Himawari-8 and 9
Himawari-8 and -9 Meteorological Missions
JMA (Japan Meteorological Agency) has operated the GMS (Geostationary Meteorological Satellite) and MTSAT (Multifunction Transport Satellite) series of satellites around the 140º east longitude to cover the East Asia and Western Pacific regions since 1978, and makes related contributions to the WMO's World Weather Watch (WWW) Program. As a follow-on to the MTSAT series, the Agency plans to operate next-generation satellites called Himawari-8 and Himawari-9 (himawari means "sunflower" in Japanese). Unlike the current MTSAT series, which performs both meteorological and aeronautical functions, to include air-traffic control communications and position information, Himawari-8 and -9 will have a dedicated meteorological mission. 1) 2) 3) 4) 5) 6)
Currently (2014), MTSAT-2 (Himawari-7) is operational, while MTSAT-1R (Himawari-6) is on standby in orbit. MTSAT-2, which took over the Earth observation mission of MTSAT-1R on July 1, 2010, is scheduled to complete its observation operation in around 2015. In order to provide continuous observation services, JMA plans to commence its operation in 2015, when MTSAT-2 is scheduled to complete its period of operation. The Agency also plans to launch Himawari-9 in 2016.
Figure 1: Schedule for the follow-on satellites to the MTSAT series (image credit: JMA)
Figure 2: Coverage of Himawari-8/-9 (image credit: JMA) 7)
Figure 3: Artist's rendition of the deployed Himawari-8 spacecraft (image credit: JMA)
In July 2009, JMA completed contract arrangements with MELCO (Mitsubishi Electric Corporation) for the manufacture of Himawari-8 and -9, which have identical specifications.
• The Himawari spacecraft is 3-axis stabilized with momentum bias. It features a MELCO DS-2000 bus. The overall size of the deployed spacecraft is: 5.2 m (X-axis), 8.0 m (Y-axis), 5.3 m (Z-axis).
• The launch mass is ~3500 kg, the dry mass is 1300 kg.
• The design life is 8 years (including In-Orbit-Test) for AHI, 15 years for the spacecraft bus.
• ADCS (Attitude Determination and Control Subsystem)
- Attitude sensors: Coarse Sun Sensor, Star Tracker, IRU (Inertial Reference Unit), Gyroscope
- Actuation device: RWA (Reaction Wheel Assembly)
• EPS (Electrical Power Subsystem): The power generated is 2.6 kW, the bus voltage is 100 V, use of a Li-ion battery.
• MDHS (Mission Data Handling Subsystem): MDHS connects with the AHI instrument using SpaceWire I/F and processes the data from the instrument into telemetry, based on the CCSDS recommendations. The processed data are sent to the Ka-band transmission system. MDHS also connects with a satellite control system by SpaceWire and sends commands to AHI.
Figure 4: Schematic view of the Himawari-8/9 satellite (image credit: JMA)
• RF communications:
- Ku-band for TT&C services. The uplink rate is 500 bit/s, the downlink data rate is 15.36 kbit/s with a modulation PCM-PSK/PM
- Ka-band for payload data transmission. The data rate is 66 Mbit/s for AHI and 100 bit/s/300 bit/s for DCS. The modulation is QPSK, PCM-PSK, no encryption.
- UHF for DCS: The data rate is 100 bit/s/300 bit/s with a modulation of PCM-PSK.
For AHI data, compression is performed according to CCSDS Recommendation for Space Data System Standards. Lossless Data Compression, CCSDS 121.0-B-1 Lossless, May 1997.
• On August 21, 2014, MELCO announced that it has completed work on the Himawari-8 satellite, the next generation geostationary meteorological satellite, based on a contract awarded by the JMA(Japan Meteorological Agency). Himawari-8 was delivered soon to Tanegashima Space Center, Japan, from where it was launched. 11)
Figure 5: Photo of the completed Himawari-8 satellite at Mitsubishi Electric's space works center (image credit: MELCO)
• In December 2013, ITT Exelis delivered the AHI instrument to Mitsubishi Electric Corporation. 12)
Launch: The Himawari-8 spacecraft was launched on October 7, 2014 (05:16:00 UTC) on a H-IIA vehicle (H-IIA F25) from the TNSC (Tanegashima Space Center) of JAXA, Japan. The launch service provider was Mitsubishi Heavy Industries, Ltd. The launch vehicle flew as planned, and, at about 27 minutes and 57 seconds after liftoff, the separation of the Himawari-8 was confirmed. 13) 14) 15)
Orbit: Geostationary orbit of Himawari-8 and Himawari-9, altitude of ~35,800 km, longitude of ~140.7º east, covering the East Asia and Western Pacific regions, succeeding the GMS and MTSAT series.
