This document is not subject to the controls of the International Traffic in Arms Regulations (ITAR) or the Export Administration Regulations (EAR) NOAA Satellite Conference 27 April – 1 May, 2015, Greenbelt Marriott, Greenbelt, MD Synopsis: This poster discusses the key weather observation performance objectives for the Canadian Polar Communication and Weather (PCW) mission and how they drive the design and operation of a PCW imager. The decreasing ice in the Arctic is leading to more personnel, ships, and operations, resulting in a greater need for more accurate, timely weather predictions. The US, Japanese, Korean, and European meteorological agencies are all upgrading their geostationary weather imagers to provide much more frequent Full Disk Earth images (every 5 to 10 minutes). Arctic weather observation, however, is still limited to a few passes a day from low Earth orbit (LEO) satellites, many of which are well beyond their intended operational life. The PCW mission concept is to provide Arctic weather observations with the same temporal fidelity and spectral resolution as equatorial and mid-latitude weather and similar spatial resolution. Key performance objectives drive the design and operation of a PCW imager. Key mission decisions include number of satellites, orbit (LEO vs. HEO; Molniya, TAP, Tundra), coverage, image collection interval, types of images (Full Disk, storm watch, etc.), spectral bands, spatial resolution, etc. Exelis’ Advanced Baseline Imager (ABI) will fly on GOES-R East, GOES-R West, GEO-KOMPSAT-2A (Korea), and is flying on Himawari (Japan), and providing these missions the additional capability for interleaved mesoscales delivering storm observations every 30 to 60 seconds. ABI’s operational flexibility also makes it an ideal solution for the PCW mission. 1. Arctic Deserves Same Quality of Weather Predictions as CONUS Geostationary weather satellites have continuous coverage of their region of the Earth, providing high temporal resolution and the ability to monitor rapidly evolving severe weather events. The U.S., Japanese, Korean, and European weather agencies are all making significant upgrades to their geostationary weather imagers, enabling Full Disk Earth images every 10 minutes instead of every 30 minutes. The U.S., Japanese, and Korean imagers will also have the capability to interleave storm watch collections every seconds. However, due to the curvature of the Earth none of these missions provide adequate spatial resolution above 60° latitude. Hence, the Arctic must rely on data from low Earth orbiting (LEO) weather satellites. At the same time, the decreasing ice in the Arctic is leading to a need for more accurate weather forecasting. There is an increase in commercial shipping, commercial operations, and permanent residents. The decreasing ice is also causing more severe weather and greater variability in the weather. (Figure 1) 2. LEO Imagers Have Many Limitations Much of the Arctic’s satellite weather data comes from LEO satellites. They provide useful data but have critical limitations. LEO data is collected one swath at a time with an orbital period of ~100 minutes. There is no ability to obtain persistent images, which means evolving weather cannot be observed in the way that it can with a geostationary imager. The long time gaps between observations means much of the Arctic weather products come from numerical weather models rather than directly from images. However, the images used to initialize and drive the models consist of pixels collected over a wide span of time (“aging pixels”), impacting the accuracy of these models. VIIRS, the next generation LEO imager, lacks the water vapor bands used for winds – a critical product for Arctic weather. 6. PCW Designed for Persistent Arctic Coverage The 100% coverage region for PCW is shown in blue in Figure 2. PCW will provide continuous coverage of the entire Arctic region, filling the gap left by the geostationary imagers. Continuous coverage is provided for all parts of the earth above 60°N latitude, which includes most of Canada, Alaska, Iceland, Greenland, etc. With ABI-class imagers on PCW, Full Disk Earth images, including the Arctic, can be collected every 10 minutes and storm watch images can be collected every minute. There is a distinct trend over the last couple of decades of warmer temperatures in the Arctic. This leads to less ice and greater weather and environmental uncertainty. The frequency and intensity of Arctic cyclones is increasing (1900 storms between 2000 and 2010). Shipping traffic and human habitation is also increasing as the ice melts. 