The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) is a Japanese-European collaborative earth observation satellite mission. The Cloud Profiling Radar (CPR) is one of the EarthCARE instruments and it is the world's first on-board millimeter-wave Doppler radar in space. The Japan Aerospace exploration agency (JAXA) is responsible for development of the CPR in this mission in cooperation with the National Institute of Information and Communications Technology (NICT). This paper mainly describes the development status and performance of EarthCARE CPR Proto Flight Model (PFM).
The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is joint mission between Europe and Japan for the launch year of 2018. Mission objective is to improve scientific understanding of cloud-aerosol-radiation interactions that is one of the biggest uncertain factors for numerical climate and weather predictions. The EarthCARE spacecraft equips four instruments such as an ultra violet lidar (ATLID), a cloud profiling radar (CPR), a broadband radiometer (BBR), and a multi-spectral imager (MSI) and perform complete synergy observation to observe aerosols, clouds and their interactions simultaneously from the orbit. Japan Aerospace Exploration Agency (JAXA) is responsible for development of the CPR in this EarthCARE mission and the CPR will be the first space-borne W-band Doppler radar. The CPR is defined with minimum radar sensitivity of -35dBz (6dB better than current space-borne cloud radar, i.e. CloudSat, NASA), radiometric accuracy of 2.7 dB, and Doppler velocity measurement accuracy of less than 1.3 m/s. These specifications require highly accurate pointing technique in orbit and high power source with large antenna dish. JAXA and National Institute of Information and Communications Technology (NICT) have been jointly developed this CPR to meet these strict requirements so far and then achieved the development such as new CFRP flex-core structure, long life extended interaction klystron, low loss quasi optical feed technique, and so on. Through these development successes, CPR development phase has been progressed to critical design phase. In addition, new ground calibration technique is also being progressed for launch of EarthCARE/CPR. The unique feature of EarthCARE CPR is vertical Doppler velocity measurement capability. Vertical Doppler velocity measurement is very attractive function from the science point of view, because vertical motions of cloud particles are related with cloud microphysics and dynamics. However, from engineering point of view, Doppler measurement from satellite is quite challenging Technology. In order to maintain and ensure the CPR performance, several types of calibration data will be obtained by CPR. Overall performance of CPR is checked by Active Radar Calibrator (ARC) equipped on the ground (CPR in External Calibration mode). ARC is used to check the CPR transmitter performance (ARC in receiver mode) and receiver performance (ARC in transmitter mode) as well as overall performance (ARC in transponder mode with delay to avoid the contamination with ground echo). In Japan, the instrument industrial Critical Design Review of the CPR was completed in 2013 and it was also complemented by an Interface and Mission aspects CPR CDR, involving ESA and the EarthCARE Prime, that was completed successfully in 2015. The CPR Proto-Flight Model is currently being tested with almost completion of Proto-Flight Model integration. After handed-over to ESA planned for the beginning of 2017, the CPR will be installed onto the EarthCARE satellite with the other instruments. After that the CPR will be tested, transported to Guiana Space Center in Kourou, French Guiana and launched by a Soyuz launcher in 2018. This presentation will show the summary of the latest CPR design and CPR PFM testing status.
Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) is a Japanese-European collaborative earth observation satellite mission aimed to deepen understanding of the interaction process between clouds and aerosols and their effects on the Earth’s radiation. The outcome of this mission is expected to improve the accuracy of global climate change prediction. As one of instruments for EarthCARE, the Cloud Profiling Radar (CPR) is the world’s first space-borne Doppler cloud radar jointly developed by the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). In Japan, the critical design review of the CPR has been completed in 2013, and CPR proto-flight model was manufactured and integrated until summer in 2015. Finally, the proto-flight test have been just started. This paper describes the design results and current status of CPR proto-flight test.
ESA and JAXA plan to launch a satellite called
EarthCARE (Earth Clouds, Aerosols and Radiation
Explorer). The Cloud Profiling Radar (CPR), which will
be the first millimeter-wave Doppler radar in space, is
installed on this satellite as one of main sensors to observe
clouds. This paper describes the design results and PFM
performance of EarthCARE CPR.