Launch: The Himawari-9 spacecraft of JAXA was launched on November 02, 2016 (6:20:00 UTC) on the H-IIA F31 vehicle of MHI (Mitsubishi Heavy Industries) from the TNSC (Tanegashima Space Center), Japan. The launch vehicle flew as planned, and at approximately 27 minutes and 51 seconds after liftoff, the separation of Himawari-9 was confirmed. 16)
Both Himawari-8 and -9 spacecraft do not carry any equipment for direct data broadcasting. Hence, JMA is discussing the utilization of ICS (Internet Cloud Service) and CTS (Commercial Telecommunication Satellite) as data distribution services (Figure 6). JMA will substitute the CTS broadcasting for current MTSAT direct broadcasting. On the other hand, the Internet Cloud Service will be newly introduced as a means of data distribution for the National Meteorological and Hydrological Services (NMHSs) and for EUMETSAT. The agency will also introduce an Archive Server that is operated by the Japanese Science Group. Users of this server will be able to obtain all types of imagery from this server. Table 9 shows the receivable imagery products via the Internet Cloud Service / the CTS broadcasting. However, the types of imagery are limited for CTS broadcasting.
Figure 6: Schematic diagram of the data distribution/dissemination plan for HIMAWARI-8 and -9 (image credit: JMA)
Table 1 shows the dataset disseminated via the HimawariCast service.
Himawari imagery in full-disk HRIT/LRIT files compatible with current MTSAT HRIT/LRIT data* is provided via the service. Files will be disseminated every 10 minutes in principle, but this interval will follow the MTSAT-2 observation schedule while MTSAT-2 is in operation. The number of bands of MTSAT-2 HRIT files is 5 out of 5, and that of Himawari-8 HRIT files is 14 out of 16.
In addition, numerical weather prediction (NWP) products GPVs (Grid Point Values) and meteorological observation data other than Himawari imagery in SATAID format are disseminated. Satellite Animation and Interactive Diagnosis (SATAID) visualization software for satellite imagery enables the superimposition of various meteorological data and products, such as NWP, in-situ observation data and ASCAT output, onto satellite imagery.
Table 1: The data set disseminated via HimawariCast (Ref. 49)
The specification list of receiver for the CTS broadcasting is shown in Table 2. To receive imagery, the specification of equipment is needed. Note that the equipment for the current MTSAT direct broadcasting is not available for the CTS broadcasting.
Table 2: The receiver specification list
• January 14, 2020: In January 2020, the Taal Volcano awoke from 43 years of quiet and spewed lava and ash, filling streets and skies of the Philippine island of Luzon with fine ash fall and volcanic gases. The eruption caused tens of thousands of people to evacuate their homes and forced the closure of several key roads, businesses, and an airport. 19)
- The volcano first unleashed a steam-driven explosion (known as a phreatic eruption) on January 12. In the early morning of January 13, eruptive activity increased and the volcano emitted a fountain of lava for about an hour and a half. According to the Philippine Seismic Network, 144 volcanic earthquakes have been recorded since January 12, suggesting continuous magmatic activity underneath Taal and potentially more eruptive activity.
- According to news reports, the eruption of Taal lofted ash up to 14 km (9 miles) into the air. The eruption was accompanied by intense thunder and lightning above the summit. Winds carried volcanic ash north across Luzon.
Figure 7: The time-series animation above shows the growth and spread of the volcanic plume from January 12-13, as observed by Japan's Himawari-8 satellite (image credit: JMA (Japan Meteorological Agency), Story by Kasha Patel)
Figure 8: This map shows stratospheric sulfur dioxide concentrations on January 13, 2020, as detected by the Ozone Mapping Profiler Suite (OMPS) on the NOAA-NASA Suomi-NPP satellite [image credit: NASA Earth Observatory, image by Lauren Dauphin, using OMPS data from the Goddard Earth Sciences Data and Information Services Center (GES DISC). Story by Kasha Patel]
- Taal is the second-most active volcano near Manila, which is located approximately 60 kilometers (40 miles) north of the volcano. In total, ten cities and municipalities surround Taal. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) has ordered a "total evacuation" for people in high-risk areas within a 14-kilometer radius from the main crater, affecting around half a million people.
