Intercomparison of atmospheric water vapor soundings from the differential absorption lidar (DIAL) and the solar FTIR system on Mt. Zugspitze

Abstract. We present an intercomparison of three years of measurements of integrated water vapor (IWV) performed by the mid-infrared solar FTIR instrument on the summit of Mt. Zugspitze (2964 m a.s.l.) and the nearby near-infrared differential absorption lidar (DIAL) at the Schneefernerhaus research station (UFS, 2675 m a.s.l.). The solar FTIR turned out to be one of the most accurate and precise IWV sounders in recent work (Sussmann et al., 2009) and is taken as the reference here. By calculating the FTIR-DIAL correlation (22 min coincidence interval, 15 min integration time) we derive an almost ideal slope of 0.99(1), a correlation coefficient of R = 0.99, an IWV intercept of 0.056(42) mm (1.8% of the mean), and a bias of 0.097(26) mm (3.1% of the mean) from the scatter plot. By selecting a subset of coincidences with an optimum temporal and spatial matching between DIAL and FTIR, we obtain a conservative estimate of the precision of the DIAL in measuring IWV which is better than 0.1 mm (3.2% of the mean). We found that for a temporal coincidence interval of 22 min the difference in IWV measured by these two systems is dominated by the volume mismatch (horizontal distance: 680 m). The outcome from this paper is twofold: (1) The IWV soundings by FTIR and DIAL agree very well in spite of the differing wavelength regions with different spectroscopic line parameters and retrieval algorithms used. (2) In order to derive an estimate of the precision of state-of-the-art IWV sounders from intercomparison experiments, it is necessary to use a temporal matching on the shorter 10-min scale and a spatial matching on the smaller 1-km scale.

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Intercomparison of atmospheric water vapor soundings from the differential absorption lidar (DIAL) and the solar FTIR system on Mt. Zugspitze

Atmospheric Measurement Techniques ◽

10.5194/amt-4-835-2011 ◽

2011 ◽

Vol 4 (5) ◽

pp. 835-841 ◽

Cited By ~ 33

Author(s):

H. Vogelmann ◽

R. Sussmann ◽

T. Trickl ◽

T. Borsdorff

Keyword(s):

Water Vapor ◽

Near Infrared ◽

Integration Time ◽

Research Station ◽

Horizontal Distance ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

The Mean ◽

The Difference ◽

Better Than

Abstract. We present an intercomparison of three years of measurements of integrated water vapor (IWV) performed by the mid-infrared solar FTIR (Fourier Transform Infra-Red) instrument on the summit of Mt. Zugspitze (2964 m a.s.l.) and by the nearby near-infrared differential absorption lidar (DIAL) at the Schneefernerhaus research station (2675 m a.s.l.). The solar FTIR was shown to be one of the most accurate and precise IWV sounders in recent work (Sussmann et al., 2009) and is taken as the reference here. By calculating the FTIR-DIAL correlation (22 min coincidence interval, 15 min integration time) we derive an almost ideal slope of 0.996 (10), a correlation coefficient of R = 0.99, an IWV intercept of −0.039 (42) mm (−1.2 % of the mean), and a bias of −0.052 (26) mm (−1.6 % of the mean) from the scatter plot. By selecting a subset of coincidences with an optimum temporal and spatial matching between DIAL and FTIR, we obtain a conservative estimate of the precision of the DIAL in measuring IWV which is better than 0.1 mm (3.2 % of the mean). We found that for a temporal coincidence interval of 22 min the difference in IWV measured by these two systems is dominated by the volume mismatch (horizontal distance: 680 m). The outcome from this paper is twofold: (1) the IWV soundings by FTIR and DIAL agree very well in spite of the differing wavelength regions with different spectroscopic line parameters and retrieval algorithms used. (2) In order to derive an estimate of the precision of state-of-the-art IWV sounders from intercomparison experiments, it is necessary to use a temporal matching on time scales shorter than 10 min and a spatial matching on the 100-m scale.

