AccuWeather’s Global Satellite API provides subscribers access to a weather map overlay service via a simple RESTful web interface. This satellite service does not include a map of any type. It returns a series of graphics in square tiles for layering on top of an existing map to illustrate weather conditions. Therefore, Global Satellite is not a stand-alone service but is intended to be paired with a Mercator projection mapping service such as Bing Maps or Google Maps. Tiles are returned one at a time in PNG format.
Different regions of the world have different satellites for gathering weather data. Because of this, the different regions all provide weather data at different intervals. For example, the United States and Asia might update more frequently than the EU and Indian Ocean regions. This update inconsistency will cause an uneven graphical representation on weather maps. If a user has the map zoomed out far enough that they can see both the United States and the European Union at the same time, the EU’s weather graphics may appear to “jump” every few frames, while the US data continuously moves with each successive frame.
To remedy this situation our Global Satellite system will examine each region of the world (called products) based on various properties. In our scenario it would be most helpful to identify all the products displayed on the user’s map. Once those products have been identified, the Global Satellite system can determine which product has the slowest data refresh rate, and then match all the faster products to that slower rate. This way the US will refresh at the same rate as the EU on the user’s map. The result is a cohesive and graceful view of the world’s weather.
Each product has a unique code that consists of two numbers separated by a dash. The first number is called the major value, and the second is the minor value. Both numbers are provided by any API response that identifies one or more products.
Some endpoints will return a list of frames. Each frame has a temporal value and defines one set of satellite tiles to be returned. The total time span encompassed by these frames will vary between products and are subject to change for each individual product. Global Satellite will match all products within the viewing area to the time span of the product with the shortest time span. For example, the US might have a longer available time span than the EU. When the user has both the US and the EU within their viewing area, Global Satellite will cut down the US frames to only cover the same time span as the EU so the weather data for both regions will match.
Normalized Radar Data
Global Satellite can use normalized radar data (NRD) to display temperature information. When activated, NRD provides all satellite graphics in the red channel only. The red value directly correlates to a temperature in Kelvin (K) for an accurate and precise reading.
The minimum and maximum red values correlate to the following Kelvin temperatures:
An increase of 1 red value equates to an increase of 0.5059 K. Temperature (K) can be calculated from any red value (R) using this equation:
K = 180 + 0.5059 (R - 1)