NOAA-15, also known as NOAA-K before launch, was a polar-orbiting, NASA-provided Television Infrared Observation Satellite (TIROS) series weather forecasting satellite operated by National Oceanic and Atmospheric Administration (NOAA). NOAA-15 was the latest in the Advanced TIROS-N (ATN) series. It provided support to environmental monitoring by complementing the NOAA/NESS Geostationary Operational Environmental Satellite program (GOES).
Launch
It was launched by the Titan 23G launch vehicle on 13 May 1998 at 15:52:04 UTC from Vandenberg Air Force Base, at Vandenberg Space Launch Complex 4 (SLW-4W), NOAA-15 replaced the decommissioned NOAA-12 in an afternoon equator-crossing orbit and is in 2021 semi-operational, in a Sun-synchronous orbit (SSO), at 808.0 km above the Earth, orbiting every 101.20 minutes.
Spacecraft The goal of the NOAA/NESS polar orbiting program is to provide output products used in meteorological prediction and warning, oceanographic and hydrologic services, and space environment monitoring. The NOAA-I Advanced TIROS-N spacecraft is based on the Defense Meteorological Satellite Program (DMSP Block 5D) spacecraft and is modified version of the TIROS-N spacecraft (NOAA-1 to NOAA-5). The spacecraft structure consists of four components: 1° the Reaction System Support (RSS); 2° the Equipment Support Module (ESM), which has been expanded from the TIROS-N design; 3° the Instrument Mounting Platform (IMP); and 4° the Solar Array (SA).
Instruments All of the instruments are located on the ESM and the IMP. The spacecraft power is provided by a direct energy transfer system from the single solar array which consists of eight panels of solar cells. The power system for the Advanced TIROS-N has been upgraded from the previous TIROS-N design. The in-orbit Attitude Determination and Control Subsystem (ADACS) provides three-axis pointing control by controlling torque in three mutually orthogonal momentum wheels with input from the Earth Sensor Assembly (ESA) for pitch, roll, and yaw updates. The ADACS controls the spacecraft attitude so that orientation of the three axes is maintained to within ± 0.2° and pitch, roll, and yaw to within 0.1°. The ADACS consists of the Earth Sensor Assembly (ESA), the Sun Sensor Assembly (SSA), four Reaction Wheel Assemblies (RWA), two roll/yaw coils (RYC), two pitch torqueing coils (PTC), four gyros, and computer software for data processing.
Instruments were flown for imaging and measurement of the atmosphere of Earth, its surface, and cloud cover, including Earth radiation, atmospheric ozone, aerosol distribution, sea surface temperature, vertical temperature and water profiles in the troposphere and stratosphere; measurement of proton and electron flux at orbit altitude, and remote platform data collection, and for SARSAT. They included: 1° an improved six-channel Advanced Very High Resolution Radiometer (AVHRR/3); 2° an improved High Resolution Infrared Radiation Sounder (HIRS/3); 3° the Search and Rescue Satellite Aided Tracking System (SARSAT), which consists of the Search and Rescue Repeater (SARR) and the Search and Rescue Processor (SARP-2); 4° the French/CNES-provided improved ARGOS Data Collection System (DCS-2); and 5° the Advanced Microwave Sounding Units (AMSUs), which replaced the previous MSU and SSU instruments to become the first in the NOAA series to support dedicated microwave measurements of temperature, moisture, surface and hydrological studies in cloudy regions where visible and infrared instruments have decreased capability.
Advanced Very High Resolution Radiometer (AVHRR/3)
The AVHRR/3 on the Advanced TIROS-N NOAA K-N series of polar orbiting meteorological satellites is an improved instrument over previous AVHRRs. The AVHRR/3 adds a sixth channel and is a cross-track scanning instrument providing imaging and radiometric data in the visible, near-IR and infrared of the same area on the Earth. Data from the visible and near-IR channels provide information on vegetation, clouds, snow, and ice. Data from the near-IR and thermal channels provide information on the land and ocean surface temperature and radiative properties of clouds. Only five channels can be transmitted simultaneously with channels 3A and 3B being switched for day/night operation. The instrument produces data in High Resolution Picture Transmission (HRPT) mode at 1.1 km resolution or in Automatic Picture Transmission (APT) mode at a reduced resolution of 4 km. The AVHRR/3 scans 55.4° per scan line on either side of the orbital track and scans 360 lines per minute. The six channels are: 1) channel 1, visible (0.58-0.68 μm); 2) channel 2, near-IR (0.725-1.0 μm); 3) channel 3A, near-IR (1.58-1.64 μm); 4) channel 3B, infrared (3.55-3.93 μm); 5) channel 4, infrared (10.3-11.3 μm); and 6) channel 5 (11.5-12.5 μm).
High Resolution Infrared Sounder (HIRS/3)
The improved High Resolution Infrared Sounder/3 (HIRS/3) on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is a 20-channel, step-scanned, visible and IR spectrometer designed to provide atmospheric temperature and moisture profiles. The HIRS/3 instrument is basically identical to the HIRS/2 flown on previous spacecraft except for changes in six spectral bands to improve the sounding accuracy. The HIRS/3 is used to derive water vapor, ozone, and cloud liquid water content. The instrument scans 49.5° on either side of the orbital track with a ground resolution at nadir of 17.4 km. The instrument produces 56 IFOVs for each 1,125 km scan line at 42 km between IFOVs along-track. The instrument consists of 19 IR and 1 visible channel centered at 14.95, 14.71, 14.49, 14.22, 13.97, 13.64, 13.35, 11.11, 9.71, 12.45, 7.33, 6.52, 4.57, 4.52, 4.47, 4.45, 4.13, 4.0, 3.76, and 0.69 μm.
