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 developed a low-power and high-sensitivity cloud profiling radar transmitting frequency modulated continuous wave (FM-CW) at 95 GHz for ground-based observations. Millimeter wave at 95 GHz is used to realize much higher sensitivity than lower frequencies to small cloud particles. An FM-CW type radar realizes similar sensitivity with much smaller output power to a pulse type radar. Two 1m-diameter parabolic antennas separated by 1.4m each other are used for transmitting and receiving the wave. The direction of the antennas is fixed at the zenith. The radar is designed to observe clouds between 0.3 and 20 km in height with a resolution of 15 m.
Using the developed millimeter-wave FM-CW radar at 95 GHz, we observed clouds in a campaign observation in Amami Island in March 2003, and on a sail on Mirai, a Japanese scientific research vessel, in September 2004 to January 2005 in the Arctic Ocean and the southwest of the Pacific Ocean. The radar provided good and sensitive data in these long-term observations.
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.
The EarthCARE (Earth Clouds, Aerosols and Radiation Explorer) mission has been recently selected as the 6th ESA's Earth Explorer Mission. The mission objective is to determine, in a radiatively consistent manner, the global distribution of vertical profiles of cloud and aerosol field characteristics. A major innovation of the EarthCARE mission is to include both active and passive instruments on a single platform, which allows for a complete 3-D spatial and temporal picture of the radiative flux field at the top of the atmosphere and the Earth's surface to be developed. While the active instruments provide vertical cloud profiles, the passive instruments (mainly the multi-spectral imager) provide supplementary horizontal data to allow for the extrapolation of the 3-D cloud and aerosol characteristics.
The EarthCARE payload is composed of four instruments: an Atmospheric backscatter Lidar, a Cloud Profiling Radar, a Multi-Spectral Imager and a Broad Band Radiometer. The mission baseline is a sun-synchronous orbit with an altitude around 450 km. The EarthCARE mission is a cooperative mission with Japan (JAXA and NiCT), which will provide the Cloud Profiling Radar. ESA will provide the ground segment and the rest of the space segment including the lidar, the imager and the broadband radiometer. The launch is planned for 2012.
We developed a cloud profiling radar transmitting frequency-modulated continuous wave (FM-CW) at 95 GHz for ground-based observations. Millimeter wave at 95 GHz is used to realize high sensitivity to small cloud particles. An FM-CW type radar would realize similar sensitivity with much smaller output to a pulse type radar. Two 1m-diameter parabolic antennas separated by 1.4m each other are used for transmitting and receiving the wave. The direction of the antennas is fixed at the zenith. The radar is designed to observe clouds between 0.3 and 15 km in height with a resolution of 15 m. Using the facility, test observations and long term campaign observations have been done. Results of observations show that the system is sensitive and stable enough to observe various clouds.
Design study and algorithm development efforts are overviewed with cloud profiling radar (CPR) for EarthCARE mission. EarthCARE is a candidate for the ESA Earth Explore Core Missions and presently Phase A study is ongoing. EarthCARE is jointly proposed by European and Japanese scientists, and CPR is being studied by CRL and NASDA, Japan. The EarthCARE CPR is characterized by very high sensitivity 94 GHz radar with nadir pointing and Doppler measurement capability. CPR is designed to maximize synergy performance in combination with other onboard active and passive sensors. In this report, after summarizing CPR objectives and expected performance in responding to requirements, study topics concerning Doppler capability and variable PRF techniques are discussed. The EarthCARE synergy algorithm development efforts through airborne campaign experiment are also introduced.
A cloud profiling radar transmitting frequency-modulated continuous wave (FM-CW) at 95 GHz is developed for ground-based observations. Millimeter wave at 95 GHz is used to realize high sensitivity to small cloud particles. Two 1m-diameter parabolic antennas separated by 1.4m each other are used for transmitting and receiving the wave. The direction of the antennas is fixed at the zenith. The radar is designed to observe clouds between 0.3 and 15 km in height with a resolution of 15 m. The system was integrated and sensitivities and stabilities have been measured. Results of test measurements of clouds show that the system is sensitive and stable enough to observe various clouds.