• December 11, 2019: Satellite remote sensing has widely been used to monitor and characterize the spatial and temporal changes of the Earth's vegetative cover. Satellites used in these analyses have conventionally been polar-orbiting satellites, which orbit from "pole to pole" and obtain only one to two images of the Earth per day. The utility of these polar-orbiting satellites has, however, often been limited because frequently occurring clouds block their view of the land surface. 20)
- New-generation geostationary satellites present an opportunity to observe land surfaces in a more efficient manner. Being in geostationary orbit, the Advanced Himawari Imager (AHI) sensor onboard Himawari-8, for example, can obtain multi-band color images over Japan every 10 minutes, increasing the chance of obtaining "cloud-free" observations.
- In a new study published in Scientific Reports, an international team of researchers, including Tomoaki Miura from University of Hawaii, Shin Nagai and Mika Takeuchi from Japan Agency for Marine-Earth Science and Technology, Kazuhito Ichii from Chiba University, and Hiroki Yoshioka from Aichi Prefectural University, examined this possibility and the utility of Himawari-8 AHI geostationary satellite data for capturing seasonal vegetation changes in Central Japan. 21)
Figure 9: Seasonal variations in vegetation index observed by Himawari-8 (middle) and Suomi-NPP (bottom) at Takayama in-site observation site and camera images taken downward at the site (top), image credit: Tomoaki Miura and Kazuhito Ichii
- Their study found that Himawari-8 AHI acquired approximately 26 times more observations than the Suomi-National Polar-orbiting Partnership (Suomi- NPP) Visible Infrared Imaging Radiometer Suite (VIIRS), one of the latest polar-orbiting satellite sensors, for the year 2016.
- As a result, there were a larger number of days with "cloud-free" observations with Himawari-8 AHI than with Suomi-NPP VIIRS. The study has demonstrated that the AHI geostationary sensor obtained one cloud-free observation data every 4 days, whereas the VIIRS polar-orbiting sensor was able to obtain one cloud-free observation every 7 to 16 days.
- Owing to this larger number of cloud-free observations, AHI "vegetation index," a satellite measure of vegetation greenness, captured the temporal changes of vegetation from leaf expansion to leaf fall continuously throughout the growing season, corresponding to the observed vegetation phenology with in situ time-lapse digital images (Figure 9). There were, however, several periods where even AHI was unable to obtain cloud-free observations due to persistent cloud cover during summer-fall seasons.
- "Detailed vegetation seasonal information from the Himawari-8 geostationary satellite can be useful for many applications such as short- term drought monitoring and assessing the impact of heavy rainfall events," said Prof Miura, the lead author of the study. "This study has shown that the Himawari-8 meteorological satellite can be used to monitor land surface and vegetation.
- With new-generation geostationary satellites, we may begin to see various types of vegetation changes that could not be seen with previous satellites. The new findings contribute to understanding land-atmosphere carbon dioxide budgets," said Prof Ichii of Chiba University, a co-author of this study.
- The Himawari-8 AHI geostationary satellite also acquires multi-band color images over the tropical Southeast Asia region every 10 minutes. It is expected that AHI geostationary sensor data would contribute to improving our understanding of vegetation dynamics and the effect of climate change in this cloud-prone tropical region.
• January 18, 2018: JMA has launched its new international HimawariRequest service, which allows National Meteorological and Hydrological Services (NMHSs) to request Target Area observation conducted by Himawari-8/9 every 2.5 minutes. 22) 23)
- JMA's latest-generation Himawari-8 geostationary meteorological satellite began operation in July 2015, with the corresponding Himawari-9 unit entering a state of backup operation in March 2017. This dual satellite system is expected to provide a continuous stream of observation data for the Asia-Oceania region until 2029.
- AHI (Advanced Himawari Imager) on board Himawari-8/9 is capable of frequent and flexible observation, providing Full-Disk images of the Earth every 10 minutes and regional images with shorter intervals. Full-Disk and other regional observations have spatial resolutions of 0.5 to 2 km and spectral coverage incorporating 16 bands.
