| publications-1391 |
PEER REVIEWED ARTICLE |
2019 |
Michael Höpfner , Jörn Ungermann , Stephan Borrmann , Robert Wagner , Reinhold Spang , Martin Riese , Gabriele Stiller , Oliver Appel , Anneke M. Ba |
Ammonium nitrate particles formed in upper troposphere from ground ammonia sources during Asian monsoons |
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10.1038/s41561-019-0385-8 |
IoT & Sensors |
Precipitation & Ecological Systems |
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No abstract available |
603557 |
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| publications-1392 |
PEER REVIEWED ARTICLE |
2017 |
Chipperfield, M.P., S. Bekki, S. Dhomse, N. Harris, B. Hassler, R. Hossaini, W. Steinbrecht, R. Thiéblemont and M. Weber |
Detecting recovery of the stratospheric ozone layer |
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10.1038/nature23681 |
Data Management & Analytics |
Groundwater |
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No abstract available |
603557 |
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| publications-1393 |
PEER REVIEWED ARTICLE |
2015 |
Markus Stoffel , Myriam Khodri , Christophe Corona , Sébastien Guillet , Virginie Poulain , Slimane Bekki , Joël Guiot , Brian H. Luckman , Clive Op |
Estimates of volcanic-induced cooling in the Northern Hemisphere over the past 1,500 years |
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10.1038/ngeo2526 |
Data Management & Analytics |
Groundwater |
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No abstract available |
603557 |
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| publications-1394 |
PEER REVIEWED ARTICLE |
2019 |
Matthew Toohey , Kirstin Krüger , Hauke Schmidt , Claudia Timmreck , Michael Sigl , Markus Stoffel , Rob Wilson |
Disproportionately strong climate forcing from extratropical explosive volcanic eruptions |
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10.1038/s41561-018-0286-2 |
Simulation & Modeling |
River Basins |
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No abstract available |
603557 |
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| publications-1395 |
PEER REVIEWED ARTICLE |
2019 |
S. Brunamonti , L. Füzér , T. Jorge , Y. Poltera , P. Oelsner , S. Meier , R. Dirksen , M. Naja , S. Fadnavis , J. Karmacharya , F. G. Wienhold , B. |
Water Vapor in the Asian Summer Monsoon Anticyclone: Comparison of Balloon‐Borne Measurements and ECMWF Data |
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10.1029/2018jd030000 |
Data Management & Analytics |
Groundwater |
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AbstractWater vapor (H2O) is the strongest greenhouse gas in our atmosphere. Hence, accurate measurements and a correct representation in global models of H2O in the upper troposphere/lower stratosphere (UTLS) are important for understanding and projecting climate. Here we compare balloon‐borne measurements of UTLS H2O, performed by cryogenic frostpoint hygrometers (CFH) and meteorological radiosondes (Vaisala RS41) during two intensive field campaigns in the Asian summer monsoon anticyclone region, with humidity data from three products of the European Centre for Medium‐range Weather Forecasts (ECMWF): operational analysis and forecast (termed OPERA), ERA‐Interim reanalysis, and the newly released ERA5 reanalysis. Taking CFH as a reference, we show that OPERA and ERA5 provide a more accurate representation of UTLS H2O than ERA‐Interim. In particular, OPERA and ERA5 similarly overestimate H2O mixing ratios by on average 0.7–0.8 ppmv (14–15%) and 0.7–0.9 ppmv (15–17%) at pressures 60–100 hPa, respectively, and both provide a good representation of the observed vertical distribution (including fine structures) and natural variability of UTLS H2O. In contrast, ERA‐Interim underestimates UTLS H2O by 0.6–1.7 ppmv (14–30%), and it fails to capture relevant features of the vertical distribution of UTLS H2O. At pressures (p) lower than 60 hPa, all three ECMWF products are in good agreement with CFH. Humidity measurements by RS41 show an average dry bias of 0.1–0.5 ppmv (3–9%) compared to CFH for 60–100 hPa, and a moist bias increasing with altitude for p < 60 hPa, exceeding 100% for p < 40 hPa. |
603557 |
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| publications-1396 |
PEER REVIEWED ARTICLE |
2018 |
Keun-Ok Lee , Thibaut Dauhut , Jean-Pierre Chaboureau , Sergey Khaykin , Martina Krämer , Christian Rolf |
Convective hydration in the tropical tropopause layer during the StratoClim aircraft campaign: Pathway of an observed hydration patch |
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10.5194/acp-2018-1114 |
Predictive Analytics |
River Basins |
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Abstract. The source and pathway of the hydration patch in the TTL (Tropical Tropopause Layer) that was measured during the StratoClim field campaign during the Asian summer monsoon in 2017, and its connection to convective overshoots are investigated. During flight #7, two remarkable layers are measured in the TTL namely, (1) moist layer (ML) with water vapour content of 4.8–5.7 ppmv in altitudes of 18–19 km altitudes in the lower stratosphere, and (2) ice layer (IL) with ice content up to 1.9 eq. ppmv in altitudes of 17–18 km in the upper troposphere around 06:30 UTC on 8 August to the south of Kathmandu (Nepal). A Meso-NH convection-permitting simulation succeeds in reproducing the characteristics of ML and IL. Through analysis, we show that ML and IL are generated by convective overshoots that occurred over the Sichuan basin about 1.5 day before. Overshooting clouds develop up to 19 km, hydrating the lower stratosphere of up to 20 km with 6401 t of water vapour by a strong-to-moderate mixing of the updraughts with the stratospheric air. A few hours after the initial overshooting phase, a hydration patch is generated, and a large amount of water vapour (above 18 ppmv) still remains at even higher altitudes up to 20.5 km a.s.l. while the anvil cloud top descends to 18.5 km. At the same time, a great part of the hydrometeors falls shortly, and the rest sublimates. Meanwhile ice sediments out, the water vapour concentration in ML and IL decreases due to turbulent diffusion by mixing with the tropospheric air. As the hydration patch continues to travel toward the south of Kathmandu, tropospheric tracer concentration increases up to ~ 30 and 70 % in ML and IL, respectively. The air mass in the layers becomes gradually diffused and it has less and less water vapour and ice content by mixing with the dry tropospheric air. |
