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Observation Sensitivity Experiments with a High Altitude Meteorological Analysis System John McCormack Space Science Division, Washington DC David Kuhl Remote Sensing Division, Washington DC SPARC Data Assimilation Workshop 27 October 2017

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SLIDE 1

Observation Sensitivity Experiments with a High Altitude Meteorological Analysis System

John McCormack

Space Science Division, Washington DC

David Kuhl

Remote Sensing Division, Washington DC

SPARC Data Assimilation Workshop 27 October 2017 Reading, UK

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SLIDE 2

SPARC DA Workshop 2017 U.S. Naval Research Laboratory

Observation Sensitivity: High-altitude DA

Earlier studies (e.g., Xu et al., JGR 2011) have shown that DA using standard meteorological obs in the troposphere and limited stratospheric obs is enough to capture mean state of winds/temperatures in the mesosphere and lower thermosphere (MLT). To what extent are middle atmospheric (10-90 km) obs. needed to accurately specify MLT conditions, particularly during periods when middle atmosphere dynamics are rapidly evolving (e.g., sudden warmings)? To address this question, we compare two sets of meteorological analyses from the HA-NAVGEM system with and without middle atmospheric obs., and validate against independent ground-based data. We also present comparisons with independent satellite data from SOFIE

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SLIDE 3

Presentation Title | 3 U.S. Naval Research Laboratory

High-Altitude NAVGEM NWP System:

DA component

Ensemble Error Covariance (B)

E

9-hr Ensemble Forecast (xb

i)

Background (xb) Observations (y) Analysis (xa) Long forecast: 10 days Short forecast: 9 hours

Data Assimilation (DA) System E4D-Var Forecast Model NAVGEM

Observation Error (R)

Physics Investigating E4D-Var Ensemble Generation Testing E4D-Var

Over 3M obs in 6-hour DA window

Radiosondes, Pibals, Dropsondes, Driftsonde Land and Ship Surface Obs, Fixed and Drifting Buoys, Aircraft Obs Surface Winds: WindSat, ASCAT, SSMIS Feature Tracked Winds: AVHRR, MODIS, VIIRS Total Water Vapor: SSMI/SSMIS GPS Bending Angle IR Sounding: IASI and AIRS (NPP CrIS) MW Sounding: AMSU-A (Ch 4-14), SSMIS (Ch 2-7, 22-24), SSMIS/MHS, NPP ATMS Middle Atmosphere: SABER T, MLS T, MLS O3, MLS H2O, SSMIS/UAS

Hybrid-4DVAR algorithm (Kuhl at al., 2013) uses linear combination of static and flow- dependent background error covariances

HYBRID α=0.5 4DVAR α=0

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SLIDE 4

SPARC DA Workshop 2017 U.S. Naval Research Laboratory

HA-NAVGEM: Middle Atmosphere Obs.

Data coverage for SABER (blue), Aura MLS (red) and SSMIS/UAS on F16, F17, F18 DMSP platforms within a 6-hour assimilation window centered on 12 UTC 30 Jan 2010. after Hoppel et al. Mon. Wea. Rev., 2013.

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SLIDE 5

NAVGEM T119 L74 Model Grid Spacing

U.S. Naval Research Laboratory

nav_L74 NOGAPS-ALPHA: lm = 74, nprlev = 38

  • 180
  • 90

90 180 longitude (oE) 20 40 60 80 100 120 pressure altitude (km) 1000 100 10 1 0.1 0.01 0.001 0.0001 pressure (hPa)

L74 NAVGEM SSMIS UAS Channels

Sponge layer

Forecast Model Setup

  • Semi-Lagrangian/semi-implicit dynamical core; T119 spectral truncation (grid spacing ~110 km)
  • 74 hybrid s-p levels, top at 6 x 10-5 hPa or ~116 km (for now); Time step = 360 sec.

Middle Atmosphere Physics:

  • Parameterized non-orographic gravity wave drag, O3 & H2O photochemistry, exothermic chemical heating

NAVGEM High Altitude NWP System:

Global forecast model component

For more information see McCormack et al., JASTP 2017 and references therein.

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SLIDE 6

SPARC DA Workshop 2017 U.S. Naval Research Laboratory

HA-NAVGEM Geopotential Height Jan 2013

With middle

  • atm. obs.

3-hourly global synoptic analyses

  • f u, v, T, Z, O3,

H2O etc.

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SLIDE 7

SPARC DA Workshop 2017 U.S. Naval Research Laboratory

HA-NAVGEM Geopotential Height Jan 2013

No middle

  • atm. obs.

3-hourly global synoptic analyses

  • f u, v, T, Z, O3,

H2O etc.

