Editing

How to use the parameters to compute some water levels (SSH, ...)

Editing to compute SSH on oceans

 

Reminder

 

 

SSH= orbit - range - corrections

SLA= SSH - SSH moyenne

MSS = MDT + geoid


(see )

 

To detect and remove data on ice there are several possible criteria:

  • latitude> |50°|:
  • Number of 20Hz measurement (num_18hz_ku_ocean) < 17
  •   |MWR – ECMWF| (|mod_wet_tropo_corr - mwr_wet_tropo_corr |)> 10cm
  • Peakiness:  ku_peak> 2
  •  |Sigma0(Ku)-Sigma0(S)| (|ku_ocean_bscat_coeff - s_ocean_bscat_coeff |)> 5dB

 


Requirements on min/max values

If one of the following requirements is not respected, the point must be removed.

 

Description

Parameter

Min value

Max value

number of valid points

num_18hz_ku_ocean

10

-

SSH

-

-130000 mm

100000 mm

SLA

-

-2000 mm

2000 mm

Rms of range at 20Hz

sd_18hz_ku_ocean

0

250 mm

Off nadir angle

off_nad_ang_wvform

-2000 10-4deg2

1600 10-4deg2

Dry troposphere

mod_dry_tropo_corr

-2500 mm

-1900 mm

Inverse barometer inverse

inv_barom_corr ou ib_MOG2D_NF

-2000 mm

2000 mm

Wet troposphere from radiometer

mwr_wet_tropo_corr

-500 mm

-1 mm

Ionospheric correction

ra2_ion_corr_ku

-400 mm

40 mm

Significant wave hights in ku band

ku_sig_wv_ht

0 mm

11000 mm

Sea state bias

sea_bias_ku ou ssb_cls

-500 mm

0 mm

Backscatter coefficient (coeff de rétrodiffusion)

ku_ocean_bscat_coeff /100

7.0 dB

30.0 dB

Oceanic tide FES04

ocean_tide_FES_04

-5000 mm

5000 mm

Long period ocean tide

long_period_ocn_tide_ht

-500 mm

500 mm

Solid earth tide

solid_earth_tide_ht

-1000 mm

1000 mm

Polar tide

geocen_pole_tide_ht

-5000 mm

5000 mm

Wind speed from altimeter

ra2_wind_sp

0 mm/s

30000 mm/s

Land flag

altim_landocean_flag a 0 ou 1

 

 

 

 

SSH computation

 

Description

 

Parametre selection

(parameters recommended by CTOH are in bold)

sign

unity (for binary format)

Comments

Altitude

alt_cog_ellip

"+"

mm

 

Range

ku_band_ocean_range

"-"

mm

 

Ionosphere correction

ra2_ion_corr_ku

"-"

mm

 

 

ra2_ion_corr_s

"-"

mm

 

 

ion_corr_doris_ku

"-"

mm

 

 

ion_corr_doris_s

"-"

mm

 

 

ion_corr_mod_ku

"-"

mm

 

 

ion_corr_mod_s

"-"

mm

 

 

gim_ku

"-"

mm

 

 

gim_s

"-"

mm

 

 

iono_lis (*)

"-"

mm

 

Dry troposphere correction

mod_dry_tropo_corr

"-"

mm

 

Wet troposphere correction

mwr_wet_tropo_corr

"-"

mm

 

 

mod_wet_tropo_corr

"-"

mm

 

 

wet_tropo_cls (*)

"-"

mm

 

Sea state bias

sea_bias_ku

"-"

mm

 

 

sea_bias_c

"-"

mm

 

Inverse barometer

inv_barom_corr

"-"

mm

 

 

ib_MOG2D_NF(*)

"-"

10-5m

This correction includes the inverse barometer effetcs and also  the non linear wind effects and of the ocean dynamic

 

ib_ECMWF_NF (*)

"-"

10-5m


Ocean tide

tot_geocen_ocn_tide_ht_sol1

"-"

mm

 

 

tot_geocen_ocn_tide_ht_sol2

"-"

mm

 

 

ocean_tide_l_GOT00 (*)

"-"

mm

Does not include the load tide, nor the permanent tide.

 

ocean_tide_FES04 (*)

"-"

mm

Does not include the load tide, nor the permanent tide.

Long tide period

long_period_ocn_tide_ht

"-"

mm

Not to be used with GDR ocean tide models (already included). 

Polar tide

geocen_pole_tide_ht

"-"

mm

 

Solide tide

solid_earth_tide_ht

"-"

mm

 

Load tide

tidal_load_ht

"-"

mm

Not to be used with GDR ocean tide models (already included).

MSS

m_sea_surf_ht

 

mm

 

 

(*) Data added by the CTOH (all the others are already provided with the GDR)

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