APPENDIX 7
OVERVIEW OF THE ADVANCED MICROWAVESCANNING RADIOMETER 3 (AMSR3)

1.

Introduction

JAXA has developed a series of the Advanced Microwave Scanning Radiometer (AMSR), which is a multifrequency, total-power microwave radiometer system with dual polarization channels for all frequency
bands from 6.9 to 89 GHz. Major objectives of the AMSR series are to produce global and comprehensive
water-related products, such as sea surface temperature, soil moisture, precipitation, sea ice, etc., for climate
and water cycle variation studies, and to apply them to operational utilizations, such as numerical weather
prediction and fisheries. AMSR series is unique due to its large size antenna (1.6 – 2.0 m) that enables
observation in high-spatial resolution and 6GHz channels for sea surface temperature and soil moistureobservations.
The first generation of AMSR series is AMSR on board the Advanced Earth Observing Satellite-II(ADEOS-II) mission, and AMSR for EOS (AMSR-E) on board the NASA’s Aqua satellite, which waslaunched in May 2002. AMSR has 7-frequency with 16-channel including 50-GHz, and AMSR-E has 6frequency with 14 channels. While mission period of AMSR was only 10-month due to trouble in satellitebass, AMSR-E continues its scientific observation more than 9 years. AMSR-E halted its scientificobservation in normal mode with 40 rpm (antenna rotation per minute) on October 4, 2011 but resumed its
observation in slow rotation mode with 2 rpm on December 4, 2012 to provide overlap observation with its
successor, AMSR2, for inter-calibration. AMSR-E has completed its mission on December 4, 2015 after
providing 3-year overlap observation data. We are planning to integrate the water-related parameters derived
from AMSR2 with those from AMSR-E to produce long-term continuous datasets for climate change
studies.
The second generation of AMSR series, AMSR2 on board the Global Change Observation Mission – Water(GCOM-W or “SHIZUKU”), was launched in May 2012 to succeed the AMSR-E observation by joining
the A-train orbit. AMSR2 has 6-frequency with 16-channel, which are almost equivalent channel set to
AMSR-E except additional 7.3 GHz channels to reduce impacts of Radio Frequency Interferences (RFIs)
to C-band. The GCOM-W satellite and AMSR2 have completed its designed mission life of 5-year in May
2017 and are currently in post-mission phase. Both satellite and instrument continue operation in the orbit.
(see APPENDIX 1)
To continue and improve current capability of water cycle/climate monitoring by AMSR2, JAXA is
currently developing the third generation of AMSR series, called AMSR3, to be installed on the Global
Observing SATellite for Greenhouse-gases and Water cycle (GOSAT-GW). The GOSAT-GW satellite will
carry two instruments, AMSR3 and the Total Anthropogenic and Natural emissions mapping SpectrOmeter3 (TANSO-3). TANSO-3, led by Japanese Ministry of the Environment (MOE) and National Institute ofEnvironment Studies (NIES), will improve observation capability of greenhouse gases from TANSO-2 onboard the Greenhouse gases Observing SATellite-2 (GOSAT-2). Target launch of the GOSAT-GW satellite
is Japanese Fiscal Tear (JFY) 2024.
This chapter presents an overview of the mission objectives, observing systems, and data products of
AMSR3.
2.

Mission Objectives

Major targets of the AMSR3 mission are to produce long-term continuous data record of AMSR series inorder to contribute scientific studies on global/regional water cycle and climate variations, and to enhance
operational utilization of near-real-time data for weather forecast including hurricane analysis, fishery incoastal area, and navigational assistance on arctic shipping route along with new geophysical parameterproducts, such as snowfall, multi-band sea surface temperature, high-resolution sea ice concentration, allweather sea surface wind speed, etc..
The mission objectives of AMSR3 are as follows.

- Understanding and prediction of water cycle variation
Ø Understanding water cycle variation related to climate change and utilizing prediction of
impacts to societal life and its response- Operational application and contribution to societyØ Weather: Operationally utilizing AMSR data forecast activities in meteorological agencies,and contributing to improvement of prediction accuracy of tropical cyclones and heavy
rainfalls
Ø Fishery: Providing sea surface temperature information, and contributing in search of fisheryfieldsØ Navigation support: Providing sea ice concentration and sea surface temperature information,and contributing to production of sea status and sea ice maps related to safety navigation ofships and selection of optimum shipping routes
3.

