http://holt.oso.chalmers.se/hgs/apload.html

HGS Air Pressure Loading
 
Here you can obtain time-series of surface displacement due to atmospheric pressure loading. The data come as 6 h samples of 3D local surface displacement (Vertical, East, North). Method is explicit convolution using Farrell's elastic Green's function on a spherical earth. Computation on a 1x1 degree grid with refinement 10 times at distances below 10 degrees. The air pressure load is derived from ECMWF surface pressure fields. The oceanic areas that are deeper than 30 m are assumed to respond instantaneously as an inverted barometer. All other areas are loaded by the full air pressure effect.

The assumption in space geodesy concurrent with International Terrestrial Reference Systems is that there is no permanent pressure loading effect. Thus, the mean of the  time series is to be subtracted before the ordinates are applied as corrections to estimated positions. This average does inevitably depend on your observation epochs. Approximative mean values of station displacement (derived from a four-year period) are available from this site as shown below.

In any case, the whole suite of files below is purely experimental.


 
 

We offer data for the following categories of stations:

 
Category 
Techniques 
Sites 
Periods 
 A

GPS

Nordic GPS stations, European IGS +
a few more global IGS
continuously after Aug 1993
1996 - 2005
 B VLBI  NASA R&D, Europe, NEOS selected experiments 1993-1997
 C VLBI NASA R&D, Europe, NEOS selected experiments 
1989-1993
 D VLBI CORE networks 1997--
 E VLBI CORE networks like D EPHEDISP format 
F
SLR
many sites
1993 thru 2005

The format for the time series is pretty obvious:
Example 
.
#1   1996jan01:00   -.00226    .00126    .00075
#2   1996jan01:06   -.00218    .00145    .00070
#3   1996jan01:12   -.00129    .00129    .00089
#4   1996jan01:18   -.00158    .00146    .00088
#1   1996jan02:00   -.00153    .00136    .00084
#2   1996jan02:06   -.00193    .00140    .00067
#3   1996jan02:12   -.00130    .00109    .00085

#n   yyyymmmdd:hh      DR         DE        DN
.
DR, DE, DN = Radial, East, North displacement
units = metre
The consequent increase of dates in the file cannot be guaranteed. Samples might be repeated, in which case the latest appearance is to be used. 

A sample plot is available for the site METS (Metsähovi, Finland)
The long-term average offset for each station (which is to be subtracted in order to obtain continuity with analyses that are uncorrected for air pressure loading ) is available here for each category:  A | B | C | D
 



NEW:                EPHEDISP

We also provide time series in EPHEDISP format, 
at least in a format very close to EPHEDISP according to NASA/GSFC. They appear on a per-site scheme. We have added two record types, designated to demarkate gaps. An B-record
 
Example 
.
B     1  50692      .0  1997.09.01-00:00:00  YLOW7296
B     n  MJD         s  yyyy.mm.dd-hh:mm:ss  site

marks the start of a contiguous segment (also the very start of the series),
and an E-record correspondingly the end of a contiguous segment. The segments are numbered (n).
 
 
 
Example 
.
E     1  50721 64800.0  1997.09.30-18:00:00  YLOW7296
E     n  MJD         s  yyyy.mm.dd-hh:mm:ss  site

Maybe we have to add the relative epoch number somewhere on these records. 

en=`awk -v ep=$ep -v dt=$ts '/^B/{print (($3+$4/86400)-ep)/dt}' $file`

where

ts=`awk '/^T sample/{print $3}' $file`
ep=`awk -v dt=$ts '/^T begin/{print ($3+$4/86400)/dt}' $file`

We just started with this business (Jan 16, 2003), so there'll be a time when there is information only for the pleasure of the viewer and the discomfort of the user. Your feedback will help to ease the pains. 
 


Time series files

Category A.

