Extreme weather such as storms, hurricanes and typhoons, also called ‘high impact weather’, is a high priority area of research for the atmospheric dynamics and meteorological science communities. 94 GHz Doppler wind radar satellite mission concepts have been elaborated, which use cloud and precipitation droplets/particles as tracers to measure 3-D wind fields. The so-called polarisation-diversity pulse-pair (PDPP) technique enables to derive line-of-sight wind speed with good accuracy (< 2-3 m/s) and large unambiguous dynamic range (e.g. 75 m/s). Two distinct system concepts have been elaborated: (1) a conically scanning radar concept with large coverage (> 800 km) and ∼50 km along-track sampling, and; (2) a stereo viewing concept with high sampling resolution (< 4 km) within an inclined cut through the atmosphere. The former concept is adequate for studying large-scale severe/extreme weather systems, whereas the latter would be more suitable for understanding of small-scale convective phenomena. For demonstrating the potential of the FDPP technique for deriving accurate Doppler observations, ground-based and airborne Doppler radar campaigns are in preparation. The Galileo 94 GHz radar, upgraded recently to include a FDPP capability, at Chilbolton in the UK, will be used for an extended ground-based campaign (6 months). For the airborne campaign, the dual-frequency (9.4 + 94 GHz) NAWX radar on board a Convair-580 aircraft of the National Science Council of Canada will be upgraded and flown. This paper describes the observation requirements, preliminary satellite mission concepts, associated wind retrieval aspects and the planned demonstration campaigns.
replace the current satellite system in the 2020 timeframe and contribute to the Joint Polar System to be set up with
NOAA. Through consultation with users and application experts, requirements have been defined for a range of
candidate missions mainly in support of operational meteorology and climate monitoring. A number of on-board
instruments, satellite platforms and ground support infrastructure are under study in coordination with ESA, NOAA,
DLR and CNES. The satellites will fly in a sun synchronous, low earth orbit at 817 km altitude and 09:30 descending
equatorial crossing time, providing observations with global coverage every 12 to 24 hours depending on instrument.
The instruments exploit a range of techniques including multi spectral imaging, atmospheric sounding in the optical and
microwave spectral domains, radio occultation sounding, scatterometry and microwave imaging. The raw instrument
data will be broadcast directly by the satellites, as well as being stored on board for their transmission, in sets spanning
up to a full orbit, to polar ground stations. These data will be collected at EUMETSAT facilities and processed to obtain
calibrated and geo-located measurements, and records of well defined geophysical variables. The data will be distributed
to the users in near real time and archived together with the data of other EUMETSAT satellite systems, making
available long term records also suitable for climate monitoring. Feasibility studies for the space and ground systems will
be done until early 2012 with the main objective to select the baseline configuration for preliminary definition,
development and operation programmes to be proposed and coordinated within the involved organisations.
A new call for Core Earth Explorer Ideas was released by the European Space Agency in March 2005. The Call focused
on the global carbon and water cycles, atmospheric chemistry and climate, as well as the human element as a cross
cutting issue. The proposals were peer reviewed by scientific panels, and also appraised technically and
programmatically by ESA. This paper describes the Earth Explorer cycle and gives an overview of the six candidate
missions selected for assessment studies.
The Living Planet Programme of the European Space Agency encompasses a science-driven strategy for monitoring the
Earth from space. The Earth Explorer missions are defined, developed and operated in close cooperation with the science
community and focus on the key components of the Earth System: the atmosphere, biosphere, hydrosphere, cryosphere
and the Earth's interior. The emphasis of these missions is on providing data to advance our understanding of these
individual components, their interaction with each other and the impacts that human activities have on natural Earth
processes.
By involving the science community from the beginning and introducing a peer-reviewed selection process, this ongoing
user-driven approach has given the Earth science community an efficient tool in their endeavor to better
understand and monitor our planet. So far, this process has resulted in six missions currently under development: GOCE,
Cryosat, ADM Aeolus, SMOS, Swarm and EarthCARE.
The third cycle of Earth Explorers Core Missions was started in 2005 to select the seventh Earth Explorer mission due to
launch in 2014/2015. At present there are six candidate missions being assessed at pre-phase A level. These missions
were chosen to enter the assessment phase as a result of the Call for Core Mission ideas released by ESA in 2005, which
resulted in 24 proposals out of which six candidates were selected:
- BIOMASS - global measurements of forest biomass and extent;
- TRAQ - (TRopospheric composition and Air Quality) - Air quality monitoring and long-range transport of air
pollutants;
- PREMIER - (PRocess Exploration through Measurements of Infrared and millimetre-wave Emitted Radiation)
Understanding the processes that link trace gases, radiation, chemistry and climate in the atmosphere;
- FLEX - (FLuorescence EXplorer) - Observation of global photosynthesis through the measurement of fluorescence;
- A-SCOPE - (Advanced Space Carbon and Climate Observation of Planet Earth) - Improving the understanding of
the global carbon cycle and regional carbon dioxide fluxes;
- CoReH2O - (Cold Regions Hydrology High-resolution Observatory) - Detailed observations of key snow, ice and
water cycle characteristics.
This paper presents an overview of the six candidate missions, describing the scientific objectives and outlining the main
aspects of the candidate implementation concept currently under evaluation.
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.
