APPENDIX 6
OVERVIEW OF
THE MULTI-SENSOR OBSERVATION LIDAR AND
IMAGER(MOLI) MISSION

7-1

1. Introduction
Forest biomass is the dry weight of trees, and half of which is carbon weight, therefore it is frequently used as aunit to evaluate carbon stocks in forests. In addition, canopy height is one of the quantitative parameters of forest
which can be measured relatively easily, and it is correlated with forest biomass. Meanwhile, in recent years, thenecessity to measure forest carbon stocks has increased in relation to the climate change. In this context, demandfor canopy height and forest biomass measurement technology is increasing significantly.
Also, the use of 3D maps has been increasing in various social fields recently. So far, JAXA has developed aglobal high-precision 3D map based on satellite images acquired by the ALOS PRISM. There is a demand for theuse of 3D maps in forested areas. However, because ground surfaces are covered with forests, ground cannot beidentified from images, and the Digital Terrain Model (DTM), which represents the height of a ground, does notsatisfy the need for elevation accuracy in infrastructure construction, flood countermeasures, etc.
Among many satellite sensors, the Light Detection and Ranging (LiDAR) is the most accurate one capable ofmeasuring those forest parameters and the height of ground. As shown in Figure 1, spaceborne LiDAR irradiates
the ground surface with laser beam, and observes the waveform of reflected beam. Analyzing such waveform makes
us possible to estimate the canopy height and the above-ground biomass (AGB) of forests. NASA's ICESat/GLAS,
operated from 2003 to 2009, was the only spaceborne LiDAR to observe the Earth's surface so far. NASA will start
to operate two spaceborne LiDAR missions i.e. ICESat-2/ATLAS and GEDI. In addition to these missions, theMulti-footprint Observation Lidar and Imager (MOLI) is expected to contribute to the semi-global forest
observation.

- ./Bin丒係
01 2500400300㍶係)㐂
200100㍶係㙊僀
0050

100150

3 ㏬倹㋭&'
2㏬倹㋭&'
452 678 9 62

Figure 1 Schematic chart of spaceborne LiDAR observation.

2. Mission Objectives of MOLIThe objectives of MOLI are to provide accurate observation data of forest biomass over a wide area to reduce theuncertainty of the forest carbon budget in the carbon cycle process, to contribute as a monitoring tool for REDD+,
one of the climate change countermeasures, and to improve the accuracy of 3D maps. Regarding the first objective,
forests and other terrestrial ecosystems have the greatest uncertainty in the carbon cycle process, and accurate
information on the distribution of forest biomass (i.e., carbon stocks) will contribute greatly to our understandingof this process. As for the second objective, the REDD+ scheme requires developing countries to have the capacity
to accurately determine the carbon balance of their forests, and MOLI is expected to contribute to this. As for thelast objective, highly accurate 3D maps are required for ground surfaces covered by forests, and MOLI is expected
to create highly accurate DTMs using LiDAR data.
Furthermore, on the technical side, in the process of developing and operating MOLI, we will acquire spaceborne
lidar technology, which will contribute to the realization of future spaceborne LiDAR missions.

7-2

3. Observation SystemMOLI will be installed on the Exposed Facility of the Japanese Experiment Module "Kibo" on the International
Space Station (ISS.) As the name suggests, MOLI is equipped with two sensors, LiDAR and imager. Table 1 shows
the main specifications of each sensor: LiDAR fires a laser 150 times per second nadir direction to observe a line
just below the ISS at an interval of 50 meters. The imager will observe an area over 1 km swath centered on theLiDAR observation line at the same time. Using these images, we will be able to monitor changes in the growth
conditions and seasonal variations of the forests around the LiDAR observation points.
Table 1 Major characteristics of MOLI instruments.
Sensor
LiDAR

ImagerParameter
Laser wavelength
Laser power
Laser pulse frequency
Laser pulse width
A/D sampling rate
Measurement range
Footprint diameter
Swath
Ground resolution
BandSpecification
1,064 nmabout 40 mJ
150 Hz< 7 nsec
500 Msps (height resolution = 30 cm)-50 m 〜 +300 m above ground level (TBD)
25 mΦ
> 1,000 m
5m
Green, Red, Near Infrared, Pan (TBD)
Along track50m50m

Beam 150m
Beam 2

Footprint25mφFigure 2 Distribution of LiDAR footprints of MOLI.

4. Products
MOLI has standard products of Level-1B and 2, and research products of Level-3 and 4 (Table 2). The L1B
LiDAR product contains observed waveform with basic information i.e. geographical coordinates of footprint. The
L2 product contains estimated values of the canopy height and AGB obtained as a result of waveform analysis foreach footprint. L2 product also contains the height of ground for each footprint. Levels 3 and 4 products are thecanopy height and AGB map created from combining LiDAR data with satellite image data. Regarding the image
data, L3 uses images acquired by the MOLI imager, and L4 uses images acquired by other satellites i.e. ALOS4/PALSAR-3 or GCOM-C/SGLI. Levels 3 and 4 products use L2 canopy height data and L2 AGB data as training
data and validation data.

Table 2 MOLI products (under designed).
Level
1B

Data source
LiDARImager

ProductWaveform data
Ortho-rectified image

Specification
Swath: > 1,000 m,7-3

2LiDAR

Canopy height
Above-ground biomass (AGB)
Height of ground

3LiDAR, Imager

Along-track canopy height mapAlong-track AGB map
LiDAR, other
Large-scale canopy height4
satellite imagemap
Large-scale AGB map
Note: target area is under 30° of ground slope.

7-4

Alignment accuracy: < 2 pixels
Accuracy: < 3 m (@ canopy height < 15 m) /< 25% (@ canopy height > 15 m)
Accuracy: < 20 Mg ha-1 (@ AGB < 100 Mgha-1) / < 25% (@ AGB > 100 Mg ha-1)
Accuracy: < 3 m (@ slope angle < 30deg) / <5m (@slope angle > 30deg)
Swath: > 1,000 m,
Ground resolution: < 100 m
Ground resolution: < 250 m