Indian sub-continent and North America
annual mean cloudiness has increased by 6 to
10. Increasing greenhouse gases are expected
to cause a rise in the global mean sea level, due
partly to oceanic thermal expansion and partly to
the melting of land-based ice masses.
21
Prediction of future climate change is assessed
when using simulation models which include
components of the climate system and their
physical features. Mostly, General Circulation
Models (GCM) are used. Associated with a doubling
of pre-industrial atmospheric CO2, the following
conclusions have been made A global average
warming at or near the Earth's surface of between
1.5 and 4.5C, with a "best guess" of 2.5C, will
occur The stratosphere will experience a
significant cooling Surface warming will be
greater at high latitudes in winter, but less
during the summer Global precipitation will
increase by 3 to 15 Year-round increases in
precipitation in high-latitude regions
are expected, whilst some tropical areas may
experience small decreases