The Earth, Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is joint mission between Europe and Japan
for the launch year of 2015. Mission objective is to improve scientific understanding of cloud-aerosol-radiation
interactions that is one of the biggest uncertain factors for numerical climate and weather predictions. The EarthCARE
spacecraft equips four instruments such as an ultra violet lidar (ATLID), a cloud profiling radar (CPR), a broadband
radiometer (BBR), and a multi-spectral imager (MSI) to observe aerosols, clouds and their interactions simultaneously
from the orbit. Japan aerospace exploration agency (JAXA) is responsible for development of the CPR that will be the
first space-borne W-band Doppler radar. The CPR is defined with minimum radar sensitivity of -35dBz, radiometric
accuracy of 2.7 dB, and Doppler velocity measurement accuracy of 1m/s. These specifications require highly accurate
pointing technique in orbit and high power source with large antenna dish. JAXA and National Institute of Information and Communications Technology (NICT) have been jointly developed this CPR to meet these requirements. In addition, new ground calibration technique is also being progressed for the launch of EarthCARE/CPR. This evaluation method will also be the first use for spacecraft as well as Doppler cloud radar. This paper shows the summary of the CPR design and verification status, and activity status of development of ground calibration method with a few results of experiment using current space-borne cloud radar (CloudSat, NASA).
The Cloud Profiling Radar (CPR) on EarthCARE satellite is the first spaceborne cloud profiling Doppler radar using Wband
frequency in order to measure vertical velocity of clouds and rain. The EarthCARE/CPR has -35dBZ in sensitivity
after 10km integration and less than 1 m/s in Doppler velocity measurement error. Because satellite velocity and beam
width spread Doppler spectrum and coherency is low, the measurement error of Doppler velocity is increased.
EarthCARE/CPR is the first Doppler radar, so we need to make simulation data for the algorithm development, but the
simulation itself is difficult in order to take into account these effects. The current method is calculated 2-dimentional
integration within illuminated area by antenna beam and hit by hit for all pulses, then it takes many computation times.
We developed the new simple calculation method, which is calculated using integrated antenna pattern, then the
computation time is decreased significantly. This paper is reported the comparison for, both methods.
The EarthCARE mission has been jointly proposed by European and Japanese scientists with the mission objective of
improving the understanding of cloud-aerosol-radiation interactions so as to include them correctly and reliably in
climate and numerical weather prediction models. This EarthCARE mission has been defined as an international
cooperative spacecraft mission between European Space Agency (ESA) and Japan Aerospace Exploration Agency
(JAXA) for the planned launch year of 2013th. The EarthCARE spacecraft equips four instruments, such as a cloud
profiling radar (CPR), an atmospheric backscatter lidar (ATLID), a multi-spectral imager (MSI) and a broadband
radiometer (BBR) to perform very accurate synergy observation to observe cloud and aerosol vertical profiles and
simultaneous radiative flux at the top of atmosphere. In this cooperation, JAXA is responsible for development of the
CPR which will be the first space-borne W-band radar with Doppler measurement capability. JAXA has developed this
Doppler radar for several years with Japanese National Institute of Information and Communications Technology
(NICT). The last year, preliminary design was finished and then fabrication and testing have been started. This
presentation shows the summary of the CPR preliminary design and reports the test status of the CPR engineering model
Global three-dimensional cloud distributions and their properties are important information to estimate the earth
radiation budget more precisely. The interactions between cloud particles and aerosols are also focused to improve
accuracies of climate model. In order to meet expectations of scientists developing climate models for global warming
problem, European and Japanese space agencies plan to launch a satellite called EarthCARE. The Cloud Profiling Radar
(CPR), which will be the first millimeter-wave Doppler radar in space, is installed on this satellite as one of main sensors
to observe clouds. This paper describes the latest design and development status of EarthCARE CPR.
EarthCARE mission has objectives to reveal aerosol and cloud interaction and to reveal relationships with radiation
budget. For this purpose, the EarthCARE satellite has four instruments, which are Atmospheric LIDAR (ATLID), Multi
Spectral Imager (MSI) and Broad Band Radiometer (BBR) in addition to Cloud Profiling Radar (CPR). CPR is
developed under cooperation of Japanese Aerospace Exploration Agency (JAXA) and National Institute of Information
and Communications Technology (NICT) in Japan.
