A positive leap second will be introduced in UTC on 31 Decembre 2008

http://hpiers.obspm.fr/eop-pc/

A leap second in 2008
Daniel Gambis
Observatoire de Paris
December 2008


On December 31, 2008 a "leap second" will be added to the world's clocks at
23 hours, 59 minutes and 59 seconds Coordinated Universal Time (UTC).
In France, due to the +1 hour time offset with respect to the meridian origin,
the talking clock will announce the affected "fourth beep" at one
o'clock legal time.

The Coordinated Universal Time (UTC, replacing GMT) is the reference time
scale derived from the Temps Atomique International (TAI) calculated by the
Bureau International des Poids et Mesures (BIPM) using a worldwide network of
atomic clocks. UTC differs from TAI by an integer number of seconds. It is the
basis of all activities in the world. UT1 is the time scale based on the
observation of the Earth's rotation. It is now derived mostly from the
observation of extragalactic radio-sources by Very Long Baseline
Interferometry techniques (VLBI).

The various irregular fluctuations progressively detected in the rotation rate
of the Earth lead in 1972 to the replacement of UT1 by UTC as the reference
time scale. However, it was desired by the scientific community to maintain
the difference UT1-UTC smaller than 0.9 second to ensure agreement between
the physical and astronomical time scales.

Why this extra second? It exists because the rotation of the Earth on its axis,
which determines the passing of days and nights, slows down over a long period,
mainly as a consequence of Moon-Sun attraction effects. In addition, the Earth
is affected by its internal (core, mantle) and external (atmosphere, oceans)
constituents. Nowadays, though, time is measured by procedures impervious to
our planet’s moods, thanks to around 250 atomic clocks belonging to several
countries. Together they are used to calculate UTC. In addition, we have to
consider that the length of the day is nowadays 2 ms longer than in the year 1820.

Not surprisingly then, the Earth's rotation slowly gets out of synchronization
with UTC.

In view of a 1972 international agreement stipulating that the difference
between the two should never exceed one second, it is necessary from time
to time to add intercalated or leap seconds to UTC. On 1st January 2009, the
difference will be 34 seconds. Since 1972, leap seconds have been added with a
rate interval varying from six months to seven years, with the last being
inserted on December 31, 2005.

Since the adoption of this system in 1972, partly due to the initial choice of
the value of the second  and secondly to the general slowing down of the Earth's
rotation, it has been necessary to add 23 s to UTC.

The decision to introduce a leap second in UTC is the responsibility of the
Earth Orientation Center of the International Earth Rotation and reference
System Service (IERS).

This center is located at the Observatoire de Paris at SYRTE department.

NO life long mail account?

Google will terminate your account in accordance with the terms of service if you fail to login to your account for a period of nine months.

Yahoo: 4 months.

Convert SRTM30 to GMT .grd format.

http://sail.ucsd.edu/~walker/grdraster.html

Getting grdraster to work

I am referring to the GMT program called "grdraster". Basically, I wanted a global topography database with 30-sec resolution, so I downloaded all the GTOPO30 database DEM files, and wanted to piece them together and form one big NetCDF grd file, which is the gridding format GMT uses. Well, I had problems with seg faults, so here is what I found. First, you need to make sure that the filename in the grdraster.info file includes the full path. This critical file is located in the $GMTHOME/share/dbase directory as a default for GMT3.3.6. To save you time if you don't already have it, here is an example of what you need in your grdraster.info file:

8   "GTOPO30 E020N40" "m" -R20/60/-10/40      -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E020N40.DEM
9   "GTOPO30 E020N90" "m" -R20/60/40/90       -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E020N90.DEM
10  "GTOPO30 E020S10" "m" -R20/60/-60/-10     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E020S10.DEM
11  "GTOPO30 E060N40" "m" -R60/100/-10/40     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E060N40.DEM
12  "GTOPO30 E060N90" "m" -R60/100/40/90      -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E060N90.DEM
13  "GTOPO30 E060S10" "m" -R60/100/-60/-10    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E060S10.DEM
14  "GTOPO30 E060S60" "m" -R60/100/-90/-60    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E060S60.DEM
15  "GTOPO30 E100N40" "m" -R100/140/-10/40    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E100N40.DEM
16  "GTOPO30 E100N90" "m" -R100/140/40/90     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E100N90.DEM
17  "GTOPO30 E100S10" "m" -R100/140/-60/-10   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E100S10.DEM
18  "GTOPO30 E120S60" "m" -R120/160/-90/-60   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E120S60.DEM
19  "GTOPO30 E140N40" "m" -R140/180/-10/40    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E140N40.DEM
20  "GTOPO30 E140N90" "m" -R140/180/40/90     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E140N90.DEM
22  "GTOPO30 E140S10" "m" -R140/180/-60/-10   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/E140S10.DEM
23  "GTOPO30 W000S60" "m" -R0/60/-90/-60      -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W000S60.DEM
24  "GTOPO30 W020N40" "m" -R-20/20/-10/40     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W020N40.DEM
25  "GTOPO30 W020N90" "m" -R-20/20/40/90      -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W020N90.DEM
26  "GTOPO30 W020S10" "m" -R-20/20/-60/-10    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W020S10.DEM
27  "GTOPO30 W060N40" "m" -R-60/-20/-10/40    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W060N40.DEM
28  "GTOPO30 W060N90" "m" -R-60/-20/40/90     -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W060N90.DEM
29  "GTOPO30 W060S10" "m" -R-60/-20/-60/-10   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W060S10.DEM
30  "GTOPO30 W060S60" "m" -R-60/-20/-90/-60   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W060S60.DEM
31  "GTOPO30 W100N40" "m" -R-100/-60/-10/40   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W100N40.DEM
32  "GTOPO30 W100N90" "m" -R-100/-60/40/90    -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W100N90.DEM
33  "GTOPO30 W100S10" "m" -R-100/-60/-60/-10  -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W100S10.DEM
34  "GTOPO30 W120S60" "m" -R-120/-80/-90/-60  -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W120S60.DEM
35  "GTOPO30 W140N40" "m" -R-140/-100/-10/40  -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W140N40.DEM
36  "GTOPO30 W140N90" "m" -R-140/-100/40/90   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W140N90.DEM
37  "GTOPO30 W140S10" "m" -R-140/-100/-60/-10 -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W140S10.DEM
38  "GTOPO30 W180N40" "m" -R-180/-140/-10/40  -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W180N40.DEM
39  "GTOPO30 W180N90" "m" -R-180/-140/40/90   -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W180N90.DEM
40  "GTOPO30 W180S10" "m" -R-180/-140/-60/-10 -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W180S10.DEM
41  "GTOPO30 W180S60" "m" -R-180/-140/-90/-60 -I0.5m P i 1 0 -9999 /janeway/usr/local/GMT3.3.6/share/dbase/W180S60.DEM

After that is in place, then you should be able to run the following:

> grdraster 11 -V -R60/100/-10/40 -I0.5m -Gtestoutput.grd
grdraster:  Reading from raster /janeway/usr/local/GMT3.3.6/share/dbase/E060N40.DEM
grdraster:  Finished reading from /janeway/usr/local/GMT3.3.6/share/dbase/E060N40.DEM
grdraster:  min max and # NaN found: -32768 32539 0

Make sure you use the -V option to be verbose if you are having problems. Also make sure you don't forget the -G in front of the filename, and that there are no spaces between the "G" and the first letter of the filename.

To check that everything went fine, try grdinfo on your newly created grd file:

> grdinfo testoutput.grd
testoutput.grd: Title: GTOPO30 E060N40
testoutput.grd: Command: grdraster 4 -V -R60/100/-10/40 -I0.5m -Gtest.grd
testoutput.grd: Remark: /janeway/usr/local/GMT3.3.6/share/dbase/E060N40.DEM
testoutput.grd: Pixel node registration used
testoutput.grd: grdfile format # 0
testoutput.grd: x_min: 60 x_max: 100 x_inc: 0.00833333 units: Longitude in degrees nx: 4800
testoutput.grd: y_min: -10 y_max: 40 y_inc: 0.00833333 units: Latitude in degrees ny: 6000
testoutput.grd: z_min: -32768 z_max: 32539 units: m
testoutput.grd: scale_factor: 1 add_offset: 0

Additional Notes

If you are troubleshooting, here are some notes that may help:

grdraster.info only needs accurate paths/filenames of those files being called on

grdraster.info file numbers can be out of order or can have gaps in the sequence

compiling grdraster.info needs the netcdf.h include file or link to in the $GMTHOME/include directory

Converting and pasting the DEM files to one GRD file

This will come in the near future. Sorry for the inconvenience.

Products of the 1st IGS Reprocessing Campaign

ftp://cddis.gsfc.nasa.gov/gps/products/wwww/repro#/cc#wwwwd.typ.Z
# Reprocessing campaign number: 1, 2, …
cc first two characters of the AC code
ig# for combined IGS products
wwww GPS week
d Day of week
typ File type: snx, ssc, sp3, clk, erp, sum

est_noise seasonal phase

the resulting phase is relative to the first observation.