- In regional monitoring, Target Area observation provides imagery covering a 1,000 x 1,000 km area every 2.5 minutes with flexibility for location changes to support JMA's national and international services. The observation is normally focused on an area of active volcanoes in the domain of the Tokyo VAAC (Volcanic Ash Advisory Center), and is adapted to encompass typhoons within the responsibility area of the RSMC (Regional Specialized Meteorological Center) Tokyo Typhoon Center.
- The HimawariRequest service enables registered NMHS users to request particular Target Area observations in order to leverage this flexibility on an international scale. The service stems from a WMO RA II (Asia) regional project to develop support for NMHSs in satellite data, products and training in collaboration with WMO RA V (South-West Pacific) Members.
- JMA expects the HimawariRequest service to support disaster risk reduction activities in the region based on the monitoring of extreme events such as tropical cyclones and volcanic eruptions.
- Figure 26 shows the Target Area in the AHI observation sequence within a 10-minute time frame.
Figure 10: Target Area observation benefits (image credit: JMA)
Table 3: Himawari-8 data assimilated simulation enables 10-minute updates of rain and flood predictions 24)
• On 24 January 2017, the first images from all 16 bands were captured by JMA's Himawari-9 geostationary meteorological satellite, which was launched on 2 November 2016. Testing and checking of the Himawari-9 system, including related ground facilities, are going well. Himawari-9 is scheduled to start operation in March 2017. 25)
Figure 11: TCR (True Color Reproduction) image of Himawari-9 (image credit: JMA)
• December 14, 2016: Himawari-8 Water Vapor (6.2 µm) images revealed the presence of a subtle packet of upper-tropospheric gravity waves propagating southeastward near the International Date Line (180º longitude over the central Pacific Ocean), just to the west/southwest of Midway Atoll on 14 December 2016 — and there were a few pilot reports of moderate to severe turbulence (which were responsible for at least one injury) in the general vicinity of this gravity wave feature from 1530 to 1740 UTC, at altitudes of 35,000 to 38,000 feet. 26)
Figure 12: Himawari-8 Water Vapor (6.2 µm) images, with pilot reports of turbulence (image credit: CIMSS, University of Wisconsin-Madison)
• On November 11, 2016, the Himawari-9 satellite entered its geostationary orbit. 27)
• November 8, 2016: After in-orbit testing, Himawari-9 will stand by until 2022 as backup for the currently operational Himawari-8 geostationary satellite. HimawariCast users will not need to modify receiving system settings to continue data service usage even after the start of Himawari-9's operation. The combination of these two new-generation geostationary satellites will allow JMA to provide stable ongoing observation of the Asia and Pacific regions until 2029. 28)
• March 2016: According to JMA, the Himawari-8 spacecraft and its payload are operating nominally. 29)
• January 2016: The GSMaP (Global Satellite Mapping of Precipitation) product is a global rainfall map that is highly accurate, highly frequent, and high-spatial resolution through the development of rain rate retrieval algorithms based on reliable precipitation physical models by using a number of microwave radiometer (imagers, sounders, and imager/sounders) observation data, and comprehensive use of the Precipitation Radar (PR) on board the TRMM (Tropical Rainfall Measuring Mission) satellite. To produce a highly frequent global rainfall map, sampling errors caused by un-observed regions by LEO (Low Earth Orbit) satellites is a problem. The GSMaP project has developed a method to interpolate observations between each microwave imager by utilizing information from the Infrared imagers on board the five geostationary satellites, which are JMA's MTSAT/Himawari satellite, two NOAA's GOES satellites, and EUMETSAT's Meteosat satellites, and achieved production of an hourly global rainfall map in 0.1º latitude/longitude grid. 30)
- JAXA has provided the near-real-time GSMaP (GSMaP_NRT) product four hours after observation through the "JAXA Global Rainfall Watch" website (http://sharaku.eorc.jaxa.jp/GSMaP/) since 2008 as a prototype of the GPM (Global Precipitation Measurement) mission.
• January 2016: ABI (Advanced Baseline Imager) class instruments of Harris Corporation are supporting three missions (Ref. 42):
- GOES-R (ABI) of NOAA, USA; Himawari: AHI (Advanced Himawari Imager) of JMA, Japan; and GEO-KOMPSAT-2A: AMI (Advanced Meteorological Imager) of KMA, Korea.