Observing Systems

3.1. GOSAT-GW satellite
Figure 1 presents an overview of the GOSAT-GW satellite; its major characteristics are listed in Table 1.
The GOSAT-GW satellite will carry AMSR3 and TANSO-3.
Orbit specification of the GOSAT-GW satellite was decided to satisfy requirements from both AMSR3 andTANSO-3 missions. Ascending orbit will be during daytime (same as GCOM-W), orbit altitude is same as
GOSAT, and local sun time is same as GCOM-W. Orbiting number of one recurrent day is 44 and smaller
compared to that of GCOM-W (233), so there are some differences in observation frequency. Unlike
AMSR2, AMSR3 cannot cover global area within 2-day and small missing areas are remained in tropics.
Observation frequency of AMSR3 is not homogeneous for every longitude due to fewer orbiting number
compared to AMSR2, and there are fixed areas less than 1 observation/day.

1

Figure 1: Overview of GOSAT-GW satellite

Instrument

Orbit
Mass

Table 1: Major characteristics of GOSAT-GW satellite
Advanced Microwave Scanning Radiometer 3 (AMSR3)
Total Anthropogenic and Natural emissions mapping SpectrOmeter-3(TANSO-3)
Sun-synchronous orbit
Altitude: 666 km (over the equator)
Reccurent cycle: 3-day
MLTAN: 13:30 +-15min
2.6 tonPower> 5.3kW

Launch

JFY2024 by H-IIA Rocket

Design Life

7 years
Direct transmission with X-band: 400 Mbps
Direct transmission with S-band: 1 Mbps (Only for AMSR3)
Development phase (Phase D) since Oct. 2023

Mission data downlink rate
Status

3.2. AMSR3 instrument
AMSR3 has 8-frequency with 21-channel. Sensor characteristics and channel sets, including center
frequency, bandwidth, polarization, instantaneous field of view (FOV) of AMSR3 are indicated inTable 2 and 3. The basic concept is almost eqlivalent to that of AMSR2; a conical scanning systemwith 2-m diameter offset parabolic antenna; feed horn cluster to realize multi-frequency observation;
external calibration with two temperature standards; and total-power radiometer systems. Due to lower
orbit altitude compared to the GCOM-W satellite, FOV of each channel is slightly smaller and swath
width of the sensor is slighthly narrower.
To achieve targets in section 2, AMSR3 will have almost equivalent channels from 6.9 to 89 GHz withadditional channels in 10.25 GHz H/V-polarization, 165.5 GHz V-polarization, 183.31+-3 GHz Vpolarization, and 183.31+-7 GHz V-polarization to improve sensor capability as shown in Table 3. New
10.25 GHz channels will have wider bandwidth compared to original X-band (10.65 GHz) channels toimprove NEDT to provide more robust SST retrievals in high spatial resolution. It will also contrinute to
reduce missing areas due to Radio Frequency Interferences (RFIs) in 10 GHz channels. Three channels ofhigh-frequency channels were selected to contribute snowfall retrievals and water vapor analysis innumerical weather prediction. There are some changes in specification of 36.0 GHz channels from that of
AMSR2 by considering future possible risk of RFIs might be caused by the 5th Generation Mobile
Communications System (5G).

Sensor type
Antenna
Swath width
Quantization
Incidence angle
X-polarization
Beam efficiency
Range
Sampling interval
Data rate
Designed Life

Table 2: AMSR3 Sensor Characteristics
Conical scanning total power microwave radiometer
Off-set parabolic antenna (φ2.0m aperture)> 1535 km (nominal)
12 bit55 deg. except 89-GHz-B, 166-GHz, 183-GHz< -20dB> 90%
2.7 - 340 K
10 km except 89GHz (5 km)
87.4 kbps (average)
7 years

* Bold indicates changes from AMSR2.

Table 3: AMSR3 Channel Set
Band width
NEDT (1σ)［MHz］

Centerfrequency
[GHz]
6.925
7.3
10.25
10.65
18.7
23.8
36.42
89.0 A/B
165.5

Polarization
H/V
H/V
H/V
H/V
H/V
H/V
H/V
H/V
V

350
350
500
100
200
400
840
3000
4000

< 0.34 K< 0.43 K< 0.33 K< 0.70 K< 0.70 K< 0.60 K< 0.70 K< 1.20 K< 1.50 K

183.31±7

V

2000×2< 1.50 K

183.31±3

V

2000×2< 1.50 K

Beam width(field of view)

1.8° (34 km x 58 km)
1.8° (34 km x 58 km)
1.2° (22 km x 38 km)
1.2° (22 km x 38 km)
0.65° (12 km x 21 km)
0.75° (14 km x 24 km)
0.35° (6 km x 11 km)
0.15° (3 km x 5 km)
Azimuth:0.23°/Elevation:0.30°(4 km×9 km)
Azimuth:0.23°/Elevation:0.27°(4 km×8 km)
Azimuth:0.23°/Elevation:0.27°(4 km×8 km)* Bold indicates changes from AMSR2.

