scholarly journals Long-term behavior of the concentration of the minor constituents in the mesosphere – a model study

2009 ◽  
Vol 9 (8) ◽  
pp. 2779-2792 ◽  
Author(s):  
M. Grygalashvyly ◽  
G. R. Sonnemann ◽  
P. Hartogh
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Model Simulation ◽  
Vapor Concentration ◽  
Mixing Ratio ◽  
Constant Growth Rate ◽  
Model Calculations ◽  
Water Vapor Mixing Ratio ◽  
Long Term Behavior

Abstract. We investigate the influence the rising concentrations of methane, nitrous oxide and carbon dioxide which have occurred since the pre-industrial era, have had on the chemistry of the mesosphere. For this investigation we use our global 3-D-model COMMA-IAP which was designed for the exploration of the MLT-region and in particular the extended mesopause region. Assumptions and approximations for the trends in the Lyman-α flux (needed for the water vapor dissociation rate), methane and the water vapor mixing ratio at the hygropause are necessary to accomplish this study. To approximate the solar Lyman-α flux back to the pre-industrial time, we derived a quadratic fit using the sunspot number record which extends back to 1749 and is the only solar proxy available for the Lyman-α flux prior to 1947. We assume that methane increases with a constant growth rate from the pre-industrial era to the present. An unsolved problem for the model calculations consists of how the water vapor mixing ratio at the hygropause should be specified during this period. We assume that the hygropause was dryer during pre-industrial times than the present. As a consequence of methane oxidation, the model simulation indicates that the middle atmosphere has become more humid as a result of the rising methane concentration, but with some dependence on height and with a small time delay of few years. The solar influence on the water vapor mixing ratio is insignificant below about 80 km in summer high latitudes, but becomes increasingly more important above this altitude. The enhanced water vapor concentration increases the hydrogen radical concentration and reduces the mesospheric ozone. A second region of stronger ozone decrease is located in the vicinity of the stratopause. Increases in CO2 concentration enhance slightly the concentration of CO in the mesosphere. However, its influence upon the chemistry is small and its main effect is connected with a cooling of the upper atmosphere. The long-term behavior of water vapor is discussed in particular with respect to its impact on the NLC region.

scholarly journals Long-term trends of the concentration of the minor constituents in the mesosphere – a model study

2007 ◽  
Vol 7 (6) ◽  
pp. 15453-15494 ◽  
Author(s):  
M. Grygalashvyly ◽  
G. R. Sonnemann ◽  
P. Hartogh
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Co2 Concentration ◽  
Small Time ◽  
Vapor Concentration ◽  
Time Range ◽  
Mixing Ratio ◽  
Model Calculations ◽  
Water Vapor Mixing Ratio ◽  
The Impact

Abstract. We investigate the influence of the rising concentrations of methane, dinitrogen oxide and carbon dioxide since the pre-industrial era upon the chemistry of the mesosphere. We use for calculations our global 3D-model COMMA-IAP designed for the exploration of the MLT-region and particularly the extended mesopause region. In order to get approximated data of the solar Lyman-α flux back to the pre-industrial time, we derived a quadratic fit using the sunspot number available since 1749 as the only solar proxy for the Lyman-α flux before 1947. The Lyman-α flux values are employed to determine the water vapor dissociation rate. The water vapor trend analysis utilizes estimated methane trends since the pre-industrial era. An unsolved problem for the model calculations consists of the water vapor mixing ratio at the hygropause during the time range of trend calculation. We assume that the hygropause was dryer at the pre-industrial time than currently. As a consequence of the methane oxidation, the middle atmosphere became more humid according to the rising methane concentration, but depending on height and with a small time delay of few years. The solar influence on the water vapor mixing ratio is insignificant below about 80 km within summery high latitudes, but it becomes increasingly more important above this altitude. The growing water vapor concentration increases the hydrogen radical concentration and reduces the mesospheric ozone. A second region of stronger ozone decrease is located in the vicinity of the stratopause. Increasing CO2 concentration enhances slightly the concentration of CO in the mesosphere, but its influence upon the chemistry is small and its main effect is connected with a cooling of the upper atmosphere. We discuss the trends particularly in view of the impact on the NLC region.

