We plan to establish a central base for aircraft observations at this center that will lead the aircraft observations in Japan by taking advantages of the immediate or direct measurements. In particular, aircraft observations are highly promising for studies on the greenhouse gases, aerosols and its interaction with clouds, and typhoons observations.
Observation of typhoons by aircraft
As shown in the figure below, we use an aircraft to observe typhoons. Dropsondes released from the aircraft measure the temperature, humidity, pressure, and wind in the region around the center of a typhoon. The dropsonde data are incorporated into the numerical cloud-resolving model developed at Nagoya University, Japan. We are trying to accurately estimate and forecast the intensity of a typhoon and its track. Furthermore, we use a ground-based balloon with a microscope camera, X-band precipitation radar, Ka-band cloud radar, aerosol sonde, and a drone to observe the typhoon, associated clouds, and precipitation. Following the test flight in 2016, typhoons will be observed for the next 4 years, i.e., 2017–2020. The main target area of our observations is to the south of Okinawa, Japan, where typhoons often change direction.
Flight plan for dropsonde observations. Closed circles indicate the dropsonde launch positions.
We are developing the aerosol-cloud-precipitation-integrated weather model based on the results of experimental and observational studies. Using the world highest level cloud simulation chamber, we investigate the physico-chemical properties (including abilities as cloud condensation nuclei and ice nuclei) of aerosols and its effect on cloud microphysical structures. We also investigate the impacts of aerosol on clouds and precipitation through analyzing observation data collected by aircraft equipped with one of the world leading measuring devices capable for comprehensively observing aerosols, clouds and precipitation. We utilize this model aiming to conduct researches regarding aerosol impacts on clouds and precipitation that contribute to the improvement of weather forecast models and climate prediction models as well as a cutting edge rain enhancement research.
Aircraft equipped with a suit of measuring devices that can comprehensively observe aerosols, clouds and precipitation.
Sea sprays are sources of water vapor and aerosols in the atmosphere. They could influence development of convective clouds. As a result, the structure and intensity of a typhoon will be affected by the amount of sea spray particles. The size distribution and number density are necessary for modeling sea spray particles. We conducted drone observation of sea spray particles in August 2016 at Tarama Island, Okinawa. The cloud particle sonde was lifted by the drone to 2 m above sea level and sea spray particles observed. Although the observation was made under weak wind conditions, sea spray particles were successfully observed. We also investigate methods to obtain the information about the surface winds and waves using a drone. These observations contribute to obtaining data near coastal regions where satellite observation is difficult.
The drone used in the observation and the lifted sonde.
We are conducting research on remote sensing of the oceans and cloud-precipitation systems using Earth observation satellites. For remote sensing of ocean color, we gather data from the GCOM-C satellite, and to conduct assimilation study of sea surface temperature using Himawari-8 satellite. We have developed and released the third-generation dataset, J-OFURO3, of the global thermal, momentum, and freshwater flux between the atmosphere and the ocean. We have begun studying the ocean surface wind using NASA’s CYGNSS, which provides very frequent observations. For our cloud-precipitation research, we are validating precipitation retrieval algorithms using radars onboard TMM and GPM and investigating future precipitation observation satellites.
Roadmap of the spaceborne precipitation radar mission.
Observational and quantitative estimation of air-sea heat, momentum and freshwater fluxes (surface flux) is necessary to understand global environmental change accompanying global climate change and to understand the related atmospheric-ocean interaction phenomena. We have constructed and released the global surface flux dataset: J-OFURO3 throughout use of observational data by numerous satellites and the development of advanced estimation methods. We also conduct research on long-term variation of surface flux using the dataset and research on flux estimation during typhoon using new observation technology such as CYGNSS.
J-OFURO3 net surface heat flux [W/m²] averaged over 2002–2013. Positive value means upward heat flux.
JAXA-EORC has been operating a geostationary meteorological satellite “Himawari-8” (which observes sea surface temperature at a horizontal resolution of 2km and every 10 min.) from August 2015, and also successfully launched a global climate change observation mission satellite "Shikisai" (which observes ocean color at a horizontal resolution of 250m - 1 km and every 3 day), and thus the leadership and international contributions to high spatiotemporal oceanic observations are expected. To progress seamless environmental analysis from open ocean to offshore regions, this study constructs three-dimensional ocean reanalysis datasets in two regions: western Pacific region where is the origin of tropical cyclones and the southeast Asia where importance of the ocean environmental monitoring is increasing. JAMSTEC provides a three-dimensional ocean assimilation system with Local Ensemble Transform Kalman Filter (LETKF) with 20 ensemble members. To validate the satellite ocean color data, we set up a instrument measuring simultaneously and continuously spectral radiance from the sun and sea surface in the Ariake Sea, and contributes to “AERONET-OC" system, which enables to share observation data with global scientists.
(Left)Equipment to measure ocean color, (right) Phytoplankton distribution in Ariake Bay estimated from ocean color measured by satellite sensor MODIS on April 23, 2017. Red circle indicates the position of the equipment.
To lead space exploration missions in future demonstrative space sciences, we are investigating and developing common bus systems for the 100–200 kg class compact satellites. Through our collaboration with a manufacturer with technical expertise of developing scientific instruments for many previous Japanese space exploration missions, we have been working on the following areas together with science and engineering researchers in Institute of Space and Astronautical Science of Japan Aerospace Exploration Agency:
1. selecting components for a common bus used for telemetry communications,
power, and satellite attitude control; .
2. developing basic designs for the mechanical configuration of satellites;
3. developing conceptual designs for an onboard propulsion system for satellite attitude and orbit controls;
4. investigating launch configurations for the insertion of a model science mission into a targeted orbit;
5. estimating and taking countermeasures of radiation dose experienced by satellite common bus systems in space.
We are integrating investigations in different fields and developing new types of common bus systems for satellites for advanced science observations. This work will allow us to satisfy the requirements for installing antennas and an onboard mast as well as to realize re-orbiting procedures, like perigee increases and changes to the formation flight configuration, and precise attitude controls.
Conceptual configuration of a 100–200 kg class compact satellite with a common bus system for future space exploration missions with a model payload.
Microsatellite is expected to enable verification of instruments based on challenging technologies and to create new industrial applications of satellites, which will stimulate aerospace industry in Chubu (central Japan) region. The second satellite whose mission includes observations of solar neutrons is launched in February 17, 2016.
ChubuSat-2 attached to the rocket (Credit: JAXA)
One of common issues for orbital and suborbital observations is reducing power consumption of electronics. This center has been developing multi channel and low power integrated circuit with high functionalities. Our integrated circuits have been employed by Hitomi X-ray satellite, solar flare observation rocket and balloon experiments, FOXSI and GRIPS, and ERG geospace exploration satellite. Currently, we are developing low power and high speed integrated circuits for photon sensors.
Photos of semiconductor sensors with integrated circuits developed by this center. From left, sensors for Hard X-ray Imager and Soft Gamma-ray Detector onboard Hitomi satellite (Credit: ISAS/JAXA), hard X-ray imager of FOXSI (Credit: SSL/UC Berkeley) and High Energy Particle instrument for electrons onboard ERG satellite (Credit: ISAS/JAXA).