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Analysis and Forecast of the Chemical and Dynamical Variability of the Middle-Upper Atmosphere during the 2009 SSW Nick Pedatella 1,2 , Hanli Liu 1 , Daniel Marsh 3 , Jeffrey Anderson 4 , and Kevin Raeder 4 1 High Altitude Observatory, NCAR 2

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SLIDE 1

Analysis and Forecast of the Chemical and Dynamical Variability of the Middle-Upper Atmosphere during the 2009 SSW

Nick Pedatella1,2, Hanli Liu1, Daniel Marsh3, Jeffrey Anderson4, and Kevin Raeder4

1High Altitude Observatory, NCAR 2COSMIC Program Office, UCAR 3Atmosphere Chemistry Observations and Modeling, NCAR 4Institute for Mathematics Applied to Geosciences, NCAR

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SLIDE 2

Motivation: “Nudging” towards reanalysis can lead to large differences at higher altitudes due to the sensitivity of the mesosphere to GW drag

Zonal Mean Temperature 70-80 N

Constrained Domain

(Pedatella et al., 2014)

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SLIDE 3

Differences in modeled MLT dynamics influence nitric oxide descent

(Siskind et al., 2015)

NO at 80 N, SD-WACCM NO at 80 N, NOGAPS-WACCM Nudged Region Nudged Region

Direct assimilation of lower, middle, and upper atmosphere observations is one approach to improving simulations of MLT dynamics

(Funke et al., 2017)

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SLIDE 4

Whole Atmosphere Community Climate Model eXtended (WACCMX)

  • WACCMX is built on top of the Whole Atmosphere Community Climate Model (WACCM), which

is the “high-top” atmosphere model component of the Community Earth System Model (CESM)

  • Finite volume dynamical core (1.9º x 2.5º resolution)
  • Latest version includes self-consistent ionosphere-

thermosphere with electrodynamics

  • Gravity waves parameterized for orographic

and nonorographic sources.

  • Comprehensive interactive chemistry

package (MOZART)

  • Solar variability (long term & impulsive)

WACCMX WACCM

  • WACCMX enables study of middle-upper atmosphere

variability due to both the lower atmosphere and solar/geomagnetic activity.

  • 126 vertical levels (surface to 4.4 x 10-10 hPa)
  • Data assimilation in WACCMX is implemented using

the Data Assimilation Research Testbed (DART) ensemble Kalman filter

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SLIDE 5

Framework for WACCMX+DART is identical to WACCM+DART (next slide)

WACCMX+DART

Same observations are assimilated in the troposphere, stratosphere, and mesosphere. Main change between WACCMX+DART and WACCM+DART is increased damping in

  • WACCMX. This was necessary for model stability, and to ensure that mixing from small

scale waves introduced by the data assimilation do not excessively reduce thermosphere O/N2 and electron density. Changes made for model stability do have a slight negative impact on performance of the data assimilation in the troposphere-stratosphere. We have performed initial WACCMX+DART analysis and forecast simulations for the 2009 SSW time period. Troposphere humidity is biased by ~20-30% due to model physics issue when using a 5 min time-step.

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SLIDE 6

WACCM+DART provides an atmospheric reanalysis from the surface to the lower thermosphere (~145 km). Typically use a 40-member ensemble, which is a tradeoff between computational expense and having a sufficiently large ensemble to capture a variety of atmospheric states.

NCEP Reanalysis WACCM+DART Pedatella, N. M., K. Raeder, J. L. Anderson, and H.-L. Liu (2014), Ensemble data assimilation in the Whole Atmosphere Community Climate Model, J. Geophys. Res., 119, doi: 10.1002/2014JD021776.

WACCM+DART

Conventional Lower Atmosphere Observations: Aircraft temperature and wind Radiosonde temperature and wind Satellite drift winds COSMIC GPS refractivity Sparse Middle/Upper Atmosphere Observations: TIMED/SABER Temperature (100 - 5×10-4 hPa) Aura MLS Temperature (260 - 1×10-3 hPa) WACCM+DART is useful for correcting model biases, studying dynamical variability due to sudden stratosphere warmings, and short-term tidal variability 500 hPa Geopotential Height 0000 UT 15 Nov., 2008

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SLIDE 7

Middle Atmosphere Variability in WACCMX+DART and SD-WACCMX SD-WACCMX: Specified Dynamics WACCMX constrained to MERRA meteorology up to 50km

(Pedatella et al., 2014)

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SLIDE 8

NO descent following the SSW

(Funke et al., 2017)

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SLIDE 9

≈√ ≈√ Stratosphere ozone variability

SABER Observation

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SLIDE 10

Diurnal Migrating Tide

(Pedatella et al., 2014)

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SLIDE 11

Semidiurnal Migrating Tide

(Pedatella et al., 2014)

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SLIDE 12

Comparison with Juliusruh MF Radar 2 4 6 8 10 12 14 Day 200912

  • 100
  • 50

50 100 (b) Juliusruh NAVGEM RADAR r = 0.55

WACCMX

Tides are too weak in WACCMX+DART due to damping

(McCormack et al., 2017)

Juliusruh Radar V (88 km, 54N, 13E)

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SLIDE 13

2 4 6 8 10 12 14 Day 200912

  • 100
  • 50

50 100 (b) Juliusruh NAVGEM RADAR r = 0.55

WACCM

Agreement with radar observations is better in WACCM+DART Juliusruh Radar V (88 km, 54N, 13E)

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2009 SSW Forecast Experiments

  • Initialize 40-member ensemble forecasts (hindcasts) of the 2009 SSW
  • n January 5, 10, 15, 20, and 25.
  • Ocean SSTs are specified as the true values (i.e., not forecasted)
  • Solar activity is specified by using 27-days prior solar activity
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SLIDE 15

2009 SSW Forecasts: Lower-Middle Atmosphere Temperature

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SLIDE 16

2009 SSW Forecasts: Lower-Middle Atmosphere Zonal Wind

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SLIDE 17

2009 SSW Forecasts: 60º N, 10 hPa Zonal Wind

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SLIDE 18

2009 SSW Forecasts: 60º N, 0.01 hPa Zonal Wind

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SLIDE 19

2009 SSW Forecasts: Upper Stratosphere Ozone

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SLIDE 20

2009 SSW Forecasts: Diurnal Migrating Tide

Forecasts run with default damping

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SLIDE 21

2009 SSW Forecasts: Diurnal Migrating Tide

Forecasts run with modified damping

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SLIDE 22

2009 SSW Forecasts: Solar+Lunar Semidiurnal Migrating Tide

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SLIDE 23

2009 SSW Forecasts: TEC at 75W

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Summary

Tidal amplitudes are generally too weak in WACCMX+DART, indicating the need to determine a better method for filtering small-scale waves introduced by DA. Recent developments in WACCMX support whole atmosphere data assimilation, providing a global view of the troposphere, stratosphere, mesosphere, thermosphere, and ionosphere state Forecast experiments for 2009 SSW show that middle-upper atmosphere variability can be qualitatively predicted ~5-10 days in advance of the SSW. Have completed WACCMX+DART analysis for 2009-2010, and 30 day forecast experiments initialized on the 1st and 15th of each month are in progress. Middle atmosphere chemical and dynamical variability are generally well reproduced in WACCMX+DART. Ionosphere variability during the 2009 SSW is reproduced in WACCMX+DART.

Results will be made available on the Earth System Grid (www.earthsystemgrid.org) when finished.

Tentatively planning (within the next few years) WACCM+DART reanalysis for 2004-present