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SLIDE 8

U.S. Naval Research Laboratory

Comparisons with meteor radar winds

NH winter 2012-2013

HA-NAVGEM T119L74 Analyses

  • Global 1o lat/lon 3 hourly output
  • Nov 2012 – March 2013

(SSW early Jan 2013)

  • Compare analyses with and without MLS/SABER/UAS

middle atmosphere obs.

Meteor radar observation sites

Location Periods Analyzed

Andenes 69.3oN , 16.0oE 1-18 Dec. 2009, 1-26 Jan 2010, 12-28 Feb 2010 1-20 Dec. 2012, 1-28 Jan 2012, 1-24 Feb. 2013 Trondheim 63.4oN , 10.5oE 1 Dec. 2012 – 28 Feb. 2013 Juliusruh 54.6oN , 13.4oE 1 Dec. 2009 – 28 Feb. 2010 1 Dec. 2012 – 28 Feb. 2013 Collm 51.3oN , 13.0oE 1 Dec. 2009 – 28 Feb. 2010 1 Dec. 2012 – 28 Feb. 2013 CMOR 43.3oN , 80.0oW 1 Dec. 2009 – 28 Feb. 2010 1 Dec. 2012 – 26 Feb. 2013 Bear Lake 41.9oN , 111.4oW 1 Dec. 2009 – 28 Feb. 2010 1 Dec. 2012 – 28 Feb. 2013 Ascension Is. 8.0oS , 14.4oW 1 Jan. 2010 – 31Mar. 2010 Tierra del Fuego 53.7oS , 67.7oW 1-31 Dec. 2012, 1 Feb. – 31 Mar 2013 Rothera 67.5oS, 68.0oW 15 Jan 2013 – 28 Feb 2013

McCormack et al., JASTP (2017)

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SLIDE 9

U.S. Naval Research Laboratory

NAVGEM vs. Meteor radar V at 88 km

HA-NAVGEM 3-hourly analyzed winds Radar 1-hourly observations

SPARC DA Workshop 2017

Day 201301

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SLIDE 10

U.S. Naval Research Laboratory

NAVGEM vs. Meteor radar V at 88 km

HA-NAVGEM 3-hourly analyzed winds Radar 1-hourly observations

SPARC DA Workshop 2017

Day 201301

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SLIDE 11

U.S. Naval Research Laboratory

NAVGEM vs. Meteor radar V at 88 km

Radar 1-hourly observations HA-NAVGEM 3-hourly analyzed winds with middle

  • atm. obs.

Histogram of meridional winds for DJG 2012-2013

SPARC DA Workshop 2017

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SLIDE 12

U.S. Naval Research Laboratory

NAVGEM vs. Meteor radar V at 88 km

Radar 1-hourly observations HA-NAVGEM 3-hourly analyzed winds, no middle

  • atm. obs.

Histogram of meridional winds for DJG 2012-2013

SPARC DA Workshop 2017

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SLIDE 13

SPARC DA Workshop 2017

Composite V profiles at Juliusruh Jan 2013

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SLIDE 14

SPARC DA Workshop 2017

Composite V profiles at Juliusruh Jan 2013

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SLIDE 15

SPARC DA Workshop 2017

Composite V time series at Juliusruh Jan 2013

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Mean Temperature Bias w.r.t. SOFIE

1. Interpolated NAVGEM reanalyses to precise latitudes, longitudes and times of each of the 1624 SOFIE limb occultations. 2. Interpolated SOFIE temperature profile onto NAVGEM full model layers

Eckermann et al. (in preparation)

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SLIDE 17

U.S. Naval Research Laboratory

Summary

  • For Jan 2013 case studied here, impact of middle atm. obs. on

HA-NAVGEM analyses is most pronounced above 0.1 hPa level. .

  • Comparisons with independent radar winds at Juliusruh show

HA-NAVGEM without middle atm. obs. overestimates amplitude

  • f semi-diurnal tide. HA-NAVGEM with middle atm. obs. has

trouble getting phase of semi-diurnal tide correct above ~90 km.

  • Hybrid 4DVAR produces lower temperature bias compared to

standard 4DVAR in SOFIE comparisons at/below 90 km.

  • Some questions going forward:

Ø What other independent observations are out there for validating stratosphere/mesosphere reanalyses? Ø What are metrics we can use to validate high-altitude reanalyses? Ø How good are 1, 5, 10, 30-day forecasts using these reanalyses as initial conditions.

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SLIDE 18

Acknowledgments

U.S. Naval Research Laboratory

Many thanks to the MLS and SABER instrument teams, to the meteor radar PIs, and to NRL-MRY NAVGEM development team. This work was supported by the Chief of Naval Research.

SPARC DA Workshop 2017

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SLIDE 19

U.S. Naval Research Laboratory

  • Obs. Sensitivity Tests

Do We Need Middle Atmosphere Obs.?

Latitude