Lidar measurement for atmospheric density and temperature in middle atmosphere over Hefei

Falling-sphere sounding remains an important method for in situ determination in the middle atmosphere and is the only determination method within the altitude range of 60–100 km. Traditional single-falling-sphere sounding indicates only the atmospheric density and horizontal wind but not the vertical wind; the fundamental reason is that the equation set for retrieving atmospheric parameters is underdetermined. For tractability, previous studies assumed the vertical wind, which is much smaller than the horizontal wind, to be small or zero. Obtaining vertical wind profiles necessitates making the equations positive definite or overdetermined. An overdetermined equation set consisting of six equations, by which the optimal solution of density and three-dimensional wind can be obtained, can be established by the double-falling-sphere method. Hence, a simulation experiment is designed to retrieve the atmospheric density and three-dimensional wind field by double falling spheres. In the inversion results of the simulation experiment, the retrieved density is consistent with the constructed atmospheric density in magnitude; the density deviation rate does not generally exceed 20% (less than 5% below 60 km). The atmospheric density retrieved by the double-falling-sphere method is more accurate at low altitudes than the single-falling-sphere method. The vertical wind below 50 km and horizontal wind retrieved by double-falling-sphere method is highly consistent with the constructed average wind field. Additionally, the wind field deviation formula is deduced. These results establish the fact that the double-falling-sphere method is effective in detecting atmospheric density and three-dimensional wind.

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Global change induced trends in ion composition of the troposphere to the lower thermosphere

Annales Geophysicae ◽

10.5194/angeo-26-1181-2008 ◽

2008 ◽

Vol 26 (5) ◽

pp. 1181-1187 ◽

Cited By ~ 5

Author(s):

G. Beig

Keyword(s):

Middle Atmosphere ◽

Anthropogenic Activities ◽

Lower Thermosphere ◽

Cluster Ions ◽

Atmospheric Density ◽

Mesosphere And Lower Thermosphere ◽

Induced Changes ◽

Positive Ion ◽

Mlt Region

Abstract. In this paper a brief overview of the changes in atmospheric ion compositions driven by the human-induced changes in related neutral species, and temperature from the troposphere to lower thermosphere has been made. It is found that ionic compositions undergo significant variations. The variations calculated for the double-CO2 scenario are both long-term and permanent in nature. Major neutrals which take part in the lower and middle atmospheric ion chemical schemes and undergo significant changes due to anthropogenic activities are: O, O2, H2O, NO, acetonitrile, pyridinated compounds, acetone and aerosol. The concentration of positive ion/electron density does not change appreciably in the middle atmosphere but indicates a marginal decrease above about 75 km until about 85 km, above which the magnitude of negative trend decreases and becomes negligible at 93 km. Acetonitrile cluster ions in the upper stratosphere are likely to increase, whereas NO+ and NO+(H2O) in the mesosphere and lower thermosphere (MLT) region are expected to decrease for the double CO2 scenario. It is also found that the atmospheric density of pyridinated cluster ions is fast rising in the troposphere.

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Temporal variability of tidal and gravity waves during a record long 10 day continuous lidar sounding

10.5194/acp-2017-537 ◽

2017 ◽

Author(s):

Kathrin Baumgarten ◽

Michael Gerding ◽

Gerd Baumgarten ◽

Franz-Josef Lübken

Keyword(s):

Gravity Waves ◽

General Circulation ◽

Middle Atmosphere ◽

Wave Interaction ◽

Weather Conditions ◽

General Circulation Models ◽

Driving Mechanism ◽

Lidar Measurement ◽

Large Variability ◽

Tidal Waves

Abstract. Gravity waves (GW) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly infected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not implemented in many circulation models. The daylight capable Rayleigh-Mie-Raman (RMR) lidar at Kühlungsborn (54° N, 12&deg E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement which shows a large variability of gravity waves and tides on time scales of days. Using a 1-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement a strong 24 h-wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4–8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement and therefore a strong GW activity. The analysis indicates a further change in wave-wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GW in general circulation models.

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Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-371-2018 ◽

2018 ◽

Vol 18 (1) ◽

pp. 371-384 ◽

Cited By ~ 16

Author(s):

Kathrin Baumgarten ◽

Michael Gerding ◽

Gerd Baumgarten ◽

Franz-Josef Lübken

Keyword(s):

Gravity Waves ◽

General Circulation ◽

Middle Atmosphere ◽

Weather Conditions ◽

General Circulation Models ◽

Driving Mechanism ◽

Lidar Measurement ◽

Large Variability ◽

Tidal Waves ◽

Measurement Period

Abstract. Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly affected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not adequately implemented in many circulation models. The daylight-capable Rayleigh–Mie–Raman (RMR) lidar at Kühlungsborn (54∘ N, 12∘ E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement, which shows a large variability of gravity waves and tides on timescales of days. Using a one-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement period a strong 24 h wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4–8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement period and therefore a strong GW activity. The analysis indicates a further change in wave–wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GWs in general circulation models.

