Post on 21-Jan-2016
description
Proposal Science Issues
• How will ozone recover over the next few decades in a changing climate?
• How has past ozone change affected the changing climate and how will future chemistry changes modify climate?
Basic Philosophy
•Get to fully interactive chemistry/dynamics through step-by-step simulations
•Key is ability to use model(s) in experiment mode.
– Get an idea from analysis – Formulate experiment– Run experiment, analyze results
•Requires computer throughput
Runs completed or now running
CTM• 50-year 1973-2022 with
Halogens, volcanic aerosols, solar cycle
• 20-year 1979-1999 without volcanic aerosols
• 9-year 1973-1981 with Pinatubo aerosols in 1975
GCM• 50-year 1949-1998 with
varying SST• 50-year 1949-1998 with
AMIP repeating SST• 50-year 1949-1998 with
mean repeating SST• 20-year with 1979 ozone
in radiation code• 20-year with 1999 ozone
in radiation code
50-year CTM IntegrationTotal Column Ozone from Model
Model run includeschlorine variationvolcanic aerosols,solar cycle, and dynamic variability.
We can deduce theimpact of each by statistical trend analysis, althoughthis is imperfect.
But with a model we can do the experiment!
Runs completed or now running
CTM• 50-year 1973-2022 with
Halogens, volcanic aerosols, solar cycle
• 20-year 1979-1999 without volcanic aerosols
• 9-year 1973-1981 with Pinatubo aerosols in 1975
GCM• 50-year 1949-1998 with
varying SST• 50-year 1949-1998 with
AMIP repeating SST• 50-year 1949-1998 with
mean repeating SST• 20-year with 1979 ozone
in radiation code• 20-year with 1999 ozone
in radiation code
CTM run Without Volcanic AerosolsDifference from basic 50-year simulation
averaged over the entire year of 1992
The model difference can be further examined for changes inchemical catalytic cycles.
NOx conversion toHNO3 decreasesozone loss
NOx conversion toHNO3 decreasesInterference withChlorine and thusIncreases ozone loss
Runs completed or now running
CTM• 50-year 1973-2022 with
Halogens, volcanic aerosols, solar cycle
• 20-year 1979-1999 without volcanic aerosols
• 9-year 1973-1981 with Pinatubo aerosols in 1975
GCM• 50-year 1949-1998 with
varying SST• 50-year 1949-1998 with
AMIP repeating SST• 50-year 1949-1998 with
mean repeating SST• 20-year with 1979 ozone
in radiation code• 20-year with 1999 ozone
in radiation code
What if Pinatubo erupted into a low-chlorine stratosphere?
Low chlorine meansthat volcanic aerosolsmostly reduce NOx loss while there isless chlorine loss to be interfered with.
Runs completed or now running
CTM• 50-year 1973-2022 with
Halogens, volcanic aerosols, solar cycle
• 20-year 1979-1999 without volcanic aerosols
• 9-year 1973-1981 with Pinatubo aerosols in 1975
GCM• 50-year 1949-1998 with
varying SST• 50-year 1949-1998 with
AMIP repeating SST• 50-year 1949-1998 with
mean repeating SST• 20-year with 1979 ozone
in radiation code• 20-year with 1999 ozone
in radiation code
SST constant in both runs
Increases in yellowto red, decreases inblue to purple.
Maximum increase and decrease about0.8K
20-year Average of Surface Temperature Difference at Each model point between
simulations for 1979 ozone and 1999 ozone
Test of Significance of Surface Temperature Changes
At each point calculatethe standard deviationdivided by the squareroot of 12 months times20 years to get standarderror of mean.
At left is ratio of meandifference at each pointdivided by the standarderror of the mean.
Yellow to red indicatesgreater than 2 standard errors of signficance
Probability Distribution of Surface Temperature Differences between GCM Runs with 1999 ozone
vs 1979 ozone in radiation code
4.9% > 2 sigma
32% > 1 sigma
i.e. Random-if there is an effectthe run is not long enough todemonstrate it.
