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Author

Rossana Dragani

Other affiliations: University of L'Aquila
Bio: Rossana Dragani is an academic researcher from European Centre for Medium-Range Weather Forecasts. The author has contributed to research in topics: Sensor fusion & Stratosphere. The author has an hindex of 11, co-authored 26 publications receiving 22485 citations. Previous affiliations of Rossana Dragani include University of L'Aquila.

Papers
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Journal ArticleDOI
TL;DR: ERA-Interim as discussed by the authors is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which will extend back to the early part of the twentieth century.
Abstract: ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society

22,055 citations

Journal ArticleDOI
TL;DR: The Stratosphere-troposphere Processes And their Role in Climate (SPARC) Reanalysis Intercomparison Project (S-RIP) is a coordinated activity to compare reanalysis data sets using a variety of key diagnostics.
Abstract: The climate research community uses atmospheric reanalysis data sets to understand a wide range of processes and variability in the atmosphere, yet different reanalyses may give very different results for the same diagnostics. The Stratosphere–troposphere Processes And their Role in Climate (SPARC) Reanalysis Intercomparison Project (S-RIP) is a coordinated activity to compare reanalysis data sets using a variety of key diagnostics. The objectives of this project are to identify differences among reanalyses and understand their underlying causes, to provide guidance on appropriate usage of various reanalysis products in scientific studies, particularly those of relevance to SPARC, and to contribute to future improvements in the reanalysis products by establishing collaborative links between reanalysis centres and data users. The project focuses predominantly on differences among reanalyses, although studies that include operational analyses and studies comparing reanalyses with observations are also included when appropriate. The emphasis is on diagnostics of the upper troposphere, stratosphere, and lower mesosphere. This paper summarizes the motivation and goals of the S-RIP activity and extensively reviews key technical aspects of the reanalysis data sets that are the focus of this activity. The special issue "The SPARC Reanalysis Intercomparison Project (S-RIP)" in this journal serves to collect research with relevance to the S-RIP in preparation for the publication of the planned two (interim and full) S-RIP reports.

239 citations

Journal ArticleDOI
TL;DR: In this article, the quality of the ERA-Interim ozone analyses was evaluated using the results of the European Centre for Medium-Range Weather Forecasts (ECMWF). But the results showed that the results were not consistent in the Tropics and Extratropics, with mean residuals typically within ± 5% around 5 hPa and within ± 10% in the region of the ozone mixing ration maximum at 10 hPa.
Abstract: This article presents an assessment of the quality of the ERA-Interim ozone analyses produced by the European Centre for Medium-Range Weather Forecasts. Ozone retrievals from a number of satellite instruments and an ad hoc generated mean total column ozone (TCO) reference are used to assess the quality of the ERA-Interim ozone analyses during the period from January 1989 to December 2008. The ERA-Interim TCO is typically within ±5 DU (about ±3%) from the TCO reference, while showing up to 2% lower values than the Ozone Monitoring Instrument TCO between 50°S and 50°N. Comparisons with SAGE, HALOE and (UARS and Aura) MLS data show consistent results both in the Tropics and Extratropics, with mean residuals typically within ±5% around 5 hPa and within ±10% in the region of the ozone mixing ration maximum at 10 hPa. However, the comparisons with POAM II and III show mean relative residuals ranging from a few percent in summer to about –40% in winter at high latitudes, partly confirming the known problems of accurately modelling the ozone field during the polar night. Mean residuals of about +10% (but up to +20% at times) and within ±20% are found both in the Tropics and Extratropics for all instruments near 30 hPa and in the lower stratosphere around 65 hPa, respectively. The quality of the ERA-Interim ozone analyses is also compared with that of ERA-40. The study shows that, until December 1995, the ERA-Interim ozone analyses are in better agreement with the independent observations than their ERA-40 equivalent in the upper troposphere and lower stratosphere, but slightly degraded on average in the middle stratosphere. With the start of the assimilation of GOME ozone profiles (January 1996 –December 2002), the agreement between the independent data and the co-located ERA-Interim analyses improves and exceeds that calculated for ERA-40 also in the middle stratosphere. Copyright © 2011 Royal Meteorological Society

82 citations


Cited by
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Journal ArticleDOI
TL;DR: ERA-Interim as discussed by the authors is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which will extend back to the early part of the twentieth century.
Abstract: ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society

22,055 citations

Journal ArticleDOI
TL;DR: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA's Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA's Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses as mentioned in this paper.
Abstract: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA’s Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA’s Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses. Focusing on the satellite era, from 1979 to the present, MERRA has achieved its goals with significant improvements in precipitation and water vapor climatology. Here, a brief overview of the system and some aspects of its performance, including quality assessment diagnostics from innovation and residual statistics, is given.By comparing MERRA with other updated reanalyses [the interim version of the next ECMWF Re-Analysis (ERA-Interim) and the Climate Forecast System Reanalysis (CFSR)], advances made in this new generation of reanalyses, as well as remaining deficiencies, are identified. Although there is little difference between the new reanalyses i...

4,572 citations

Journal ArticleDOI
TL;DR: An overview of the MERRA-2 system and various performance metrics is provided, including the assimilation of aerosol observations, several improvements to the representation of the stratosphere including ozone, and improved representations of cryospheric processes.
Abstract: The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), is the latest atmospheric reanalysis of the modern satellite era produced by NASA’s Global Modeling and Assimilation Office (GMAO). MERRA-2 assimilates observation types not available to its predecessor, MERRA, and includes updates to the Goddard Earth Observing System (GEOS) model and analysis scheme so as to provide a viable ongoing climate analysis beyond MERRA’s terminus. While addressing known limitations of MERRA, MERRA-2 is also intended to be a development milestone for a future integrated Earth system analysis (IESA) currently under development at GMAO. This paper provides an overview of the MERRA-2 system and various performance metrics. Among the advances in MERRA-2 relevant to IESA are the assimilation of aerosol observations, several improvements to the representation of the stratosphere including ozone, and improved representations of cryospheric processes. Other improvements in the quality of M...

4,524 citations

Journal ArticleDOI
TL;DR: The Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT) as mentioned in this paper is one of the most widely used models for atmospheric trajectory and dispersion calculations.
Abstract: The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), developed by NOAA’s Air Resources Laboratory, is one of the most widely used models for atmospheric trajectory and dispersion calculations. We present the model’s historical evolution over the last 30 years from simple hand-drawn back trajectories to very sophisticated computations of transport, mixing, chemical transformation, and deposition of pollutants and hazardous materials. We highlight recent applications of the HYSPLIT modeling system, including the simulation of atmospheric tracer release experiments, radionuclides, smoke originated from wild fires, volcanic ash, mercury, and wind-blown dust.

3,875 citations