This is an introduction for readers who are not familiar with the GOES-R satellite program. It provides enough background to help the reader understand the context for the rest of the Algorithm Working Group web site. Links are provided for readers seeking more detailed or advanced materials. The Mission section of the GOES-R project web site is an excellent source for the full range of GOES-R information.
Artist's rendition of GOES-R in orbit
The Geostationary Operational Environmental Satellite R-Series is the next generation of geostationary weather satellites scheduled to launch in early 2016 with an operational lifetime through December 2036. Geostationary means that the satellite's orbit keeps it in the same location relative to the ground. This means that the satellite will complete exactly one orbit of the Earth every day. This distinguishes it from satellites in lower orbits which orbit the Earth many times per day. Operational means that GOES satellites provides data to support weather forecasting and to meet other on going needs. Operational is distinguished from research or experimental satellites that are not relied upon for such operational requirements. Environmental Satellites provide Earth observations, compared to other satellites launched for telecommunications, global positioning, or other purposes. R is the next alphabetic letter to be assigned to GOES satellites. GOES satellites that are (or were) actively providing operational data are assigned numbers. Letters are used to identify satellites during their development, through launch, and until the satellite becomes operational. The GOES satellites work in pairs, GOES East providing data from the eastern United States and Atlantic Ocean, and GOES West providing data from the wesern United States and eastern Pacific Ocean.
Orbit and Observations
Locations of GOES Satellites
The normal mode of operations for GOES-R is to collect data from the continguous United States (CONUS) every 5 minutes, with full disk (hemispheric) data every 15 minutes. Along with the CONUS and full disk data, "mesoscale" data can be collected from a 600 mile (1000 km) square areas of special interested every 30 seconds without impacting the CONUS and full disk data. Alternatively, in continuous full disk mode, uninterrupted full scans can be available every 5 minutes. This means that mesoscale hazardous weather such as tornado formation, severe storms, hurricanes, or wild fires can be available every 5 minutes...far faster than currently available.
The advantage of geostationary satellites being in one location at a high altitude, is this very rapid update of data for a large area. This complements the data from other environmental satellites (for example, currenlty Aqua, Terra, NPP) that collect data at a higher resolution but for a smaller area much less frequently. A significant portion of the Algorithm Working Group's effort is comparision between the data from geostationary and low Earth orbit satellites to properly calibrate and validate the GOES-R data in comparison to existing sources that have already been calibrated and validated.
The majority of GOES-R data for which the AWG produces algorithms to create products comes from two of the GOES-R instruments - the Advanced Baseline Imager (ABI) and the Geostationary Lightning Mapper (GLM).
Advanced Baseline Imager
The best analogy to describe the ABI is that it is like a high resolution camera that is sensitive to more of the spectrum than the human eye can see. Unlike an everyday digital (or video) camera which is designed to detect and record 3 spectral bands (red, blue, and green), the ABI has 16 spectral bands in the visual, near infrared, and thermal infrared ranges.
|Spectral coverage||16 bands||5 bands|
|0.64 mm visible||0.5 km||Approx. 1 km|
|Other visible, near-IR||1.0 km||none|
|Bands (>2 mm)||2 km||Approx. 4 km|
|Full disk||4 per hour||Scheduled (3 hourly)|
|CONUS||A12 per hour||~4 per hour|
|Mesoscale||Every 30 seconds||none|
Further details about ABI include:
Geostationary Lightning Mapper
The GLM optically detects lightning flashes in the near-IR spectrum (777.4 nm) and locates the flashes within a 10 km grid for the Americas and adjacent oceans. The instrument detects both lightning within clouds and between clouds and the ground. Detection is possible both day and night. The GLM will provide early indication of storm intensification and severe weather events, including improved tornado warning lead time.
Further details about GLM include:
The majority of GOES-R data for which the AWG produces algorithms to create products comes from two of the GOES-R instruments - the Advanced Baseline Imager (ABI) and the Geostationary Lightning Mapper (GLM). "Products" are the results from processing of relatively raw satellite data using various algorithms (developed by the AWG) into a more widely usable form. For example, the raw data from the ABI is electrical signal strengths corresponding to the intensity of electromagnetic radiation (ultraviolet, visible, infrared, etc.) at different wavelengths.