4.

Products

List of AMSR3 standard products are shown in Table 4. A “standard” product is defined as a productwith proven accuracy that is to be operationally processed and distributed. In contrast, a “research”
product is a prototype for a standard product and is processed on a research basis. Both tables indicate
standard products with shading. Several products that are research product in AMSR2 are upgraded tostandard product in AMSR3. Tables 5-7 indicates a list of research products for AMSR3. Table 5 shows
products that can be obtained from AMSR3 onlt, while Tables 6 and 7 are multi-satellite products. In
AMSR3, we plan to produce Climate Data Record (CDR) from the AMSR series and other sensors toprovide long-term water cycle datasets (Table 7).
Table 4: Standard Geophysical Products of AMSR3
Product Name
(ID)

Brightness
Temperature(L1B)

Resampled
Brightness
Temperature
(L1R)

Total
Precipitable
Water (TPW)

StoredParameter

Area

SpatialResolution

Range

ReleaseAccuracyStandard
Accuracy

Brightness
Temperature(6-89GHz)

Global5-50 km

2.7-340 K±1.5 K±0.3 K

Highfrequency
Brightness
Temperature(166,183GHz)

Global10 km

2.7-340 K±1.5 K±1.0 K

Brightness
Temperature(6-89GHz)

Global5-50 km

2.7-340 K±1.5 K±0.3 K

Highfrequency
Brightness
Temperature(166,183GHz)

Global10 km

2.7-340 K±1.5 K±1.0 K

Total
Precipitable
Water overGlobal
Ocean

15 km

0-70 kg/m2

3.5 kg/m2

3.0 kg/m2

Note

TB differences between
Asc. and Dsc. orbits
after removing bias
based on AMSR2 or TB
estimate from numericalprediction model overocean & in clear sky
condition.
Requirements for highfrequency channels(center frequency, band
width etc.) is equal tothat of GMI.

RMSE to GPS and/or
sonde observation.

oceanTotal
Precipitable
Water overLand

Global
Land*

15 km

0-70 kg/m2

6.5 kg/m2

3.5 kg/m2

RMSE to GPS and/or
sonde observation.
* Sparse vegetation area

Table 4: Standard Geophysical Products of AMSR3 (cont.)
Product Name
(ID)

StoredParameter

Area

SpatialResolution

Range

ReleaseAccuracyStandard
Accuracy

Note

Integrated
Cloud Liquid
Water Content(CLW)

Integrated
Cloud Liquid
Water Content

Global
Ocean

15 km

0-1.0
kg/m2

0.10 kg/m2

0.05 kg/m2

RMSE to opticalimager observation.

Ocean:50 %Land:120 %Relative error to
GPM/DPR and/or
ground radar network
in 0.5-degree
equivalent grid.

Ocean:130%*
Land:200%*

Relative error to
GPM/DPR and/or
EarthCARE/CPR in
0.5-degree equivalent
grid.
* Evaluate withmonthly precipitation
more than
1mm/month.

LiquidPrecipitation

Global

15 km

0-20
mm/h

Ocean :50 %Land:120 %Precipitation
(PRC)
Solid
Precipitation

Global

6-GHz Sea
SurfaceTemperature
Sea Surface
Temperature(SST)

10-GHz Sea
SurfaceTemperature

10 km

0-4 mm/h

Ocean :130%*
Land:200%*

50 km
GlobalOcean

Multi-band Sea
SurfaceTemperature

30 km

0.5 ℃

-2 -35 ℃

0.8 ℃

30 km

0.6 ℃

RMSE to buoys
observation.

0.6 ℃

Sea Surface
Wind Speed(SSW)

Sea Surface
Wind Speed

GlobalOcean

All-weather
Sea Surface
Wind Speed(ASW)

All-weather
Sea Surface
Wind Speed

Global
Ocean

50 km

0-70 m/s

Sea Ice
Concentration(SIC)

Sea Ice
Concentration

Polar
Ocean

15 km

Highresolution Sea
Ice
Concentration(HSI)

Highresolution Sea
Ice
Concentration

Polar
Ocean

Soil Moisture
Content(SMC)

Soil Moisture
Content

Snow Depth(SND)

Snow Depth(Snow Water
Equivalent)

1.0 m/s

RMSE to buoys
observation.

