The Experts below are selected from a list of 342 Experts worldwide ranked by ideXlab platform
Stefan Metzger - One of the best experts on this subject based on the ideXlab platform.
-
eddy covariance flux Measurements with a weight shift microlight aircraft
Atmospheric Measurement Techniques, 2012Co-Authors: Stefan Metzger, W Junkermann, Matthias Mauder, Frank Beyrich, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. The objective of this study is to assess the feasibility and quality of eddy-covariance flux Measurements from a weight-shift microlight aircraft (WSMA). Firstly, we investigate the precision of the Wind Measurement (σu,v ≤ 0.09 m s−1, σw = 0.04 m s−1), the lynchpin of flux calculations from aircraft. From here, the smallest resolvable changes in friction velocity (0.02 m s−1), and sensible- (5 W m−2) and latent (3 W m−2) heat flux are estimated. Secondly, a seven-day flight campaign was performed near Lindenberg (Germany). Here we compare Measurements of Wind, temperature, humidity and respective fluxes between a tall tower and the WSMA. The maximum likelihood functional relationship (MLFR) between tower and WSMA Measurements considers the random error in the data, and shows very good agreement of the scalar averages. The MLFRs for standard deviations (SDs, 2–34%) and fluxes (17–21%) indicate higher estimates of the airborne Measurements compared to the tower. Considering the 99.5% confidence intervals, the observed differences are not significant, with exception of the temperature SD. The comparison with a large-aperture scintillometer reveals lower sensible heat flux estimates at both tower (−40 to −25%) and WSMA (−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and Wind Measurement at the tower and (ii) the Measurement platforms' differing abilities to capture contributions from non-propagating eddies. These findings encourage the use of WSMA as a low cost and highly versatile flux Measurement platform.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s −1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s −1 . (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s −1 for the horizontal and ≈0.3 m s −1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude ( −1 ) or true airspeed (ranging from 23–30 m s −1 ) is found. Hence our analysis provides the necessary basis to study the Wind Measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux Measurements.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
-
measuring the 3 d Wind vector with a weight shift microlight aircraft
Atmospheric Measurement Techniques Discussions, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
Thomas Foken - One of the best experts on this subject based on the ideXlab platform.
-
eddy covariance flux Measurements with a weight shift microlight aircraft
Atmospheric Measurement Techniques, 2012Co-Authors: Stefan Metzger, W Junkermann, Matthias Mauder, Frank Beyrich, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. The objective of this study is to assess the feasibility and quality of eddy-covariance flux Measurements from a weight-shift microlight aircraft (WSMA). Firstly, we investigate the precision of the Wind Measurement (σu,v ≤ 0.09 m s−1, σw = 0.04 m s−1), the lynchpin of flux calculations from aircraft. From here, the smallest resolvable changes in friction velocity (0.02 m s−1), and sensible- (5 W m−2) and latent (3 W m−2) heat flux are estimated. Secondly, a seven-day flight campaign was performed near Lindenberg (Germany). Here we compare Measurements of Wind, temperature, humidity and respective fluxes between a tall tower and the WSMA. The maximum likelihood functional relationship (MLFR) between tower and WSMA Measurements considers the random error in the data, and shows very good agreement of the scalar averages. The MLFRs for standard deviations (SDs, 2–34%) and fluxes (17–21%) indicate higher estimates of the airborne Measurements compared to the tower. Considering the 99.5% confidence intervals, the observed differences are not significant, with exception of the temperature SD. The comparison with a large-aperture scintillometer reveals lower sensible heat flux estimates at both tower (−40 to −25%) and WSMA (−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and Wind Measurement at the tower and (ii) the Measurement platforms' differing abilities to capture contributions from non-propagating eddies. These findings encourage the use of WSMA as a low cost and highly versatile flux Measurement platform.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s −1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s −1 . (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s −1 for the horizontal and ≈0.3 m s −1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude ( −1 ) or true airspeed (ranging from 23–30 m s −1 ) is found. Hence our analysis provides the necessary basis to study the Wind Measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux Measurements.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
-
measuring the 3 d Wind vector with a weight shift microlight aircraft
Atmospheric Measurement Techniques Discussions, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
W Junkermann - One of the best experts on this subject based on the ideXlab platform.
