Nonlinear modulation of O3 and CO induced by mountain waves in the UTLS region during TREX

1
Nonlinear modulation of O3 and CO induced by
mountain waves in the UTLS region during TREX

• Mohamed Moustaoui(1), Alex Mahalov(1), Hector
  Teitelbaum(2) and Vanda Grubisic (3)
• (1) Arizona State University
• (2) Laboratoire de Meteorologie Dynamique, Paris
• (3) University of Vienna

2
TREX data used in this study are O3, CO and
temperature obtained from NCAR/HIAPER aircraft
measurements on March 25, 2006.
Topography for the microscale nest (domain 4).
The black curve shows the path of the plane.
Vertical cross section of eastward wind and
potential temperature on 25 Mars 2006. The
simulation uses three nested WRF domains (dx
27km, 9km, 3km) and a microscale nest
(dx1km). The microscale nest uses grid
refinement in the vertical with increased
resolution in the UTLS (dz 80 m). The parent
domain uses data from ECMWF T799L91 for
initialization and the boundary conditions.
3
HIAPER observations
Simulations
q
q
O3
O3
q
O3
Averaged vertical profile of Ozone as a function
of potential temperature calculated from aircraft
observations on 03-25-2006.
4
Potential temperature (black, K), O3 (blue, ppb)
and CO (red, ppb) mixing ratio as a function of
time (hour) measured by HIAPER aircraft for Leg1.
The time is relative to 25 March, 2006 15 UTC.
The time reflects the spatial variation along the
path of the aircraft
5
Potential temperature (black, K), O3 (blue, ppb)
and CO (red, ppb) mixing ratio as a function of
time (hour) measured by HIAPER aircraft for Leg2.
The time is relative to 25 March, 2006 15 UTC.
The time reflects the spatial variation along the
path of the aircraft
6
Vertical profiles of O3 (blue) and the averaged
O3 (black) from the aircraft measurements.
CO (red) as a function of potential temperature
from the aircraft measurements and the averaged
vertical profile (black) of CO
7
Filtered variations of potential temperature
(black), O3 (blue) and the altitude of the
aircraft (dashed, km) as a function of time.
8
Potential temperature (black, K), O3 (blue, ppb)
as a function of time measured by HIAPER aircraft
for Leg1. The dashed curves are the filtered
variations.
Potential temperature (black, K), O3 (blue, ppb)
as a function of time measured by HIAPER aircraft
for Leg1. The dashed curves are the filtered
variations.
9
Potential temperature (black, K), O3 (blue, ppb)
as a function of time measured by HIAPER aircraft
for Leg2. The dashed curves are the filtered
variations.
Potential temperature (black, K), O3 (blue, ppb)
as a function of time measured by HIAPER aircraft
for Leg2. The dashed curves are the filtered
variations.
10
Schematic showing the reversal of correlation
seen by the aircraft
positive correlation
aircraft
Negative correlation
11
Variations of O3 (blue) and reconstructed O3
(red) as a function of time calculated from
potential temperature (black) for Leg1.
Variations of O3 (blue) and reconstructed O3
(red) as a function of time calculated from
potential temperature (black) for Leg1
12
Variations of O3 (blue) and reconstructed O3
(red) as a function of time calculated from
potential temperature (black) for Leg2
Variations of CO (blue) and reconstructed CO
(red) as a function of time calculated from
potential temperature (black) for Leg2
13
Vertical profiles of potential temperature as a
function of altitude (km) from dropsondes
(black-dashed, K) and averaged profiles of
potential temperature (black-solid, K), O3 (blue,
ppb) and CO (red, ppb).
averaged vertical profiles of O3 (blue) and CO
(red) as a function of potential temperature.
14
Variations of potential temperature (black), O3
(blue) and CO (red) as a function of distance
(km) simulated for altitude (a) z 11.64 km and
(b) z12.1 km
15
Variations of potential temperature (black), O3
(blue) and CO (red) as a function of distance
(km) simulated for altitude z12.1 km in the
linear case.
16
Reconstructed O3 using CAS at 342 K initialized
with ozone from HIRDLS measurements. The wind
fields used for advection are from ECMWF. The
ozone fields are shown at 342K on (a) 23 March,
(b) 24 March and (c) 25 March. (d) (e) and (f)
are the same as (a), (b) and (c) but at 355 K.
The red dot indicates the location of TREX
observations
355K
342K
17
Conclusion

• Ozone, CO and potential temperature obtained from
  aircraft measurements in the UTLS region show
  fluctuations with modulations in phases and
  amplitudes.
• The phase relation between ozone and potential
  temperature varies in the horizontal. In some
  legs, ozone and temperature are positively
  correlated while in other legs the correlation is
  negative.
• The vertical profile of ozone exhibits decreases
  within a layer in the lower stratosphere, with
  positive gradients above and below
• The phase and amplitude modulations in ozone, CO
  and potential temperature are produced by
  interactions of mountains waves with different
  wavenumbers