Marine Data Literacy 2.0

Providing instruction for managing, converting, analyzing and displaying oceanographic station data, marine meteorological data, GIS-compatible marine and coastal data or model simulations, and mapped remote sensing imagery

 

 

 

 

Home > 8. Access & Services > 8.11 SST Time-Series

8.11 Managing SST Time-Series from Long-Term or Classic Climatologies:  NODC LAS

  • Exercise Title:  Managing Sea Surface Temperature (SST) Time-Series from Long-Term or Classic Climatologies:  US National Oceanographic Data Center (NODC) Live Access Server (LAS)

  • Abstract: Abstract:  In this exercise you'll learn how to find and inspect the massive data resources available through a relatively new LAS published by the US NODC.  The NODC is the final depository for a number of satellite imagery products from other programs, and they have boldly taken on the job of organizing huge amounts of data into an easily usable LAS.  In addition to raster products described at 2.31 Importing Satellite SST and Sea Ice Climatologies into Marine GIS: NODC LAS, the time-series functions of the LAS can be invoked with any appropriate dataset.  Time-series plots from the latest version of LAS may include these options, depending on the types of climatologies found:

    • "Long-term" global analysis rasters covering specific time periods (e.g. weeks, months) over periods of years, for example daily SST for the 3rd week in July, 2001, or all daily SSTs from 1983-2012; can be made from most LAS raster datasets;

    • "Classic" climatologies (in the NODCs own terminology) which are daily, weekly or monthly averages of all data, for example the average of all July SSTs in the entire database; can only be visualized from LAS datasets that are already multi-year aggregates.

  • Using this LAS or any of the many LAS installations available on the net, you can revisit global conditions for specific times in the past (various intervals; sometimes very distant), or (for sites with "classic" climatologies) you can see the usual conditions (averaged over many years) for particular days, weeks, months or seasons . [ A limited list of LAS sites is linked just below.]

  • Preliminary Reading (in OceanTeacher, unless otherwise indicated):

    • N/A

  • Required Software:

  • Other Resources: 

  • Author:  Murray Brown

  • Version:  2-8-2014

1.  Open the NODC LAS and take some time to explore the interface.

2.  The author has explored the main menu items, and offers the following summary.  Items that will be or have been covered in MDL exercises are indicated in yellow.

  • AVHRR Pathfinder SST Climatology at 9 km - Global rasters of sea temperature- and ice-related parameters; 1 grid for each of the 366 year-days (1962-2008 data)

  • CoRTAD - Tiled rasters from the Coral Reef Temperature Anomaly Database (1981-2010); various parameters for assessing impacts

  • Experimental Datasets, Under Testing - Not explored yet; some data apparently not yet loaded

  • GCOS - Global Climate Observing System datasets; numerous global SST rasters at 5-deg and 1-deg resolution, for 1981 to 2007 (roughly); "pilot study" of reconstructed global SST rasters for many other periods

  • GHRSST Aggregation - Group for High Resolution SST; L2 through L4 SST global analysis grids for 1981-2011 or later in some cases; includes nearly all of the Group's archived products

  • Jason-2 Granule Statistics-Per Pass - Not explored

  • Jason-2 Gridded Cycle Mean-Per Pass - Global rasters of altimeter data (winds, waves, sea height) for 2008-2013; an "operational" product is current to -3 weeks!

  • NODE - Regional raster products related to NOAA's studies of impacts on coral reefs from acidification; includes a few related global products also available elsewhere; a single tide dataset for Port Aransas, TX is included (!).

  • Pathfinder 5.2 RI Statistics - Multi-year (1981-2012) daily global grids of temperature-, ice-, and wind-related parameters; daily regionally-averaged time-series of temperature-, ice-, and wind-related parameters

  • Regional Climatologies - S and T climatology grids for the Arctic Ocean and Greenland-Iceland-Norwegian Sea

  • Version 5.0/5.1 AVHRR Pathfinder Sea Surface Temperature - Global rasters of sea temperature- and ice-related parameters for 1962-2008; various time periods, quality flags, and conditions

    • Classic Climatologies - Daily to monthly true climatologies from entire period of record

  • Version 5.2 AVHRR Pathfinder Sea Surface Temperature - Global rasters of sea temperature- and ice-related parameters for 1962-2008; various time periods, quality flags, and conditions

  • World Ocean Atlas 09 - Familiar global multi-depth grids used in 3.4 Obtaining Standard-Depth Analyzed Parameters from the World Ocean Atlas (WOA)

This exercise will focus on the first item above, in yellow.

