OPUS 4 | Universitätspublikationen

On the structural changes in the Brewer-Dobson circulation after 2000 (2010)

Harald Bönisch Andreas Engel Thomas Birner Peter Hoor David W. Tarasick Eric A. Ray

In this paper we present evidence that the observed increase in tropical upwelling after the year 2000 may be attributed to a change in the Brewer-Dobson circulation pattern. For this purpose, we use the concept of transit times derived from residual circulation trajectories and different in-situ measurements of ozone and nitrous dioxide. Observations from the Canadian midlatitude ozone profile record, probability density functions of in-situ N2O observations and a shift of the N2O-O3 correlation slopes, taken together, indicate that the increased upwelling in the tropics after the year 2000 appears to have triggered an intensification of tracer transport from the tropics into the extratropics in the lower stratosphere below about 500 K. This finding is corroborated by the fact that transit times along the shallow branch of the residual circulation into the LMS have decreased for the same time period (1993–2003). On a longer time scale (1979–2009), the transit time of the shallow residual circulation branch show a steady decrease of about −1 month/decade over the last 30 years, while the transit times of the deep branch remain unchanged. This highlights the fact that a change in the upwelling across the tropical tropopause is not a direct indicator for changes of the whole Brewer-Dobson circulation.

Saharan dust and ice nuclei over Central Europe (2010)

Holger Klein Slobodan Nickovic Werner Haunold Ulrich Bundke Björn Nillius Martin Ebert Stephan Weinbruch Lothar Schuetz Zev Levin Leonard A. Barrie Heinz Bingemer

Surface measurements of aerosol and ice nuclei (IN) at a Central European mountain site during an episode of dust transport from the Sahara are presented. Ice nuclei were sampled by electrostatic precipitation on silicon wafers and were analyzed in an isothermal static vapor diffusion chamber. The transport of mineral dust is simulated by the Eulerian regional dust model DREAM. Ice nuclei and mineral dust are significantly correlated, in particular IN number concentration and aerosol surface area. The ice nucleating characteristics of the aerosol as analyzed with respect to temperature and supersaturation are similar during the dust episode than during the course of the year. This suggests that dust may be a main constituent of ice nucleating aerosols in Central Europe.

Saharan dust and ice nuclei over Central Europe (2010)

Holger Klein Slobodan Nickovic Werner Haunold Ulrich Bundke Björn Nillius Martin Ebert Stephan Weinbruch Lothar Schuetz Zev Levin Leonard A. Barrie Heinz Bingemer

Surface measurements of aerosol and ice nuclei (IN) at a Central European mountain site during an episode of dust transport from the Sahara are presented. Transport is simulated by the Eulerian regional dust model DREAM. Ice nuclei and mineral dust are significantly correlated. The highest correlation is found between IN concentration and aerosol surface area. The ice nucleating characteristics of the aerosol with respect to temperature and supersaturation are similar during the dust episode than during the course of the year. This suggests that dust is always a dominant constituent of ice nucleating aerosols in Central Europe.

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion (2010)

Camille E. Yver Isabelle C. Pison Audrey Fortems-Cheiney Martina Schmidt Frédéric Chevallier Michel Ramonet Armin Jordan Ole Amund Søvde Andreas Engel Rebecca E. Fisher David Lowry Euan G. Nisbet Ingeborg Levin Samuel Hammer Jaroslaw Necki Jakub Bartyzel Stefan Reimann Martin Vollmer Martin Steinbacher Tuula Aalto Michela Maione Jgor Arduini Simon O'Doherty Aoife Grant William T. Sturges Grant L. Forster Chris Rene Lunder Viacheslav I. Privalov Nina N. Paramonova

This paper presents an analysis of the recent tropospheric molecular hydrogen (H2) budget with a particular focus on soil uptake and surface emissions. A variational inversion scheme is combined with observations from the RAMCES and EUROHYDROS atmospheric networks, which include continuous measurements performed between mid-2006 and mid-2009. Net H2 surface flux, soil uptake distinct from surface emissions and finally, soil uptake, biomass burning, anthropogenic emissions and N2 fixation-related emissions separately were inverted in several scenarios. The various inversions generate an estimate for each term of the H2 budget. The net H2 flux per region (High Northern Hemisphere, Tropics and High Southern Hemisphere) varies between −8 and 8 Tg yr−1. The best inversion in terms of fit to the observations combines updated prior surface emissions and a soil deposition velocity map that is based on soil uptake measurements. Our estimate of global H2 soil uptake is −59 ± 4.0 Tg yr−1. Forty per cent of this uptake is located in the High Northern Hemisphere and 55% is located in the Tropics. In terms of surface emissions, seasonality is mainly driven by biomass burning emissions. The inferred European anthropogenic emissions are consistent with independent H2 emissions estimated using a H2/CO mass ratio of 0.034 and CO emissions considering their respective uncertainties. To constrain a more robust partition of H2 sources and sinks would need additional constraints, such as isotopic measurements.