-
eddy covariance flux Measurements with a weight shift microlight aircraft
Atmospheric Measurement Techniques, 2012Co-Authors: Stefan Metzger, W Junkermann, Matthias Mauder, Frank Beyrich, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. The objective of this study is to assess the feasibility and quality of eddy-covariance flux Measurements from a weight-shift microlight aircraft (WSMA). Firstly, we investigate the precision of the Wind Measurement (σu,v ≤ 0.09 m s−1, σw = 0.04 m s−1), the lynchpin of flux calculations from aircraft. From here, the smallest resolvable changes in friction velocity (0.02 m s−1), and sensible- (5 W m−2) and latent (3 W m−2) heat flux are estimated. Secondly, a seven-day flight campaign was performed near Lindenberg (Germany). Here we compare Measurements of Wind, temperature, humidity and respective fluxes between a tall tower and the WSMA. The maximum likelihood functional relationship (MLFR) between tower and WSMA Measurements considers the random error in the data, and shows very good agreement of the scalar averages. The MLFRs for standard deviations (SDs, 2–34%) and fluxes (17–21%) indicate higher estimates of the airborne Measurements compared to the tower. Considering the 99.5% confidence intervals, the observed differences are not significant, with exception of the temperature SD. The comparison with a large-aperture scintillometer reveals lower sensible heat flux estimates at both tower (−40 to −25%) and WSMA (−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and Wind Measurement at the tower and (ii) the Measurement platforms' differing abilities to capture contributions from non-propagating eddies. These findings encourage the use of WSMA as a low cost and highly versatile flux Measurement platform.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s −1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s −1 . (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s −1 for the horizontal and ≈0.3 m s −1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude ( −1 ) or true airspeed (ranging from 23–30 m s −1 ) is found. Hence our analysis provides the necessary basis to study the Wind Measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux Measurements.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
-
measuring the 3 d Wind vector with a weight shift microlight aircraft
Atmospheric Measurement Techniques Discussions, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
Klaus Butterbachbahl - One of the best experts on this subject based on the ideXlab platform.
-
eddy covariance flux Measurements with a weight shift microlight aircraft
Atmospheric Measurement Techniques, 2012Co-Authors: Stefan Metzger, W Junkermann, Matthias Mauder, Frank Beyrich, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. The objective of this study is to assess the feasibility and quality of eddy-covariance flux Measurements from a weight-shift microlight aircraft (WSMA). Firstly, we investigate the precision of the Wind Measurement (σu,v ≤ 0.09 m s−1, σw = 0.04 m s−1), the lynchpin of flux calculations from aircraft. From here, the smallest resolvable changes in friction velocity (0.02 m s−1), and sensible- (5 W m−2) and latent (3 W m−2) heat flux are estimated. Secondly, a seven-day flight campaign was performed near Lindenberg (Germany). Here we compare Measurements of Wind, temperature, humidity and respective fluxes between a tall tower and the WSMA. The maximum likelihood functional relationship (MLFR) between tower and WSMA Measurements considers the random error in the data, and shows very good agreement of the scalar averages. The MLFRs for standard deviations (SDs, 2–34%) and fluxes (17–21%) indicate higher estimates of the airborne Measurements compared to the tower. Considering the 99.5% confidence intervals, the observed differences are not significant, with exception of the temperature SD. The comparison with a large-aperture scintillometer reveals lower sensible heat flux estimates at both tower (−40 to −25%) and WSMA (−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and Wind Measurement at the tower and (ii) the Measurement platforms' differing abilities to capture contributions from non-propagating eddies. These findings encourage the use of WSMA as a low cost and highly versatile flux Measurement platform.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s −1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s −1 . (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s −1 for the horizontal and ≈0.3 m s −1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude ( −1 ) or true airspeed (ranging from 23–30 m s −1 ) is found. Hence our analysis provides the necessary basis to study the Wind Measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux Measurements.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
-
measuring the 3 d Wind vector with a weight shift microlight aircraft
Atmospheric Measurement Techniques Discussions, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
H P Schmid - One of the best experts on this subject based on the ideXlab platform.