603557 |
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| publications-1397 |
PEER REVIEWED ARTICLE |
2015 |
C. Brühl , J. Lelieveld , H. Tost , M. Höpfner , N. Glatthor |
Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC |
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10.1002/2014jd022430 |
Data Management & Analytics |
Precipitation & Ecological Systems |
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AbstractMultiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low‐latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions. |
603557 |
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| publications-1398 |
PEER REVIEWED ARTICLE |
2015 |
N. Glatthor , M. Höpfner , I. T. Baker , J. Berry , J. E. Campbell , S. R. Kawa , G. Krysztofiak , A. Leyser , B.-M. Sinnhuber , G. P. Stiller , J. S |
Tropical sources and sinks of carbonyl sulfide observed from space |
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10.1002/2015gl066293 |
Uncategorized |
Natural Water Bodies |
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AbstractAccording to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore, COS has been suggested as cotracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 parts per trillion by volume (pptv) in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large‐scale COS depletion, which in austral summer amounts up to −40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications are assumed. |
603557 |
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| publications-1399 |
PEER REVIEWED ARTICLE |
2016 |
Bo Christiansen , Shuting Yang , Marianne Sloth Madsen |
Do strong warm ENSO events control the phase of the stratospheric QBO? |
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10.1002/2016gl070751 |
Uncategorized |
Groundwater |
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AbstractAlthough there in general are no significant long‐term correlations between the quasi‐biennial oscillation (QBO) and the El Niño–Southern Oscillation (ENSO) in observations, we find that the QBO and the ENSO were aligned in the 3 to 4 years after the three warm ENSO events in 1982, 1997, and 2015. We investigate this indicated relationship with a version of the EC‐Earth climate model which includes nonorographic gravity waves. We analyze the modeled QBO in ensembles forced with climatological sea surface temperatures (SSTs) and observed SSTs. In the ensemble with observed SSTs we find a strong and significant alignment of the ensemble members in the equatorial stratospheric winds in the 2 to 4 years after the strong ENSO event in 1997. This alignment also includes the observed QBO. No such alignment is found in the ensemble with climatological SSTs. These results indicate that strong warm ENSO events can lock the phase of the QBO. |
603557 |
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| publications-1400 |
PEER REVIEWED ARTICLE |
2018 |
Kreyling, D., Wohltmann, I., Lehmann, R., and Rex, M.: |
The Extrapolar SWIFT model (version 1.0): fast stratospheric ozone chemistry for global climate models |
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10.5194/gmd-11-753-2018 |
Uncategorized |
Groundwater |
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Abstract. The Extrapolar SWIFT model is a fast ozone chemistry scheme for interactive calculation of the extrapolar stratospheric ozone layer in coupled general circulation models (GCMs). In contrast to the widely used prescribed ozone, the SWIFT ozone layer interacts with the model dynamics and can respond to atmospheric variability or climatological trends. The Extrapolar SWIFT model employs a repro-modelling approach, in which algebraic functions are used to approximate the numerical output of a full stratospheric chemistry and transport model (ATLAS). The full model solves a coupled chemical differential equation system with 55 initial and boundary conditions (mixing ratio of various chemical species and atmospheric parameters). Hence the rate of change of ozone over 24 h is a function of 55 variables. Using covariances between these variables, we can find linear combinations in order to reduce the parameter space to the following nine basic variables: latitude, pressure altitude, temperature, overhead ozone column and the mixing ratio of ozone and of the ozone-depleting families (Cly, Bry, NOy and HOy). We will show that these nine variables are sufficient to characterize the rate of change of ozone. An automated procedure fits a polynomial function of fourth degree to the rate of change of ozone obtained from several simulations with the ATLAS model. One polynomial function is determined per month, which yields the rate of change of ozone over 24 h. A key aspect for the robustness of the Extrapolar SWIFT model is to include a wide range of stratospheric variability in the numerical output of the ATLAS model, also covering atmospheric states that will occur in a future climate (e.g. temperature and meridional circulation changes or reduction of stratospheric chlorine loading). For validation purposes, the Extrapolar SWIFT model has been integrated into the ATLAS model, replacing the full stratospheric chemistry scheme. Simulations with SWIFT in ATLAS have proven that the systematic error is small and does not accumulate during the course of a simulation. In the context of a 10-year simulation, the ozone layer simulated by SWIFT shows a stable annual cycle, with inter-annual variations comparable to the ATLAS model. The application of Extrapolar SWIFT requires the evaluation of polynomial functions with 30–100 terms. Computers can currently calculate such polynomial functions at thousands of model grid points in seconds. SWIFT provides the desired numerical efficiency and computes the ozone layer 104 times faster than the chemistry scheme in the ATLAS CTM. |
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