scholarly journals The Impact of Transiting Planet Science on the Next Generation of Direct-Imaging Planet Searches

2008 ◽  
Vol 4 (S253) ◽  
pp. 556-559
Author(s):  
Joseph C. Carson
Keyword(s):  
A Priori ◽  
Major Axis ◽  
Next Generation ◽  
A Priori Information ◽  
Direct Imaging ◽  
Semi Major Axis ◽  
Absorption Bands ◽  
Imaging Results ◽  
Priori Information ◽  
The Impact

AbstractWithin the next five years, a number of direct-imaging planet search instruments, like the VLT SPHERE instrument, will be coming online. To successfully carry out their programs, these instruments will rely heavily on a-priori information on planet composition, atmosphere, and evolution. Transiting planet surveys, while covering a different semi-major axis regime, have the potential to provide critical foundations for these next-generation surveys. For example, improved information on planetary evolutionary tracks may significantly impact the insights that can be drawn from direct-imaging statistical data. Other high-impact results from transiting planet science include information on mass-to-radius relationships as well as atmospheric absorption bands. The marriage of transiting planet and direct-imaging results may eventually give us the first complete picture of planet migration, multiplicity, and general evolution.

scholarly journals Synergy of stereo cloud top height and ORAC optimal estimation cloud retrieval: evaluation and application to AATSR

2016 ◽  
Vol 9 (3) ◽  
pp. 909-928 ◽  
Author(s):  
Daniel Fisher ◽  
Caroline A. Poulsen ◽  
Gareth E. Thomas ◽  
Jan-Peter Muller
Keyword(s):  
A Priori ◽  
Single Layer ◽  
Optimal Estimation ◽  
Open Water ◽  
A Priori Information ◽  
Cloud Parameters ◽  
Cloud Properties ◽  
Priori Information ◽  
Cloud Parameter ◽  
The Impact

Abstract. In this paper we evaluate the impact on the cloud parameter retrievals of the ORAC (Optimal Retrieval of Aerosol and Cloud) algorithm following the inclusion of stereo-derived cloud top heights as a priori information. This is performed in a mathematically rigorous way using the ORAC optimal estimation retrieval framework, which includes the facility to use such independent a priori information. Key to the use of a priori information is a characterisation of their associated uncertainty. This paper demonstrates the improvements that are possible using this approach and also considers their impact on the microphysical cloud parameters retrieved. The Along-Track Scanning Radiometer (AATSR) instrument has two views and three thermal channels, so it is well placed to demonstrate the synergy of the two techniques. The stereo retrieval is able to improve the accuracy of the retrieved cloud top height when compared to collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), particularly in the presence of boundary layer inversions and high clouds. The impact of the stereo a priori information on the microphysical cloud properties of cloud optical thickness (COT) and effective radius (RE) was evaluated and generally found to be very small for single-layer clouds conditions over open water (mean RE differences of 2.2 (±5.9) microns and mean COD differences of 0.5 (±1.8) for single-layer ice clouds over open water at elevations of above 9 km, which are most strongly affected by the inclusion of the a priori).

scholarly journals Synergy of stereo cloud top height and ORAC optimal estimation cloud retrieval: evaluation and application to AATSR

2015 ◽  
Vol 8 (5) ◽  
pp. 5283-5327
Author(s):  
D. Fisher ◽  
C. A. Poulsen ◽  
G. E. Thomas ◽  
J.-P. Muller
Keyword(s):  
Cloud Model ◽  
A Priori ◽  
Single Layer ◽  
Optimal Estimation ◽  
A Priori Information ◽  
Cloud Parameters ◽  
Microphysical Properties ◽  
Priori Information ◽  
The Impact ◽  
High Clouds

