scholarly journals Quasi 18 h wave activity in ground-based observed mesospheric H<sub>2</sub>O over Bern, Switzerland

2017 ◽  
Vol 17 (24) ◽  
pp. 14905-14917 ◽  
Author(s):  
Martin Lainer ◽  
Klemens Hocke ◽  
Rolf Rüfenacht ◽  
Niklaus Kämpfer
Keyword(s):  
Water Vapor ◽  
Pressure Range ◽  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Low Frequency ◽  
Wave Interaction ◽  
High Temporal Resolution ◽  
Data Sets ◽  
Wave Signature ◽  
The Impact

Abstract. Observations of oscillations in the abundance of middle-atmospheric trace gases can provide insight into the dynamics of the middle atmosphere. Long-term, high-temporal-resolution and continuous measurements of dynamical tracers within the strato- and mesosphere are rare but would facilitate better understanding of the impact of atmospheric waves on the middle atmosphere. Here we report on water vapor measurements from the ground-based microwave radiometer MIAWARA (MIddle Atmospheric WAter vapor RAdiometer) located close to Bern during two winter periods of 6 months from October to March. Oscillations with periods between 6 and 30 h are analyzed in the pressure range 0.02–2 hPa. Seven out of 12 months have the highest wave amplitudes between 15 and 21 h periods in the mesosphere above 0.1 hPa. The quasi 18 h wave signature in the water vapor tracer is studied in more detail by analyzing its temporal evolution in the mesosphere up to an altitude of 75 km. Eighteen-hour oscillations in midlatitude zonal wind observations from the microwave Doppler wind radiometer WIRA (WInd RAdiometer) could be identified within the pressure range 0.1–1 hPa during an ARISE (Atmospheric dynamics Research InfraStructure in Europe)-affiliated measurement campaign at the Observatoire de Haute-Provence (355 km from Bern) in France in 2013. The origin of the observed upper-mesospheric quasi 18 h oscillations is uncertain and could not be determined with our available data sets. Possible drivers could be low-frequency inertia-gravity waves or a nonlinear wave–wave interaction between the quasi 2-day wave and the diurnal tide.

scholarly journals Quasi 18-hour wave activity in ground-based observed mesospheric H<sub>2</sub>O over Bern, Switzerland

2017 ◽  
Author(s):  
Martin Lainer ◽  
Klemens Hocke ◽  
Rolf Rüfenacht ◽  
Franziska Schranz ◽  
Niklaus Kämpfer
Keyword(s):  
Water Vapor ◽  
Gravity Waves ◽  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Chemical Species ◽  
Wind Data ◽  
Horizontal Wind ◽  
Time Range ◽  
High Temporal Resolution ◽  
The Impact

Abstract. Observations of oscillations in the abundance of middle atmospheric trace gases can provide insight into the dynamics of the middle atmosphere. Long term, high temporal resolution and continuous measurements of dynamical tracers within the strato- and mesosphere are rare, but would be important to better understand the impact of planetary and gravity waves on the middle atmosphere. Here we report on water vapor measurements from the ground-based microwave radiometer MIAWARA located close to Bern during two winter periods of 6 months from October to March. Oscillations with periods between 6 and 30 hours are analyzed in the pressure range 0.01–10 hPa. Seven out of twelve months have the highest wave amplitudes between 15 and 21 hour periods in the mesosphere above 0.1 hPa. The quasi 18-hour wave is studied in more detail. We examine the temporal behavior and use SD-WACCM simulations for comparison and to derive characteristic wave features considering low-frequency gravity-waves being involved in the observed water vapor oscillations. The 18-hour wave is also found in SD-WACCM horizontal wind data and in measured zonal wind from the microwave Doppler wind radiometer WIRA. For two cases in January 2016 we derive the propagation direction, intrinsic period, horizontal and vertical wavelength of the model resolved 18-hour wave. A south-westward to westward propagation with horizontal wavelengths of 1884 and 1385 km and intrinsic periods close to 14 h are found. Vertical wavelengths are below 6 km. We were not able to single out a distinct temporal correlation between 18-hour band-pass filtered water vapor and wind data time series, although H2O should mostly be dynamically controlled in the mesosphere and sub-diurnal time range. More sophisticated numerical model studies are needed to uncover the manifold effects of gravity waves on the abundance of chemical species.

scholarly journals Assessment of Sampling Effects on Various Satellite-Derived Integrated Water Vapor Datasets Using GPS Measurements in Germany as Reference