The requirement of sensitivity is -35dBZ, therefore CPR uses W-band frequency and needs a large (2.5m) antenna
reflector. The large antenna has small footprint and is to give up antenna scanning. From this, some difficulty of external
calibration using active radar calibrator (ARC) is recognized.
One solution of external calibration is using scattering from natural distributed target, such as sea surface. Then the
measurement of sea surface scattering using airborne cloud radar was performed. The sea surface scattering property is
being prepared. Second solution is that ARC puts on exact location of sub-satellite track. Precise sub-satellite track
prediction is necessary. We focus second solution in this paper. The test experiment was demonstrated using CloudSat of
NASA/JPL, which is provided CPR using W-band frequency. The feasibility of this calibration method is discussed.
We have studied a 2-micron airborne coherent Doppler lidar to observe wind profile downward from flying object. We
investigated the algorithms required to extract the Doppler-shifted frequency compensating for a speed of the flying
object. The airborne experiments were conducted to demonstrate the feasibility of the airborne coherent Doppler lidar
from a flying object in 2002, 2004 and 2006. We extracted the Doppler-shifted frequency corresponding to aircraft
speed with developed algorithms and obtained wind profiles through airborne experiment. To examine wind profiles
measured by the airborne coherent Doppler lidar, we compared those profiles with profiles measured by a
GPS-dropsonde and a windprofiler. Although the volume measured by the airborne coherent Doppler lidar system
differed spatially and temporally from those by other instruments, the wind profiles observed by the airborne coherent
Doppler lidar agreed well with those observed by other instruments.
EarthCARE Phase-A study was successfully conducted in collaboration between ESA and Japan (JAXA and NICT). In this study, high sensitivity Cloud Profiling Radar (CPR) design with Doppler capability was studied and demonstrated that the CPR satisfies mission requirements, system resource and launcher constraint. As a result of the study, a nadir looking CPR at 94 GHz with a 2.5 m diameter antenna reflector is designed with sensitivity exceeding -36 dBZ of requirement at TOA with 10 km horizontal integration. The Doppler measurement is a new challenge to attain velocity accuracy less than 1 m/s in vertical direction. In parallel to the CPR system design, algorithm development efforts have been conducted through field campaign. A suite of measured quantities that are very similar combination to the EarthCARE data was collected and applied to the retrieval algorithm test.
Vertical profile of liquid water cloud microphysics is retrieved by a newly proposed algorithm using radar and microwave radiometer. The data used in this algorithm is obtained form a 95-GHz cloud profiling radar (CPR) and a dual-wavelength microwave radiometer. This technique is applicable to liquid water clouds and its products are vertical profiles of attenuation-corrected radar reflectivity factor, liquid water content (LWC), and cloud dropsize distribution. The basic idea of this algorithm is to solve the radar equation with a constraint of integrated liquid water content (LWP: liquid water path) obtained from microwave radiometer. The main features of this algorithm are that it yields an attenuation-corrected radar reflectivity factor and the analytical solution is stable for the attenuation expected in typical stratocumulus clouds. Examples of its application to cloud data observed with a 95 GHz CPR and a microwave radiometer at Kashima, Japan on 4 February 2000 are described. The larger cloud drop size than the typical value retrieved and descending motion seen in the clouds examined is explained by the existence of drizzle particles in the lower part of cloud layer.
In this paper, we report the preliminary studies of cloud microphysics by using ground-based 95GHz cloud radar and lidar systems. Although the active sensors are expected to increase our knowledge about clouds, e.g., vertical profiles of clouds, the single use of radar or lidar gives limited information and it is difficult to retrieve the ice water content (IWC and effective radius of cloud particles. We develop the new method for the combinational use of radar and lidar signals. The algorithm includes the attenuation corrections on both signals which is a long standing problems especially in the analysis of lidar signals. The system enables to retrieve the vertical profiles of effective radius and IWC in each cloud layer. Since both active sensors have dual polarization capabilities, the system provides a unique opportunity to study cloud microphysics form many aspects, e.g., vertical profiles of the relationship between effective radius, IWC and/or depolarization ratio. This system also has a great potential to study aerosol-cloud interaction studies.