The information on this page was published in the past, thus it may be different from the current status.
To check the date of issuance, please refer to the following URL for the list of interviews, or for the list of special articles.

Conquering Global Warming: Contributing to the GEO Global Carbon Project
Researching the Carbon Dioxide Cycle Masakatsu Nakajima Mission Manager, JAXA’s Greenhouse Gases Observing Satellite IBUKI

Better data through cooperation

Q. What kind of data is JAXA’s Greenhouse Gases Observing Satellite IBUKI providing for the GEO Carbon Project?

Global distribution of CO2 concentrations in June (top) and August (bottom) 2010 (Level 3 Image). Cool colors indicate low concentrations; warm colors indicate high concentrations. We can see that CO2 concentrations are low in August because the Northern hemisphere is in summer and plant photosynthesis is active.

Currently, IBUKI is providing data on carbon dioxide and methane gas concentration distribution. It will soon start providing data on the net flux- in other words, the difference between the absorption and emission of carbon dioxide. If the amount of absorption is less than the amount of emissions, the concentration of carbon dioxide in the atmosphere is going to go up.
The data is provided at levels 1A, 1B, 2, 3, 4A and 4B, depending on the processing conditions. JAXA is providing 1B-level data on the spectrum to organizations such as the National Institute for Environmental Studies (NIES), the NASA Jet Propulsion Laboratory (JPL), and the European Space Agency (ESA). Level 1B data measures the reflection of sunlight from the ground and thermal emissions from the ground and atmosphere at different wavelengths. Gaseous matter in the atmosphere absorbs light at specific wavelengths, so by measuring the wavelengths absorbed by gaseous matter, we can calculate the amount of carbon dioxide and methane in the atmosphere. But you cannot determine the concentration of carbon dioxide just by looking at level 1B data.
Therefore, NIES and JPL calculate the concentration at each point, based on level 1B data combined with weather data (level 2) and create images of global concentration distribution (level 3). NASA had been planning to launch the Orbiting Carbon Observatory (OCO) in 2009, and was scheduled to perform cross-calibration and validation between its data and IBUKI’s, but the OCO launch ended in failure. Currently, NASA is working with us to verify the processed results by calibrating the data from IBUKI.
Meanwhile, NIES is creating a distribution map of the net flux of carbon dioxide (level 4A), and three-dimensional distribution maps of carbon dioxide, by assimilating the data into numerical models. The level 4 data is calculated not just from the satellite data but also from a combination of data such as the concentration of carbon dioxide, temperature and barometric pressure measured on the ground. This ground observation data for 2009 has only just been released, so right now, NIES is working on creating the level 4 data. These images are scheduled for release in the spring of 2011.
NIES distributes the data on its website, so everyone can look at it. For GEO, we are going to provide open data that can be analyzed by anyone. GEO is trying to collect all the observation data from space, airplanes and the ground, in order to create a data archive. So in the future we would like to store all the data from IBUKI in the GEO archive.

Aiming at high accuracy through cross-calibration, validation and standardization

Q. How is IBUKI involved in data standardization for the GEO Carbon Project?

Greenhouse Gases Observing Satellite IBUKI
Greenhouse Gases Observing Satellite IBUKI

I think that standardization means providing data in a user-friendly unified format, but in the case of IBUKI this is still a work in progress. At the moment we are coordinating things with GEO-related space agencies and organizations.
When satellites such as IBUKI measure greenhouse gases from space, they can observe gas concentration in the entire three-dimensional area that the sensor’s light travels through. Observations from the ground, however, are often more localized. Sometimes gas concentrations are measured using sensors mounted on towers - for instance, 10 meters or 50 meters from the ground. But there are many kinds of observation tools, and other ground-based observation methods do allow us to measure the entire area that the observation waves go through, just like observation from space.
Because there are so many different observation methods, there are differences between observation data from satellites and from the ground. In order to make IBUKI’s observation data more reliable, our challenge in the data standardization process is to correct for those differences.
Additionally, we need to compare data with other satellites, as well as ground observations. Several satellites have greenhouse gas observation sensors similar to IBUKI’s: the European Space Agency’s Envisat and MetOp, etc. We are thinking of cooperating with the Centre National d’Études Spatiales (CNES), which developed the sensor for MetOp, to cross-validate our data. Furthermore, NASA is scheduled to launch the Orbiting Carbon Observatory OCO-2 in February 2013, so we are hoping for a successful launch this time, and cooperation with IBUKI on data standardization.

