scholarly journals Long-term evolution and seasonal modulation of methanol above Jungfraujoch (46.5° N, 8.0° E): optimisation of the retrieval strategy, comparison with model simulations and independent observations

2014 ◽  
Vol 7 (5) ◽  
pp. 4659-4692 ◽  
Author(s):  
W. Bader ◽  
T. Stavrakou ◽  
J.-F. Muller ◽  
S. Reimann ◽  
C. D. Boone ◽  
...  
Keyword(s):  
Peak Amplitude ◽  
Systematic Bias ◽  
Retrieval Strategy ◽  
Model Simulations ◽  
Term Evolution ◽  
Time Period ◽  
Independent Observations ◽  
June July

Abstract. Methanol (CH3OH) is the second most abundant organic compound in the Earth's atmosphere after methane. In this work, we present the first long-term time series of methanol total, lower tropospheric and upper tropospheric-lower stratospheric partial columns derived from the analysis of high resolution Fourier transform infrared solar spectra recorded at the Jungfraujoch station (46.5° N, 3580 m a.s.l.). The retrieval of methanol is very challenging due to strong absorptions of ozone in the region of the selected υ8 band of CH3OH. Two wide spectral intervals have been defined and adjusted in order to maximize the information content. Methanol does not exhibit a significant trend over the 1995–2012 time period, but a strong seasonal modulation characterized by maximum values and variability in June–July, minimum columns in winter and a peak-to-peak amplitude of 130%. In situ measurements performed at the Jungfraujoch and ACE-FTS occultations give similar results for the methanol seasonal variation. The total and lower tropospheric columns are also compared with IMAGESv2 model simulations. There is no systematic bias between the observations and IMAGESv2 but the model underestimates the peak-to-peak amplitude of the seasonal modulations.

scholarly journals Long-term evolution and seasonal modulation of methanol above Jungfraujoch (46.5° N, 8.0° E): optimisation of the retrieval strategy, comparison with model simulations and independent observations

2014 ◽  
Vol 7 (11) ◽  
pp. 3861-3872 ◽  
Author(s):  
W. Bader ◽  
T. Stavrakou ◽  
J.-F. Muller ◽  
S. Reimann ◽  
C. D. Boone ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Atmospheric Chemistry ◽  
Peak Amplitude ◽  
Systematic Bias ◽  
Model Simulations ◽  
Time Period ◽  
Independent Observations ◽  
June July

Abstract. Methanol (CH3OH) is the second most abundant organic compound in the Earth's atmosphere after methane. In this study, we present the first long-term time series of methanol total, lower tropospheric and upper tropospheric–lower stratospheric partial columns derived from the analysis of high resolution Fourier transform infrared solar spectra recorded at the Jungfraujoch station (46.5° N, 3580 m a.s.l.). The retrieval of methanol is very challenging due to strong absorptions of ozone in the region of the selected υ8 band of CH3OH. Two wide spectral intervals have been defined and adjusted in order to maximise the information content. Methanol does not exhibit a significant trend over the 1995–2012 time period, but a strong seasonal modulation characterised by maximum values and variability in June–July, minimum columns in winter and a peak-to-peak amplitude of 130%. Analysis and comparisons with in situ measurements carried out at the Jungfraujoch and ACE-FTS (Atmospheric Chemistry Experiment-Fourier transform spectrometer) occultations have been performed. The total and lower tropospheric columns are also compared with IMAGESv2 model simulations. There is no systematic bias between the observations and IMAGESv2 but the model underestimates the peak-to-peak amplitude of the seasonal modulations.

scholarly journals ROGUE WAVE ASYMMETRY IN THE DIRECT NUMERICAL SIMULATIONS OF DIRECTIONAL JONSWAP WAVES

2020 ◽  
pp. 48
Author(s):  
Alexey Slunyaev ◽  
Anna Kokorina
Keyword(s):  
Water Wave ◽  
Rogue Wave ◽  
Rogue Waves ◽  
Hydrodynamic Equations ◽  
Laboratory Measurements ◽  
Term Evolution ◽  
Typical Picture ◽  
High Order Spectral Method

The asymmetry between the troughs from the rear and front sides of rogue waves is the particular object of the present study. In our previous simulations of unidirectional waves the typical picture of a rogue waves possesses the trend that most of the rogue waves where characterized by deeper rear troughs. In the present work we broaden the discussion of the rogue wave front-to-crest asymmetry to the directional case. The direct numerical simulation of primitive water equations is an affordable alternative to the in-situ or laboratory measurements, in particularly when the interest is focused on the long-term evolution or on the detailed consideration of the water wave movement in space and time. In this work we simulate irregular surface waves in the hydrodynamic equations using the High-Order Spectral Method, and focus on the so-called rogue waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/plseXdjpE6c

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 Ground-based FTIR retrievals of SF<sub>6</sub> at Réunion Island