Relating hygroscopicity and composition of organic aerosol particulate matter (2010)

Jonathan Duplissy Peter F. DeCarlo Josef Dommen M. Rami Alfarra Axel Metzger Iakovos Barmpadimos André S. H. Prevot Ernest Weingartner Torsten Tritscher Martin Gysel Allison C. Aiken Jose Luis Jimenez Manjula R. Canagaratna Douglas R. Worsnop Donald R. Collins Jason M. Tomlinson Urs Baltensperger

A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f44). m/z 44 is due mostly to the ion fragment CO2+ for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κorg" parameter, and f44 was determined and is given by κorg=2.2×f44−0.13. This approximation can be further verified and refined as the database for AMS and HTDMA measurements is constantly being expanded around the world. The use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f44 is correlated with the photochemical age of an air mass.

Jahresbericht 2009 Geo-Agentur (2010)

Groundwater use for irrigation - a global inventory (2010)

Stefan Siebert Jacob Burke Jean-Marc Faures Karen Frenken Jippe Hoogeveen Petra Döll Felix Theodor Portmann

Irrigation is the most important water use sector accounting for about 70% of the global freshwater withdrawals and 90% of consumptive water uses. While the extent of irrigation and related water uses are reported in statistical databases or estimated by model simulations, information on the source of irrigation water is scarce and very scattered. Here we present a new global inventory on the extent of areas irrigated with groundwater, surface water or non-conventional sources, and we determine the related consumptive water uses. The inventory provides data for 15 038 national and sub-national administrative units. Irrigated area was provided by census-based statistics from international and national organizations. A global model was then applied to simulate consumptive water uses for irrigation by water source. Globally, area equipped for irrigation is currently about 301 million ha of which 38% are equipped for irrigation with groundwater. Total consumptive groundwater use for irrigation is estimated as 545 km3 yr−1, or 43% of the total consumptive irrigation water use of 1 277 km3 yr−1. The countries with the largest extent of areas equipped for irrigation with groundwater, in absolute terms, are India (39 million ha), China (19 million ha) and the United States of America (17 million ha). Groundwater use in irrigation is increasing both in absolute terms and in percentage of total irrigation, leading in places to concentrations of users exploiting groundwater storage at rates above groundwater recharge. Despite the uncertainties associated with statistical data available to track patterns and growth of groundwater use for irrigation, the inventory presented here is a major step towards a more informed assessment of agricultural water use and its consequences for the global water cycle.

Groundwater use for irrigation - a global inventory (2010)

Stefan Siebert Jacob Burke Jean-Marc Faures Karen Frenken Jippe Hoogeveen Petra Döll Felix Theodor Portmann

Irrigation is the most important water use sector accounting for about 70% of the global freshwater withdrawals and 90% of consumptive water uses. While the extent of irrigation and related water uses are reported in statistical databases or estimated by model simulations, information on the source of irrigation water is scarce and very scattered. Here we present a new global inventory on the extent of areas irrigated with groundwater, surface water or non-conventional sources, and we determine the related consumptive water uses. The inventory provides data for 15 038 national and sub-national administrative units. Irrigated area was provided by census-based statistics from international and national organizations. A global model was then applied to simulate consumptive water uses for irrigation by water source. Globally, area equipped for irrigation is currently about 301 million ha of which 38% are equipped for irrigation with groundwater. Total consumptive groundwater use for irrigation is estimated as 545 km3 yr−1, or 43% of the total consumptive irrigation water use of 1277 km3 yr−1. The countries with the largest extent of areas equipped for irrigation with groundwater, in absolute terms, are India (39 million ha), China (19 million ha) and the USA (17 million ha). Groundwater use in irrigation is increasing both in absolute terms and in percentage of total irrigation, leading in places to concentrations of users exploiting groundwater storage at rates above groundwater recharge. Despite the uncertainties associated with statistical data available to track patterns and growth of groundwater use for irrigation, the inventory presented here is a major step towards a more informed assessment of agricultural water use and its consequences for the global water cycle.

Ordnung des Fachbereichs Geowissenschaften/Geographie an der Johann Wolfgang Goethe-Universität für den Bachelorstudiengang Geographie mit den Abschlüssen „Bachelor of Arts“ oder „Bachelor of Science“ vom 19. Mai 2008 in der Fassung vom 20. September 2010 : genehmigt vom Präsidium der Johann Wolfgang Goethe- Universität Frankfurt am Main am 28.09.2010 (2010)

Ordnung des Fachbereichs Geowissenschaften/Geographie an der Johann Wolfgang Goethe-Universität für das Nebenfach Geographie in einem Bachelorstudiengang vom 05. Februar 2007 in der Fassung vom 20. September 2010 : genehmigt vom Präsidium der Johann Wolfgang Goethe-Universität Frankfurt am Main am 28.09.2010 (2010)

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