West Coast/Alaska Tsunami Warning
Center
Operations Manual
NOAA/NWS/WCATWC
Palmer,
http://wcatwc.arh.noaa.gov
Section
4.1.9 – lpproc
Last
Updated: 5/2007
Date
Written: 4/2001
Development Language: MicroSoft C/C++ v6.0 using WinAPI
Necessary Rings:
Input Ring - WAVE_RING_LP;
reads TYPE_TRACEBUF format messages
Input
Ring - HYPO_RING; reads TYPE_HYPOTWC format messages
Output
Ring - PICK_RING; writes TYPE_PICKTWC format messages (with MS parameters)
Output Ring - ALARM_RING;
writes TYPE_ALARM format messages
Necessary Data Files:
StaFile
– lpproc configuration file
StaDataFile - seismometer
location, elevation, etc.
DummyFile - Hypo-parameters of last
located quake
LPRTFile - MS data
computed for last quake
QuakeFile - List of automatically
located quakes
Initialization File:
lpproc.d - read on
module start-up
Module Description:
This module takes long period waveforms from the WAVE_RING and displays
them on a window. The display is similar to an old-style develocorder (with no
film delay). Every X seconds the screen scrolls to the left. The most recent
data is shown on the right of the screen. The display can be "held"
and manually scrolled through previous times (the time limit of saved data is
specified in the .d file).
Hypocenters entered to HYPO_RING are obtained by this module. If the hypocenter
has a magnitude greater than 5.0 Mb, Ml, or Mwp, this module will compute
expected Rayleigh wave times at stations listed in StaFile and will evaluate
the data in the window for Ms for up to 30 minutes passed the expected Rayleigh
wave arrival time. When an Ms is computed, the data is sent in the TYPE_PICKTWC
message format to PICK_RING with P-time=0 and the magnitude is displayed on the
lpproc screen.
As data is read from the WAVE_RING, it can be processed by an LP alarm with
parameters specified in the initialization file and the StaFile. If a large
signal is found by the alarm function, an alarm is reported to ALARM_RING.
NOTE: A semaphore is accessed in lpproc so that LP processing can be triggered
by program LOCATE. This semaphore should not prevent the program from working
if LOCATE is not running.
Program Controls:
This module has a Windows graphical interface.
Due to this interface, the module will only compile and run under Windows (NT,
2K, or XP). The display shows real-time, long period data. The most recent time
is shown on the right side of the screen. As new data arrives, the screen
scrolls left. A "Hold Screen" menu option is available to stop the
automatic scrolling. Then, the horizontal scroll bars can be used to manually
scroll through all the data which is in memory.
Surface wave data processing is triggered automatically via the HYPO_RING.
Computed MS is shown near the trace name and an average is shown in the title
bar. The MS processing can be started or stopped manually through the magnitude
menu option. As magnitudes are computed, the expected Rayleigh wave start time
is displayed on each trace, and the cycle which is used to compute MS is marked
with a plus sign.
Mouse Buttons:
Right button on trace toggles trace display.
Right button on station name calls station manipulation menu (for trace scaling, trace
display on/off, alarm on/off).
Menu Options:
Hold Screen: Prevent automatic scrolling so that
scroll bars can be used to move through data.
Horizontal Scale: Change screen time scale.
Vertical Trace Scale - All: Change vertical scale for all stations.
Traces Per Screen: Number of traces vertically to show on the screen, rest will scroll.
Display Filtered Data: Check -> screen shows LP filtered signal for
broadband stations.
Display Broadband Data: Check -> screen shows unfiltered traces for all
stations.
Magnitude:
Compute Ms: Using last location in dummy file, process LP data
for MS. After processing, a plus sign
is marked on the cycle used to compute MS.
Stop Processing: Stop ongoing computations (usually used when automatic location has
been updated).
ClipIt: Limit trace amplitudes.
Refresh: Re-paint the screen