2020 ◽  
Vol 12 (7) ◽  
pp. 1170 ◽  
Author(s):  
Cintia Carbajal Henken ◽  
Lisa Dirks ◽  
Sandra Steinke ◽  
Hannes Diedrich ◽  
Thomas August ◽  
...  
Keyword(s):  
Water Vapor ◽  
Pairwise Comparison ◽  
Weather Conditions ◽  
Satellite System ◽  
High Temporal Resolution ◽  
Data Sets ◽  
Frequency Distributions ◽  
Temporal Sampling ◽  
Global Navigation Satellite ◽  
Satellite Instruments

Passive imagers on polar-orbiting satellites provide long-term, accurate integrated water vapor (IWV) data sets. However, these climatologies are affected by sampling biases. In Germany, a dense Global Navigation Satellite System network provides accurate IWV measurements not limited by weather conditions and with high temporal resolution. Therefore, they serve as a reference to assess the quality and sampling issues of IWV products from multiple satellite instruments that show different orbital and instrument characteristics. A direct pairwise comparison between one year of IWV data from GPS and satellite instruments reveals overall biases (in kg/m 2 ) of 1.77, 1.36, 1.11, and −0.31 for IASI, MIRS, MODIS, and MODIS-FUB, respectively. Computed monthly means show similar behaviors. No significant impact of averaging time and the low temporal sampling on aggregated satellite IWV data is found, mostly related to the noisy weather conditions in the German domain. In combination with SEVIRI cloud coverage, a change of shape of IWV frequency distributions towards a bi-modal distribution and loss of high IWV values are observed when limiting cases to daytime and clear sky. Overall, sampling affects mean IWV values only marginally, which are rather dominated by the overall retrieval bias, but can lead to significant changes in IWV frequency distributions.

scholarly journals Evaluation of CLaMS, KASIMA and ECHAM5/MESSy1 simulations in the lower stratosphere using observations of Odin/SMR and ILAS/ILAS-II

2009 ◽  
Vol 9 (1) ◽  
pp. 1977-2020
Author(s):  
F. Khosrawi ◽  
R. Müller ◽  
M. H. Proffitt ◽  
R. Ruhnke ◽  
O. Kirner ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Lagrangian Model ◽  
Data Sets ◽  
Data Set ◽  
The Impact

Abstract. 1-year data sets of monthly averaged nitrous oxide (N2O) and ozone (O3) derived from satellite measurements were used as a tool for the evaluation of atmospheric photochemical models. Two 1-year data sets, one derived from the Improved Limb Atmospheric Spectrometer (ILAS and ILAS-II) and one from the Odin Sub-Millimetre Radiometer (Odin/SMR) were employed. Here, these data sets are used for the evaluation of two Chemical Transport Models (CTMs), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) and the Chemical Lagrangian Model of the Stratosphere (CLaMS) as well as for one Chemistry-Climate Model (CCM), the atmospheric chemistry general circulation model ECHAM5/MESSy1 (E5M1) in the lower stratosphere with focus on the Northern Hemisphere. Since the Odin/SMR measurements cover the entire hemisphere, the evaluation is performed for the entire hemisphere as well as for the low latitudes, midlatitudes and high latitudes using the Odin/SMR 1-year data set as reference. To assess the impact of using different data sets for such an evaluation study we repeat the evaluation for the polar lower stratosphere using the ILAS/ILAS-II data set. Only small differences were found using ILAS/ILAS-II instead of Odin/SMR as a reference, thus, showing that the results are not influenced by the particular satellite data set used for the evaluation. The evaluation of CLaMS, KASIMA and E5M1 shows that all models are in good agreement with Odin/SMR and ILAS/ILAS-II. Differences are generally in the range of ±20%. Larger differences (up to −40%) are found in all models at 500±25 K for N2O mixing ratios greater than 200 ppb. Generally, the largest differences were found for the tropics and the lowest for the polar regions. However, an underestimation of polar winter ozone loss was found both in KASIMA and E5M1 both in the Northern and Southern Hemisphere.

scholarly journals Evaluation of two Vaisala RS92 radiosonde solar radiative dry bias correction algorithms

2015 ◽  
Vol 8 (10) ◽  
pp. 10755-10792
Author(s):  
A. M. Dzambo ◽  
D. D. Turner ◽  
E. J. Mlawer
Keyword(s):  
Water Vapor ◽  
Statistical Significance ◽  
Microwave Radiometer ◽  
Precipitable Water ◽  
Upper Troposphere ◽  
Clear Sky ◽  
Microwave Radiometers ◽  
The Impact ◽  
Dry Bias ◽  
Better Than

