the nature of weather and climate - texas master...
TRANSCRIPT
The Nature of Weather and
Climate
Steven QuiringDepartment of Geography
Texas A&M University
El Camino Real Texas Master Naturalist Chapter
April 14, 2009
Outline
• Climate Controls
– Precipitation and clouds
– Temperature
• Climate Variability in Texas- El Niño
• Climate Change
• Weather & Climate Information
Climate and Ecosystems
• Rainfall, temperature, sunshine, humidity
• Means and extremes
• Climate controls distribution of natural vegetation
• Plants in Texas must be:
– Drought tolerant (esp. in West)
– Heat tolerant
– Cold tolerant in North
Generalized Climate Regions
Figure 10.4
Major Terrestrial Biomes
Biome = A large terrestrial ecosystem characterized by specific plant & animal
communities; named based on the dominant vegetation
Figure 20.3
What is needed for precipitation to
occur?
How does the air get cooled?
A) Convergent Lifting
B) Convectional Lifting
C) Orographic Lifting
D) Frontal Lifting (Cold/Warm)
A) Cyclonic Lifting
e.g., ITCZ
• Horizontal convergence of air results in
upward vertical motion, and
precipitation
lower density
B) Convectional Lifting
b. Convective Precipitation
• Convection = upward motion of heated
air (convection cells)
• Caused by uneven surface heating or
mechanical turbulence
• Convective precipitation is short, intense
events
• Can be scattered, or organized (squall
line, tropical cyclone)
Convection over Florida
Figure 8.8
b. Convective Precipitation
• If the air is moist, the release of latent heat will ensure that the parcel of air remains warmer than the surrounding air
• If conditions remain favorable, the rising thermal will grow into a thunderstorm
C) Orographic Lifting
Figure 8.9
c. Orographic Lifting
• Warm moist air is forced over a mountain barrier
• it cools adiabatically [adiabatic process = air
temperature changes due to changes in
atmospheric pressure]
• at the LCL, condensation (and often precipitation)
occurs
Figure 8.10
C) Orographic
Lifting
Orographic Lifting
D) Frontal Lifting
• Cold Fronts
– Cold air forces warm air aloft
• Warm Fronts
– Warm air moves up and over cold air
Cold Front
Figure 8.11
D. Frontal Lifiting
• Frontal Uplift - air can be forced upward is through the
movement of air masses
• Air masses = a large body of air, with a set of relatively
uniform temperature and moisture properties
Cold Front
and
Squall Line
Figure 8.12
Warm Front
Figure 8.13
To get precipitation, you need:
1) Moisture in the atmosphere
2) Cloud condensation nuclei
3) Atmospheric lifting mechanism
– cause water vapor to cool & condense
– 4 basic mechanisms
What Controls Precipitation?
• Cool the air until it is ‘saturated’
• Water vapor condenses onto tiny
particles as a liquid or solid
• Precipitation forms when:
– enough moisture condenses to start
droplets falling and colliding, or
– the air cools enough to start forming ice
Cloud & Rain Formation
Figure 7.20
Growth of cloud droplets: 1) condensation; 2) collision-
coalescence; 3) ice crystal growth (Bergeron process)
Cloud Types and
Identification
Figure 7.23
19000 ft
6000 to 19000 ft
< 6000 ft
Named based on:
a) Height
b) Shape
Figure 3.2
• Layers based on:
– Composition
– Temperature
– Function
Profile of
Atmosphere
Cirrus = thin and wispy
Figure 7.23
Composed of ice crystals; average thickness = ~1 mi
Stratus = flat clouds in layers
Figure 7.23
Cumulus = puffy clouds in heaps
Figure 7.23
Nimbostratus = rain
Figure 7.23
Cumulonimbus =
thunderstorm
Figure 7.23
Cirrostratus
Figure 7.23
Altocumulus
Figure 7.23
Altostratus
Figure 7.23
Advection Fog
Figure 7.25
Annual Precipitation
January Precipitation
February Precipitation
March Precipitation
April Precipitation
May Precipitation
June Precipitation
July Precipitation
August Precipitation
September Precipitation
October Precipitation
November Precipitation
December Precipitation
What controls temperature?
Energy Pathways
Figure 4.1
Solar Energy:
Electromagnetic Spectrum
Fig. 2.8
Solar constant = 1372 W m-2
Solar Energy:
Electromagnetic Spectrum
McKnight and Hess, 2004
8% 47% 45%
Principal Temperature Controls
1) Latitude
Amount of solar radiation
2) Altitude
High altitude has greater daily range, lower annual average
3) Cloud Cover
High albedo = moderate temperatures (cooler days, warmer nights)
4) Land/water (continental vs. maritime)
Altitude
• Lower density reduced ability to
absorb and radiate infrared radiation
• Higher altitudes solar radiation more
intense
• Result = lower avg. temperatures,
greater nightime cooling, larger daily
temperature range
Cloud Cover
• Clouds lower daily maximum
temperatures and raise nighttime
minimum temperatures. Why?