4. Orbit Choice Balances Resolution and Lifetime The Tundra orbit is a moderately eccentric orbit, as shown in Figure 3. Apogee is ~20% higher than a geostationary orbit and perigee is ~20% lower. The orbital period is twenty-four hours. Two satellites are used, orbiting twelve hours apart. There is a significant difference in the radiation environments between the Molniya, TAP, and Tundra orbits, leading to very different expected mission lifetimes of the imager. Shown in Table 1 are the estimated lifetimes of the ABI payload in all three orbits. As can be seen, the “better” resolution Molniya orbit comes at a cost three times that of the Tundra orbit mission. Tundra provides significant lifetime improvement (3x Molniya) and a very significant life cycle cost advantage over the other two orbits. Mission optimization: Tundra is best providing significantly lower 15 year life cycle cost while still meeting Arctic needs and the added benefit of significant Antarctica coverage. 5. PCW Imagery Will Improve Arctic Weather Knowledge and Forecasts ABI provides sixteen channels selected for weather data products (listed in Table 2). They include the water vapor channels used for assessing winds as well as channels for identifying fires and tracking volcanic ash. ABI has the flexibility to swap out certain channels to meet specific mission needs (Table 3). Although located at a much higher orbit than the LEO constellation, the resolution of an ABI on PCW is comparable and offers the advantage of being uniform (no distortion caused by abrupt resolution changes). The resolution is compatible with the current numerical weather models. The resolution is also as good as or better than that obtained for CONUS imagery from GOES-R because the area of interest is directly beneath the satellite (see Figure 4). The ability to collect an entire image within 10 minutes will significantly improve knowledge of current Arctic weather. It will also improve the models by eliminating the “aging pixels” issue. One minute updates for severe weather events will provide one hundred times the temporal fidelity of current LEO imagers. Like a LEO instrument, PCW will provide coverage for the entire globe. Unlike a LEO instrument, it can provide persistent coverage of the Arctic. Figure 2 shows the global coverage for PCW when flying in a 90° Tundra orbit. The blue region is 24 hours of coverage per day and every spot on the earth is observed for more than 4 hours per day. Antarctica is observed for more than 8 hours per day. PCW will also provide significant coverage in the Indian Ocean region which will be of particular importance with the planned retirement of Meteosat 7 in Wavelength (µm)GSD (km) † Main Applications Surface, clouds, aerosols Wind, clouds, ice mapping Wind, aerosols, vegetation Cirrus detection Snow-cloud distinction, ice cover Aerosol, smoke, cloud phase Fog, fire detection, ice/cloud separation, wind Wind, high level humidity Wind, mid level humidity Wind, low level humidity,SO Total water, cloud phase Total ozone Cloud, surface, cirrus Cloud, Sea Surface Temperature (SST), ash Ash, SST Cloud height Figure 4: Resolution of Arctic images from PCW will be similar to CONUS images from GOES-R Table 2: ABI spectral channels selected for weather data products † Nadir GSD at PCW reference altitude (apogee ±3 hours) Arctic Weather Every 10 Minutes: Exelis ABI on PCW Dr. Paul Griffith and Sue Wirth Exelis Geospatial Systems Figure 2: ABI on PCW provides 24/7 coverage of Arctic with updated images every 10 minutes 3. Maximize Quality and Quantity of Weather Data Products at Minimum Cost and Risk Identify the fundamental mission objective, which is to produce high quality weather data products. Success is defined as mission-level optimization rather than optimizing the mission elements (payload, satellite, ground). The key parameters for obtaining high quality weather data products are: Spatial resolution, Coverage – both area and repetition interval (i.e. temporal resolution), Spectral bands, SNR, and Radiometric Accuracy A key mission parameter derived from these data product parameters is orbit. Credit: United States Navy CONUS Arctic GEO HEO True-color composite (Band 1 (blue), Band 2 (green), Band 3 (red)) from Japan Meteorological Agency website eng/satellite/news/himawari89/ _himawari8_first_images.htmlhttp:// eng/satellite/news/himawari89/ _himawari8_first_images.html FPMFPA Resolution (km) Center wavelength (µm) ABIAHIAMIPCW † VNIR A A A A A A MWIR A A A A A LWIR A A A A A Color Key: Not in ABI Different FPA Figure 3: HEO orbit options (Molniya, TAP, and Tundra) shown relative to geostationary altitude for reference Table 3: Spectral channels for ABI, AHI, AMI, and PCW Table 1: Comparison of HEO Orbits Figure 1: Sea routes expanding due to reduction in ice Hours