Concept and expected performance of cloud profiling radar (CPR) for EarthCARE are described based on preliminary design study conducted to date. High sensitivity and Doppler capability are two significant new features in this CPR. Particularly, Doppler capability is the first attempt to spaceborne atmospheric radar, which requires great efforts in technical development and feasibility validation. We have developed a new numerical simulation method to assess Doppler velocity accuracy applicable to this application, and results are compared with conventional approximation method. Validity and limitation of the approximation method are indicated from comparison with numerical method. It is shown that requirements to radar sensitivity and Doppler measurements will be satisfied. However, because these requirements to CPR are very tough, further detailed study on both design optimization and assessment technique development are necessary. Under radar operation with very high pulse repetition frequency (PRF) required in this CPR, surface clutter interference caused through antenna sidelobes is an important issue. Analysis on this issue and preliminary requirements to the antenna sidelobes are also discussed.
IPCC third report says that we have still a lot of uncertainties to predict global warming even using latest GCMs. Regarding atmospheric radiation, uncertainty of the radiative forcing is still large, which is mainly caused by aerosols, clouds, and water vapor interacting among them. National Space Development Agency of JAPAN (NASDA) and Communications Research Laboratory (CRL) started Phase-A study with European Space Agency (ESA) in the EarthCARE project. The objectives of EarthCARE project are to observe vertical and horizontal distributions and physical characteristics of aerosols and clouds from a satellite, and also to measure the precise Earth radiation budget simultaneously. Finally we will be able to evaluate physical processes of clouds and aerosols regarding the radiative budget and forcing. The EarthCARE satellite carries 5 sensors, namely Cloud Profiling RADAR (CPR), Atmospheric LIDAR (ATLID), Multi-Spectral Imager (MSI), Broad Band Radiometer (BBR) and Fourier Transform Spectrometer (FTS). The result of the pre-Phase A study shows the synergy observation benefits using some compensative combinations of sensors, such as CPR/ATLID for clouds, ATLID/MSI for aerosols, BBR/FTS for the radiation budget. NASDA and CRL are studying FTS and CPR, respectively. CPR is a 94GHz RADAR using 2.5m diameter reflector with Doppler measurement mode. The sensitivity is -38dBZ. The vertical and horizontal resolution is 100 m, 1 km, respectively. FTS is a Michelson interferometer of which spectral measurement range is from 5.7 μm to 25 μm with 0.5 cm-1 unapodized spectral resolution. FOV is 10 km by 10 km. EarthCARE is planned to be launched in 2008 for 2 years mission. Phase-A study will continue until the end of 2003.
EarthCARE is one of the candidates for the future ESA Earth Explorer Core Missions. The mission major objective is to determine, in a radiatively consistent manner, the global distribution of vertical profiles of cloud and aerosol field characteristics. A major innovation of the EarthCARE mission is to include both active and passive instruments together on a single platform, which allows a complete 3-D spatial and temporal picture to be developed of the radiative flux field at the top of the atmosphere and the Earth's surface. While the active instruments provide vertical cloud profiles, the passive instruments (mainly the multi-spectral imager) provide supplementary horizontal data to allow extrapolation of the 3-D cloud and aerosol characteristics. The EarthCARE payload is composed of five instruments: an Atmospheric Lidar, a Cloud Profiling Radar, a Fourier Transform Spectrometer, a Multi-Spectral Imager and a Broad Band Radiometer. The mission baseline is a sun synchronous orbit with 10.30 descending node crossing time and an altitude around 400 km. EarthCARE is an ESA mission proposed in collaboration with NASDA.
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.
An eight-element of bread board model for TRMM (Tropical Rainfall Measuring Mission) precipitation radar has been developed in Communications Research Laboratory (CRL), Japan. The active array system, which consists of all solid components, such as SSPA, LNA, and PIN-diode phase shifter, is integrated to check the basic performance as the spaceborn rain radar. After describing the characteristics of major components, overall performance of antenna scanning is described.