scholarly journals Contrail study with ground-based cameras

2013 ◽  
Vol 6 (4) ◽  
pp. 7425-7472
Author(s):  
U. Schumann ◽  
R. Hempel ◽  
H. Flentje ◽  
M. Garhammer ◽  
K. Graf ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Ambient Air ◽  
Lagrangian Model ◽  
Wake Vortex ◽  
The Moon ◽  
Movement Data ◽  
Different Types ◽  
Nwp Model ◽  
Better Than

Abstract. Photogrammetric methods and analysis results for contrails observed with wide-angle cameras are described. Four cameras of two different types (view angle < 90° or whole-sky imager) at the ground at various positions are used to track contrails and to derive their altitude, width, and horizontal speed. Camera models for both types are described to derive the observation angles for given image coordinates and their inverse. The models are calibrated with sightings of the Sun, the Moon and a few bright stars. The methods are applied and tested in a case study. Four persistent contrails crossing each other together with a short-lived one are observed with the cameras. Vertical and horizontal positions of the contrails are determined from the camera images to an accuracy of better than 200 m and horizontal speed to 0.2 m s−1. With this information, the aircraft causing the contrails are identified by comparison to traffic waypoint data. The observations are compared with synthetic camera pictures of contrails simulated with the contrail prediction model CoCiP, a Lagrangian model using air traffic movement data and numerical weather prediction (NWP) data as input. The results provide tests for the NWP and contrail models. The cameras show spreading and thickening contrails suggesting ice-supersaturation in the ambient air. The ice-supersaturated layer is found thicker and more humid in this case than predicted by the NWP model used. The simulated and observed contrail positions agree up to differences caused by uncertain wind data. The contrail widths, which depend on wake vortex spreading, ambient shear and turbulence, were partly wider than simulated.

scholarly journals Contrail study with ground-based cameras

2013 ◽  
Vol 6 (12) ◽  
pp. 3597-3612 ◽  
Author(s):  
U. Schumann ◽  
R. Hempel ◽  
H. Flentje ◽  
M. Garhammer ◽  
K. Graf ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Ambient Air ◽  
Lagrangian Model ◽  
Wake Vortex ◽  
The Moon ◽  
Movement Data ◽  
Different Types ◽  
Nwp Model ◽  
Better Than

Abstract. Photogrammetric methods and analysis results for contrails observed with wide-angle cameras are described. Four cameras of two different types (view angle < 90° or whole-sky imager) at the ground at various positions are used to track contrails and to derive their altitude, width, and horizontal speed. Camera models for both types are described to derive the observation angles for given image coordinates and their inverse. The models are calibrated with sightings of the Sun, the Moon and a few bright stars. The methods are applied and tested in a case study. Four persistent contrails crossing each other, together with a short-lived one, are observed with the cameras. Vertical and horizontal positions of the contrails are determined from the camera images to an accuracy of better than 230 m and horizontal speed to 0.2 m s−1. With this information, the aircraft causing the contrails are identified by comparison to traffic waypoint data. The observations are compared with synthetic camera pictures of contrails simulated with the contrail prediction model CoCiP, a Lagrangian model using air traffic movement data and numerical weather prediction (NWP) data as input. The results provide tests for the NWP and contrail models. The cameras show spreading and thickening contrails, suggesting ice-supersaturation in the ambient air. The ice-supersaturated layer is found thicker and more humid in this case than predicted by the NWP model used. The simulated and observed contrail positions agree up to differences caused by uncertain wind data. The contrail widths, which depend on wake vortex spreading, ambient shear and turbulence, were partly wider than simulated.

scholarly journals Horoscopes of the Moon: Weather Prediction as Astrology in Ptolemy’s Tetrabiblos

2021 ◽  
Vol 26 (3) ◽  
pp. 231-253
Author(s):  
Claire Hall
Keyword(s):  
Scientific Practice ◽  
Weather Prediction ◽  
The Moon ◽  
Sextus Empiricus ◽  
Greco Roman ◽  
The Way

Abstract Ptolemy’s Tetrabiblos is not usually considered as a meteorological text. I examine the sections of the Tetrabiblos that deal with weather prediction and argue that Ptolemy considers it part of astrology. I show that the way Ptolemy categorises weather prediction differs significantly from other Greco-Roman writers, including Cicero (On Divination) and Sextus Empiricus (Against the Astrologers). I argue for these conclusions: first, that Ptolemy considers weather prediction to be part of astrology – i.e., a scientific practice which includes giving an account of the causes of phenomena with reference to the stars; to give such an account for the weather requires a practitioner to go beyond the observation and cataloguing of weather signs. Secondly, I argue that understanding weather prediction as astrology means that the distinction between horoscopic and general astrology is more fluid than is sometimes thought. Finally, I will show that Ptolemy’s views on weather prediction provide a case study for his view of astral causation.

WRF model moisture adjustment method; a case study with winter-time cloudy biases in Xinjiang, China.

