view_hdf Kam-Pui Lee Science Applications International Corporation CERES Data Management Team Linda Hunt Computer Sciences Corporation Atmospheric Sciences Data Center NASA Langley Research Center Atmospheric Sciences Data Center NASA LaRC

Introduction NASA Langley Research Center has developed the Clouds and the Earth’s Radiant Energy System (CERES) instrument to study the Earth’s climate and environment The CERES Data Management System has been developed to generate science data products from the instrument measurements This system is now operational at the Atmospheric Sciences Data Center (DAAC) producing archival data sets written in Hierarchical Data Format (HDF) A visualization and analysis tool, view_hdf, has been written in Research Systems’ Interactive Data Language (IDL) to access data from HDF products Atmospheric Sciences Data Center NASA LaRC

view_hdf overview Consists of IDL routines and a C shared library, with a graphical user interface (GUI) to manipulate the data Developed on a Unix platform; built and tested on Solaris, Irix, HP-UX, and DEC/Compaq Alpha operating systems Currently being tested on PC platforms An IDL-only version is under development that eliminates the C shared library, making view_hdf portable to any system which can run IDL Developed for the CERES project but useful with other data sets written in HDF and HDF-EOS Atmospheric Sciences Data Center NASA LaRC

Capabilities of view_hdf Select and subset variables from either Science Data Sets (SDS) or vdata structures Render both two- and three-dimensional graphics Plot geolocated data onto various world map projections Plot multiple variables Perform simple arithmetic operations on two variables Compute statistics Create subsets of data based on the value of another criterion variable Perform curve fitting and regression Create histograms Atmospheric Sciences Data Center NASA LaRC

Capabilites of view_hdf Display data values to the screen Export data to a file in ASCII or HDF formats Save plots in PostScript or GIF format Send plots directly to a printer Execute a user-defined IDL procedure Atmospheric Sciences Data Center NASA LaRC

Obtaining view_hdf view_hdf is distributed by the Atmospheric Sciences Data Center at NASA Langley: support is available from Science, User and Data Services Atmospheric Sciences Data Center NASA Langley Research Center MS 157 D, 2 S. Wright St. Hampton, VA USA Phone: Fax: Atmospheric Sciences Data Center NASA LaRC

Main Menu

Open with vgroup

List SDS and vdata Names

Range Input Window

Import Data

Select Function Menu

Geolocated Plot

Daytime Total Filtered Radiance

Show Subset Range

Histogram of Scene ID

Multivariable Plot

Grid Contour Plot

Curve Fit