科学网-超导重力数据处理-homework-邢乐林的博文

超导重力数据处理-homework

2016-1-28 11:22

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标签：连续, 超导, 重力, TSOFT

以下是Hwang大牛给其学生的作业，需要的可以参考。

Guideline of basicsuperconducting gravimeter data processing

Thestation information

GGP, Global Geodynamics Project is aninternational organization designated for superconducting gravimeter usersaround the world. Members join this organization as the representative of theircountry. The basic information of SG observatory of Hsinchu station isavailable at this webpage

GGP homepage http://www.eas.slu.edu/GGP/ggphome.html

Thedata series of superconducting gravimeter

There are several optional file formats ofSG series, all of them have a file head contains the metadata and theinformation of observatory, followed by a sequence of observations. Eachobservation records the date and time of observation epoch, gravity reading,and the barometer reading. A SG data file is always named to label the time,for example

GW0603.GGP

Indicates that this is the data for March(told by digits “03”), 2006 (told by digits “06”), and the file format is“preterna” (told by “.GGP”).

Toolsoftware

Download Tsoft from http://seismologie.oma.be/TSOFT/tsoft.html

Find Download Tsoft package

C:Tsoft

Tsoft manual is available at Download TSoftmanual

Read in an .GGP file

Select “Free Preterna” format.

The Tsoft needs some station information toprocess some computations, so you need to create a site information record forHsinchu. Go to Tides=>Synthetic tides and click the “open locationdatabase”. Under the “location”, select “add new” to key in basic informationfor Hsinchu station.

Voltageto gravity

Convert the voltage into micro-gal byfactor. The conversion factor was determined by parallel observation of thesuperconducting gravimeter with an absolute gravimeter. The conversion factorfor T048 at Hsinchu is calibrated as (-75.944). By multiplication of thisfactor, data in voltage will be converted into gravity in the unit ofmicro-gal. Also note that an alternative gravity unit nm/s² can beconverted by: 1 nm/s² equals to 0.1 micro-gal.

RemoveEarth tide and Ocean tidal loading

Go to Tides=>synthetic tides=>openlocation database

Add location: input site latitude,longitude, and height

Select a station, click “add new” (tidalparameter set), copy and paste the tidal parameter

Generate the synthetic tidal effect(theoretical Earth tide+ocean loading).

To remove the Earth tide and Ocean tidalloading, take the SG series and minus the output channel computed above.

Removeatmospheric loading

[SG time series ]+ [atmospheric correctionseries]

The atmospheric correction series iscalculated by

0.35*([barometer reading]-1002.77)

The barometer readings are in the unit ofhPa (and mm-Hg equally). The output is in the unit of micro-gal. Note that theconstant 1002.77 is the nominal atmospheric pressure at the height of 86.7m,where the T048 is installed.

Removepolar motion

Polar motion

Go to webpage ftp://hpiers.obspm.fr/iers/eop/eopc04/

Create a directory TsoftDatabaseEOPC

Download EOPC04.yy under the directory TsoftDatabaseEOPC. Go to

Tides=>synthetictides=>open location database

Select the site (HS,for example), click a Synthetic tide, then pull down “Theotide”, click the“Calculate the polar motion effect”, you will see the computed polar motioneffect in a new channel.

To correct polar motioneffect, you need to take the SG series and minus the output channel of computedpolar motion effect.

Earth tide and Oceanic loadings generated by GOTIC

http://www.miz.nao.ac.jp/staffs/nao99/index_En.html

Go find “Zip file containing GOTIC2 and NAOocean tide model” to download. Extract the downloaded package to gotic2. Itwould contain two directories data and source, along with the main executableprogram and some examples. The simple instruction can be found at README fileon the webpage.

The control parameters for GOTIC are set ina control file. A typical control file, gt_exam.crd, looks like this

*********************[Mandatory Cards ]**********************

STAPOSDHSINCHU , 120.985543, 24.792579, 87.601,225.0

WAVE ALL

KIND GV

**********************[Option Cards ]************************

PREDICT 1,201012250000, 201012252359, 1.0

#PREXFL result.test3

PREFMT 5, 4

PREOUT E+O.tide

END

The computation of theoretic tidal effectis carried out in the MD-DOS prompt environment.