assessing%the%performance%of%thermospheric...

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! Fig. 2 shows resul*ng densi*es at the la*tude, longitude, and height of CHAMP (TIEGCM values have been interpolated). ! DTM performs best at solar min, however TIEGCM also agrees well, both having a small number of outliers. ! Fig. 3 shows resul*ng densi*es at the la*tude, longitude, and height of CHAMP. ! Both models are less accurate at solar max, generally underes*ma*ng the density. TIEGCM performs best overall. ! DTM mirrors some increases/decreases in CHAMP densi*es well, par*cularly when mul*ple MI and XI class flares occur (not necessarily reflected in Kp and F10.7 values). Assessing the performance of thermospheric modelling with data assimila*on: results of the EU FP7 ATMOP project Sophie A. Murray 1 , E. M. Henley 1 , D. R. Jackson 1 , S. L. Bruinsma 2 1 Met Office, UK 2 CNES, France © Crown copyright Met Office and the Met Office logo are registered trademarks Contact Email: sophie.murray@metoffice.gov.uk Met Office FitzRoy Road, Exeter, Devon, EX1 3PB United Kingdom Tel: 01392 885680 Fax: 01392 885681 References [1] Henley, E., et al., 2013, ESWW 10, S. 12. [2] Murray, S. A., et al., 2014, Space Weather, in prep. [3] Bruinsma, S., et al., 2012, JSWSC, 2: A04. [4] Richmond, A. D., et al., 1992, Geophys. Res. Le;., 19: 601 I 604. [5] Heelis, R. A., et al., 1982, JGR, 87: 6339. [6] Harris, M. J., 2000, PhD Thesis, UCL. Figure 1: a) DTM and b) TIEGCM densiDes on 2009 March 01 00:00UT; c) CHAMP densiDes between 00:00 UT – 01:30 UT. ! Neutral density observa*ons inferred from CHAMP accelerometer (see Fig. 1c). CHAMP orbiged at ~400km in 2003 and ~330km in 2009. ! Results from the two models using DA were compared for two 60Iday periods; solar minimum in 2009 March I May, and maximum in 2003 March – May (solar equinox periods). The ATMOP project was designed to provide a European capability for nowcas*ng and forecas*ng of the thermosphere. As part of this project, data assimila*on (DA) procedures have been developed [1] for two thermospheric models using satellite density measurements I one a general circula*on model (TIEGCM) and the other a semiIempirical model (DTM). Results of runs using DA with these models were compared with observa*ons at solar max and min [2]. Both models show similar behaviour, underes*ma*ng densi*es at solar max and overes*ma*ng at solar min. A mean improvement of ~3.5% was found using hourly DA with TIEGCM over a 60Iday period. Further work will allow nearIrealI*me assimila*on of thermospheric data into these models for improved forecas*ng. ! Using 1Ihour DA with TIEGCM yields a mean improvement of ~3.5% over both *me periods studied (see Table 1). ! Both models perform well at solar min. Improvements to the models may be needed to reproduce stormy condi*ons beger at solar max [2]. ! The inclusion of more satellite data in the TIEGCM DA (such as GRACE and GOCE) may improve results, as well as Incremental Analysis Updates. Figure 2: Upper row: OrbitRaveraged CHAMP, TIEGCM, and DTM densiDes. Upper Middle: Density difference between CHAMP and the two models. Lower Middle: F10.7 and K p values used as inputs to the models. Lower: GOES soY XRray flux. Figure 3: Upper row: OrbitRaveraged CHAMP, TIEGCM, and DTM densiDes. Upper Middle: Density difference between CHAMP and the two models. Lower Middle: F10.7 and K p values used as inputs to the models. Lower: GOES soY XRray flux. ρ [x 10 -12 kg m 3 ] Model Run Mean % Difference Solar min (2009) Solar max (2003) CMAT2 I45.8 38.4 TIEGCM I24.9 29.1 TIEGCM (DA) I21.4 25.3 DTM 2012 I18.9 57.7 Table 1: Mean percentage difference between measured CHAMP densiDes and resulDng densiDes from various model runs. Note that results from TIEGCM runs without DA, as well as CMAT2 runs [6], were included here in order to compare models with GCMs that do not include DA. ! DTMI2012 [3] : ! F10.7 solar and A m auroral indices used as inputs; DA of mul*Isatellite observa*ons. ! Resul*ng parameter at a specific la*tude, longitude, and al*tude between 200 I 1000km, and up to resolu*on (see Fig. 1a). ! TIEGCM [4] : ! F10.7 and K p were used as inputs, with the Heelis ion convec*on pagern [5]; hourly DA procedure using CHAMP or GRACE data [1]. ! 3D model atmosphere ~90 I 500km; 5° resolu*on (Fig. 1b).

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Page 1: Assessing%the%performance%of%thermospheric ......Fig.%2%shows%resul*ng%densi*es%at%the%la*tude,%longitude,%and%height% of%CHAMP%(TIEGCM%values%have%been%interpolated).% % %! DTM%performs%best%at%solar%min,%however

!  Fig.%2%shows%resul*ng%densi*es%at%the%la*tude,%longitude,%and%height%of%CHAMP%(TIEGCM%values%have%been%interpolated).%

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!  DTM%performs%best%at%solar%min,%however%TIEGCM%also%agrees%well,%both%having%a%small%number%of%outliers.%

!  Fig.%3%shows%resul*ng%densi*es%at% the% la*tude,% longitude,%and%height%of%CHAMP.%

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!  Both%models% are% less% accurate% at% solar%max,% generally% underes*ma*ng%the%density.%TIEGCM%performs%best%overall.%

!  DTM% mirrors% some% increases/decreases% in% CHAMP% densi*es% well,%par*cularly%when%mul*ple%MI% and% XI% class% flares% occur% (not% necessarily%reflected%in%Kp%and%F10.7%values).%

