DYNAMIC OCEANS:  A science activity using sea level and ocean heat content data

INTRODUCTION:  This page provides links to downloadable netCDF (.nc) files designed to be used by educators desiring to develop earth science lessons addressing rising global sea levels and their connection to rising ocean heat content worldwide. These files, links, and instructions were developed as part of NODC staff participation with other scientists and education professionals during the course of the Digital Library for Earth System Education (DLESE)* workshop April 30-May 3, 2008. The focus of the workshop is to bridge the gap between educators and data holders through the creation of online chapters for the Earth Exploration Toolbook*. The Earth Exploration Toolbook is a collection of computer-based Earth science lessons. Each lesson, or chapter, introduces one or more data sets and an analysis tool that enables users to explore some aspect of the Earth system. Step-by-step instructions in each chapter walk users through a case study in which they access data and use the featured tool to explore issues or concepts in Earth system science. In the course of completing a chapter, users produce and analyze maps, graphs, images, or other data products. The ultimate goal of each activity is to build users' skills and confidence in order to encourage further use of environmental data in their own investigations of the Earth system. The workshop combines teams of data representatives with online tool experts, educators, and others to fashion a chapter during the course of the workshop.

The central feature of this activity is a collection of netCDF data files for both sea level and the global heat content of the ocean developed at the NODC by Dr. Yongsheng Zhang (Lead, NODC Satellite Altimetry Data) and Upendra Dadi. The global ocean heat content files were converted from original ASCII files developed at NODC's Ocean Climate Laboratory by Dr. Sydney Levitus (Division Chief, NODC Ocean Climate Laboratory) and Dr. John Antonov. The sea level data were converted from original data developed by Archiving, Validation and Interpretation of Satellite Oceanographic Data (AVISO*) and by the NOAA Laboratory for Satellite Altimetry. The netCDF format allows users to view the data graphically with a viewer such as ncBrowse, and initiate discussions about the correlation between rising sea level and rising ocean heat content.

This activity was designed to facilitate discussions on the utilization of satellite altimetry data and the importance of ocean heat content by using data collected both at the surface and at depth, and foster discussions on the scientific method and oceanographic methods. For specific details regarding this earth science activity, educators should refer to the corresponding chapter in the Earth Exploration Toolbook.

INSTRUCTIONS:

1)  The netCDF* files offered on this page may be imported into ncBrowse or compatible software able to utilize files in netCDF format.  ncBrowse is a Java application that provides interactive visual displays of data and attributes from a wide range of netCDF data file conventions. ncBrowse is downloadable from the NOAA Pacific Marine Environmental Laboratory at:  http://www.epic.noaa.gov/java/ncBrowse/ *

2)  The four files shown have been placed in a single WinZip® folder "sea_level_and_hc_files.zip".  Download this folder to your computer by clicking here.  Decompress the files to your computer using WinZip® (it will be easiest if the files are placed in a single folder together). There should be two sea level files (MSL_TSerie_Global.nc and TP_annual_sla.nc) and two heat content files (global_heat_content.nc and HC_3month_global.nc). Files can also be browsed and downloaded individually via OPeNDAP here.

3). Open ncBrowse.

A.  To view the file MSL_TSerie_Global.nc, go to file, open, navigate and select the file. To the right, you will see a small screen titled "Select variable for display".  DOUBLE-CLICK ON THE "msl". A new window will pop open (note that in this window the start and end dates of the data to be displayed can be changed). Here you can see the "long name" of the variable, which for this file is mean sea level. Click the button "Graph Variable" and a new window will pop open, displaying the data.

B. To view the file HC_3month_global.nc, go to file, open, navigate and select the file. To the right, you will see a small section screen titled "Select variable for display".  DOUBLE-CLICK ON THE "mohc". A new window will pop open (note that in this window the start and end dates of the data to be displayed can be changed). Here you can see the "long name" of the variable, which for this file is sea level anomaly. FOR COMPARISON PUPOSES, CHANGE THE START DATE TO 1993-01-01!!. Click the button "Graph Variable" and a new window will pop open, displaying the data.