On the long term evolution of noctilucent clouds

2020 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten
Keyword(s):  
Water Vapor ◽  
Middle Atmosphere ◽  
Vapor Concentration ◽  
Noctilucent Clouds ◽  
Mesopause Region ◽  
Water Ice ◽  
Term Evolution ◽  
Time Period ◽  
Modern Era

<p>Some of the earliest observations in the transition region between the Earth's atmosphere and space (roughly at 80-120km) come from so called `noctilucent clouds' (NLC) which are located around 83km altitude and consist of water ice particles. They owe their existence to the very cold summer mesopause region (~130K) at mid and high latitudes. There is a long standing dispute whether NLC are indicators of climate change in the middle atmosphere. We use model simulations of the background atmosphere and of ice particle formation for a time period of 138 years to show that an increase of NLC appearance is expected for recent decades due to increased anthropogenic release of methane being oxidized to water vapor in the middle atmosphere. Since the beginning of industrialization the water vapor concentration at NLC heights has presumably increased by about 40 percent (1 ppmv). The water vapor increase leads to a large enhancement of NLC brightness. Increased cooling by enhanced carbon dioxide alone (assuming no water vapor increase) counter-intuitively would lead to a decrease(!) of NLC brightness. NLC existed presumably since centuries, but the chance to observe them by naked eye was very small before the 20th century, whereas it is likely to see an NLC in the modern era. The eruption of volcano Krakatoa in 1883 has seemingly triggered the first observation of an NLC in 1885. In this presentation we extend our analysis from middle to polar latitudes and expand comparison with observations.</p>

scholarly journals Intercomparison of two cavity ring-down spectroscopy analyzers for atmospheric <sup>13</sup>CO<sub>2</sub>  ∕ <sup>12</sup>CO<sub>2</sub> measurement

2016 ◽  
Vol 9 (8) ◽  
pp. 3879-3891 ◽  
Author(s):  
Jiaping Pang ◽  
Xuefa Wen ◽  
Xiaomin Sun ◽  
Kuan Huang
Keyword(s):  
Water Vapor ◽  
Co2 Concentration ◽  
Calibration Method ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Mixing Ratio ◽  
Ambient Conditions ◽  
Significant Linear Correlation ◽  
The Difference ◽  
Water Vapor Mixing Ratio

Abstract. Isotope ratio infrared spectroscopy (IRIS) permits continuous in situ measurement of CO2 isotopic composition under ambient conditions. Previous studies have mainly focused on single IRIS instrument performance; few studies have considered the comparability among different IRIS instruments. In this study, we carried out laboratory and ambient measurements using two Picarro CO2δ13C analyzers (G1101-i and G2201-i (newer version)) and evaluated their performance and comparability. The best precision was 0.08–0.15 ‰ for G1101-i and 0.01–0.04 ‰ for G2201-i. The dependence of δ13C on CO2 concentration was 0.46 ‰ per 100 ppm and 0.09 ‰ per 100 ppm, the instrument drift ranged from 0.92–1.09 ‰ and 0.19–0.37 ‰, and the sensitivity of δ13C to the water vapor mixing ratio was 1.01 ‰ ∕ % H2O and 0.09 ‰ ∕ % H2O for G1101-i and G2201-i, respectively. The accuracy after correction by the two-point mixing ratio gain and offset calibration method ranged from −0.04–0.09 ‰ for G1101-i and −0.13–0.03 ‰ for G2201-i. The sensitivity of δ13C to the water vapor mixing ratio improved from 1.01 ‰ ∕ % H2O before the upgrade of G1101-i (G1101-i-original) to 0.15 ‰ ∕ % H2O after the upgrade of G1101-i (G1101-i-upgraded). Atmospheric δ13C measured by G1101-i and G2201-i captured the rapid changes in atmospheric δ13C signals on hourly to diurnal cycle scales, with a difference of 0.07 ± 0.24 ‰ between G1101-i-original and G2201-i and 0.05 ± 0.30 ‰ between G1101-i-upgraded and G2201-i. A significant linear correlation was observed between the δ13C difference of G1101-i-original and G2201-i and the water vapor concentration, but there was no significant correlation between the δ13C difference of G1101-i-upgraded and G2201-i and the water vapor concentration. The difference in the Keeling intercept values decreased from 1.24 ‰ between G1101-i-original and G2201-i to 0.36 ‰ between G1101-i-upgraded and G2201-i, which indicates the importance of consistency among different IRIS instruments.

scholarly journals Inter-comparison of two cavity ring-down spectroscopy analyzers for atmospheric <sup>13</sup>CO<sub>2</sub> / <sup>12</sup>CO<sub>2</sub> measurement

2016 ◽  
Author(s):  
Jiaping Pang ◽  
Xuefa Wen ◽  
Xiaomin Sun ◽  
Kuan Huang
Keyword(s):  
Water Vapor ◽  
Co2 Concentration ◽  
Calibration Method ◽  
Vapor Concentration ◽  
Mixing Ratio ◽  
Ambient Conditions ◽  
Significant Linear Correlation ◽  
Before And After ◽  
The Difference ◽  
Water Vapor Mixing Ratio