Four flight models were delivered:
- ABI PFM: Integrated on GOES-R spacecraft
- AHI-8: Operating on orbit (Himawari-8)
- ABI FM2: Delivered
- AHI-9: Integrated on Himawari-9 spacecraft.
Three more in production at Harris
- ABI FM3, ABI FM4, AMI.
• Sept. 2, 2015: JAXA/EORC (Earth Observation Research Center) has released a new webpage, "JAXA Himawari Monitor" 31) , showing the color images and the quicklook images of the geophysical data from Himawari-8. 32)
- JAXA and JMA have exchanged the agreement on the distribution and the release of meteorological data. Under this agreement, EORC has released the data from Himawari-8 to research communities and has been creating the geophysical data that are consistent with JAXA's Earth observation satellites in order to release them widely to the general public. Other than releasing the images in the JAXA Himawari Monitor, EORC also stated to distribute via FTP the Himawari Standard Data and the geophysical data produced by JAXA.
- The Himawari Standard Data includes the visible to infrared radiances (Band 1 to 16) for three regions of Full Disk (global), Japan Area and Target Area. The observation data can be achieved every 10 minutes for Full Disk and every 2.5 minutes for Japan Area and Target Area. Using the observation bands that enable the world's first "color image" from geostationary satellite, one of the advanced aspects of Himawari-8, the JAXA Himawari Monitor shows the visible RGB composite images (Figure 13).
Figure 13: An example of a visible RGB image in the JAXA Himawari Monitor (image credit: JAXA/EORC)
- In addition, for the Himawari geophysical data, JAXA/EORC produces the properties of atmospheric particles (called aerosols), such as desert dusts and PM2.5 and the sea surface temperature. Both applied the algorithm developed for the JAXA's Earth observation satellites, including the GCOM-C ( Global Change Observation Mission – Climate) satellite, in order to produce, in the future, datasets that are consistent between the satellites and can compensate each other's observations.
Figure 14: An example of the atmospheric particle property (aerosol optical depth) in the JAXA Himawari Monitor (image credit: JAXA/EORC)
- There are two kinds of SST (Sea Surface Temperature) products: an ordinary product and a nighttime product. The ordinary SST product (Figure 15) is a dataset produced every 10 minutes, regardless of day or night, with the spatial resolution of 2 km. In order to reduce the missing area by clouds, hourly averaged products are also created. The nighttime SST product uses Band 7 (3.9 µm wavelength) and, although it can only be retrieved at nighttime, its advantage is in its high accuracy. The dataset of the nighttime SST is an hourly averaged product with a spatial resolution of 2 km.
Figure 15: An example of sea surface temperature in the JAXA Himawari Monitor (image credit: JAXA/EORC)
• July 7, 2015: The Himawari-8 geostationary meteorological satellite, managed by JMA (Japan Meteorological Agency), began its operational phase at 02:00 UTC on 7 July 2015, replacing the previous MTSAT-2 operational satellite (now in standby). 33)
- During the commissioning phase, Himawari-8's capacity for superior Earth monitoring with multi-band, high-resolution and high-frequency observation was verified. JMA firmly believes that Himawari-8 will open the door to a new generation of satellite meteorology, and that it will contribute to the prevention and mitigation of weather-related disasters in the East Asia and Western Pacific regions as past satellites have done.
• July 1, 2015: JMA started Himawari-8 imagery dissemination via the HimawariCast service at 02:00 UTC on 1 July 2015, prior to Himawari-8 officially enters operation on 7 July. 34)
• In early 2015, Himawari-8 is testing and checking all systems in orbit and is scheduled to start operation in mid-2015. 35)
• On December 18, 2014, the first images from all 16 bands of the AHI (Advanced Himawari Imager) were captured by JMA's Himawari-8 next-generation geostationary meteorological satellite. 36)
Figure 16: True color composite image of AHI captured on Dec. 18, 2014 showing a sunlit and cloud-covered Japan, Pacific Ocean and Australia (image credit: JMA)
• Himawari-8, entered the geostationary orbit on October 16, 2014 as planned. The satellite is expected to start operation in mid-2015 after the completion of in-orbit testing and checking of the overall system including related ground facilities. 37)
Figure 17: Chronology of JMA meteorological satellites as of Oct. 7, 2014 (image credit: JMA) 38)
Sensor complement: (AHI, SEDA, DCS)
The functions and specifications of the Himawari-8 and -9 sensor complement are notably improved from those of the on-board imager of MTSAT. The Himawari-8 and -9 spacecraft carry the AHI (Advanced Himawari Imager) instrument to enable enhanced nowcasting, NWP (Numerical Weather Prediction) and environment monitoring. 39) 40)
Figure 18: Enhancement of the observation function of Himawari-8/9 when compared to that of MTSAT-1R/2 (image credit: JMA)
AHI (Advanced Himawari Imager):
AHI is an ABI (Advanced Baseline Imager) class instrument, designed and developed at Exelis Inc. of Rochester, N.Y., and similar to the one that will be integrated onto the GOES-R spacecraft series of NASA/NOAA. - Note: In May 2015, Harris Corp. of Melbourne, FL. acquired Exelis Inc. of Fort Wayne, IN. 41) 42)
ABI and AHI both have 16 spectral channels in the visible and infrared spectrum, which is a significant increase in the number of spectral channels in comparison to heritage instruments. The two instruments have similar spectral bands with two main differences: ABI includes a 1.38 µm channel (for cirrus cloud detection), while this channel is replaced with a 0.51 µm channel (green band – to produce color composite imagery) on AHI (Ref.12) .