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Assessing%the%performance%of%thermospheric%%modelling%with%data%assimila*on:%%

results%of%the%EU%FP7%ATMOP%project%%%

Sophie%A.%Murray1,%E.%M.%Henley1,%D.%R.%Jackson1,%S.%L.%Bruinsma2%%1Met%Office,%UK%%2CNES,%France%

©%Crown%copyright%%%%%%Met%Office%and%the%Met%Office%logo%are%registered%trademarks%

Contact!%

Email:%[email protected]%%Met%Office%FitzRoy%Road,%Exeter,%Devon,%EX1%3PB%United%Kingdom%Tel:%01392%885680%%%Fax:%01392%885681%

References!%

[1]!Henley,%E.,%et%al.,%2013,%ESWW%10,%S.%12.%[2]!Murray,%S.%A.,%et%al.,%2014,%Space%%% %%%%%%%%%%%%%%%%%%%%Weather,%in%prep.%[3]!Bruinsma,%S.,%et%al.,%2012,%JSWSC,%2:%A04.%!!

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[4]!Richmond,%A.%D.,%et%al.,%1992,%Geophys.%%%%%%%Res.%Le;.,%19:%601%I%604.%%[5]!Heelis,%R.%A.,%et%al.,%1982,%JGR,%87:%6339.%%[6]!Harris,%M.%J.,%2000,%PhD%Thesis,%UCL.%

%%

!!

Figure'1:% %a)%DTM%and%b)%TIEGCM%densiDes%on%

2009% March% 01% 00:00UT;% c)% CHAMP% densiDes%

between%00:00%UT%–%01:30%UT.%%

!  Neutral% density% observa*ons% inferred% from% CHAMP% accelerometer% (see%Fig.%1c).%CHAMP%orbiged%at%~400km%in%2003%and%~330km%in%2009.%

!  Results% from% the% two%models% using%DA%were% compared% for% two% 60Iday%periods;% solar% minimum% in% 2009% March% I% May,% and% maximum% in% 2003%March%–%May%(solar%equinox%periods).%

The% ATMOP% project% was% designed% to% provide% a% European% capability% for%nowcas*ng% and% forecas*ng% of% the% thermosphere.% As% part% of% this% project,%data% assimila*on% (DA)% procedures% have% been% developed% [1]% for% two%thermospheric%models%using%satellite%density%measurements%I%one%a%general%circula*on% model% (TIEGCM)% and% the% other% a% semiIempirical% model% (DTM).%Results% of% runs% using% DA% with% these% models% were% compared% with%observa*ons%at%solar%max%and%min%[2].%Both%models%show%similar%behaviour,%underes*ma*ng% densi*es% at% solar%max% and% overes*ma*ng% at% solar%min.% A%mean%improvement%of%~3.5%%was%found%using%hourly%DA%with%TIEGCM%over%a%60Iday% period.% Further% work% will% allow% nearIrealI*me% assimila*on% of%thermospheric%data%into%these%models%for%improved%forecas*ng.

!  Using%1Ihour%DA%with%TIEGCM%yields%a%mean%improvement%of%~3.5%%over%both%*me%periods%studied%(see%Table%1).%

!  Both%models%perform%well%at%solar%min.%Improvements%to%the%models%may%be%needed%to%reproduce%stormy%condi*ons%beger%at%solar%max%[2].%%

!  The% inclusion% of%more% satellite% data% in% the% TIEGCM%DA% (such% as%GRACE%and%GOCE)%may%improve%results,%as%well%as%Incremental%Analysis%Updates.%

Figure'2:%Upper% row:%OrbitRaveraged%CHAMP,% TIEGCM,%and%DTM%densiDes.%Upper%Middle:%Density%

difference%between%CHAMP%and%the%two%models.%Lower%Middle:%F10.7%and%Kp%values%used%as%inputs%to%

the%models.%Lower:%GOES%soY%XRray%flux.%

Figure'3:%Upper% row:%OrbitRaveraged%CHAMP,% TIEGCM,%and%DTM%densiDes.%Upper%Middle:%Density%

difference%between%CHAMP%and%the%two%models.%Lower%Middle:%F10.7%and%Kp%values%used%as%inputs%to%

the%models.%Lower:%GOES%soY%XRray%flux.%

ρ [x 10-12 kg m3]

Model%Run%Mean%%%Difference%

Solar%min%(2009)% Solar%max%(2003)%CMAT2% I45.8% 38.4%TIEGCM% I24.9% 29.1%TIEGCM%(DA)% I21.4% 25.3%DTM%2012% I18.9% 57.7%

Table' 1:% Mean% percentage% difference%

between% measured% CHAMP% densiDes% and%

resulDng%densiDes% from%various%model% runs.%

Note%that%results%from%TIEGCM%runs%without%

DA,% as% well% as% CMAT2% runs% [6],% were%

included% here% in% order% to% compare% models%

with%GCMs%that%do%not%include%DA.%

!  DTMI2012%[3]%:%!  F10.7% solar% and% Am% auroral%

indices% used% as% inputs;% DA% of%mul*Isatellite%observa*ons.%%

!  Resul*ng% parameter% at% a%specific% la*tude,% longitude,%and% al*tude% between% 200% I%1000km,% and% up% to% 1°%%resolu*on%(see%Fig.%1a).%

!  TIEGCM%[4]%:%!  F10.7% and% Kp% were% used% as%

inputs,% with% the% Heelis% ion%convec*on%pagern%[5];%hourly%DA% procedure% using% CHAMP%or%GRACE%data%[1].%%%

!  3D% model% atmosphere% ~90% I%500km;%5°%resolu*on%(Fig.%1b).%%