– Night – delay release of LW radiation
– Day – reflect insolation
Clouds and Temperature
Figure 4.7
Stratus (90% albedo)
Cirrus(50% albedo)
Land and Water Contrasts
5) Low albedo5) High albedo
January Average Daily Maximum
January Average Daily Minimum
July Average Daily Maximum
July Average Daily Minimum
What are the main causes of
climate variability?
1 MONTH 3 MONTHS
6 MONTHS 18 MONTHS
Ending April 13, 2009
Ending April 13, 2009 Ending April 13, 2009
Ending April 13, 2009
TAMU OSC
EXCEPTIONAL
EXTREME
SEVERE
MODERATE
ABNORMALLY DRY
NO DROUGHT
Climate Variability: El Niño
(ENSO)
Normal SSTs in the Central Pacific
ENSO
• In the late 1890s, fishermen along the coast of Peru begin to realize that every 2 to 10 years, with an average frequency of 7 years, there is a failure of the anchovy catch
• Anchovies feed on phytoplankton which, in turn, feed on nutrients from cold, upwelling waters
ENSO
• The loss of the anchovy catch was
termed an El Niño event – literally, the
male child although, in this case, it refers
to the Christ Child since the loss occurs in
the Southern Hemisphere Summer
(around Christmas)
Later references sometimes refer to this
event as a Warm Phase, although El
Niño is still used
El Niño Conditions
From International Research Institute for Climate Prediction
El Niño SSTs in the Central Pacific
Sea Surface Temperature Anomalies: El Nino Years
La Niña Conditions
La Niña SSTs in the Central Pacific
Sea Surface Temperature Anomalies: La Nina Years
U.S. & Global Weather
Anomalies
El Nino Cool-Season Precipitation
El Nino Cool-Season Temperature
La Nina Cool-Season Precipitation
La Nina Cool-Season Temperature
Current Conditions
http://www.cpc.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml
Niño Region SST Departures (oC)
Recent Evolution
The latest weekly SST departures are:
Niño 4 0.0ºC
Niño 3.4 -0.1ºC
Niño 3 0.1ºC
Niño 1+2 0.1ºC
U.S. Temperature and Precipitation Departures
During the Last 90 Days
90-day (ending 12 Apr 2009) % of
average precipitation
90-day (ending 11 Apr 2009)
temperature departures (degree C)
These seasonal outlooks combine long-term trends, soil
moisture, and some aspects of La Niña.
U. S. Seasonal Outlooks
April – June 2009
Temperature Precipitation
What evidence is there of climate
change?
State of the Climate (through 2007)
• 2007 = 5th warmest year in the 120+ year instrumental record
[2005/1998 = tied for warmest, 2002 = 2nd
warmest, 2003 = 3rd warmest, 2004 = 4th
warmest]
• Global temperatures were +0.5°C above the 1961-1990 mean
• 10 warmest years observed in the instrumental record (begins in 1880) have all occurred since 1995
2007 Temperature Anomalies
Temperature Trends
• Temperature rise of about 0.17C/decade (since
1979)
• Rate of warming is about 3X greater since 1979
– consider T of 1.5 C in last 10,000 years and T of
1.0 C in last 1,000 years
Climate Trends• Diurnal temperature range has decreased (min T are
warming twice as fast as max T)
• Precipitation trend = +5–10% for 30–85°N since 1900
• Sea level rise = +2.8 mm/yr since 1993
• Snow cover extent has generally decreased
• Earlier spring melt, later fall frost = longer growing
season
Climate Change 2007:
The Physical Basis
IPCC Summary for
Policy Makers
Earlier spring melt, later fall frost = longer growing season
Sea Level
Rise
•Since 1996, rate of loss from Greenland ice sheet has increased by 67%
•If all of the Greenland ice sheet melted, global sea-level would rise 23 ft
(7 m)
•Annually, it contributes about 0.5 mm (0.02 in.) to global sea-level rise
Shrinking glaciers
What is causing the climate to
change?
Causes of Climate Change
1) Natural mechanisms:
-variations in solar output
-orbital variations
-movement of continents
-atmosphere/ocean variability
-volcanic activity
2) Human mechanisms:
-land use/land cover change (e.g.,
deforestation)
-changing atmospheric chemistry
(greenhouse gases)
Carbon Dioxide• Radiative forcing of
greenhouse gases is
due primarily (~64%)
to CO2
• Concentrations have
increased from 330 to
383 ppm in the last 30
years
• Rate of increase
since Industrial
Revolution
unprecedented in the
last 10,000 years
How is the climate going to
change?
