UTLS temperature validation of MPI-ESM decadal hindcast experiments with GPS radio occultations

Global Positioning System (GPS) radio occultation (RO) temperature data are used to validate MPI-ESM (Max Planck Institute – Earth System Model) decadal hindcast experiments in the upper troposphere and lower stratosphere (UTLS) region between 300 hPa and 10 hPa (8 km and 32 km) for the time period between 2002 and 2011. The GPSRO dataset is unique since it is very precise, calibration independent and covers the globe better than the usual radiosonde dataset. In addition it is vertically finer resolved than any of the existing satellite temperature measurements available for the UTLS and provides now a unique one decade long temperature validation dataset. The initialization of the MPI-ESM decadal hindcast runs mostly increases the skill of the atmospheric temperatures when compared to uninitialized climate projections with very high skill scores for lead-year one, and gradually decreases for the later lead-years. A comparison between two different initialization sets (b0, b1) of the low-resolution (LR) MPI-ESM shows increased skills in b1-LR in most parts of the UTLS in particular in the tropics. The medium resolution (MR) MPI-ESM initializations are characterized by reduced temperature biases in the uninitialized runs as compared to observations and a better capturing of the high latitude northern hemisphere interannual polar vortex variability as compared to the LR model version. Negative skills are found for the b1-MR hindcasts however in the regions around the mid-latitude tropospheric jets on both hemispheres and in the vicinity of the tropical tropopause in comparison to the b1-LR variant. It is interesting to highlight that none of the model experiments can reproduce the observed positive temperature trend in the tropical tropopause region since 2001 as seen by GPSRO data

Updating ESA's Earth System Model for Gravity Mission Simulation Studies: 3. A Realistically Perturbed Non-Tidal Atmosphere and Ocean De-Aliasing Model

The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations. For such simulations, a suitable source model is required to represent (i) high-frequency (i.e., sub-daily to weekly) mass variability in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (i.e., monthly to interannual) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model documented here attempts to fulfil both requirements: Based on ECMWF’s recent atmospheric reanalysis ERA-Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic coefficients of the time-variable global gravity field due to mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers, as well as the solid Earth. Simulated features range from sub-daily to multiyear periods with a spatial resolution of spherical harmonics degree and order 180 over a period of 12 years. In addition to the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability with augmented systematic and random noise is required for a realistic simulation of the gravity field retrieval process, whose necessary error characteristics are discussed. The documentation is organized as follows: The characteristics of the updated ESM along with some basic validation are presented in Volume 1 of this report (Dobslaw et al., 2014). A detailed comparison to the original ESA ESM (Gruber et al., 2011) is provided in Volume 2 (Bergmann-Wolf et al., 2014), while Volume 3 (Forootan et al., 2014) contains a description of the strategy to derive a realistically noisy de-aliasing model for the high-frequency mass variability in atmosphere and oceans. The files of the updated ESA Earth System Model for gravity mission simulation studies are accessible at DOI:10.5880/GFZ.1.3.2014.001

Evolution of Global Ocean Tide Levels Since the Last Glacial Maximum

This study addresses the evolution of global tidal dynamics since the Last Glacial Maximum focusing on the extraction of tidal levels that are vital for the interpretation of geologic sea-level markers. For this purpose, we employ a truly-global barotropic ocean tide model which considers the non-local effect of Self-Attraction and Loading. A comparison to a global tide gauge data set for modern conditions yields agreement levels of 65%–70%. As the chosen model is data-unconstrained, and the considered dissipation mechanisms are well understood, it does not have to be re-tuned for altered paleoceanographic conditions. In agreement with prior studies, we find that changes in bathymetry during glaciation and deglaciation do exert critical control over the modeling results with minor impact by ocean stratification and sea ice friction. Simulations of 4 major partial tides are repeated in time steps of 0.5–1 ka and augmented by 4 additional partial tides estimated via linear admittance. These are then used to derive time series from which the tidal levels are determined and provided as a global data set conforming to the HOLSEA format. The modeling results indicate a strengthened tidal resonance by M2, but also by O1, under glacial conditions, in accordance with prior studies. Especially, a number of prominent changes in local resonance conditions are identified, that impact the tidal levels up to several meters difference. Among other regions, resonant features are predicted for the North Atlantic, the South China Sea, and the Arctic Ocean