Abstract. The isotope ratio infrared spectroscopy (IRIS) permits in situ and continuous measurements of CO2 isotopic composition under ambient conditions. Previous studies mainly focused on single IRIS instrument performance, few studies have paid attention to the comparability among different IRIS instruments. In this study, we carried out laboratory and ambient measurements of two Picarro CO2 δ13C analyzers (G1101-i and G2201-i), and evaluated their performance and comparability. The best precision were 0.08 ~ 0.15 ‰ and 0.01 ~ 0.04 ‰, the dependence of δ13C on CO2 concentration were 0.46 ‰ per 100 ppm and 0.09 ‰ per 100 ppm, the instrument drift ranged from 0.92 ~ 1.09 ‰ and 0.19 ~ 0.37 ‰. After upgradation of G1101-i, the sensitivity of δ13C on water vapor mixing ratio were 0.15 ‰ / % H2O and 0.13 ‰ / % H2O for the G1101-i and G2201-i, respectively. The accuracy after corrected by the two-point mixing ratio gain and offset calibration method ranged from −0.04 ~ 0.09 ‰ and −0.13 ~ 0.03 ‰ for G1101-i and G2201-i, respectively. Atmospheric δ13C measurements captured the rapidly changing atmospheric δ13C signals, with the difference of 0.07 ± 0.24 ‰ and 0.05 ± 0.30 ‰ between G1101-i upgraded before and after and G2201-i. Before upgradation of G1101-i, a significant linear correlation was observed between the δ13C difference and water vapor concentration, but there is no significant correlation after upgradation of G1101-i. The difference of Keeling intercept values between G1101-i and G2201-i decrease from 1.24 ‰ to 0.36 ‰, which indicate the importance of consistency among different IRIS instruments.

The seasonal correlation between atmospheric water vapor and aerosol extinction and the relationship between aerosol, NO2, SO2 and water vapor during haze pollution in Qingdao, China

2020 ◽  
Author(s):  
Hongmei Ren ◽  
Ang Li ◽  
Zhaokun Hu ◽  
Yeyuan Huang ◽  
Jin Xu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Moisture Absorption ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Aerosol Extinction ◽  
Mixing Ratio ◽  
Haze Pollution ◽  
Water Vapor Mixing Ratio ◽  
Seasonal Correlation ◽  
The Relationship

&lt;p&gt;MAX-DOAS observations was carried out from March 1, 2019 to December 31, 2019 in Qingdao, China, to measure the O&lt;sub&gt;4&lt;/sub&gt;, NO&lt;sub&gt;2&lt;/sub&gt;, SO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O absorption, to retrieve AOD and the troposphere vertical column concentration of NO&lt;sub&gt;2&lt;/sub&gt;, SO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O.We use PriAM algorithm which based on the optimal estimation to calculating volume mixing ratio profile of trace gases, aerosol and water vapor during 0 ~ 4 km. The correlation between AOD and H&lt;sub&gt;2&lt;/sub&gt;O VCD was analyzed in every month, the results showed that the AOD and H&lt;sub&gt;2&lt;/sub&gt;O VCD has good linear relationship in each month., illustrate the increase of water vapor concentration will lead to the increase of moisture absorption of aerosol. The seasonal variation of the four seasonal correlation slopes in the order of summer &lt; autumn &lt; spring &lt; winter. The influence of concentration change of NO&lt;sub&gt;2&lt;/sub&gt; VCD, SO&lt;sub&gt;2&lt;/sub&gt; VCD, H&lt;sub&gt;2&lt;/sub&gt;O VCD and AOD is discussed in a haze episodes occurred in December 2019. Discovery that the H&lt;sub&gt;2&lt;/sub&gt;O VCD and AOD was increased at the same time in the haze pollution incident, but with the increase of water vapor concentration, the concentration of NO&lt;sub&gt;2&lt;/sub&gt; and SO&lt;sub&gt;2&lt;/sub&gt; decreases, indicated that due to the increase of concentration of water vapor, NO&lt;sub&gt;2&lt;/sub&gt; and SO&lt;sub&gt;2&lt;/sub&gt; heterogeneous reaction will happen to generate nitrate and sulfate aerosols, so that the concentration of NO&lt;sub&gt;2&lt;/sub&gt; and SO&lt;sub&gt;2 &lt;/sub&gt;concentration was decreased. The relationship between NO&lt;sub&gt;2&lt;/sub&gt;, SO&lt;sub&gt;2&lt;/sub&gt;, AOD and water vapor mixing ratio of 50m, 200m, 400m and 600m during haze pollution period was also studied, and it was indicated that phenomenon aerosol extinction increased with the increase of water vapor mixing ratio, while NO&lt;sub&gt;2&lt;/sub&gt; and SO&lt;sub&gt;2&lt;/sub&gt;, on the contrary, were more obvious at 50m and 200m near the ground.&lt;/p&gt;