BIFROST GPS

 ARJE | BORA | BRUS | HASS | HERS | JOEN | JONK
 KARL | KEVO | KIRU | KIVE | KOSG | LEKS | LOVO
 MADR | MART | MATE | METS | NORR | NYAL | OLKI
 ONSA | ONSB | OSKA | OSTE | OULU | OVER | POTS
 REYK | RIGA | ROMU | SAAR | SKEL | SUND | SVEG
 TROM | TUOR | UMEA | VAAS | VANE | VILH | VIRO
 VISB | WETB

.More IGS sites in a one big tar
 Klick here for a site list


Category B.

VLBI
1993--1997

 CRIMEA   | DSS15    | EFLSBERG | FD-VLBA
 FORTLEZA | GILCREEK | KOKEE    | KP-VLBA
 LA-VLBA  | MADRID64 | MATERA   | MEDICINA
 MK-VLBA  | NOTO     | NRAO85   | NYALES20
 OHIGGINS | ONSALA60 | OV-VLBA  | PIETOWN
 SC-VLBA  | SESHAN25 | WESTFORD | WETTZELL
 YEBES    | YLOW7296.

.
Category C.

VLBI
1989-1993

 ALGOPARK | AZORES   | BR-VLBA  | CRIMEA
 DSS15    | DSS45    | DSS65    | EFLSBERG
 FD-VLBA  | FORTLEZA | GGAO7108 | GILCREEK
 GOLDVENU | GORF7102 | HARTRAO  | HATCREEK
 HAYSTACK | HN-VLBA  | HOBART26 | HOFN
 HOHNBERG | HRAS     | KARLBURG | KASHIM34
 KASHIMA  | KAUAI    | KOKEE    | KP-VLBA
 LA-VLBA  | MARCUS   | MARPOINT | MATERA
 MEDICINA | MIZNAO10 | MK-VLBA  | MOJAVE12
 MOJAVLBA | NL-VLBA  | NOBEY    | NOTO
 NRAO20   | NRAO85   | NRAO85   | NRAO
 NYALES20 | OHIGGINS | ONSALA60 | OV-VLBA
 PENTICTN | PIETOWN  | PLATTVIL | RICHMOND
 SANTIA12 | SC-VLBA  | SESHAN25 | TOULOUSE
 TRYSILNO | VLBA85   | VLBA85   | VNDNBERG
 WESTFORD | WETTZELL | YLOW7296. .
Category D.

CORE-VLBI
1997--
For this category 
we can also provide
the station pressure 
series as interpolated 
from the 
meteorological fields 
- on request.
 

 ALGOPARK | BR-VLBA  | CRIMEA   | EFLSBERG 
 FD-VLBA  | FORTLEZA | GGAO7108 | GILCREEK 
 HARTRAO  | HN-VLBA  | HOBART26 | KASHIM34 
 KASHIMA  | KOGANEI  | KOKEE    | KP-VLBA  
 LA-VLBA  | MADRID64 | MATERA   | MEDICINA 
  METSHOVI | MIURA    | MIZNAO10 | MK-VLBA    
 MOJAVLBA
| NL-VLBA  | NOTO     | NRAO20 
 NYALES20
OHIGGINS | ONSALA60 | OV-VLBA
 SC-VLBA  | 
SESHAN25 | SVETLOE  | SYOWA  
 TATEYAMA | TIGOCONC | TSUKUB32  

 URUMQI   | VLBA85-3 | WESTBRK0 | WESTFORD 
 WETTZELL | YEBES    | YLOW7296 

Category F

SLR 1993-2005
All in three + two tars.
Here is the
station file.

(Yes, we have no non-ib loading files
.)
Loading displacements relative to solid earth centre
(19 Mb)

Loading displacements relative to joint mass centre SE+ATM

(19 Mb)

Rigid earth translations in Radial East North at the stations

(17 Mb)

Loading displacements relative to joint mass centre SE+ATM assuming non-inverse barometer ocean response
(19 Mb)

Rigid earth translations in Radial East North at the stations assuming non-inverse barometer ocean response
(17 Mb)

 

.bye