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Future performance of ground-based and airborne water-vapor differential absorption lidar II Simulations of the precision of a near-infrared, high-power system

Applied Optics ◽

10.1364/ao.40.005321 ◽

2001 ◽

Vol 40 (30) ◽

pp. 5321 ◽

Cited By ~ 26

Author(s):

Volker Wulfmeyer ◽

Craig Walther

Keyword(s):

Water Vapor ◽

Power System ◽

High Power ◽

Near Infrared ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

Future Performance

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Airborne remote sensing of tropospheric water vapor with a near–infrared differential absorption lidar system

Applied Optics ◽

10.1364/ao.32.004534 ◽

1993 ◽

Vol 32 (24) ◽

pp. 4534 ◽

Cited By ~ 54

Author(s):

G. Ehret ◽

C. Kiemle ◽

W. Renger ◽

G. Simmet

Keyword(s):

Remote Sensing ◽

Water Vapor ◽

Near Infrared ◽

Differential Absorption ◽

Airborne Remote Sensing ◽

Lidar System ◽

Differential Absorption Lidar

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Differential absorption lidar measurements of water vapor by the High Altitude Lidar Observatory (HALO): Retrieval framework and validation

10.5194/amt-2021-229 ◽

2021 ◽

Author(s):

Brian J. Carroll ◽

Amin R. Nehrir ◽

Susan Kooi ◽

James Collins ◽

Rory A. Barton-Grimley ◽

...

Keyword(s):

Water Vapor ◽

High Altitude ◽

Dynamic Range ◽

Precipitable Water ◽

Spatiotemporal Variability ◽

High Spectral Resolution ◽

Atmospheric Conditions ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

Wide Range

Abstract. Airborne differential absorption lidar (DIAL) offers a uniquely capable solution to the problem of measuring water vapor (WV) with high precision, accuracy, and resolution throughout the troposphere and lower stratosphere. The High Altitude Lidar Observatory (HALO) airborne WV DIAL was recently developed at NASA Langley Research Center and was first deployed in 2019. It uses four wavelengths at 935 nm to achieve sensitivity over a wide dynamic range, and simultaneously employs 1064 nm backscatter and 532 nm high spectral resolution lidar (HSRL) measurements for aerosol and cloud profiling. A key component of the WV retrieval framework is flexibly trading resolution for precision to achieve optimal data sets for scientific objectives across scales. A technique for retrieving WV in the lowest few hundred meters of the atmosphere using the strong surface return signal is also presented. The five maiden flights of the HALO WV DIAL spanned the tropics through midlatitudes with a wide range of atmospheric conditions, but opportunities for validation were sparse. Comparisons to dropsonde WV profiles were qualitatively in good agreement, though statistical analysis was impossible due to systematic error in the dropsonde measurements. Comparison of HALO to in situ WV measurements onboard the aircraft showed no substantial bias across three orders of magnitude, despite variance (R2 = 0.66) that may be largely attributed to spatiotemporal variability. Precipitable water vapor measurements from the spaceborne sounders AIRS and IASI compared very well to HALO with R2 > 0.96 over ocean and R2 = 0.86 over land.

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Development of a widely tunable amplified diode laser differential absorption lidar for profiling atmospheric water vapor

Journal of Applied Remote Sensing ◽

10.1117/1.3383156 ◽

2010 ◽

Vol 4 (1) ◽

pp. 043515 ◽

Cited By ~ 4

Author(s):

Kevin S. Repasky

Keyword(s):

Water Vapor ◽

Diode Laser ◽

Atmospheric Water Vapor ◽

Differential Absorption ◽

Atmospheric Water ◽

Differential Absorption Lidar

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Comparison of active and passive water vapor remote sensing from space: An analysis based on the simulated performance of IASI and space borne differential absorption lidar

Remote Sensing of Environment ◽

10.1016/j.rse.2004.12.019 ◽

2005 ◽

Vol 95 (2) ◽

pp. 211-230 ◽

Cited By ~ 21

Author(s):

V. Wulfmeyer ◽

Heinz Bauer ◽

Paolo Di Girolamo ◽

Carmine Serio

Keyword(s):

Remote Sensing ◽

Water Vapor ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

Simulated Performance

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Validation of a Water Vapor Micropulse Differential Absorption Lidar (DIAL)

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0119.1 ◽

2016 ◽

Vol 33 (11) ◽

pp. 2353-2372 ◽

Cited By ~ 38

Author(s):

Tammy M. Weckwerth ◽

Kristy J. Weber ◽

David D. Turner ◽

Scott M. Spuler

Keyword(s):