General Circulation Models
(GCMs)
• GCMs are the best tool for projecting the
response of Earth systems to human (&
natural) influences
GCM Projections• The projected rise in air temperature is 1.8°C
to 4.0°C by the year 2100 (best estimate ~3.0°C)
• Precipitation will likely increase (decrease) in some regions 10 to 20%
• Decrease in snow cover and sea-ice depth and extent
• More frequent and intense heat waves, droughts, and heavy precipitation
• Tropical cyclones may be more intense(IPCC, FAR SPM)
- all models produce maximum warming in high northern latitudes
-warming is largest in late autumn and early winter, due to sea ice
forming later
Climate Change and Drought in
Texas:
Past vs. Future
John Nielsen-Gammon
Texas State Climatologist
Texas A&M University
The Impact of Global Warming in Texas:
http://www.texasclimate.org/
PANHANDLE
AND PLAINS
FAR WEST
TEXAS
WEST
CENTRAL
TEXAS
SOUTH
CENTRAL
TEXAS
SOUTH
TEXAS
SOUTHEAST
TEXAS
NORTH
CENTRAL
TEXAS
EAST
TEXAS
Dec-Feb Temperatures
-3
-2
-1
0
1
2
3
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Ave
ra
ge
Te
mp
era
ture
(F)
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
Mar-Apr, Oct-Nov Temperature
-3
-2
-1
0
1
2
3
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Te
mp
era
ture
(F)
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
May-Sept Temperature
-3
-2
-1
0
1
2
3
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Te
mp
era
ture
(F)
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
6
5
4
3
2
1
0
-1
Te
mp
era
ture
Chang
e (
F)
2060205020402030202020102000
Texas A1B Projections
Climate model projections: + 4 °F by 2050
Temperature Projections for Texas
Precipitation trends at century-
long USHCN stations
Blue: Increasing
Precipitation Red:
Decreasing Precipitation
1901-
19251926-
1950
1951-
1975
1976-
2000
Fraction of months below 20th percentile of PDF, 12-month
precip
We were spoiled
during 1976-2000!
December-March Smoothed Precipitation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1899
1902
1905
1908
1911
1914
1917
1920
1923
1926
1929
1932
1935
1938
1941
1944
1947
1950
1953
1956
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
Year
Fra
cti
on
of
Lo
ng
-Te
rm
Me
an
Pre
cip
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
April-July Smoothed Precipitation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1899
1902
1905
1908
1911
1914
1917
1920
1923
1926
1929
1932
1935
1938
1941
1944
1947
1950
1953
1956
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
Year
Fra
cti
on
of
Lo
ng
-Te
rm
Me
an
Pre
cip
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
August-November Smoothed Precipitation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1899
1902
1905
1908
1911
1914
1917
1920
1923
1926
1929
1932
1935
1938
1941
1944
1947
1950
1953
1956
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
Year
Fra
cti
on
of
Lo
ng
-Te
rm
Me
an
Pre
cip
Panhandle and Plains Far West Texas West Central Texas South Central Texas
North Central Texas East Texas South Texas Southeast Texas
-20
-10
0
10
20
Perc
enta
ge P
recip
itatio
n C
han
ge
2060205020402030202020102000
Texas A1B Projections
Climate model projections: probably drier by
2050
Precipitation Projections for Texas
• IPCC estimates that global sea level will
rise 0.18 to 0.59 m (7 to 23 in.) by 2100
• However, this estimate does not consider
the large changes in ice sheet mass flux
that have been observed since 2003
• Actual sea level changes may by larger
than those predicted by the IPCC
Sea Level Rise
Sea Level Rise
• Beach erosion
• Loss of agricultural land
• Loss of thousands of kilometers of land
• Displacement of millions of coastal residents
http://www.cresis.ku.edu/research/data/sea_level_rise/index.html
1 m Sea-Level Rise
Climate Change Summary
• Yes, global surface temperatures are
rising due to human activities
• Future = certainly warmer, maybe less
rain, definitely more evaporation
• That scenario could easily happen (and
has) even without global warming
• Year-to-year changes strongly driven by
nature
Headline: Hundreds Attend
Global Warming Protest
Weather and Climate
Resourceshttp://atmo.tamu.edu/osc
– Office of the State Climatologist, Texas
• www.met.tamu.edu/class/wflm– Online Weather Forecasting learning modules
• meted.ucar.edu– Online training for weather forecasters
• www.cdc.noaa.gov– Monitoring Earth’s climate on medium range to
interannual time scales
Weather and Climate
Resources• www.srh.noaa.gov/hgx
– Warnings, short-range forecasts, radar
• www.tceq.state.tx.us/nav/data/air_met_data.h
tml
– Ozone and air quality (current and historic)
• weather.msfc.nasa.gov
– Real-time satellite image browser
• www.txwin.net
– TX Water Information Network (drought, etc.)
Help Improve Local Monitoring
• Community Collaborative Rain, Hail, and
Snow Network (CoCoRaHS)
• http://www.cocorahs.org/
• Volunteer high-density rain gauge
monitoring network
• More volunteers needed in Texas!
Local Monitoring Tools
• Office of the State Climatologist, Texas
• http://atmo.tamu.edu/osc
• Weekly/monthly climate reports
• Climate monitoring tools under
development
The End
• Contact Info:
– Steven Quiring, Texas A&M University
– http://geog.tamu.edu/~squiring/
– (979) 458-1712