Low-frequency ocean bottom pressure variations in the North Pacific in response to time-variable surface winds

One decade of time-variable gravity field observations from the GRACE satellite mission reveals low-frequency ocean bottom pressure (OBP) variability of up to 2.5 hPa centered at the northern flank of the subtropical gyre in the North Pacific. From a 145 year-long simulation with a coupled chemistry climate model, OBP variability is found to be related to the prevailing atmospheric sea-level pressure and surface wind conditions in the larger North Pacific area. The dominating atmospheric pressure patterns obtained from the climate model run allow in combination with ERA-Interim sea-level pressure and surface winds a reconstruction of the OBP variability in the North Pacific from atmospheric model data only, which correlates favorably (r=0.7) with GRACE ocean bottom pressure observations. The regression results indicate that GRACE-based OBP observations are indeed sensitive to changes in the prevailing sea-level pressure and thus surface wind conditions in the North Pacific, thereby opening opportunities to constrain atmospheric models from satellite gravity observations over the oceans

Updating ESA's Earth System Model for gravity mission simulation studies: 2. Comparison with the original model

The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations. For such simulations, a suitable source model is required to represent (i) high-frequency (i.e., sub-daily to weekly) mass variability in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (i.e., monthly to interannual) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model documented here attempts to fulfil both requirements: Based on ECMWF’s recent atmospheric reanalysis ERA-Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic coefficients of the time-variable global gravity field due to mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers, as well as the solid Earth. Simulated features range from sub-daily to multiyear periods with a spatial resolution of spherical harmonics degree and order 180 over a period of 12 years. In addition to the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability with augmented systematic and random noise is required for a realistic simulation of the gravity field retrieval process, whose necessary error characteristics are discussed. The documentation is organized as follows: The characteristics of the updated ESM along with some basic validation are presented in Volume 1 of this report (Dobslaw et al., 2014). A detailed comparison to the original ESA ESM (Gruber et al., 2011) is provided in Volume 2 (Bergmann-Wolf et al., 2014), while Volume 3 (Forootan et al., 2014) contains a description of the strategy to derive a realistically noisy de-aliasing model for the high-frequency mass variability in atmosphere and oceans. The files of the updated ESA Earth System Model for gravity mission simulation studies are accessible at DOI:10.5880/GFZ.1.3.2014.001

Updating ESA's Earth System Model for gravity mission simulation studies: 1. Model description and validation

The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations. For such simulations, a suitable source model is required to represent (i) high-frequency (i.e., subdaily to weekly) mass variability in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (i.e., monthly to interannual) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model documented here attempts to fulfil both requirements: Based on ECMWF’s recent atmospheric reanalysis ERA-Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic coefficients of the time-variable global gravity field due to mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers, as well as the solid Earth. Simulated features range from sub-daily to multiyear periods with a spatial resolution of spherical harmonics degree and order 180 over a period of 12 years. In addition to the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability with augmented systematic and random noise is required for a realistic simulation of the gravity field retrieval process, whose necessary error characteristics are discussed. The documentation of the updated ESA Earth System Model (updated ESM) for gravity mission simulation studies is organized as follows: The characteristics of the updated ESM along with some basic validation is presented in Volume 1. A detailed comparison to the original ESA ESM (Gruber et al., 2011) is provided in Volume 2, while Volume 3 contains the description of a strategy to derive realistic errors for the de-aliasing model of high-frequency mass variability in atmosphere and ocean

Comparison of inoculums in the removal of 2-butoxyethanol from air emissions by biotrickling filter: Performance and microbial monitoring

