Transcript Solar Forcing on Climate Through Stratospheric Ozone Change

Solar Forcing on Climate
Through
Stratospheric Ozone Change
Le Kuai
Objectives
Quantify the solar influence on the climate
change.
- UV radiation changes ~3.4%
- through ozone in stratosphere
Explore the effect of the solar variability –
-on ozone, radiative heating rates
-influences on climate dynamics and
stratosphere-troposphere coupling
The Statement of Problem
Stratosphere
Dynamical interannual variability
1) the annular modes (NAM, SAM)
2) QBO in the tropics
3) Solar cycle
Solar Cycle vs Annular Modes
 Solar UV variations
temperature and
ozone changes in
stratosphere
Propagate downwards
to troposphere
 NAM tends to its
negative phase at
solar min
 SAM
- extend to upper
stratosphere at solar
max
- confined in troposphere at solar min
Quasi-biennial Oscillation
(QBO)
Driven by small scale wave and tropical
circulation.
An alternation of anomalous eastward
and westward equatorial stratospheric
winds
QBO and solar cycle
Mayr et al. (2006):
the QBO serves as an amplifier of the solar
influence in the lower stratosphere.
Hines(1974):
solar variability could influence the
interaction between planetary waves and
zonal mean flow.
This interaction is affected by solar variability
and dependent on the QBO phase.
50-hpa geopotential height
solar minima: low during the w QBO phase
high during the e QBO phase
solar maxima: opposite relationship
Ozone in stratosphere
EOF First mode: 45%, PC 28 months
EOF Second mode: 34%, PC 11-yr
- 10 DU about 4% of mean column ozone
QBO
11-yr
Previous achievement
Ruzmaikin and Feynman (2002):
relation between NAM and QBO
Ruzmaikin et al. (2004):
patterns of climate change at the Maunder Minimum
Limpasuvan et al. (2005):
PVI and SSW
Camp et al. (2003):
QBO and solar cycles as leading modes in ozone.
Ruzmaikin et al. (2005):
QBO signature in the Brewer-Dobson circulation.
Jiang et al. (2005):
modeling of QBO in column O3 in the tropics
Winter stratoshperic polar vortex
weaken
Sudden Stratospheric Warming (SSW)
temperature
westerly zonal mean wind
Planetary waves propagating from the
troposphere (Andrew et al., 1987, … …)
Polar vortex intensification (PVI)
The circumpolar wind and polar cooling
Induced by the gradual radiative
cooling under reduced wave activity
Proposal
Approach
Observation
Idealized models
1-D photochemical model (Allen et al. 1981)
2-D model with simplified chemistry but more
realistic transport (Yung and Miller 1997; Morgan
et al. 2004)
interactive 2-D model: THIN AIR (K. K. Tung)
Whole Atmospheric Community Climate Model
(WACCM)
Coupled models
Task 1: Solar variability in UV, O3
and radiative heating
Ozone layer is the link of sun and
climate
Ozone concentration depends on
temperature
Temperature varies according to the UV
changes and dynamical processes (27day range)
Ozone connects the solar UV changes
to heating rates and dynamics.
Problem and Solution
1. Ozone
Observed Ozone Variation ~ 4% at 1-3 hPa
Modeled Ozone Variation ~ 2% at 5 hPa
Model/observation comparison
- using the SORCE solar UV flux data
- the MLS O3 over 27-day solar
rotation cycle.
2. Heating Rate
3 DU increase in the ozone column
- 0.3 °C warming in the stratosphere
- 10 m increase in geopotential height.
(Camp, et al. 2003)
- will be confirmed by MODTRAN (Moderate
resolution Transmittance) code
(Berk et al. 1998)
To improve the heating rate algorithms used
in the interactive codes.
Task 2: Impact of Ozone changes in GCM
Without resolved gravity waves, most models
(WACCM) do not exhibit an accurate QBO.
Ozone variability underestimate.
Large difference between model and
observations.
New physical parameterizations are included.
(travaling gravity waves, a longwave radiation
and merged shortwave radiation
parameterization)
Extended Investigation and Perceived Impact
To investigate the role of QBO on vortex
intensification and breakdown
To exam possible influences of the ENSO and
Pacific-North American (PNA) patterns on
evolution of the polar vortex forced by solar
UV
The simple dynamical model (SDM) could be
used to study QBO effects and solar variability.
The EMD method will be applied to analysis of
data on the 11-year time scale
Plan for proposal study and
paper review
R-L Shia: introduce 2-D model,
especially the THIN AIR.
Xun: talk about the ozone (QBO,
interannual variability, N/SAM, … …)
Fai: the paper about solar cycle
Le Kuai: the paper about QBO,
interaction of QBO and solar cycle
Thank you!
Questions