Q. What are difficulties of standardizing satellite data from all over the world?

The difficult part is that every satellite’s sensors are different: their methods and specifications vary. So in order to get accurate numbers, we have to find out what those differences are, and adjust for them. That’s difficult. We have to understand the characteristics of each sensor, so for instance before the OCO launch, we calibrated its sensors with ours. The American team brought their measuring device over to Japan and we compared the data on the brightness of each light source’s wavelength between IBUKI’s sensor and OCO’s. The Japanese team also went to the U.S. and did the same thing over there. In order to standardize the data, I think it is necessary to perform such common calibration in ground examinations prior to launch. I’d like to lead the IBUKI mission in this direction, so that we can perform this kind of joint examination with other satellites to be launched in the future.

Q. For this type of data standardization, does JAXA collaborate with other Japanese research organizations?

The greenhouse gas observation sensor aboard IBUKI consists of short-wavelength infrared, and thermal-infrared band sensors. We are cooperating with NIES to calculate the concentration of carbon dioxide from the short-wavelength infrared observation data. On calculation of carbon dioxide and methane concentration from the thermal-infrared observation data, we are cooperating with the Atmosphere and Ocean Research Institute (AORI) at the University of Tokyo. IBUKI has so far had three open calls for research topics, so there is also cooperation with scientists at other research institutions.
Additionally, to create the level 4 images I mentioned before, ground observation data is required. Besides our work with AORI, we’ve been performing observations from oceans in cooperation with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), so we would like to deepen our cooperation with such research organizations.

Research that benefits the world

Q. How do you want to expand the utility of the carbon data from IBUKI?

Greenhouse Gases Observing Satellite IBUKI
Greenhouse Gases Observing Satellite IBUKI

We would like to use the data from IBUKI not only from a scientific viewpoint with respect to measuring the increase and decrease of carbon dioxide, but also from the viewpoint of social contribution. In particular, we would like to contribute to the efforts of UN-REDD-Plus, under the United Nations Framework Convention on Climate Change (UNFCCC). The original UN-REDD program aimed to reduce carbon emissions that result from the disappearance and degradation of forests. The "Plus" reflects a new goal - to increase forest cover by planting new trees.
Forests absorb carbon dioxide in the atmosphere, but due to the gradual reduction of tree cover caused by illegal logging and global warming, and loss of forests from fires, the amount of carbon dioxide absorption has decreased. As a result, the concentration of carbon dioxide in the atmosphere has increased. So the goal of UN-REDD-Plus is to prevent forest degradation and decrease the concentration of carbon dioxide in the atmosphere through the planting of trees.
JAXA’s Advanced Land Observing Satellite DAICHI is already providing data on changes in forested area for UN-REDD-Plus. We would like to contribute to the program through IBUKI as well by providing data on changes in the concentration of carbon dioxide. Q. Can you tell us about your future ambitions? In the future, we would like to be able to measure the amount of each country’s carbon dioxide emissions. With this in mind, there are some aspects where we are not satisfied with the accuracy of IBUKI’s observation sensor. I think we need to launch successors to IBUKI in order to develop more accurate observation devices.
However, just providing satellite data is not enough. To obtain more-reliable data, we need to combine it with ground observation data while correcting for the discrepancies. To accomplish this goal, cooperation with organizations that have ground observation data is essential. We would like to increase data accuracy while cooperating with related organizations, so that we are not seen as just a data provider.
Additionally, global warming issues are common throughout the world. Observations from space are very effective, so we hope to start providing highly accurate data on carbon dioxide absorption/emissions to countries that don’t have their own observation capabilities.

Masakatsu Nakajima
Mission Manager, Satellite Applications and Promotion Center, JAXA Space Application Mission Directorate
Mr. Nakajima graduated from Nagoya University in 1985. He has been working in Earth-observation research since starting work on optical sensors in 1987. Mr. Nakajima worked on the development of the Global Imager (GLI) aboard the Advanced Earth Observing Satellite MIDORI-II.

Return to top