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.
Six candidate Earth Explorer (satellite) missions were undergoing phase A industrial studies and science consolidation from 2002 to early 2004. They included 3 'Core' missions (EarthCARE, SPECTRA and WALES) and 3 'Opportunity' missions (ACE+, EGPM, SWARM). Three of the candidate missions carry microwave payloads for atmospheric sensing. In April 2004, a selection workshop was held, and recommendations for implementation (phases B, C, D) were made by the Earth Sciences Advisory Committee (ESAC) and an implementation decision was taken by the Programme Board on Earth Observation (PB-EO) in May. SWARM, a magnetometry mission, was selected for full implementation as a 5th Explorer mission. The decision for the 6th Explorer mission was postponed to Nov. 2004 between EarthCARE and SPECTRA candidates, pending on the confirmation by JAXA on its contribution to EarthCARE and a re-examination by ESA. EGPM was recommended for implementation under the GMES, a new ESA programme of operational missions. In this paper, EarthCARE and EGPM are described with a particular emphasis on the microwave payloads.
EarthCARE, a candidate Earth Explorer Core mission of ESA, aims to improve our knowledge of the impact of clouds and aerosols on the Earth's radiative budget. The satellite will carry two nadir sounding active instruments: a Cloud Profiling Radar (CPR) and a backscatter lidar. In addition, a multispectral cloud-imager, a Fourier transform spectrometer and a broadband radiometer complement the payload. The objective of the present study was to optimize the parameters of the CPR for retrieving accurate radiative profiles for highly layered cloud structures. Realistic cloud scenarios taken from ground-based experiments have been used for simulating the radar response to cloud layers. A radar simulator was developed initially for one-dimensional simulation of the radar echos. The cloud microphysical properties were retrieved using a model as a function of the reflectivity factor and temperature, based on information from in-situ measurements. An extensive parametric analysis was performed for various vertical resolutions and sensitivities which have direct impacts on the radar design and necessary resources on-board the satellite. The analysis demonstrated that the proposed radar characteristics will meet the top-of-the-atmosphere radiative flux density estimation accuracy of 10 W/m2 as recommended by WCRP.
The European Space Agency has undertaken exploratory studies to define future space borne microwave instruments for application in numerical weather prediction (NWP) and climate research in the 2015 to 2020 time frame. Teams involving scientist and industrial partners were following an approach that in a first stage reviewed and defined the user requirements for both applications. NWP requires mainly existing observables at an improved spatial and temporal resolution, and in addition operational observation of ice clouds. Climate user requirements are quite similar but do not call for the same temporal resolution and additionally observations of cirrus and surface parameters are needed. The user requirements were translated into system requirements that, at this point appear challenging but in most cases feasible in the envisaged time frame. The industrial teams traded the user requirements, system requirements and implementation issues. The derived mission and instrument concepts include improved cross-track sounders with AMSU heritage as well as conical scanning instruments (partly including sounding capabilities) on polar orbiting platforms.
KEYWORDS: Antennas, Signal to noise ratio, Radar, Device simulation, Polarimetry, Polarization, Backscatter, Computer simulations, Spatial resolution, Ku band
The primary mission of a wind scatterometer is to determine wind speed and direction over the ocean. This is achieved by performing a set of radar cross-section measurements at different azimuth view-angles over the resolution cell, and inverting the backscatter model, a so-called geophysical model function (GMF), to extract the wind information using the azimuth anisotropy of the radar backscatter by sea-surface in presence of wind. A new concept of rotating fanbeam radar was introduced which operates in C-band. The present paper describes an analysis of the new concept by means of wind retrieval simulations and an investigation of advanced features such as multi-beam, dual-polarisation, dual-frequency and polarimetric capabilities in improving the wind retrieval accuracy. End-to-end simulations of the complete system are performed starting from wind-fields which are sampled by the scatterometer model. The simulated radar echos are then converted to sets of backscattering coefficients (sigma-naught) which are inverted to obtain again the wind-fields containing measurement errors and noise. The performance of the system is assessed by analysing the quality of retrieved wind as functions of the instrument configuration and characteristics (parameters).
Chung-Chi Lin, Peter de Maagt, T. Naerhi, Paivi Piironen, Juergen Mees, T. Weber, J. Mosig, P. Otero, Volkert Hansen, Thomas Vaupel, Hans Hartnagel, C.-I. Lin, Alexander Simon, V. Moettoenen, A. Raeisaenen, Erik Kollberg, Harald Merkel, Peter Zimmermann
KASIMIR initiative is a development program started in early 1996 by the ESA in order to advance the mm-and sub-mm-wave sensor technology for satellite-based atmospheric observations. The initial goal of the project is to build integrated antenna/mixer frontends at 650 GHz which are qualifiable for the low Earth orbit environment. All of the frontends will make use of the so-called integrated quasi- vertical Schottky diodes developed at Technical University of Darmstadt in Germany.
This paper gives the current status of a medium resolution SAR definition prephase A study. The objective of such a novel SAR instrument is the global monitoring of land surfaces and polar region. The study was conducted in order to analyze all the possible concepts that could be compliant with this mission definition. Several trade-offs were performed in order to select an instrument concept compatible with large coverage, medium spatial resolution, good absolute radiometric accuracy, low mass and low power consumption.
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