2017 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Corinne Vigouroux ◽  
Pucai Wang ◽  
Christian Hermans ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
In Situ Measurements ◽  
Annual Growth Rate ◽  
Retrieval Strategy ◽  
Satellite Measurements ◽  
Individual Layer ◽  
Time Period ◽  
Independent Information ◽  
Air Column

Abstract. SF6 total columns are successfully retrieved from FTIR measurements (Saint Denis and Maïdo) at Réunion Island (21° S, 55° E) between 2004–2016 using the SFIT4 algorithm: the retrieval strategy and the error budget are presented. The FTIR SF6 retrieval has independent information in only one individual layer, covering the whole troposphere and the lower stratosphere. The trend of SF6 is analysed based on the FTIR retrieved dry air column-averaged mole fractions (XSF6) at Réunion Island, the in-situ measurements at America Samoa (SMO) and the collocated satellite measurements (MIPAS and ACE-FTS) in the southern tropics. The SF6 annual growth rate from FTIR retrievals is 0.265 ± 0.013 pptv/year for 2004–2016, which is slightly weaker than that from the SMO in-situ measurements (0.285 ± 0.002 pptv/year) for the same time period. The SF6 trend in the troposphere from MIPAS and ACE-FTS observations is also close to the ones from the FTIR retrievals and the SMO in-situ measurements.

scholarly journals The International Soil Moisture Network: a data hosting facility for global in situ soil moisture measurements

2011 ◽  
Vol 8 (1) ◽  
pp. 1609-1663 ◽  
Author(s):  
W. A. Dorigo ◽  
W. Wagner ◽  
R. Hohensinn ◽  
S. Hahn ◽  
C. Paulik ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Water Cycle ◽  
Soil Moisture Data ◽  
The North ◽  
Time Period ◽  
Different Depths ◽  
Operational Networks

Abstract. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, long-term time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol. To overcome many of these limitations, the International Soil Moisture Network (ISMN; http://www.ipf.tuwien.ac.at/insitu) was initiated to serve as a centralized data hosting facility where globally available in situ soil moisture measurements from operational networks and validation campaigns are collected, harmonized, and made available to users. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no-cost basis. Incoming soil moisture data are automatically transformed into common volumetric soil moisture units and checked for outliers and implausible values. Apart from soil water measurements from different depths, important metadata and meteorological variables (e.g., precipitation and soil temperature) are stored in the database. These will assist the user in correctly interpreting the soil moisture data. The database is queried through a graphical user interface while output of data selected for download is provided according to common standards for data and metadata. Currently (status January 2011), the ISMN contains data of 16 networks and more than 500 stations located in the North America, Europe, Asia, and Australia. The time period spanned by the entire database runs from 1952 until the present, although most datasets have originated during the last decade. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. Hence, it will become an increasingly important resource for validating and improving satellite-derived soil moisture products and studying climate related trends. As the ISMN is animated by the scientific community itself, we invite potential networks to enrich the collection by sharing their in situ soil moisture data.

scholarly journals Long-term evolution of antibiotic persistence in P. aeruginosa lung infections

2021 ◽  
Author(s):  
Melanie Ghoul ◽  
Sandra B Andersen ◽  
Helle Krogh Johansen ◽  
Lars Jelsbak ◽  
Søren Molin ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Resistance Mechanisms ◽  
Term Evolution ◽  
Bacterial Clone ◽  
Evolution Of Resistance ◽  
Lung Infections

Pathogenic bacteria respond to antibiotic pressure with the evolution of resistance but survival can also depend on their ability to tolerate antibiotic treatment, known as persistence. While a variety of resistance mechanisms and underlying genetics are well characterised in vitro and in vivo, the evolution of persistence, and how it interacts with resistance in situ is less well understood. We assayed for persistence and resistance with three clinically relevant antibiotics: meropenem, ciprofloxacin and tobramycin, in isolates of Pseudomonas aeruginosa from chronic cystic fibrosis lung infections spanning up to forty years of evolution. We find evidence that persistence is under positive selection in the lung and that it can particularly act as an evolutionary stepping stone to resistance. However, this pattern is not universal and depends on the bacterial clone type and antibiotic used, indicating an important role for antibiotic mode of action.

scholarly journals The International Soil Moisture Network: a data hosting facility for global in situ soil moisture measurements

2011 ◽  
Vol 15 (5) ◽  
pp. 1675-1698 ◽  
Author(s):  
W. A. Dorigo ◽  
W. Wagner ◽  
R. Hohensinn ◽  
S. Hahn ◽  
C. Paulik ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Water Cycle ◽  
Soil Moisture Data ◽  
Time Period ◽  
Surface Models ◽  
Different Depths ◽  
Operational Networks