2021 ◽  
Author(s):  
Guiting Song ◽  
Robert Huva ◽  
Yu Xing ◽  
Xiaohui Zhong
Keyword(s):  
Weather Prediction ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Adjustment Method ◽  
Surface Irradiance ◽  
Convective Processes ◽  
Systematic Biases ◽  
Nwp Model ◽  
Winter Time

AbstractFor most locations on Earth the ability of a Numerical Weather Prediction (NWP) model to accurately simulate surface irradiance relies heavily on the NWP model being able to resolve cloud coverage and thickness. At horizontal resolutions at or below a few kilometres NWP models begin to explicitly resolve convection and the clouds that arise from convective processes. However, even at high resolutions, biases may remain in the model and result in under- or over-prediction of surface irradiance. In this study we explore the correction of such systematic biases using a moisture adjustment method in tandem with the Weather Research and Forecasting model (WRF) for a location in Xinjiang, China. After extensive optimisation of the configuration of the WRF model we show that systematic biases still exist—in particular for wintertime in Xinjiang. We then demonstrate the moisture adjustment method with cloudy days for January 2019. Adjusting the relative humidity by 12% through the vertical led to a Root Mean Square Error (RMSE) improvement of 57.8% and a 90.5% reduction in bias for surface irradiance.

Quality Control and Verification of Weather Radar Wind Profiles

2005 ◽  
Vol 22 (10) ◽  
pp. 1541-1550 ◽  
Author(s):  
Iwan Holleman
Keyword(s):  
Quality Control ◽  
Weather Prediction ◽  
Weather Radar ◽  
Ground Level ◽  
Limited Area ◽  
Wind Profiles ◽  
Nwp Model ◽  
Radial Velocity Data ◽  
Better Than

Abstract Weather radar wind profiles (WRWPs) have been retrieved from Doppler volume scans using different implementations of the velocity–azimuth display (VAD) and volume velocity processing (VVP) methods. An extensive quality control of the radial velocity data and the retrieved wind vectors has been applied. The quality and availability of the obtained wind profiles have been assessed by comparisons with collocated radiosonde observations and numerical weather prediction (NWP) data over a 9-month period. The comparisons reveal that the VVP methods perform better than the VAD methods, and that the simplest implementation of the VVP (VVP1) method performs the best of all. The availability fraction of VVP1 wind vectors is about 0.39 at ground level and drops below 0.16 at a 6-km altitude. The observation minus background statistics of the VVP1 wind profiles against the High Resolution Limited Area Model (HIRLAM) NWP model are at least as good as those of the radiosonde profiles. This result clearly demonstrates the high quality of (quality controlled) weather radar wind profiles.

scholarly journals Effect of Question Structure on College Students’ Electronic Reflection Outcomes: A Case Study

2012 ◽  
Vol 2 (2) ◽  
pp. 45
Author(s):  
Pao-Nan Chou
Keyword(s):  
College Students ◽  
Quantitative Analysis ◽  
Qualitative Analysis ◽  
Cognitive Learning ◽  
Research Focus ◽  
Surface Reflection ◽  
Significant Difference ◽  
Different Types ◽  
Better Than

This study aims to design different types of reflection questions to support college students’ electronic reflection. Whether or not the reflection question structure may influence students’ reflection outcomes is the research focus. According to various cognitive learning concepts, three types of reflection questions, which include surface, medium and deep questions, are designed and implemented in three weeks of the class. Forty college students majoring in instructional technology participated in this study. The results of the qualitative analysis showed that the surface reflection question yields swallow reflection works, and the medium and deep reflection questions allow students to produce meaningful reflection contents. The results of the quantitative analysis showed that the medium and deep reflection questions are better than the surface reflection question in terms of critical thinking. However, no significant difference is found between the medium and deep reflection questions.

scholarly journals GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

2018 ◽  
Vol 10 (7) ◽  
pp. 1113 ◽  
Author(s):  
Ying Xu ◽  
Chen Wu ◽  
Lei Li ◽  
Lizi Yan ◽  
Min Liu ◽  
...  
Keyword(s):  
Long Range ◽  
Phase Measurement ◽  
Weather Prediction ◽  
Vertical Direction ◽  
Global Navigation Satellite Systems ◽  
Convergence Time ◽  
Tropospheric Delay ◽  
Gps Rtk ◽  
Nwp Model ◽  
Better Than

Tropospheric delay is a major error source that affects the performance of the Global Navigation Satellite Systems (GNSS) Real Time Kinematic (RTK) positioning especially for the medium/long-range baseline. Although high precision tropospheric delay can be estimated by GNSS carrier phase measurement, together with position and ambiguity, a relatively long period of convergence time is necessary. In this study, we develop a new GPS/BDS RTK algorithm constrained with a tropospheric delay parameters from Numerical weather prediction (NWP) model for medium/long-range baselines. The accuracy of the tropospheric delays derived from NWP is assessed through comparisons with the results of GAMIT (GNSS at MIT). The positioning performance with standard GPS RTK, standard GPS/BDS RTK, the developed NWP-constrained GPS RTK and NWP-constrained GPS/BDS RTK over medium/long-range baselines are compared in terms of the initialization time and the positioning accuracy. Experiment results show that the mean differences between the NWP and GAMIT zenith tropospheric delay (ZTD) are between −5.50 mm and 5.60 mm, and the RMS values of the NWP ZTD residuals are from 24.02 mm to 32.62 mm. A reduction in the initialization time of over 41% and 58% for medium- and long-range baselines can be achieved with the NWP-constrained RTK (both GPS alone and GPS/BDS RTK solutions) compared to the standard RTK solution, respectively. An improvement of over 30% can be found with the GPS/BDS RTK compared with that of the GPS alone RTK for both standard and the NWP-constrained modes. The positioning precision of NWP-constrained GPS/BDS RTK is better than 3 cm in the horizontal direction and better than 5 cm in the vertical direction, which satisfies the requirement of the precise positioning service.