3.  In the various data product categories, you'll find frequent references to Quality Flags.  The author provides this direct quote from the Pathfinder User Guide to help explain these flags:

"The overall quality flag is a relative assignment of SST quality based on a hierarchical suite of tests. The Quality Flag varies from 0 to 7, with 0 being the lowest quality and 7 the highest. For most applications, using SST observations with quality levels of 4 to 7 is typical. For applications requiring only the best-available observations (at the expense of the number of observations), use quality levels of 7 only."  Pathfinder User Guide

You will also find data products identified as DAY or NIGHT or sometimes DAY-NIGHT.  The NODC has reported that DAY-NIGHT means the average of the daytime and nighttime values.  They recommend this value for routine use, unless you have a special reason to use only the DAY or NIGHT values.

4.  Select CHOOSE DATASET to open this main menu. Then navigate down to PATHFINDER 5.2 RI STATISTICS > GRID > DAY-ONLY
5.  Navigate down and select the MEAN SEA SURFACE SKIN TEMP IN AVHRR PATHFINDER V5.2 SST QUALITY LEVEL = 5
6.  This data map window will open, probably without any data visible (due to lack of data on this particular day (JAN 1, 1981).
7.  You can pick a different day to check that the LAS is working.
8.  Now, we'll leave the MAP MODE of the LAS and use the TIME-SERIES MODE.
9.  In the left-side menu, select LINE PLOTS > TIME-SERIES

The map changes to show a single cursor location, marked by a small brown circle.  It is located at the main origin for earth mapping, the 0,0 location in the Gulf of Guinea.

10.  Now we need an exact latitude-longitude location for our data time-series.  Let's use the capitol of Liberia, Monrovia.  We need the Batch Geocoding database to do that.   Open it by clicking the above link.
11.  This is the complete main page for the site.

12.  Enter the location name in the INPUT window.
13.  Make these choices and then click on GEOCODE.
14.  These values will appear in the OUTPUT window. 
15. Copy the latitude and longitude values into the LAS geographic location panel.

NOTE:  You can also simply drag the circle to a desired location (approximately)

16.  Select any date range you want.  Here the available maximum window is selected.
17.  Then find and check the UPDATE PLOT control.
18.  The time-series appears.  Examine it to get a good idea of the size of the signal, the obvious annual signal, and the unfortunate gap near the middle of the record.

This graphic can be captured for use in publication/reports, with the PRINT control (along the top row.  [Don't forget appropriate credit to the NODC.]

19.  Select SAVE AS along the top row of controls.  There are several format choices,, including these:
  • NetCDF - Binary format, already familiar to you; compatible with Saga, IDV and ncBrowse. 
  • CSV - Comma-separated variables (ASCII); useful to load into Excel or any other software that can analyze time-series data
20.  Here is the dataset you see above, exported as CSV.  There's plenty of good metadata to identify the data, and they are in a very simple format for loading into your own software.

If you need to use these data, make sure to save them in an appropriate location with a good, long filename.

21.  Now we need to look at a "classic climatology".
22.  Navigate in the main menu to this location for the CLASSIC grids.

Open the 1982-2008 MONTHLY dataset.

23.  There are many products and quality levels provided here, so take the time to explore through them and get a good idea of what's available.
24.  Navigate to and select MONTHLY SST CLIMATOLOGY; DAY-NIGHT AVERAGE, QUALITY FLAG 7

NOTE:  The term "day-night" means a combination of both, not the difference between them.

25.  If UPDATE PLOT is checked, this graph will appear (after a short wait).  This is exactly the same as the climate graphs used by local tourist agencies and travel companies to describe conditions at coastal locations. +

 

26.  These data can also be saved for use in other applications, as you did above.
27.  As an example of how to use these links, here's a GIS-produced map where we can give users a simple CLICK HERE link to SST climate data.

You can use FrontPage or ArcGIS to place a "hot spot" on the map at Monrovia, and link that to either of the 2 graphics above.

Go ahead and click on the map to see one possibility.  You can do this to make a national or local "atlas" of seasonal conditions at resorts, beaches or ports, for example.

28.  As always, you should copy any URLs of interest into a log where you can keep them for later work.