Abstract. In situ measurements of soil moisture are invaluable for calibrating and validating land surface models and satellite-based soil moisture retrievals. In addition, long-term time series of in situ soil moisture measurements themselves can reveal trends in the water cycle related to climate or land cover change. Nevertheless, on a worldwide basis the number of meteorological networks and stations measuring soil moisture, in particular on a continuous basis, is still limited and the data they provide lack standardization of technique and protocol. To overcome many of these limitations, the International Soil Moisture Network (ISMN; http://www.ipf.tuwien.ac.at/insitu) was initiated to serve as a centralized data hosting facility where globally available in situ soil moisture measurements from operational networks and validation campaigns are collected, harmonized, and made available to users. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no-cost basis. Incoming soil moisture data are automatically transformed into common volumetric soil moisture units and checked for outliers and implausible values. Apart from soil water measurements from different depths, important metadata and meteorological variables (e.g., precipitation and soil temperature) are stored in the database. These will assist the user in correctly interpreting the soil moisture data. The database is queried through a graphical user interface while output of data selected for download is provided according to common standards for data and metadata. Currently (status May 2011), the ISMN contains data of 19 networks and more than 500 stations located in North America, Europe, Asia, and Australia. The time period spanned by the entire database runs from 1952 until the present, although most datasets have originated during the last decade. The database is rapidly expanding, which means that both the number of stations and the time period covered by the existing stations are still growing. Hence, it will become an increasingly important resource for validating and improving satellite-derived soil moisture products and studying climate related trends. As the ISMN is animated by the scientific community itself, we invite potential networks to enrich the collection by sharing their in situ soil moisture data.

scholarly journals Validation of the IASI FORLI/EUMETSAT ozone products using satellite (GOME-2), ground-based (Brewer–Dobson, SAOZ, FTIR) and ozonesonde measurements

2018 ◽  
Vol 11 (9) ◽  
pp. 5125-5152 ◽  
Author(s):  
Anne Boynard ◽  
Daniel Hurtmans ◽  
Katerina Garane ◽  
Florence Goutail ◽  
Juliette Hadji-Lazaro ◽  
...  
Keyword(s):  
High Latitudes ◽  
Long Term Stability ◽  
Time Period ◽  
Comparison Results ◽  
Independent Observations ◽  
Negative Drift ◽  
Mean Differences ◽  
Global Mean

Abstract. This paper assesses the quality of IASI (Infrared Atmospheric Sounding Interferometer)/Metop-A (IASI-A) and IASI/Metop-B (IASI-B) ozone (O3) products (total and partial O3 columns) retrieved with the Fast Optimal Retrievals on Layers for IASI Ozone (FORLI-O3; v20151001) software for 9 years (2008–July 2017) through an extensive intercomparison and validation exercise using independent observations (satellite, ground-based and ozonesonde). Compared with the previous version of FORLI-O3 (v20140922), several improvements have been introduced in FORLI-O3 v20151001, including absorbance look-up tables recalculated to cover a larger spectral range, with additional numerical corrections. This leads to a change of ∼4 % in the total ozone column (TOC) product, which is mainly associated with a decrease in the retrieved O3 concentration in the middle stratosphere (above 30 hPa/25 km). IASI-A and IASI-B TOCs are consistent, with a global mean difference of less than 0.3 % for both daytime and nighttime measurements; IASI-A is slightly higher than IASI-B. A global difference of less than 2.4 % is found for the tropospheric (TROPO) O3 column product (IASI-A is lower than IASI-B), which is partly due to a temporary issue related to the IASI-A viewing angle in 2015. Our validation shows that IASI-A and IASI-B TOCs are consistent with GOME-2 (Global Ozone Monitoring Experiment-2), Dobson, Brewer, SAOZ (Système d'Analyse par Observation Zénithale) and FTIR (Fourier transform infrared) TOCs, with global mean differences in the range of 0.1 %–2 % depending on the instruments compared. The worst agreement with UV–vis retrieved TOC (satellite and ground) is found at the southern high latitudes. The IASI-A and ground-based TOC comparison for the period from 2008 to July 2017 shows the long-term stability of IASI-A, with insignificant or small negative drifts of 1 %–3 % decade−1. The comparison results of IASI-A and IASI-B against smoothed FTIR and ozonesonde partial O3 columns vary with altitude and latitude, with the maximum standard deviation being seen for the 300–150 hPa column (20 %–40 %) due to strong ozone variability and large total retrievals errors. Compared with ozonesonde data, the IASI-A and IASI-B O3 TROPO column (defined as the column between the surface and 300 hPa) is positively biased in the high latitudes (4 %–5 %) and negatively biased in the midlatitudes and tropics (11 %–13 % and 16 %–19 %, respectively). The IASI-A-to-ozonesonde TROPO comparison for the period from 2008 to 2016 shows a significant negative drift in the Northern Hemisphere of -8.6±3.4 % decade−1, which is also found in the IASI-A-to-FTIR TROPO comparison. When considering the period from 2011 to 2016, the drift value for the TROPO column decreases and becomes statistically insignificant. The observed negative drifts of the IASI-A TROPO O3 product (8 %–16 % decade−1) over the 2008–2017 period might be taken into consideration when deriving trends from this product and this time period.

Sign in / Sign up

Export Citation Format

Share Document