scholarly journals Experimental assimilation of synthetic bogus tropical cyclone pressure observations into a high-resolution rapid-update NWP model

2020 ◽  
Author(s):  
Susan Rennie ◽  
Jim Fraser
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
Weather Prediction ◽  
Central Pressure ◽  
Convective Scale ◽  
Potential Impact ◽  
Cycling System ◽  
Nwp Model ◽  
Large Improvement

The effect of synthetic ‘bogus’ tropical cyclone (TC) central pressure observations on TC Owen was tested in a convective-scale numerical weather prediction (NWP) system with hourly 4D-Var assimilation. TC Owen traversed the Gulf of Carpentaria over 10–14 December 2018, entering from the east and briefly making landfall on the western edge before reversing course and retracing its path east to cross the northern tip of Queensland. The Australian Bureau of Meteorology runs a high-resolution NWP model centred over Darwin, which covers much of the Gulf of Carpentaria. The next-generation developmental version of this model includes data assimilation. Therefore, when TC Owen presented the opportunity to investigate the simulation of a TC within the domain, the developmental system was run as a case study. The modelled cyclone initially failed to intensify. The case study was then repeated including assimilation of bogus central pressure observations. This new run showed a large improvement in the intensity throughout the simulation; however, the TC track was not substantially improved. This demonstration of the potential impact of using synthetic observations may guide whether the development of a bogus observation source with sufficiently low latency for use in an hourly-cycling system should be prioritised.

Participatory Mapping in Browns Canyon National Monument, Colorado (USA)

2017 ◽  
Vol 1 (1) ◽  
pp. 1-16
Author(s):  
John Harner ◽  
Lee Cerveny ◽  
Rebecca Gronewold
Keyword(s):  
Land Management ◽  
Planning Process ◽  
Management Plan ◽  
Bureau Of Land Management ◽  
National Monument ◽  
Resource Managers ◽  
Different Types ◽  
Us Forest Service ◽  
Natural Resource Managers

Natural resource managers need up-to-date information about how people interact with public lands and the meanings these places hold for use in planning and decision-making. This case study explains the use of public participatory Geographic Information System (GIS) to generate and analyze spatial patterns of the uses and values people hold for the Browns Canyon National Monument in Colorado. Participants drew on maps and answered questions at both live community meetings and online sessions to develop a series of maps showing detailed responses to different types of resource uses and landscape values. Results can be disaggregated by interaction types, different meaningful values, respondent characteristics, seasonality, or frequency of visit. The study was a test for the Bureau of Land Management and US Forest Service, who jointly manage the monument as they prepare their land management plan. If the information generated is as helpful throughout the entire planning process as initial responses seem, this protocol could become a component of the Bureau’s planning tool kit.

Design, Development and Comparison of Heuristic Driven Algorithms Based on the Crossed Domain Products’ Reviews for User’s Summarization

2020 ◽  
Vol 13 (5) ◽  
pp. 884-892
Author(s):  
Sartaj Ahmad ◽  
Ashutosh Gupta ◽  
Neeraj Kumar Gupta
Keyword(s):  
Decision Making ◽  
Online Shopping ◽  
Recent Time ◽  
Design Development ◽  
Different Types ◽  
Feature Based ◽  
Use Of Internet ◽  
Day By Day ◽  
Better Than

Background: In recent time, people love online shopping but before any shopping feedbacks or reviews always required. These feedbacks help customers in decision making for buying any product or availing any service. In the country like India this trend of online shopping is increasing very rapidly because awareness and the use of internet which is increasing day by day. As result numbers of customers and their feedbacks are also increasing. It is creating a problem that how to read all reviews manually. So there should be some computerized mechanism that provides customers a summary without spending time in reading feedbacks. Besides big number of reviews another problem is that reviews are not structured. Objective: In this paper, we try to design, implement and compare two algorithms with manual approach for the crossed domain Product’s reviews. Methods: Lexicon based model is used and different types of reviews are tested and analyzed to check the performance of these algorithms. Results: Algorithm based on opinions and feature based opinions are designed, implemented, applied and compared with the manual results and it is found that algorithm # 2 is performing better than algorithm # 1 and near to manual results. Conclusion: Algorithm # 2 is found better on the different product’s reviews and still to be applied on other product’s reviews to enhance its scope. Finally, it will be helpful to automate existing manual process.

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