NOAA Office of Satellite and Product Operations

NUCAPS Skew-T Website with Global Coverage

Gerasimos "Geri" Michalitsianos
Oleg Roytburd
SGT, Inc.
Last Updated: 27 August, 2020


Vertical profiles of the Temperature and Dew Point temperature are derived from the CrIS/ATMS instruments onboard the NOAA SNPP satellite, as well as the IASI instruments aboard the MetOp-A and MetOp-B satellites. They are dynamically displayed using the Javascript D3 library with a Skew-T Log-P diagram format. Skew-T Coverage exists for the entire globe. Previously, this coverage was restricted to only the U.S. continental region (CONUS). Using this map, one can view a NUCAPS sounding plots, as well as the corresponding aerologic and profile data tables, all as part of a 10-day animation (separate page).

This website shows Skew-T plots and the relevant profile and aerologic data tables based on data output from the nucaps algorithm.

There are a couple ways to show NUCAPS Skew-T data tables and soundings plots. First, the user must click the button on the upper-left side of the map with the black rectangle ("Draw a rectangle"). By clicking this button, the user can click and drag to draw a rectangular domain of interest on the interactive and zoomable map. After drawing the rectangle, colored dots will appear on the map in the domain of interest. These colored dots represent the age of the latest sounding at that particular location.

By checking the "Hover Thumbnail Viewer" checkbox above the map, the user can hover over each square (dot) on the map to view a thumbnail (for the most recent day) sounding plot. By actually clicking a square (dot) on the map, the user will navigate to a 10-day sounding animation page for that particular sounding location. For each step in this animation page, sounding profiles are plotted, along with the relevant profile and aerologic data tables for that particular sounding for that particular day.

The color of each dot (square) on the map represents the age of the profile ranging from 0 to 24 hours, with an increment of 1.7 hours. This most recent profile generated is less than 1.7 hours as shown by a blue color and the oldest profile older than 24 hours is shown by a black square color. The XML data powering the data behind the map is refreshed every power and the whole globe is divided into a 0.5 X 0.5 degree grid. Each grid may contain more than one CrIS FOV but the closest FOV to the center of the grid was selected for the purposes of displaying a sounding plot and profile.

To download XML Skew-T for some user-defined rectangular domain, the user may click the button "Download XML Data for Area of Interest" above the map. To this end, some domain should have been drawn on the map. Clicking this button will open a new, blank page in which, after some time, a window will appear in which the user can download "out.xml", which contains all of the relevant NUCAPS Skew-T data for the rectangular region, for all 10-days of the animation (10 day range). This includes all of the temperatures, pressures, as well as aerologic table data. Note that the domain size is limited to a rectangular domain no larger than 50 deg. N-S by 100 deg. E-W.

The user can use the checkboxes above the map to show or hide the following map layers on the map:

  1. Country and U.S. state political boundaries
  2. Gridlines for longitudes and latitudes (every 10 degrees)
  3. GOES Cloud Composite image for global coverage
  4. The sounding preview panel with profile plots for nucaps soundings (Log-P diagram).


  1. Javascript programming language
  2. jQuery, a Javascript language library
  3. Perl, a programming language for for back-end to download Skew-T XML data
  4. HTML/CSS, for defining the structure of the page and styling.
  5. d3, a Javascript library for dynamically created browser-based, client-side soundings plots.
  6. Leaflet, a Javascript library for creating interactive and user-friendly web maps in the browser.