Abstract. Solar heating of the relative humidity (RH) probe on Vaisala RS92 radiosondes results in a large dry bias in the upper troposphere. Two different algorithms (Miloshevich et al., 2009, MILO hereafter; and Wang et al., 2013, WANG hereafter) have been designed to account for this solar radiative dry bias (SRDB). These corrections are markedly different with MILO adding up to 40 % more moisture to the original radiosonde profile than WANG; however, the impact of the two algorithms varies with height. The accuracy of these two algorithms is evaluated using three different approaches: a comparison of precipitable water vapor (PWV), downwelling radiative closure with a surface-based microwave radiometer at a high-altitude site (5.3 km MSL), and upwelling radiative closure with the space-based Atmospheric Infrared Sounder (AIRS). The PWV computed from the uncorrected and corrected RH data is compared against PWV retrieved from ground-based microwave radiometers at tropical, mid-latitude, and arctic sites. Although MILO generally adds more moisture to the original radiosonde profile in the upper troposphere compared to WANG, both corrections yield similar changes to the PWV, and the corrected data agree well with the ground-based retrievals. The two closure activities – done for clear-sky scenes – use the radiative transfer models MonoRTM and LBLRTM to compute radiance from the radiosonde profiles to compare against spectral observations. Both WANG- and MILO-corrected RH are statistically better than original RH in all cases except for the driest 30 % of cases in the downwelling experiment, where both algorithms add too much water vapor to the original profile. In the upwelling experiment, the RH correction applied by the WANG vs. MILO algorithm is statistically different above 10 km for the driest 30 % of cases and above 8 km for the moistest 30 % of cases, suggesting that the MILO correction performs better than the WANG in clear-sky scenes. The cause of this statistical significance is likely explained by the fact the WANG correction also accounts for cloud cover – a condition not accounted for in the radiance closure experiments.

scholarly journals Water Vapor Retrieval using the Precision Solar Spectroradiometer

2017 ◽  
Author(s):  
Panagiotis-Ioannis Raptis ◽  
Stelios Kazadzis ◽  
Julian Gröbner ◽  
Natalia Kouremeti ◽  
Lionel Doppler ◽  
...  
Keyword(s):  
Water Vapor ◽  
Single Channel ◽  
Microwave Radiometer ◽  
Coefficient Of Determination ◽  
High Temporal Resolution ◽  
Spectral Approach ◽  
Spectral Measurements ◽  
Channel Wavelength ◽  
Relative Differences ◽  
High Absorption

Abstract. The Precision Solar SpectroRadiometer (PSR) is a new spectroradiometer developed at Physikalisch-Meteorologisches Observatorium Davos-World Radiation Center (PMOD-WRC), Davos, measuring Direct Solar Irradiance at the surface, in the 300–1020 nm spectral range at high temporal resolution. The purpose of this work is to investigate the instrument's potential of retrieving Integrated Water Vapor (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV, the first one using single channel/wavelength measurements, following a theoretical water vapor high absorption wavelength, and the second one using direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year dataset, consisting of an AERONET sun- photometer Cimel CE318, a Global Positioning System (GPS), a Microwave Radiometer Profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods/instruments was achieved using the 946 nm channel, while for the spectral approach using the 934–948 nm window. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R2) being in the region of 0.87–0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R2 in the region of 0.96–0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08–0.30 cm and only in extreme cases would reach up to 15 %.

scholarly journals Validating HY-2A CMR Precipitable Water Vapor Using Ground-based and Shipborne GNSS Observations

2020 ◽  
Author(s):  
Zhilu Wu ◽  
Yanxiong Liu ◽  
Yang Liu ◽  
Jungang Wang ◽  
Xiufeng He ◽  
...  
Keyword(s):  
Water Vapor ◽  
Microwave Radiometer ◽  
Precipitable Water ◽  
Global Navigation Satellite Systems ◽  
High Temporal Resolution ◽  
Satellite Systems ◽  
The Indian Ocean ◽  
Global Navigation Satellite ◽  
Gnss Data ◽  
Gnss Observations

Abstract. The calibration microwave radiometer (CMR) onboard Haiyang-2A satellite provides wet tropospheric delays correction for altimetry data, which can also contribute to the understanding of climate system and weather processes. Ground-based Global Navigation Satellite Systems (GNSS) provide precise PWV with high temporal resolution and could be used for calibration and monitoring of the CMR data, and shipborne GNSS provides accurate PWV over open oceans, which can be directly compared with uncontaminated CMR data. In this study, the HY-2A CMR water vapor product is validated using ground-based GNSS observations of 100 IGS stations along the coastline and 56-day shipborne GNSS observations over the Indian Ocean. The processing strategy for GNSS data and CMR data is discussed in detail. Special efforts were made to the quality control and reconstruction of contaminated CMR data. The validation result shows that HY-2A CMR PWV agrees well with ground-based GNSS PWV with 2.67 mm in RMS within 100 km. Geographically, the RMS is 1.12 mm in the polar region and 2.78 mm elsewhere. The PWV agreement between HY-2A and shipborne GNSS shows a significant correlation with the distance between the ship and the satellite footprint, with an RMS of 1.57 mm for the distance threshold of 100 km. Ground-based GNSS and shipborne GNSS agree with HY-2A CMR well with no obvious system error.

