As the debates over climate change and sea level change rage on, now an app developed by researchers at Lamont-Doherty Earth Observatory of Columbia University brings a host of such important data in your hand. Instantly. All you need an iPhone and a steady Internet connection.
Want to know which are the areas the sea level rising? Or why does sea level change and how much is the contribution from glaciers? What are future predictions along the US coast? Or which are the most vulnerable areas on earth? Polar Explorer: Sea Level tells you all that. And much more.
Presented by researchers at last week’s American Geophysical Union’s Fall Meeting in San Francisco, Polar Explorer: Sea Level is an education mobile app that allows users to navigate data-based map layers to explore questions about climate change and gives information about the sea level and the various processes that control the location of the shoreline.
The app deals with seven important questions: What is sea level; Why does sea level change; Where is the sea level rising; What about the polar regions; What about climate change in the past; what are future predictions for sea level; and Who is at risk. The interactive app features global multi-resolution digital elevation model for land and ocean, scrollable and cascading list of available topics. Category functions are organized like book chapters, and users can click on categories like they choose chapters to look at a selection of map layers that will help them better understand their topic.
In addition to overlay of selected thematic content with adjustable opacity and info button for each subject that opens a browser window with further content description, animations, data sources, credits and citations along with external links, there is a choice of either text and audio to introduce each topic, legends and also their numerical values revealed at locations with the tap of a finger. A user can also capture of current map to photo library for email to others.
The app can be downloaded from the Education Category of the App Store for free but is available only on iPad and iPhone currently. A user needs a steady Wi-Fi or 3G network connection with iOS 6.0 or more recent operating system. Recently retrieved tiles are cached to allow limited review of previously explored regions without a live connection. An internet connection is mandatory to fetch fresh content.
How to use the app
Once a user has downloaded the app, he needs to open the interface and press the ‘New User’ icon in the lower center of the screen. One can pan by dragging a single finger in contact with and across the screen and zoom by squeezing or expanding two fingers also in contact with the screen.
The ‘Menu Panel’ can be opened by pressing the > icon in the lower right corner of the map and a title or layer name can be chosen on the scrollable list in the panel. If the title is followed by an arrow, the action opens a sub-menu with choices of layers related in theme to the parent layer. To confirm a successful selection, the title region darkens and a check mark appears to the right of the title. Pressing the ‘Done’ button returns to the map with the selected layer displayed as an overlay on the Basemap.
Pressing the ‘i’ icon to the left of the layer title to open a browser window containing content description, data sources, credits, citations and external links.
To change the opacity (transparency) of a displayed layer, one needs to drag the small circular button along the slider bar in the map window. However, the opacity of the Basemap layer can’t be changed, neither can the Basemap be superimpose on other layers.
The green border on the map indicates that there are more content available at higher zoom levels and it appears even if the application is unsuccessful in uploading (refreshing) tiles while panning and zooming.
On the other hand, a red border on the map indicates the maximum zoom level (image resolution) has been reached for the current content while yellow lines indicate that these are borders of tiles being requested from the server. The lines disappear as soon as the required tiles have been fetched successfully.
The basemap consists of sun-illuminated elevations on land and depths for the oceans and seas. The illumination is computer-generated and directed from the upper left. For land regions the elevations and their shading derive from gridded digital elevation models (DEMs). DEMs obtained from the ASTER satellite mission have been used for the land regions at approximately 30 m grid-node resolution and DEMs from the National Elevation Dataset at 10 m grid-node separation for the US mainland and Hawaii and 25 m for Alaska, Puerto Rico and Mexico. For the oceans, the GEBCO_08 global bathymetric grid at 30 arc-seconds (~1 km) grid-node separation has been used which is supplemented by high-resolution digital multibeam echo-sounding surveys down to 50 m grid-node separation for deep regions and to 4 m grid-node separation for some coastal areas and harbors.