Abstract. In this paper we evaluate the retrievals of cloud top height when stereo derived heights are combined with the radiometric cloud top heights retrieved from the ORAC (Optimal Retrieval of Aerosol and Cloud) algorithm. This is performed in a mathematically rigorous way using the ORAC optimal estimation retrieval framework, which includes the facility to use independent a priori information. Key to the use of a priori information is a characterisation of their associated uncertainty. This paper demonstrates the improvements that are possible using this approach and also considers their impact on the microphysical cloud parameters retrieved. The AATSR instrument has two views and three thermal channels so is well placed to demonstrate the synergy of the two techniques. The stereo retrieval is able to improve the accuracy of the retrieved cloud top height when compared to collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), particularly in the presence of boundary layer inversions and high clouds. The impact on the microphysical properties of the cloud such as optical depth and effective radius was evaluated and found to be very small with the biggest differences occurring over bright land surfaces and for high clouds. Overall the cost of the retrievals increased indicating a poorer radiative fit of radiances to the cloud model, which currently uses a single layer cloud model. Best results and improved fit to the radiances may be obtained in the future if a multi-layer model is used.

Wavelength and vulnerability to atrial fibrillation: Insights from a computer model of human atria

EP Europace ◽  
2005 ◽  
Vol 7 (s2) ◽  
pp. S83-S92 ◽  
Author(s):  
Vincent Jacquemet ◽  
Nathalie Virag ◽  
Lukas Kappenberger
Keyword(s):  
Atrial Fibrillation ◽  
Computer Model ◽  
A Priori ◽  
Temporal Organization ◽  
A Priori Information ◽  
Clinical Methods ◽  
Spatio Temporal ◽  
Priori Information ◽  
The Impact ◽  
The Relationship

Abstract Aim To explain the contradictory results related to the concept of critical cardiac wavelength in the initiation and perpetuation of atrial fibrillation (AF). Methods A biophysically based computer model was used to: (1) study the relationship between wavelength and AF perpetuation in the presence of multiple re-entrant wavelets, (2) evaluate the performance of different existing methods for wavelength estimation in the presence of different arrhythmogenic substrates, and (3) document the impact of either heterogeneities in refractoriness or the presence of a mother rotor on wavelength estimation. Results The simulations confirmed that the wavelength must be below a critical value for AF to be sustained, when the perpetuation mechanism relies on multiple re-entrant wavelets. The estimated value of wavelength was not the same for all methods tested and depended in part on the nature of the spatio-temporal organization of the AF dynamics. Conclusion A priori information about the underlying wavelet dynamics is needed for a correct interpretation of the cardiac wavelength as estimated by the current clinical methods.

A New Approach of Quantifying Top-Tensioned Risers Clashing by Using Wavelet Scalograms

2015 ◽  
Author(s):  
Shutao Xing ◽  
Wentao Dai ◽  
Dakshina Moorthy ◽  
Gangqiang Li
Keyword(s):  
Numerical Simulation ◽  
A Priori ◽  
Dynamic Responses ◽  
Impact Behavior ◽  
Design Phase ◽  
A Priori Information ◽  
New Approach ◽  
Priori Information ◽  
The Impact ◽  
Critical Consideration

Clashing or colliding can take place between a riser and its adjacent risers or other lines/structures. Clashing is of great concern for the design of top-tensioned riser (TTR) arrays in deep water. Understanding the impact behavior between risers is essential for developing reliable clashing mitigation approaches during design phase. Further, monitoring of risers clashing is useful during operation and installation of the systems. A critical consideration of clashing monitoring is how to quantify the impact. Traditional methods need a priori information which is difficult to be obtained accurately. This paper proposed a new method of monitoring risers clashing by using wavelet scalograms of dynamic responses that doesn’t need such priori information. The method was investigated through numerical simulation of a pair of TTR risers operated from tension-leg platform (TLP) that are subjected to current and floater motions. The wavelet scalograms of the risers’ velocities and accelerations were utilized to quantify impact. It was verified that the wavelet scalograms can indicate clashing severity quite well.

SEISMIC INVERSION AND THE IMPACT OF A PRIORI INFORMATION

1994 ◽  
pp. 525-636
Author(s):  
Vincent Richard ◽  
F. Rocca ◽  
G. Bernasconi ◽  
A. De Nicolao ◽  
J. Drufuca ◽  
...  
Keyword(s):  
A Priori ◽  
Seismic Inversion ◽  
A Priori Information ◽  
Priori Information ◽  
The Impact
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