Difference x 108-8 0
On-line chemistry• 1-year using
stratospheric integrator
• Testing strat-trop integrator
Runs completed or now running
Coupled Chemistry• None yet
Runs we would like to (should) do
CTM• Time-slice with more chlorine (~5-7 ppbv)
– Test cycle interaction at larger chlorine– Also evaluates what could have been
• Chlorine change without solar cycle– Clearly separates solar cycle– Basis for tests of possible solar cycle in circulation
• Hindcast with cold NH winter (GMI)– Gives envelope for ozone recovery
• Hindcast with warm NH winter (GMI)– Gives other side of envelope for ozone recovery
• Extend ozone recovery of 50-year run beyond 2022 to maybe 2050– Go to “complete” recovery
Runs we would like to (should) doGCM
• Redo 20-year delta ozone runs with interactive SST
– Surface temperature changes are dampened in constant SST runs– Gives full response to test radiative forcing
• Extend 20-year delta ozone runs for increased significance of changes
– Only significant difference so far is delay of Antarctic vortex breakup and a change in residual circulation
• 20-year run with PV-theta ozone climatology– Test the importance of having ozone heating correlate with wave
structures for radiative damping
• Time slice run (20+ years) preindustrial vs present tropospheric ozone
– Test impact of changes in tropospheric ozone from 1900 to present on surface temperature and meteorology
Runs we would like to (should) do
On-line chemistry
• 5-year test with stratospheric integrator– On-line/off-line test– Preparation for coupled stratospheric chemistry
• Few-month test with strat-trop integrator– Test timing to see how much speed up is necessary for useful
experiments
• Speed up options tests with strat-trop integrator
– Evaluate various methods that are suggested
Runs we would like to (should) do
Coupled Chemistry• Ozone hole recovery test
– Chemistry simulation with interactive vortex
• 50-year stratospheric hindcast/forecast run– Extend hindcast to model with all connections that we know– Does it reproduce data better?
• Time slice preindustrial trop-strat chemistry– Preparation for long simulation run
• Time slice present trop-strat chemistry– Get statistics of present chemical situation rather than just the
meteorology of a single year
• Time slice future (2100) trop-strat chemistry– Statistics of where we think we are going
• THINK BIG - 250 year trop strat run 1850-2100– The ultimate simulation
What should be scope of proposal?
• Preliminary experiments to understand feedbacks
• Online chemistry
• Fully-coupled stratosphere
• Fully-coupled strat-trop chemistry
• Tropospheri chemistry experiments
Interactions
• What is relationship with GMI?
• How do we relate to GMAO?
• How does GISS figure in this?
• What about WACCM?
Fully interactive model
Dynamical Coreheating,
surface stress
RadiationTa, Ts, solar,
LandQ, solar
ChemistrySource gases, solar, T,wind
OceanQ, solar
Tests:1979 ozone1999 ozone
Tests:Varying SSTFixed SST
Model variables for time slice experiments (current model)
• Chemical source gases • Green house gas levels (pre-industrial to doubled CO2)• Volcanic aerosol levels (background or Pinatubo)• Solar (max/min or mean)• Sea surface temperatures (max/min or mean)
Extreme chemistry - use that to test radiative impact (1-7 ppb Cly)
Extreme radiative forcing - use that to test chemistry (250 ppm - 680 ppm CO2)
Extreme surface conditions - test radiative & dynamical changes (warm year vs. cold year)
CTM/FVGCM: Run FVGCM run CTM re-run FVGCM with CTM O3 compare runs
Tests between chemistry and radiation (non-interactive)
High ozone
Cly = 1 ppb
Low ozone
Cly = 5 ppb
Low CO2
CO2=250 ppm
Pre-industrial
High CO2
CO2=680 ppm
2050 Future avoided