Water Vapor ◽

Correlation Coefficient ◽

Microwave Radiometer ◽

Temporal Trends ◽

Differential Absorption ◽

Differential Absorption Lidar ◽

Pearson’S Correlation ◽

Pearson’S Correlation Coefficient ◽

Pearson's Correlation ◽

Pearson's Correlation Coefficient

AbstractA water vapor micropulse differential absorption lidar (DIAL) instrument was developed collaboratively by the National Center for Atmospheric Research (NCAR) and Montana State University (MSU). This innovative, eye-safe, low-power, diode-laser-based system has demonstrated the ability to obtain unattended continuous observations in both day and night. Data comparisons with well-established water vapor observing systems, including radiosondes, Atmospheric Emitted Radiance Interferometers (AERIs), microwave radiometer profilers (MWRPs), and ground-based global positioning system (GPS) receivers, show excellent agreement. The Pearson’s correlation coefficient for the DIAL and radiosondes is consistently greater than 0.6 from 300 m up to 4.5 km AGL at night and up to 3.5 km AGL during the day. The Pearson’s correlation coefficient for the DIAL and AERI is greater than 0.6 from 300 m up to 2.25 km at night and from 300 m up to 2.0 km during the day. Further comparison with the continuously operating GPS instrumentation illustrates consistent temporal trends when integrating the DIAL measurements up to 6 km AGL.

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Effects of Orthokeratology Lens On Axial Length Elongation in Myopia With Anisometropia Children

10.21203/rs.3.rs-741927/v1 ◽

2021 ◽

Author(s):

Ziyang Chen ◽

Kai-Ming Chen ◽

Ying Shi ◽

Zhao-Da Ye ◽

Sheng Chen ◽

...

Keyword(s):

Retrospective Study ◽

Axial Length ◽

Statistical Significance ◽

Spherical Equivalent ◽

Significant Difference ◽

The Mean ◽

The Difference ◽

Better Than ◽

Group 1

Abstract AimTo investigate the effect of orthokeratology (OK) lens on axial length (AL) elongation in myopia with anisometropia children.MethodsThirty-seven unilateral myopia (group 1) and fifty-nine bilateral myopia with anisometropia children were involved in this 1-year retrospective study. And bilateral myopia with anisometropia children were divided into group 2A (diopter of the lower SER eye under − 2.00D) and group 2B(diopter of the lower SER eye is equal or greater than − 2.00D). The change in AL were observed.The datas were analysed using SPSS 21.0.Results(1) In group 1, the mean baseline AL of the H eyes and L eye were 24.70 ± 0.89 mm and 23.55 ± 0.69 mm, respectively. In group 2A, the mean baseline AL of the H eyes and L eyes were 24.61 ± 0.84 mm and 24.00 ± 0.70 mm respectively. In group 2B, the mean baseline AL of the H eyes and L eyes were 25.28 ± 0.72 mm and 24.70 ± 0.74 mm. After 1 year, the change in AL of the L eyes was faster than the H eyes in group 1 and group 2A (all P<0.001).While the AL of the H eyes and L eyes had the same increased rate in group 2B. (2) The effect of controlling AL elongation of H eyes is consistent in three groups (P = 0.559).The effect of controlling AL elongation of L eyes in group 2B was better than that in group 1 and group 2A (P < 0.001). And the difference between group 1 and group 2A has no statistical significance. (3) The AL difference in H eyes and L eyes decreased from baseline 1.16 ± 0.55mm to 0.88 ± 0.68mm after 1 year in group 1.And in group 2A, the AL difference in H eyes and L eyes decreased from baseline 0.61 ± 0.34mm to 0.48 ± 0.28mm. There was statistically significant difference (all P<0.001). In group 2B, the baseline AL difference in H eyes and L eyes has no significant difference from that after 1 year (P = 0.069).ConclusionsMonocular OK lens is effective on suppression AL growth of the myopic eyes and reduce anisometropia value in unilateral myopic children. Binocular OK lenses only reduce anisometropia with the diopter of the low eye under − 2.00D. Binocular OK lenses cannot reduce anisometropia with the diopter of the low eye equal or greater than − 2.00D. Whether OK lens can reduce refractive anisometropia value is related to the spherical equivalent refractive of low refractive eye in bilateral myopia with anisometropia children after 1-year follow-up.

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