7 m/s

5 m/s

RMSE to dropsonde
observation (winds
speed more than 15
m/s).

0-100 %

10 %

10 %

RMSE to opticalimager observation.

5 km

0-100 %

15 %

15 %

RMSE to opticalimager observation.

GlobalLand

50 km

0-40 %

10 %5%

MAE to ground-based
observation.

Globalland

30 km

0-100 cm

20 cm

20 cm

MAE to ground-based
observation.

15 km

0-30 m/s

1.5 m/sTable 5: Research Products of AMSR3 (AMSR3 only product)
Product Name (ID)
FOV-center Matched
Brightness Temperature
(L1C)

Area

GlobalSpatialResolution

5-50kmRange

2.7-340 K

ReleaseAccuracyNote±1.5 KTB differences between Asc. and Dsc.
orbits after removing bias based on
AMSR2 or TB estimate from numericalprediction model over ocean & in clear
sky condition.

High-resolution
Brightness Temperature(L1H)

Global20-30 km

2.7-340 K±1.5 K

6-89GHz only. TB differences between
Asc. and Dsc. orbits after removing bias
based on AMSR2 or TB estimate fromnumerical prediction model over ocean& in clear sky condition.

High-resolution Sea
Surface Temperature(HST)

GlobalOcean

20 km*-2 -35 ℃

0.8 ℃

RMSE to buoys observation.
*Input high-resolution brightness
temperature

Land Surface Temperature(LST)

GlobalLand

15 km

0 - 50 ℃

Forest: 3 ℃
Non-dense
vegetation: 4 ℃

RMSE to ground-based observation.

Vegetation Water Content(VWC)

GlobalLand

10 km

0 - 4 kg/m2

1.0 kg/m2

RMSE to optical imager and/or groundbased observations.

Thin Ice Detection (TSI)

Polar
Ocean

15 km

N/A

80 %

Right answer ratio to optical imager
and/or ground-based observations.

Sea Ice Motion Vector
(SIM)

Polar
Ocean

50 km

0 – 40 cm

6 cm/s

Output zonal/meridional components.

Table 6: Research Products of AMSR3 (merged product)
Product Name (ID)
Soil Moisture andVegetation Water
Contents based on
Land Surface Data
Assimilation (LDA)* to be extended in future

Area

SpatialResolution

GlobalLand
25 km(snow freearea)*

Range
Soil Moisture
Content:
0 – 40 %Vegetation
Water
Content: 0 -2
kg/m2

Release Accuracy

Note

Soil Moisture
Content: 8 %Vegetation Water
Content: 1 kg/m2

AMSR3 + Land model
product.
MAE to ground-based
and/or optical imager
observations.
Need improvements incomputer capability.

Table 7: Research Products of AMSR3 (Climate Data Record (CDR))
Product Name

Area

SpatialResolution

Range

Release Accuracy

PeriodBrightness Temperature CDR

Global5-50 km

2.7-340 K±1.5K

2002 - present

Total Precipitable Water CDR

Global Ocean

15 km

0-70 kg/m2

3.5 kg/m2

1987 - present

Integrated Cloud Liquid Water
Content CDR

Global Ocean

15 km

0-1.0 kg/m2

0.10 kg/m2

1987 - present

Sea Surface Temperature CDR

Global Ocean

50 km-2 -35 ℃

0.8 ℃

2002 - present

Sea Surface Wind Speed CDR

Global Ocean

15 km

0-30 m/s

1.5 m/s

1987 - present

All-weather Sea Surface Wind
Speed CDR

Global Ocean

50 km

0-70 m/s

7 m/s

2002 - present

Sea Ice Concentration CDR

Polar Ocean

15 km

0-100 %

10 %1978 - present

Snow Depth CDR

Global Land30 km

0-100 cm

20 cm

2002 - present

Soil Moisture Content CDR

Global Land50 km

0-40 %

10 %2002 - present

0-20 mm/h

Liquid Precipitation:
Ocean:50%/Land:120 %Solid Precipitation:
Ocean:80 %/Land:150 %1998 - present

Precipitation CDR(GSMaP Product)

Global10 km