-
eddy covariance flux Measurements with a weight shift microlight aircraft
Atmospheric Measurement Techniques, 2012Co-Authors: Stefan Metzger, W Junkermann, Matthias Mauder, Frank Beyrich, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. The objective of this study is to assess the feasibility and quality of eddy-covariance flux Measurements from a weight-shift microlight aircraft (WSMA). Firstly, we investigate the precision of the Wind Measurement (σu,v ≤ 0.09 m s−1, σw = 0.04 m s−1), the lynchpin of flux calculations from aircraft. From here, the smallest resolvable changes in friction velocity (0.02 m s−1), and sensible- (5 W m−2) and latent (3 W m−2) heat flux are estimated. Secondly, a seven-day flight campaign was performed near Lindenberg (Germany). Here we compare Measurements of Wind, temperature, humidity and respective fluxes between a tall tower and the WSMA. The maximum likelihood functional relationship (MLFR) between tower and WSMA Measurements considers the random error in the data, and shows very good agreement of the scalar averages. The MLFRs for standard deviations (SDs, 2–34%) and fluxes (17–21%) indicate higher estimates of the airborne Measurements compared to the tower. Considering the 99.5% confidence intervals, the observed differences are not significant, with exception of the temperature SD. The comparison with a large-aperture scintillometer reveals lower sensible heat flux estimates at both tower (−40 to −25%) and WSMA (−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and Wind Measurement at the tower and (ii) the Measurement platforms' differing abilities to capture contributions from non-propagating eddies. These findings encourage the use of WSMA as a low cost and highly versatile flux Measurement platform.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s −1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s −1 . (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s −1 for the horizontal and ≈0.3 m s −1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude ( −1 ) or true airspeed (ranging from 23–30 m s −1 ) is found. Hence our analysis provides the necessary basis to study the Wind Measurement precision and spectral quality, which is prerequisite for reliable Eddy-Covariance flux Measurements.
-
corrigendum to measuring the 3 d Wind vector with a weight shift microlight aircraft published in atmos meas tech 4 1421 1444 2011
Atmospheric Measurement Techniques, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. We draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
-
measuring the 3 d Wind vector with a weight shift microlight aircraft
Atmospheric Measurement Techniques Discussions, 2011Co-Authors: Stefan Metzger, W Junkermann, Klaus Butterbachbahl, H P Schmid, Thomas FokenAbstract:Abstract. This study investigates whether the 3-D Wind vector can be measured reliably from a highly transportable and low-cost weight-shift microlight aircraft. Therefore we draw up a transferable procedure to accommodate flow distortion originating from the aircraft body and -wing. This procedure consists of the analysis of aircraft dynamics and seven successive calibration steps. For our aircraft the horizontal Wind components receive their greatest single amendment (14 %, relative to the initial uncertainty) from the correction of flow distortion magnitude in the dynamic pressure computation. Conversely the vertical Wind component is most of all improved (31 %) by subsequent steps considering the 3-D flow distortion distribution in the flow angle computations. Therein the influences of the aircraft's trim (53 %), as well as changes in the aircraft lift (16 %) are considered by using the measured lift coefficient as explanatory variable. Three independent lines of analysis are used to evaluate the quality of the Wind Measurement: (a) A Wind tunnel study in combination with the propagation of sensor uncertainties defines the systems input uncertainty to ≈0.6 m s−1 at the extremes of a 95 % confidence interval. (b) During severe vertical flight manoeuvres the deviation range of the vertical Wind component does not exceed 0.3 m s−1. (c) The comparison with ground based Wind Measurements yields an overall operational uncertainty (root mean square error) of ≈0.4 m s−1 for the horizontal and ≈0.3 m s−1 for the vertical Wind components. No conclusive dependence of the uncertainty on the Wind magnitude (