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Density correction of NRLMSISE-00 in the middle atmosphere (20–100 km) based on TIMED/SABER density data

10.5194/angeo-2019-93 ◽

2019 ◽

Author(s):

Xuan Cheng ◽

Junfeng Yang ◽

Cunying Xiao ◽

Xiong Hu

Keyword(s):

Correction Factor ◽

Middle Atmosphere ◽

Geomagnetic Storms ◽

Correction Function ◽

Quiet Period ◽

Atmospheric Density ◽

Density Data ◽

Density Correction ◽

Correction Effect ◽

Relative Errors

Abstract. This paper describes the density correction of the NRLMSISE-00 using more than 15 years (2002–2016) of TIMED/SABER satellite atmospheric density data from the middle atmosphere (20–100 km). A bias correction factor dataset is established based on the density differences between the TIMED/SABER data and NRLMSISE-00. Seven height nodes are set in the range 20–100 km. The different scale oscillations of the correction factor are separated at each height node, and the spherical harmonic function is used to fit the coefficients of the different timescale oscillations to obtain a spatiotemporal function at each height node. Cubic spline interpolation is used to obtain the correction factor at other heights. The spatiotemporal correction function proposed in this paper achieves a good correction effect on the atmospheric density of the NRLMSISE-00 model. The correction effect becomes more pronounced as the height increases. After correction, the relative error of the model decreased by 40–50 % in July, especially at ±40° N in the 80–100 km region. The atmospheric model corrected by the spatiotemporal function achieves higher accuracy for forecasting the atmospheric density during different geomagnetic activities. During geomagnetic storms, the relative errors in atmospheric density at 100 km, 72 km, and 32 km decrease from 41.21 %, 28.56 %, and 3.03 % to −9.65 %, 5.38 %, and 1.44 %, respectively, after correction. The relative errors in atmospheric density at 100 km, 72 km, and 32 km decrease from 68.95 %, 24.98 %, and 3.56 % to 3.49 %, 3.02 %, and 1.77 %, respectively, during geomagnetic quiet period. The correction effect during geomagnetic quiet period is better than that during geomagnetic storms at a height of 100 km. The subsequent effects of geomagnetic activity will be considered, and the atmospheric density during magnetic storms and quiet periods is corrected separately near 100 km. The ability of the model to characterize the mid-atmosphere (20–100 km) is significantly improved compared with the pre-correction performance. As a result, the corrected NRLMSISE-00 can provide more reliable atmospheric density data for scientific research and engineering fields such as data analysis, instrument design, and aerospace vehicles.

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Density Correction of NRLMSISE-00 in the Middle Atmosphere (20–100 km) Based on TIMED/SABER Density Data

Atmosphere ◽

10.3390/atmos11040341 ◽

2020 ◽

Vol 11 (4) ◽

pp. 341

Author(s):

Xuan Cheng ◽

Junfeng Yang ◽

Cunying Xiao ◽

Xiong Hu

Keyword(s):

Geomagnetic Activity ◽

Correction Factor ◽

Middle Atmosphere ◽

Geomagnetic Storms ◽

Correction Function ◽

Quiet Period ◽

Atmospheric Density ◽

Density Data ◽

Correction Effect ◽

Relative Errors

This paper describes the density correction of the NRLMSISE-00 using more than 15 years (2002–2016) of TIMED/SABER satellite atmospheric density data from the middle atmosphere (20–100 km). A bias correction factor dataset is established based on the density differences between the TIMED/SABER data and NRLMSISE-00. Seven height nodes are set in the range between 20 and 100 km. The different scale oscillations of the correction factor are separated at each height node, and the spherical harmonic function is used to fit the coefficients of the different timescale oscillations to obtain a spatiotemporal function at each height node. Cubic spline interpolation is used to obtain the correction factor at other non-node heights. The spatiotemporal correction function depends on six key parameters, including height, latitude, longitude, local time, day, and year. The evaluation results show that the spatiotemporal correction function proposed in this paper achieves a good correction effect on the atmospheric density of NRLMSISE-00. The correction effect becomes more pronounced as the height increases. After correction, the relative error of the model decreased by 40%–50% in July, especially at ±40° N in the 80–100 km region. The correction effect of the spatiotemporal correction function under different geomagnetic activity may have some potential relationships with geomagnetic activities. During geomagnetic storms, the relative errors in atmospheric density at 100, 70, and 32 km decrease from 41.21%, 22.09%, and 3.03% to −9.65%, 2.60%, and 1.44%, respectively, after correction. The relative errors in atmospheric density at 100, 70, and 32 km decrease from 68.95%, 21.02%, and 3.56% to 3.49%, 2.20%, and 1.77%, respectively, during the geomagnetic quiet period. The correction effect during the geomagnetic quiet period is better than that during geomagnetic storms at a height of 100 km. The subsequent effects of geomagnetic activity will be considered, and the atmospheric density during magnetic storms and quiet periods will be corrected separately near 100 km. The ability of the model to characterize the mid-atmosphere (20–100 km) is significantly improved compared with the pre-correction performance. As a result, the corrected NRLMSISE-00 can provide more reliable atmospheric density data for scientific researches and engineering fields, such as data analysis, instrument design, and aerospace vehicles.

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