Marine Trackline Search Criteria Selection - You can Search the Marine Trackline Geophysics
database by choosing among various search criteria below. Search will return those surveys which meet your criteria. Normally the
area will be automatically set from the previous page (Trackline Map Viewer), but this area can be changed. You can also start the
process from this page. At the completion of the Search you will have direct access to survey metadata (MGD77 Format Documentation Headers)
and cruise plots (track coverage) for those cruises resulting from your Search. You may then continue on to download the data.
Use the Advanced button to make more Search criteria available.
Your Operating System - The type of computer you are using is, in most cases, automatically determined.
Change this only if you wish to output files to a format different from the one which was determined for you.
Type of Data - Choose to Search for cruises which contain Analog Data, Digital Data, or Analog or Digital Data.
Digital data can be downloaded immediately within this system. Analog data found can be accessed through a link which may connect you to a link for downloading
images of the data, or to a contact which can arrange for the data to be mailed to you.
Geophysical Parameters Surveyed - Choose to restrict your Search to cruises which collected specific geophysical parameters.
If you choose multiple parameters and the UNION(OR) option, cruises which contain at least one of the parameters will meet the criteria. If you choose
the INTERSECTION (AND) option, cruises must have all the chosen parameters to meet the Search criteria.
Lat/Lon Area Bounds - Choose the latitude/longitude boundaries of your Search area in decimal degrees or in degrees,
minutes and seconds. Switch between the 2 above methods with the button in the center of the lat/lon boxes.
Latitudes must be between 90 degrees North and 90 degrees South.
Longitude values must be between 180 degrees West and 180 degrees East (or -180 and +180).
Your area may not cross both 0 degrees and 180 degrees (e.g. 120E to 120E will not work).
If you wish your area to span the entire globe longitudinally, you should choose bounds of 180W to 180E (or -180 to +180),
or just click the World button. This has the effect of not using area as a Search criteria.
Entering/Editing Intersect Line in the Text Box -
The lat,lon pts in the text box deliniates a line which will result in a Search hit whenever the
line intersects a survey's area.
Enter each point of your Search Area(s) on a separate line, separating the latitude and
longitude with a comma (use no spaces). Example:
Latitude Longitude
---------------- ----------------
5.932 deg North 172.000 deg East
12.500 deg North 150.370 deg West
30.000 deg South 142.600 deg West
This line would be entered as:
5.932,172
12.5,-150.37
-30,-142.6
If a line segment is more than 180 degrees longitude, the segment will go around the world in the shortest (wrong) direction,
therefore add an extra point on such segments.
Use the Rectangle or the Polygon(s) button to re-do your Search area as a box or as (multiple) polygons.
Note: You can enter your polygon area(s) directly in the text box,
or click the Use Java Map button to choose the area(s) graphically. You may leave this help open while
using the Java Map.
If a polygon segment is more than 180 degrees longitude, the segment will go around the world in the shortest (wrong) direction,
therefore add an extra polygon point on such segments.
Entering Areas using the Java Map -
Search Polygon area(s) can be entered using the Java map (if Java is enabled
in your Browser). You can create mulitple Polygons/Rectangle areas. The Search will look for data found in any of these defined areas.
First choose radio button PolygonRectangle or Zoom. Zoom: Drag a box with mouse to define the area to zoom to. This will be the new map area. Rectangle: Drag box(s) with mouse to define rectangular Search Area(s). Polygon: Click 1st pt, move mouse and click suceeding pts, double click last pt (don't
re-click the 1st pt). Repeat for additional polygons.
Click Accept Button to accept polygons and rectangles plotted on the map. The resulting
areas will show up in the list box in the main window. You can alter these areas
(see Entering Areas Directly in the Text Box below).
Entering/Editing Polygon Areas Directly in the Text Box -
Enter each point of your Search Area(s) on a separate line, separating the latitude and
longitude with a comma (use no spaces). If you have more than one area, use the "Enter"
key to place a blank line between each of the areas. Example:
2 areas, one a triangle and one a rectangle,
are defined as follows:
Latitude Longitude
-------------------- --------------------
5.932 degrees North 172.000 degrees East
12.500 degrees North 150.370 degrees West
30.000 degrees South 142.600 degrees West
60 deg 30 min North 150 deg 30 min East
60 deg 30 min North 160 deg 20 min East
50 deg 15 min North 160 deg 20 min East
50 deg 15 min North 150 deg 30 min East
They would be entered as:
5.932,172
12.5,-150.37
-30,-142.6
60.5,150.5
60.5,160.333
50.25,160.333
50.25,150.5
You may enter up to 20 areas with up to 22 points (lat/lon
pairs) each. However, the total number of points is restricted to
100.
Use the Rectangle or the Polygon(s) button to re-do your Search area as a box or as (multiple) polygons.
Cruise Id(s) - Restrict the Search to specific cruise(s) (generally port-to-port operations) by its identifier(s). You can Search either by
NGDC Number (Data Center Identifier) or by the Survey Id (Identifier supplied by contributing institution).
Data Source(s) - Restrict your Search to specific Source(s) (Institutions, or sometimes countries). Choosing ALL SOURCES causes Search to ignore Source criteria,
and thus accept cruises from any Source.
DATE Added to System - Restrict your SEARCH by the date the surveys were assimilated into this System.
This give you the opportunity to easily check for new data. Enter beginning and ending dates in the format YYYYMMDD (year-month-day) to
define a range of dates.
Year Data was Collected - Use
this option to restrict your Search to data collected during a
specific span of years. Enter beginning and ending years to
define a range of years. Enter 4 digits for year (e.g. 1994). If
you only want to find surveys which contain data in a single
year, simply repeat the beginning year as the ending year. If any
part of a survey took place within the range of years you
specify, that survey will match the year criteria.
Marine Trackline Search Criteria Selection