The AHI instrument provides the following general characteristics:
• Multi-purpose imagery for weather watch, NWP utilization and environment monitoring; and wind derivation by tracking clouds and water vapor features
• 16 channels operating in the VIS, NIR, SWIR, MWIR and TIR spectral bands, i.e. from ~ 0.43 to ~13.4 µm.
• AHI is replacing JAMI flown on Himawari-6 (MTSAT-1R) and IMAGER on Himawari-7 (MTSAT- 2)
• Scanning technique: Mechanical, 3-axis stabilized satellite, E-W continuous, S-N stepping
• Spatial resolution: From 0.5 km to 2 km, depending on spectral band
• Coverage/cycle: Full disk in 10 minutes, limited areas in proportionally shorter intervals.
Table 4: Characteristics of the AHI instrument
Figure 19: AHI optical architecture (image credit: Harris Corp.) 45)
Table 5: AHI Channels Optimized for JMA's Mission (Ref. 42)
• AHI & AMI added 1-km 0.51 µm channel (green)
- True 3-color visible images
- Improved ocean images
• Retained 1-km 0.865 µm channel
- Shifted to HgCdTe detector array
• Changed 1.61 µm channel to 2-km
• Eliminated one NIR channel
- AHI: 1.378 µm
- AMI: 2.25 µm
Figure 20: AHI's 2-mirror scanner is key to operational flexibility, delivering fast slews and accurate slow scans with minimal disturbance (image credit: Harris Corp.)
Table 6: Comparision of imaging capabilities between MI and AHI
Figure 21: SRF (Spectral Response Functions) of AHI in the VNIR bands (image credit: JMA)
Figure 22: SRF (Spectral Response Functions) of AHI in the IR bands (image credit: JMA)
Figure 23: Photo of the AHI instrument (image credit: ITT Exelis, JMA)
Figure 24: Photo of the cryocooler electronics (image credit: ITT Exelis, JMA)
Figure 25: Photo of the electronics unit (image credit: ITT Exelis, JMA)
Figure 26: A sequence of AHI observations in a 10 minute time frame (image credit: JMA)
AHI instrument calibration means:
• ICT (Internal Calibration Target) accurately calibrates emissive channels on-orbit
• SCA (Solar Calibration Assembly) delivers on-orbit calibration over mission life
• ECAL (Electronic Calibration) verifies linearity throughout mission
• Operational calibration is routinely performed:
- Spacelook collected at least every 30 s (automatically collected as part of every Full Disk swath)
- Blackbody (ICT) observed at start of each timeline
- Solar calibration scheduled when needed.
Onboard microvibration measures for AHI pointing error reduction:
One of the greatest obstacles to achieve high pointing accuracy is microvibration, which is induced by the dozens of the disturbance sources inside the satellite; examples include reaction wheels, mechanical gyros, and coolers. In order to satisfy the requirement, an evaluation of the influence of microvibration before launch is necessary. 46)
In order for the AHI to achieve high accuracy observations, the strict LOS (Line of Sight) pointing error is required. The LOS pointing error requirements for the AHI are shown in Table 7. The influence of the satellite bus system is considered in the requirements. Therefore, in order to satisfy the requirements for LOS pointing error, a high accuracy attitude control system, technology for reducing the influence of microvibration, and a low thermal expansion optical bench, etc. are adopted.