Subcloud and Cloud-Base Latent Heat Fluxes during Shallow Cumulus Convection

2019 ◽  
Vol 77 (3) ◽  
pp. 1081-1100 ◽  
Author(s):  
Neil P. Lareau
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Latent Heat ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Cloud Base ◽  
Cumulus Convection ◽  
Mixing Ratio ◽  
Convective Boundary ◽  
Water Vapor Mixing Ratio

Abstract Doppler and Raman lidar observations of vertical velocity and water vapor mixing ratio are used to probe the physics and statistics of subcloud and cloud-base latent heat fluxes during cumulus convection at the ARM Southern Great Plains (SGP) site in Oklahoma, United States. The statistical results show that latent heat fluxes increase with height from the surface up to ~0.8Zi (where Zi is the convective boundary layer depth) and then decrease to ~0 at Zi. Peak fluxes aloft exceeding 500 W m−2 are associated with periods of increased cumulus cloud cover and stronger jumps in the mean humidity profile. These entrainment fluxes are much larger than the surface fluxes, indicating substantial drying over the 0–0.8Zi layer accompanied by moistening aloft as the CBL deepens over the diurnal cycle. We also show that the boundary layer humidity budget is approximately closed by computing the flux divergence across the 0–0.8Zi layer. Composite subcloud velocity and water vapor anomalies show that clouds are linked to coherent updraft and moisture plumes. The moisture anomaly is Gaussian, most pronounced above 0.8Zi and systematically wider than the velocity anomaly, which has a narrow central updraft flanked by downdrafts. This size and shape disparity results in downdrafts characterized by a high water vapor mixing ratio and thus a broad joint probability density function (JPDF) of velocity and mixing ratio in the upper CBL. We also show that cloud-base latent heat fluxes can be both positive and negative and that the instantaneous positive fluxes can be very large (~10 000 W m−2). However, since cloud fraction tends to be small, the net impact of these fluxes remains modest.

scholarly journals A practical information-centered technique to remove a priori information from lidar optimal-estimation-method retrievals

2019 ◽  
Vol 12 (7) ◽  
pp. 3943-3961 ◽  
Author(s):  
Ali Jalali ◽  
Shannon Hicks-Jalali ◽  
Robert J. Sica ◽  
Alexander Haefele ◽  
Thomas von Clarmann
Keyword(s):  
Water Vapor ◽  
A Priori ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Mixing Ratio ◽  
A Priori Information ◽  
Fine Grid ◽  
Large Power ◽  
Priori Information ◽  
Water Vapor Mixing Ratio

Abstract. Lidar retrievals of atmospheric temperature and water vapor mixing ratio profiles using the optimal estimation method (OEM) typically use a retrieval grid with a number of points larger than the number of pieces of independent information obtainable from the measurements. Consequently, retrieved geophysical quantities contain some information from their respective a priori values or profiles, which can affect the results in the higher altitudes of the temperature and water vapor profiles due to decreasing signal-to-noise ratios. The extent of this influence can be estimated using the retrieval's averaging kernels. The removal of formal a priori information from the retrieved profiles in the regions of prevailing a priori effects is desirable, particularly when these greatest heights are of interest for scientific studies. We demonstrate here that removal of a priori information from OEM retrievals is possible by repeating the retrieval on a coarser grid where the retrieval is stable even without the use of formal prior information. The averaging kernels of the fine-grid OEM retrieval are used to optimize the coarse retrieval grid. We demonstrate the adequacy of this method for the case of a large power-aperture Rayleigh scatter lidar nighttime temperature retrieval and for a Raman scatter lidar water vapor mixing ratio retrieval during both day and night.

Water-vapor Measurements in the Lower Stratosphere

1974 ◽  
Vol 52 (8) ◽  
pp. 1527-1531 ◽  
Author(s):  
H. J. Mastenbrook
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Marked Decrease ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Mixing Ratio ◽  
Stratospheric Water Vapor ◽  
Mixing Ratios ◽  
Natural Concentration ◽  
General Range

Nearly 10 years of water-vapor measurements to heights of 30 km provide a basis for assessing the natural concentration of stratospheric water vapor and its variability. The measurements which began in 1964 have been made at monthly intervals from the mid-latitude location of Washington, D.C, using a balloon-borne frost-point hygrometer. The observations show the mixing ratio of water-vapor mass to air mass in the stratosphere to be in the general range of 1 to 4 p.p.m. with a modal concentration between 2 and 3 p.p.m. An annual cycle of mixing ratio is evident for the low stratosphere. A trend of water-vapor increase observed during the first 6 years does not persist beyond 1969 or 1970. The 6 year increase was followed by a marked decrease in 1971, with mixing ratios remaining generally below 3 p.p.m. thereafter. The measurements of recent years suggest that the series of observations may have begun during a period of low water-vapor concentration in the stratosphere.

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