[Dart-users] DART and obs_def_upper_atm_mod.f90

[Tomoko Matsuo]

Hi Tim,

As I said in the earlier correspondences, it appears GND_GPS_VTEC is designed for GITM for hypothetical data.
It integrates the electron density vertically within the model domain (up to ~500 km), but In reality, VTEC observations
include the contribution of plasma density above 500-700km.

I and some of my collaborators use CHAMP_DENSITY to assimilate in-situ neutral mass density data.

VTEC is usually given in TECU, and TECU is defined as 10e+16/m2.

O_N2 is a unit-less ratio (the column density of O above an altitude where the N2 column density is 10e+17/cm2),
ranging from 0 to infinity, but typical values go up to ~1.5 or so.

Tomoko

On May 19, 2016, at 1:08 PM, Tim Hoar <thoar at ucar.edu<mailto:thoar at ucar.edu>> wrote:

Hello all ...

I am interested in hearing from anyone/everyone who uses the obs_def_upper_atm_mod.f90

I need to know who is using it - for what kinds of observations - and where those observations come from (so I can test my changes).
I'm trying to ensure the forward operators for

SAT_RHO,                         KIND_DENSITY
GND_GPS_VTEC,                    KIND_GND_GPS_VTEC
CHAMP_DENSITY,                   KIND_DENSITY
MIDAS_TEC,                       KIND_VERTICAL_TEC
SSUSI_O_N2_RATIO,                KIND_O_N2_COLUMN_DENSITY_RATIO

work correctly across a variety of models. To do this, I need to know the units of the observations,
and ensure that the models provide get_expected_upper_atm_density(),
get_expected_vtec(), get_expected_gnd_gps_vtec(), and get_expected_O_N2_ratio()
the proper quantities. I have no reason to believe they are wrong, but the way they are written now
prevents TIEGCM from assimilating GND_GPS_VTEC observations.

I also don't know if anyone is using 'CHAMP_DENSITY' observations, particularly since the
observations/CHAMP/CHAMP_density_text_to_obs.f90  converter creates 'SAT_RHO' observations.

If you, or anyone you know, is using or is planning on using obs_def_upper_atm_mod.f90, I'd like to hear from you.

Thanks --

Tim Hoar
Data Assimilation Research Section
Institute for Mathematics Applied to Geosciences
National Center for Atmospheric Research
thoar at ucar.edu<mailto:thoar at ucar.edu>
303.497.1708
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