Yuichi Ohno

The EarthCARE Satellite: The Next Step Forward in Global Measurements of Clouds, Aerosols, Precipitation, and Radiation

AbstractThe collective representation within global models of aerosol, cloud, precipitation, and their radiative properties remains unsatisfactory. They constitute the largest source of uncertainty in predictions of climatic change and hamper the ability of numerical weather prediction models to forecast high-impact weather events. The joint European Space Agency (ESA)–Japan Aerospace Exploration Agency (JAXA) Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) satellite mission, scheduled for launch in 2018, will help to resolve these weaknesses by providing global profiles of cloud, aerosol, precipitation, and associated radiative properties inferred from a combination of measurements made by its collocated active and passive sensors. EarthCARE will improve our understanding of cloud and aerosol processes by extending the invaluable dataset acquired by the A-Train satellites CloudSat, Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Aqua. Specifically, EarthCARE’s c...

Observation of the Kyucho in the Bungo Channel by HF Radar

Observations of sea surface currents by HF radar were carried out in the Bungo Channel in summer 1992. The current ellipses of M2 constituent obtained by the observational results agree quite well with those obtained by the ADCP observations, showing that the accuracy of the HF radar measurements is of the same level as ADCP. The results revealed the current structures and their change with the Kyucho in detail. The Kyucho is influenced by the complicated coastal geometry and does not propagate straightly into the Bungo Channel. It propagates further inward after charging the coastal bays with warm water. The current directions change largely, since the currents turn around the stagnant region in the bay filled with the warm water. The northward intrusion begins to be weakened in the southern part of the channel, while it still persists in the northern part. The northward current speeds of the observed Kyucho are about 50 cm/s and sometimes attain 60 to 70 cm/s.

Simulation of EarthCARE Spaceborne Doppler Radar Products Using Ground-Based and Airborne Data: Effects of Aliasing and Nonuniform Beam-Filling

This paper describes the expected performance of the Doppler cloud profiling radar being built for the Earth Cloud Aerosols Radiation Explorer (EarthCARE) mission of the Japanese Aerospace Exploration Agency and the European Space Agency. Spaceborne Doppler radar data are simulated starting from high-resolution Doppler measurements provided by ground-based and airborne Doppler radars, ranging from nonconvective to moderately convective scenarios. The method hinges upon spatial and spectral resampling to consider the specificities of the spaceborne configuration. An error analysis of the resulting Doppler product is conducted to address aliasing and nonuniform beam-filling (NUBF) problems. A perturbation analysis is applied to explore the latter problem and allow for a self-standing systematic correction of NUBF using merely the received reflectivity factor and mean Doppler velocities as measured by the instrument. The results of our simulations show that, at a horizontal integration of 1 km, after proper de-aliasing and NUBF correction, the radar will typically yield a velocity accuracy in the order of 1.3 m·s-1 over intertropical regions where the pulse-repetition frequency (PRF)=6.1 kHz, of 0.8 m·s-1 where the cloud-profiling radar (CPR) operates at PRF=7 kHz, and, of 0.7 m·s-1 over high latitudes where the CPR of EarthCARE will operate at PRF=7.5 kHz.

The external calibration study for EarthCARE/CPR

The Cloud Profiling Radar (CPR) is one of key sensors on EarthCARE for joint project between Europe and Japan. The CPR is developed by National Institute of Information and Communications Technology (NICT) in Japan and Japanese Aerospace Exploration Agency (JAXA). The CPR uses W-band frequency and large antenna diameter in order to obtain enough sensitivity. In other words, beam footprint becomes small but antenna scanning cannot be performed. Two external calibration methods are considered. The first method is external calibration using active radar calibrator (ARC). It is foreseen the difficulty to place exact location on sub-satellite track. The second method is external calibration using naturally distributed target, such as sea surface. We describe about test experiment for first method and statistical analysis using satellite data for second method as the feasibility study.

Design and development status of the EarthCARE Cloud Profiling Radar

The Cloud Profiling Radar (CPR) for the EarthCARE mission has been jointly developed by JAXA and NICT in Japan. The CPR is a millimeter-wave radar which has a large deployable antenna and its unique feature is vertical Doppler velocity measurement capability. The Engineering Model development and testing are now ongoing and the predicted performance will be verified after a series of tests. This paper will present the latest design and development status of the EarthCARE CPR.

Development status of cloud profiling radar for EarthCARE

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.

System Design of Cloud Profiling Radar for Earthcare

European and Japanese space agencies 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 a main sensor to observe clouds. This paper describes the outline of the system design of EarthCARE CPR.

Study for external calibration method for cloud profiling radar on EarthCARE

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.

Development of 2-micron airborne coherent Doppler lidar at NICT

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.

Cloud profiling radar (CPR) for EarthCARE and synergy algorithm studies

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.