C.  To view the file TP_annual_sla.nc, go to file, open, navigate and select the file. To the right, you will see a small section screen titled "Select variable for display".  DOUBLE-CLICK ON THE "sla". A new window will pop open (note that in this window the start and end dates of the data to be displayed can be changed). Here you can see the "long name" of the variable, which for this file is mean sea level.
CHANGE THE DATE RANGE TO START DATE, 1997-01-01.  Ignore the END DATE (This confines the data display to 1997, the year of a strong El Niño.)
WHERE YOU SEE THE COLUMN "DEPENDENT VARIABLE, MAKE SURE "LAT" DEGREES NORTH IS CHECKED Y, AND "LON" DEGREES EAST IS CHECKED X!! Click the button "Graph Variable" and a new window will pop open, displaying the data.

D.  To view the file global_ocean_heat_content.nc, go to file, open, navigate and select the file. To the right, you will see a small section screen titled "Select variable for display".  DOUBLE-CLICK ON THE "ohc". A new window will pop open (note that in this window the start and end dates of the data to be displayed can be changed). Here you can see the "long name" of the variable, which for this file is ocean heat content.
CHANGE THE DATE RANGE TO START DATE, 1997-01-01 AND SET END DATE TO 1997-12-31. (This confines the data display to 1997, the year of a strong El Niño.)
WHERE YOU SEE THE COLUMN "DEPENDENT VARIABLE, MAKE SURE "LAT" DEGREES NORTH IS CHECKED Y, AND "LON" DEGREES EAST IS CHECKED X!! Click the button "Graph Variable" and a new window will pop open, displaying the data.

TIPS and ADDITIONAL ACTIVITIES using ncBrowse 

(1) For comparison and discussion puposes, the second part of this exercise confines the data displays to 1997.  The strong El Niño that occured in this year resulted in strong data signals that are readily observed.
(2) Heat content data is available from 1955-present; satellite altimetry data is newer technology beginning with the Topex/Poseidon mission and continuing to the present with the international Jason-1 and Jason-2 missions.
For discussion purposes, this exercise confines data displays from 1993-2009 for both heat content and sea level. Users are encouraged to experiment with different data ranges and different data files. A set of additiona data files
that focus on the Pacific Ocean, "more_sealevel_and_HC.zip" is available here. Files can also be browsed and downloaded individually via OPeNDAP here.
(3) When using ncBrowse, the program allows multiple ncBrowse windows to be open to facilitate data comparisons.  Users are encouraged to read the program's ncBrowse Help for installation and use information.

LINKS FOR ADDITIONAL INFORMATION:

The Digital Library for Earth System Information* (DLESE) is a distributed community effort involving educators, students, and scientists working together to improve the quality, quantity, and efficiency of teaching and learning about the Earth system at all levels.

The NOAA Laboratory for Satellite Altimetry hosts pages detailing satellite altimetry missions and studies of sea level rise using satellite data.

NetCDF User Guide* is an online detailed technical guide for the .nc format, with useful explanations in each chapter (Copyright (C) 1996 University Corporation for Atmospheric Research, Boulder, Colorado).

The NOAA Education Resources aids students and teachers to access educational activities, publications and booklets produced throughout NOAA.

The NOAA Central Library contains thousands of books, journals, publications and images on a huge range of subjects from the marine and earth sciences to historical interest. User searches are facilitated by WINDandSEA, an Internet guide built in response to the many reference questions that are posed to the library. WINDandSEA is designed to make Internet searching more efficient for the NOAA community, the academic community, other government agencies concerned with oceanic and atmospheric issues, and the general public. Presently WINDandSEA has over 1,000 selected links to science and policy sites organized by topic and alphabetically within topic. All of these sites have been reviewed and annotated by NOAA Central Library and NOAA Regional Libraries staff. In addition, images from the popular NOAA Photo Library are downloadable and can be used freely.

NOAA Teacher at Sea Program: Past, Present, and Future: Since 1990, NOAA's Teacher at Sea program, managed by the NOAA Office of Marine and Aviation Operations, has enabled qualified teachers of kindergarten through college to go to sea aboard NOAA research and survey vessels and work side-by-side with scientists, officers, and crew.

The Radar Altimetry Tutorial*, produced by CLS* for the Centre National D'etudes Spatiales (CNES)* and the European Space Agency (ESA)*, is an excellent introduction to radar altimetry, instruments, techniques, data acquisition and processing, missions, and data products.

OceanTeacher* is a training resource for data and information management related to oceanography and marine meteorology.

UCAR's Windows to the Universe® hosts basic educational pages on the temperature of ocean water*.

Unidata hosts the netCDF* technical pages and provides netCDF libraries and utilities.

If you have specific questions or would like to request more information, please contact Tess Brandon or Sheri Phillips.