Table 7: LOS pointing error requirements for the AHI
In addition to the conventional attitude determination system for attitude control, the high accuracy and broadband attitude determination system of the optical bench is provided for correcting images for the ground system of the Himawari-8 and -9. The attitude determination system of the optical bench functions in combination with the data from the STT (Star Tracker), IRU (Inertial Reference Unit), ARS (Angular Rate Sensor), and ACC (Accelerometer) installed on the optical bench.
Some measures were taken to reduce the influence of microvibration induced with disturbance sources. Low disturbance RWAs (Reaction Wheel Assemblies) are adopted, and an IRU (mechanical gyro), which generates the least level of disturbance, was selected. However, the LOS pointing error of a mission sensor is not only induced by disturbances generated from the disturbance sources discussed previously, but is also affected by characteristics of the satellite structure. Therefore, in the early development phase of the Himawari-8, the disturbance analysis was conducted, using transfer functions calculated by finite element analysis, and the data of disturbance sources, and in the final development phase, the microvibration test was conducted using the protoflight model of the Himawari-8.
In summary, the motion of the optical bench, induced by disturbance sources installed in the Himawari-8, was evaluated with the data acquired in both the ground test and orbit. The results showed that the vibration level predicted from the ground test data, almost exactly coincided with the data measured in orbit. The health of the onboard sensors was confirmed by comparing the ground test data with the in-orbit data. It was confirmed that the dominant disturbance sources in the Himawari-8 were the IRU and the cooler in the AHI. However, the microvibration level of Himawari-8 was still very quiet, compared to the ESA and JAXA satellite models.
SEDA (Space Environment Data Acquisition Monitor)
SEDA will measure the radiation to which Himawari-8/-9 satellites are exposed in their geostationary Earth orbits. SEDA's design is basically identical to the EMU (Environmental Monitoring Unit) developed for the European satellite navigation system Galileo.
Table 8: Specification of the SEDA instrument
Figure 27: Illustration of the SEDA instrument (image credit: NICT)
DCS (Data Collection Subsystem)
The Himawari-8/-9 missions support the collection of surface-based observation data obtained by ground segments with corresponding on-board DCSs (Data Collection System) in the same manner as provided by the MTSAT series. DCP channels relay their data from the DCPs through a UHF transponder, which outputs the Ka-band signal.
The Himawari-8 and -9 ground segment, designed, built and installed by MELCO, consists of antennas of 9 m diameter and radio frequency and satellite control equipment installed at the main unit in Hiki-gun, Saitama Prefecture, and the sub unit in Ebetsu, Hokkaido. 47)
In August 2010, Himawari Operation Enterprise was established as Special Purpose Company to operate the Himawari series spacecraft. This consortium is composed of Mitsubishi UFJ Lease & Finance Company Limited (representative company, management of office), NS Solutions Corporation (development of ground facilities, systems and maintenance work), and Space Engineering Development Co., Ltd. (service delivery), and has contracted this project with JMA in 2010 for the duration of 20 years until the end of March 2030 ((4 year and 7 month development period, 15 year maintenance and service delivery period).
Figure 28: Main Unit (at Hiki-gun, Saitama, left); Sub Unit (at Ebetsu, Hokkaido, right)
Legend to Figure 29: Himawari-8/9 will not carry equipment for direct dissemination. Instead, all imagery derived from the satellites will be distributed to NMHSs (National Meteorological and Hydrological Services) via an Internet cloud service (see (a) in the Figure 29). Full sets of data will also be provided to researchers via archive servers operated by the Japanese Science Group on a best-effort basis (b). The HimawariCast service will additionally disseminate primary sets of imagery via a communication satellite using Digital Video Broadcasting — Satellite — Second Generation (DVB-S2) technology (c). Note: NREN (National Research and Education Network).
In addition, JMA will continue the current online imagery distribution service; WIS Portal (d) and the JDDS (JMA Data Dissemination System), (e) even after Himawari-8 takes over as the main operational satellite.
The HimawariCast service:
- MTSAT-2 imagery is currently provided directly via MTSAT-1R through the L-band frequency HRIT (High-Rate Information Transmission) and LRIT (Low-Rate Information Transmission) services. JMA will terminate these services in around November 2015. As a replacement of these services, JMA started the HimawariCast service which disseminates primary sets of imagery via a communication satellite from January 2015 onwards.