scholarly journals Evaluation of two Vaisala RS92 radiosonde solar radiative dry bias correction algorithms

2016 ◽  
Vol 9 (4) ◽  
pp. 1613-1626 ◽  
Author(s):  
Andrew M. Dzambo ◽  
David D. Turner ◽  
Eli J. Mlawer
Keyword(s):  
Water Vapor ◽  
Statistical Significance ◽  
Microwave Radiometer ◽  
Precipitable Water ◽  
Upper Troposphere ◽  
Clear Sky ◽  
Microwave Radiometers ◽  
The Impact ◽  
Dry Bias ◽  
Better Than

Abstract. Solar heating of the relative humidity (RH) probe on Vaisala RS92 radiosondes results in a large dry bias in the upper troposphere. Two different algorithms (Miloshevich et al., 2009, MILO hereafter; and Wang et al., 2013, WANG hereafter) have been designed to account for this solar radiative dry bias (SRDB). These corrections are markedly different with MILO adding up to 40 % more moisture to the original radiosonde profile than WANG; however, the impact of the two algorithms varies with height. The accuracy of these two algorithms is evaluated using three different approaches: a comparison of precipitable water vapor (PWV), downwelling radiative closure with a surface-based microwave radiometer at a high-altitude site (5.3 km m.s.l.), and upwelling radiative closure with the space-based Atmospheric Infrared Sounder (AIRS). The PWV computed from the uncorrected and corrected RH data is compared against PWV retrieved from ground-based microwave radiometers at tropical, midlatitude, and arctic sites. Although MILO generally adds more moisture to the original radiosonde profile in the upper troposphere compared to WANG, both corrections yield similar changes to the PWV, and the corrected data agree well with the ground-based retrievals. The two closure activities – done for clear-sky scenes – use the radiative transfer models MonoRTM and LBLRTM to compute radiance from the radiosonde profiles to compare against spectral observations. Both WANG- and MILO-corrected RHs are statistically better than original RH in all cases except for the driest 30 % of cases in the downwelling experiment, where both algorithms add too much water vapor to the original profile. In the upwelling experiment, the RH correction applied by the WANG vs. MILO algorithm is statistically different above 10 km for the driest 30 % of cases and above 8 km for the moistest 30 % of cases, suggesting that the MILO correction performs better than the WANG in clear-sky scenes. The cause of this statistical significance is likely explained by the fact the WANG correction also accounts for cloud cover – a condition not accounted for in the radiance closure experiments.

Observational evidence of polar mesospheric ozone loss following substorm events

2021 ◽  
Author(s):  
Keeta Chapman-Smith ◽  
Annika Seppälä ◽  
Craig Rodger ◽  
Aaron Hendry
Keyword(s):  
Middle Atmosphere ◽  
Energetic Particles ◽  
Observational Evidence ◽  
Electron Precipitation ◽  
Data Sets ◽  
Ozone Loss ◽  
Mesospheric Ozone ◽  
Ozone Monitoring ◽  
The Impact

&lt;p&gt;Ozone in the polar middle atmosphere is known to be affected by charged energetic particles precipitating into the atmosphere from the magnetosphere. In recent years there has been increased interest in the sources and consequences of electron precipitation into the atmosphere. Substorms are an important source of electron precipitation. They occur hundreds of times a year and drive processes which cause electrons to be lost into our atmosphere. The electrons ionise neutrals in the atmosphere resulting in the production of HO&lt;sub&gt;x&lt;/sub&gt;&amp;#160;and NO&lt;sub&gt;x&lt;/sub&gt;, which catalytically destroy ozone. Simulations have examined substorm driven ozone loss and shown it is likely to be significant. However, this has not previously been verified from observations. Here we use polar mesospheric ozone observations from the Global Ozone Monitoring by Occultation of Stars (GOMOS) and Microwave Limb Sounder (MLS) instruments to investigate the impact of substorms. Using the superposed epoch technique we find consistent 10-20% reduction in mesospheric ozone in both data sets. This provides the first observational evidence that substorms are important to the ozone balance within the atmosphere.&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;/p&gt;

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