Omg

Error in offsets time cam produce large bias

even several days

how to install chinese input for 1.1.5

the wefit and  icosta cannot bebew supported.

1.1.5 installer error after apache

bash-3.2# su mobile
$ bash
bash-3.2$ /var/Applications/Installer.app/Installer --launchedFromSB
2008-12-03 20:43:10.289 Installer[305:d03] ATInstaller: Initializing...
2008-12-03 20:43:10.298 Installer[305:d03] ATPackageManager: Initializing...
DataFile: file open error: /var/mobile/Library/Keyboard/zh_CN-dynamic-text.dat,
(Permission denied)
^C

Free access to Springer journals now.

Free access for the next 30 days, read and download all articles from these journals

Journal of Geodesy GPS Solutions Bulletin of Earthquake Engineering

Less memory comsumption by est_noise6ac.

By default, est_noise6ac will take up about 1.8GB RAM to run. Although RAM is very cheap; however, not everyone had upgraded their hardware configuration. Fortunately, the memory usage can be greatly cut by small modifications to the raw source code.

The below is the original variables declaration:
character*3 net,instname(30),netx
character*132 string,filename
character*8 bsta(82), line(82), header(9)
character*1 ans
integer instnum(30),insol(30),intot(30),infunc(30)
integer instart(30),instop(30)
real inparam(30,10)
character*7 choice(10),exp_choice(10),exp_type(10)
dimension ran1(65536),ran2(65536),ran3(65536),ran4(65536)
double precision t_start,t_stop,rat_chg1(82),per(82),off(82),
& dest(82),timex,t_year(8103),texp(10),tpress,dtime(8103),
& dtime_orig(8103),rat_chg2(82), dec_timed,fjul,fjul1,fjul2,
& t(8103),rat_chng_norm(82)
dimension az(82),rc(20),d(8103),A(8103,82)
dimension d_orig(8103),A_orig(8103,82),t_orig(8103)
dimension res(8103),covinv(8103,8103),covar(8103,8103),x(82),
& e(82),dith(7),xx(7),bexp(10)
dimension ambp(8,7),amby(8),acov(8,8),cov(8,8),wz(23)
dimension vsig(8),vamp1(8),vexp1(8),vamp_bp(8),valpha(8),vamp2(8),
& vexp2(8)
dimension covarpl1(8103,8103),covarpl2(8103,8103),
& covarbp(8103,8103)
dimension press(8103),aux_norm(82)

Note that, the default size for most arrays is 8103. This threshold has exceeded the observation length of most CGPS site around the globe. For example, the site WUHN (1996.0697 - 2008.8374), a value of 5000 is suffice. Thus, we can modify the source to as follows:
integer*4 maxn
c parameter(maxn=3999)
parameter(maxn=5000)
character*3 net,instname(30),netx
character*132 string,filename
character*8 bsta(82), line(82), header(9)
character*1 ans
integer instnum(30),insol(30),intot(30),infunc(30)
integer instart(30),instop(30)
real inparam(30,10)
character*7 choice(10),exp_choice(10),exp_type(10)
dimension ran1(65536),ran2(65536),ran3(65536),ran4(65536)
double precision t_start,t_stop,rat_chg1(82),per(82),off(82),
& dest(82),timex,t_year(maxn),texp(10),tpress,dtime(maxn),
& dtime_orig(maxn),rat_chg2(82), dec_timed,fjul,fjul1,fjul2,
& t(maxn),rat_chng_norm(82)
dimension az(82),rc(20),d(maxn),A(maxn,82)
dimension d_orig(maxn),A_orig(maxn,82),t_orig(maxn)
dimension res(maxn),covinv(maxn,maxn),covar(maxn,maxn),x(82),
& e(82),dith(7),xx(7),bexp(10)
dimension ambp(8,7),amby(8),acov(8,8),cov(8,8),wz(23)
dimension vsig(8),vamp1(8),vexp1(8),vamp_bp(8),valpha(8),vamp2(8),
& vexp2(8)
dimension covarpl1(maxn,maxn),covarpl2(maxn,maxn),
& covarbp(maxn,maxn)
dimension press(maxn),aux_norm(82)
This will reduce the memory required to run est_noise from 1.8GB to about 632MB.

Warning: if you want to process sites with a long history, say from 1992 to present, you may need to set the threshold (maxn) larger.

Compile est_noise6ac in Sun Soalris with f90

f90 -f77 -ftrap=%none -O3 -xlic_lib=sunperf est_noise6ac.f -o est_noise6ac

Sun Studio with Performance Libarary
Sun Solaris X86 10