- The interval between full-disk observations by Himawari-8 will be 10 minutes, which is much shorter than the 30/60 minutes of the MTSAT series. The HimawariCast service will provide full-disk imagery with this high 10-minute observation frequency.
- JMA successfully launched Himawari-8 in October 2014 and will switch over operations from MTSAT-2 in mid-2015.
- The HimawariCast service is disseminating imagery of the current operational satellite, MTSAT-2, and Himawari-8 imagery will be disseminated after Himawari-8 becomes operational. JMA has a plan to disseminate Himawari-8 imagery on a trial basis while MTSAT-2 is in operation.
Figure 30: : Schedule for transition from the MTSAT HRIT/LRIT service to the HimawariCast service (image credit: JMA)
The JCSAT-2A communication satellite located at 154 ºE is used to broadcast data for the HimawariCast service. The JCSAT-2B unit will then take over from JCSAT-2A as the communication satellite in Q4 of 2015 at the same location. HimawariCast users will need to prepare for the transition from JCSAT-2A to JCSAT-2B during a dual operation period (approx. 1 week) of JCSAT-2A and JCSAT-2B.
The HimawariCloud service:
To distribute the enormous volumes of Himawari-8/9 imagery that will be produced, JMA will establish an Internet cloud service (HimawariCloud) mainly for NMHSs (National Meteorological and Hydrological Services) in the East Asia and Western Pacific regions.
Table 9 shows the tentative data set to be distributed via the cloud service. Himawari Standard Data will be used to create all products related to Himawari-8/9 as master data from all 16 bands with the finest spatial resolution. The true-color images will be provided in Portable Network Graphics (PNG) format. For rapid scanning observation, imagery in Network Common Data Form (NetCDF) will also be created and distributed.
Table 9: The tentative data set to be distributed via the HimawariCloud
Each NMHS will be able to access the cloud and get data using an HTTP 1.1 client such as a Web browser or Wget. It is important to note that an Internet connection with a speed of at least 25 Mbit/s will be required to download all Himawari Standard Data. These data will be separately created for each band and divided into 10 segments from north to south so that NMHSs can select only the files necessary for their operation.
Overview of the Himawari-8/9 ground segment and operations:
The Himawari-8/9 satellites and their ground stations will be operated by Himawari Operation Enterprise Corporation (HOPE) — a special-purpose company (SPC) established under JMA's Private Finance Initiative (PFI) project. Observation data from the AHI (Advanced Himawari Imager) and DCP (Data Collection Platform) data will be transmitted through HOPE to JMA, which will process the information and disseminate products to users (Figure 31).
Site diversity: Himawari-8/9 will use the Ka-band for AHI and DCP data downlink frequency, and will adopt the Ku-band for TT&C (Telemetry, Tracking and Command). To minimize the potential for negative data impacts from these bands, which both tend to be affected by rain attenuation, site diversity will be introduced by establishing two antenna sites (ASs). One will be in the Kanto region (the primary station) and the other will be in the Hokkaido region (the secondary station), meaning that their locations will be around 800 km apart and in different weather conditions. The two data centers (DCs) for processing data received will also be located in the Kanto and Hokkaido regions.
Operation by HOPE: HOPE will operate the ASs and DCs. The ASs will house transmitting/receiving equipment including antennas with a diameter of 9 m, and the DCs will have equipment for satellite control and AHI/DCP data processing. AHI and DCP data received at ASs will be transmitted to DCs, where the former will be processed to create level 1a data (raw data with calibration/navigation parameters attached) and the latter will be converted for use with JMA's telecommunications system. The processed data will be transmitted to JMA's Meteorological Satellite Center (Tokyo) and its Osaka Regional Headquarters (Osaka). In the event that the primary station becomes dysfunctional, the secondary station will take over its operations.
Operation by JMA: The MSC (Meteorological Satellite Center) will receive data from both the primary and secondary stations for preprocessing, and Himawari Standard Data, HRIT files and edited DCP data will then be produced and provided to users. The Osaka Regional Headquarters will receive data from the secondary station only. In the event that the MSC system becomes dysfunctional (e.g., due to a malfunction caused by a natural disaster), data/products will be provided from Osaka.
Figure 31: Illustration of the Himawari-8/9 ground segment (image credit: JMA)
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).