Advanced Microwave Sounding Unit (AMSU-A) The AMSU is a new instrument on the Advanced TIROS-N (ATN) NOAA K-N series of operational meteorological satellites. The AMSU consists of two functionally independent units, AMSU-A and AMSU-B. The AMSU-A is a line-scan instrument designed to measure scene radiance in 15 channels, ranging from 23.8 to 89 GHz, to derive atmospheric temperature profiles from the Earth's surface to about 3 millibar pressure height. The instrument is a total power system having a field of view (FOV) of 3.3° at half-power points. The antenna provides cross track scan 50 degrees on either side of the orbital track at nadir with a total of 30 IFOVs per scan line. The AMSU-A is calibrated on-board using a blackbody and space as references. The AMSU-A is physically divided into two separate modules which interface independently with the spacecraft. Channel Frequency (GHz) Module 1 23.8 GHz AMSU-A2 2 31.4 GHz AMSU-A2 3 50.3 GHz AMSU-A1 4 52.8 GHz AMSU-A1 5 53.596 GHz AMSU-A1 6 54.4 GHz AMSU-A1 7 54.94 GHz AMSU-A1 8 55.5 GHz AMSU-A1 9 57.29 GHz AMSU-A1 10 57.29 GHz AMSU-A1 11 57.29 GHz AMSU-A1 12 57.29 GHz AMSU-A1 13 57.29 GHz AMSU-A1 14 57.29 GHz AMSU-A1 15 89.0 GHz AMSU-A1
Advanced Microwave Sounding Unit 1 (AMSU-A1) The AMSU-A1 is the primary module of the AMSU-A instrument, containing 13 channels that operate between 50 and 90 GHz. It includes 12 oxygen absorption channels for temperature sounding and one 89 GHz window channel for surface information. The first AMSU-A was launched on May 13, 1998, aboard NOAA-15, and has since flown on multiple NOAA satellites as well as NASA's Aqua and EUMETSAT's MetOp series.
Advanced Microwave Sounding Unit A2 (AMSU-A2)
The AMSU-A2 module is the second component of AMSU-A, containing just two low-frequency channels at 23.8 GHz and 31.4 GHz. These channels measure surface temperature and atmospheric moisture, including total precipitable water and cloud liquid water content. The A2 module was developed by Northrop Grumman and works alongside AMSU-A1 to provide complete atmospheric sounding data from different altitudes.
Advanced Microwave Sounding Unit (AMSU-B) Channel Frequency Bandwidth (MHz) Purpose 16 89.00 GHz <6000 Window channel (surface) 17 150.00 GHz <4000 Window channel (surface) 18 183.31 GHz 500 Water vapor line 19 183.31 GHz 1000 Water vapor line 20 183.31 GHz 2000 Water vapor line
The AMSU is a new instrument on the Advanced TIROS-N (ATN) NOAA K-N series of operational meteorological satellites. The AMSU consists of two functionally independent units, AMSU-A and AMSU-B. The AMSU-B is a line-scan instrument designed to measure scene radiance in five channels, ranging from 89 GHz to 183 GHz for the computation of atmospheric water vapor profiles. The AMSU-B is a total power system with a FOV of 1.1° at half-power points. The antenna provides a cross-track scan, scanning 50° on either side of the orbital track with 90 IFOVs per scan line at approximately 22.5 scans per minute. One scan line is completed in 2.67 seconds. On-board calibration is accomplished with blackbody targets and space as references. The AMSU-B channels at the center frequency (GHz) are: 90, 157, and 3 channels at 183.31, providing a nominal horizontal resolution at nadir of approximately 16 kilometers. However, the footprint size increases significantly at the edges of the scan swath, reaching resolutions between 50 and 150 kilometers depending on scan angle.
Space Environment Monitor (SEM-2) The SEM-2 on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites provides measurements to determine the population of the Earth's radiation belts and data on charged particle precipitation in the upper atmosphere as a result of solar activity. The SEM-2 consists of two separate sensors the Total Energy Detector (TED) and the Medium Energy Proton/Electron Detector (MEPED). In addition, the SEM-2 includes a common Data Processing Unit (DPU). The TED uses eight programmed swept electrostatic curved-plate analyzers to select particle type and energy and Channeltron detectors to measure the instensity in the selected energy bands. The particle energies range from 50 eV to 20 keV. The MEPED detects protons, electrons, and ions with energies from 30 keV to several tens of MeV. The MEPED consists of four directional solid-state detector telescopes and four omnidirectional sensors. The DPU sorts and counts the events and the results are multiplexed and incorporated into the satellite telemetry system. Once received on the ground, the SEM-2 data is separated from the rest of the data and sent to the NOAA Space Environment Laboratory in Boulder, Colorado, for processing and dissemination.
Solar Backscatter Ultraviolet Radiometer (SBUV/2)
The SBUV/2 on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is a dual monochromator ultraviolet grating spectrometer for stratospheric ozone measurements. The SBUV/2 is designed to measure scene radiance and solar spectral irradiance in the ultraviolet spectral range from 160 to 406 nm. Measurements are made in discrete mode or sweep mode. In discrete mode, measurements are made in 12 spectral bands from which the total ozone and vertical distribution of ozone are derived. In the sweep mode, a continuous spectral scan from 160 to 406 nm is made primarily for computation of ultraviolet solar spectral irradiance. The 12 spectral channels are (nm): 252.0, 273.61, 283.1, 287.7, 292,29, 297.59, 301.97, 305.87, 312.57, 317.56, 331.26, and 339.89.
Search and Rescue Satellite Aided Tracking System (SARSAT)