2-butoxyethanol is one of the most used glycol ether in industrial activities and the treatment of air 2-butoxyethanol-emissions become necessary. Biotechnologies are potential treatment technologies due to their low operational costs. The use of two inoculums in the treatment of 2-butoxyethanol by biotrickling filters (BTFs) packed with polyurethane-foam was studied. A pure culture of Pseudomonas putida, previously adapted to 2-butoxyethanol, was used as inocula in a BTF operated in the University of Stuttgart. Fresh activated sludge from a municipal waste water treatment plant was used as inocula in a BTF operated in the University of Valencia. An empty bed residence time of 12.5 s and inlet concentrations of 400 and 800 mg/Nm3 were applied. After 40 days of operation at 400 mg/Nm3, the BTF inoculated with Pseudomonas putida reached removal efficiencies (REs) ∼ 80%, whereas the BTF inoculated with activated sludge presented REs ∼ 60%. At 800 mg/Nm3, the BTF inoculated with Pseudomonas putida reached REs ∼ 60%. Microbial community was monitored in both BTFs by using denaturing gradient gel electrophoresis analysis (DGGE) with subsequent 16S sequencing and plating methods using 2-butoxyethanol as sole carbon source

The International Mass Loading Service

The International Mass Loading Service computes four loadings: a) atmospheric pressure loading; b) land water storage loading; c) oceanic tidal loading; and d) non-tidal oceanic loading. The service provides to users the mass loading time series in three forms: 1) pre-computed time series for a list of 849 space geodesy stations; 2) pre-computed time series on the global 1deg x 1deg grid; and 3) on-demand Internet service for a list of stations and a time range specified by the user. The loading displacements are provided for the time period from 1979.01.01 through present, updated on an hourly basis, and have latencies 8-20 hours.Comment: 8 pages, 3 figures, to appear in the Proceedings of the Reference Frames for Applications in Geosciences Simposium, held in Luxemboug in October 201

Impact of the solar cycle and the QBO on the atmosphere and the ocean

The Solar Cycle and the Quasi-Biennial Oscillation are two major components of natural climate variability. Their direct and indirect influences in the stratosphere and troposphere are subject of a number of studies. The so-called ``top-down' mechanism describes how solar UV changes can lead to a significant enhancement of the small initial signal and corresponding changes in stratospheric dynamics. How the signal then propagates to the surface is still under investigation. We continue the ``top-down' analysis further down to the ocean and show the dynamical ocean response with respect to the solar cycle and the QBO. For this we use two 110-year chemistry climate model experiments from NCAR's Whole Atmosphere Community Climate Model (WACCM), one with a time varying solar cycle only and one with an additionally nudged QBO, to force an ocean general circulation model, GFZ's Ocean Model for Circulation and Tides (OMCT). We find a significant ocean response to the solar cycle only in combination with a prescribed QBO. Especially in the Southern Hemisphere we find the tendency to positive Southern Annular Mode (SAM) like pattern in the surface pressure and associated wind anomalies during solar maximum conditions. These atmospheric anomalies propagate into the ocean and induce deviations in ocean currents down into deeper layers, inducing an integrated sea surface height signal. Finally, limitations of this study are discussed and it is concluded that comprehensive climate model studies require a middle atmosphere as well as a coupled ocean to investigate and understand natural climate variability. Key Points: - Modeled oceanic solar cycle response depends on realistically modeled stratosphe - A realistically modeled stratospheric solar cycle response requires a QB

Acceleration of Greenland ice mass loss in spring 2004

In 2001 the Intergovernmental Panel on Climate Change projected the contribution to sea level rise from the Greenland ice sheet to be between -0.02 and +0.09 m from 1990 to 2100 (ref. 1). However, recent work has suggested that the ice sheet responds more quickly to climate perturbations than previously thought, particularly near the coast. Here we use a satellite gravity survey by the Gravity Recovery and Climate Experiment (GRACE) conducted from April 2002 to April 2006 to provide an independent estimate of the contribution of Greenland ice mass loss to sea level change. We detect an ice mass loss of 248 +/- 36 km3 yr(-1), equivalent to a global sea level rise of 0.5 +/- 0.1 mm yr(-1). The rate of ice loss increased by 250 per cent between the periods April 2002 to April 2004 and May 2004 to April 2006, almost entirely due to accelerated rates of ice loss in southern Greenland; the rate of mass loss in north Greenland was almost constant. Continued monitoring will be needed to identify any future changes in the rate of ice loss in Greenland