Download ESWW13_GOCE-densities_Bruinsma

Model evaluation with low-altitude
GOCE densities
Sean Bruinsma
CNES - Space Geodesy
Toulouse, France
PREGO: ESA CONTRACT
4000115173/15/F/MOS
Adrian Jäggi, Daniel Arnold – AIUB, Bern, Switzerland
Noelia Sánchez-Ortiz – Deimos Space, Tres Cantos, Spain
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(1/10)
Introduction
 CIRA models are evaluated: NRLMSISE-00, JB2008 and DTM2013
 GOCE density data from 11/2009 – 11/2013 is used (270-170 km),
scaled to HASDM (operational Air Force model)
 Metric: mean, sigma, RMS and correlation of density ratio O/C
 Evaluate long (years), medium (month) and short (day) time scales
GOCE (2009 – 2013):
• Acc. resolution: 1·10-12 m/s2/Hz0.5
• ion propulsion
• GPS and SLR
• inclination: 96.5°
• Altitude: 270-170 km
 densities 0.1Hz, precision 1-2%
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(2/10)
Introduction
GOCE densities:
•
Low altitude
•
Low-medium solar activity
•
6-8am/pm local solar time
Models: solar proxies:
NRLMSISE-00: F10.7
JB2008: S81, F10.7, M10
DTM2013: F30
ftp://ftpsedr.cls.fr/pub/previsol/solarflux/final
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(3/10)
Long time scales – O/C
On time scales of year(s), JB2008 and DTM2013 are nearly unbiased
(mission design, lifetime estimation)
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(4/10)
Daily time scales – O/C NRLMSISE-00
Mean / s of annual time series:
ESWW13, 18 November 2016
1.058 / 0.051
of monthly time series:
1.055 / 0.067
of daily time series:
1.047 / 0.098
S. Bruinsma, CNES - Space Geodesy
(5/10)
Daily time scales – O/C JB2008
Mean / s of annual time series:
ESWW13, 18 November 2016
1.035 / 0.020
of monthly time series:
1.032 / 0.042
of daily time series:
1.034 / 0.066
S. Bruinsma, CNES - Space Geodesy
(6/10)
Daily time scales – O/C DTM2013
Mean / s of annual time series:
ESWW13, 18 November 2016
1.007 / 0.014
of monthly time series:
1.006 / 0.037
of daily time series:
1.005 / 0.061
S. Bruinsma, CNES - Space Geodesy
(7/10)
Daily time scales – RMS of (O/C – 1)
Mean/s : 0.101 / 0.027
Mean/s : 0.117 / 0.038
Mean/s : 0.143 / 0.047
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(8/10)
Daily time scales – correlation DTM2013
No solar
rotation period
Mean / s of daily time series:
(NRLMSISE-00:
(JB2008:
ESWW13, 18 November 2016
0.943 / 0.028
0.930 / 0.033)
0.934 / 0.031)
S. Bruinsma, CNES - Space Geodesy
(9/10)
Summary and Conclusions
High resolution GOCE densities available
CIRA models evaluated in the 270-170 km altitude range
 DTM2013 and JB2008 most accurate, NRLMSISE-00 biased (slope)
All models biased for lowest activity in 2009-10, most NRLMSISE-00
 Standard deviation of CIRA models at the 10% level (1-s)
High correlation, variation with solar rotation period reproduced
 Representative results for all local times (using CHAMP, not shown)
• Model errors at time scales of months: unexplained (ap/kp?)
• Still large model error for enhanced-storm conditions
ESWW13, 18 November 2016
S. Bruinsma, CNES - Space Geodesy
(10/10)