MERRA: NASA’s Modern-Era Retrospective Analysis for Research and Applications

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 in many aspects of climate variability, substantial differences remain in poorly constrained quantities such as precipitation and surface fluxes. These differences, due to variations both in the models and in the analysis techniques, are an important measure of the uncertainty in reanalysis products. It is also found that all reanalyses are still quite sensitive to observing system changes. Dealing with this sensitivity remains the most pressing challenge for the next generation of reanalyses. Production has now caught up to the current period and MERRA is being continued as a near-real-time climate analysis. The output is available online through the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC).

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The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2)

Journal of Climate ◽

10.1175/jcli-d-16-0758.1 ◽

2017 ◽

Vol 30 (14) ◽

pp. 5419-5454 ◽

Cited By ~ 1538

Author(s):

Ronald Gelaro ◽

Will McCarty ◽

Max J. Suárez ◽

Ricardo Todling ◽

Andrea Molod ◽

...

Keyword(s):

Retrospective Analysis ◽

System Analysis ◽

Performance Metrics ◽

Water Cycle ◽

Global Modeling ◽

Earth Observing System ◽

Analysis Scheme ◽

Climate Analysis ◽

Modern Era

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 MERRA-2 compared with MERRA include the reduction of some spurious trends and jumps related to changes in the observing system and reduced biases and imbalances in aspects of the water cycle. Remaining deficiencies are also identified. Production of MERRA-2 began in June 2014 in four processing streams and converged to a single near-real-time stream in mid-2015. MERRA-2 products are accessible online through the NASA Goddard Earth Sciences Data Information Services Center (GES DISC).

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Sea Surface Temperature–Precipitation Relationship in Different Reanalyses

Monthly Weather Review ◽

10.1175/mwr-d-12-00214.1 ◽

2013 ◽

Vol 141 (3) ◽

pp. 1118-1123 ◽

Cited By ~ 31

Author(s):

Arun Kumar ◽

Li Zhang ◽

Wanqiu Wang

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Time Scales ◽

Department Of Energy ◽

Sea Surface ◽

Climate Forecast System ◽

Climate Forecast System Reanalysis ◽

Temperature And Precipitation ◽

The Relationship ◽

Modern Era

Abstract The focus of this investigation is how the relationship at intraseasonal time scales between sea surface temperature and precipitation (SST–P) varies among different reanalyses. The motivation for this work was spurred by a recent report that documented that the SST–P relationship in Climate Forecast System Reanalysis (CFSR) was much closer to that in the observation than it was for the older generation of reanalyses [i.e., NCEP–NCAR reanalysis (R1) and NCEP–Department of Energy (DOE) reanalysis (R2)]. Further, the reason was attributed either to the fact that the CFSR is a partially coupled reanalysis, while R1 and R2 are atmospheric-alone reanalyses, or that R1 and R2 use the observed weekly-averaged SST. The authors repeated the comparison of the SST–P relationship among R1, R2, and CFSR, as well as two recent generations of atmosphere-alone reanalyses, the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and the ECMWF Re-Analysis Interim (ERA-Interim). The results clearly demonstrate that the differences in the SST–P relationship at intraseasonal time scales across different reanalyses are not due to whether the reanalysis system is coupled or atmosphere alone, but are due to the specification of different SSTs. The SST–P relationship in different reanalyses, when computed against a single SST for the benchmark, demonstrates a relationship that is common across all of the reanalyses and observations.

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A Comparison of Extratropical Cyclones in Recent Reanalyses ERA-Interim, NASA MERRA, NCEP CFSR, and JRA-25

Journal of Climate ◽

10.1175/2011jcli4097.1 ◽

2011 ◽

Vol 24 (18) ◽

pp. 4888-4906 ◽

Cited By ~ 206

Author(s):

K. I. Hodges ◽

R. W. Lee ◽

L. Bengtsson

Keyword(s):

The Other ◽

Extratropical Cyclones ◽

Forecast System ◽

Climate Forecast System ◽

Climate Forecast System Reanalysis ◽

Spatial Differences ◽

The Mean ◽

Using Data ◽

Modern Era ◽

Ncep Climate Forecast System

Abstract Extratropical cyclones are identified and compared using data from four recent reanalyses for the winter periods in both hemispheres. Results show the largest differences occur between the older lower resolution 25-yr Japanese Reanalysis (JRA-25) when compared with the newer high resolution reanalyses, particularly in the Southern Hemisphere (SH). Spatial differences between the newest reanalyses are small in both hemispheres and generally not significant except in some common regions associated with cyclogenesis close to orography. Differences in the cyclone maximum intensitites are generally related to spatial resolution except in the NASA Modern Era Retrospective-Analysis for Research and Applications (NASA MERRA), which has larger intensities for several different measures. Matching storms between reanalyses shows the number matched between the ECMWF Interim Re-Analysis (ERA-Interim) and the other reanalyses is similar in the Northern Hemisphere (NH). In the SH the number matched between JRA-25 and ERA-Interim is lower than in the NH; however, for NASA MERRA and the NCEP Climate Forecast System Reanalysis (NCEP CFSR), the number matched is similar to the NH. The mean separation of the identically same cyclones is typically less than 2° geodesic in both hemispheres for the latest reanalyses, whereas JRA-25 compared with the other reanalyses has a broader distribution in the SH, indicating greater uncertainty. The instantaneous intensity differences for matched storms shows narrow distributions for pressure, while for winds and vorticity the distributions are much broader, indicating larger uncertainty typical of smaller-scale fields. Composite cyclone diagnostics show that cyclones are very similar between the reanalyses, with differences being related to the intensities, consistent with the intensity results. Overall, results show NH cyclones correspond well between reanalyses, with a significant improvement in the SH for the latest reanalyses, indicating a convergence between reanalyses for cyclone properties.

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Evaluation of Reanalyses over British Columbia. Part II: Daily and Extreme Precipitation

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-18-0188.1 ◽

2019 ◽

Vol 58 (2) ◽

pp. 291-315 ◽

Cited By ~ 1

Author(s):

Pedro Odon ◽

Gregory West ◽

Roland Stull

Keyword(s):

British Columbia ◽

Complex Terrain ◽

Climate Forecast System ◽

Climate Forecast System Reanalysis ◽

Weather Forecasts ◽

Time Period ◽

Medium Range ◽

L Moments ◽

Modern Era ◽

Terrain Characteristics

AbstractThis study evaluates how well reanalyses represent daily and multiday accumulated precipitation (hereinafter daily PCP) over British Columbia, Canada (Part I evaluated 2-m temperature). Reanalyses are compared with observations from 66 meteorological stations distributed over the complex terrain of British Columbia, separated into climate regions by k-means clustering. Systematic error, two-sample χ2 statistic, and frequency of daily PCP occurrence are evaluated from the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim), the Climate Forecast System Reanalysis (CFSR), the Japanese 55-year Reanalysis (JRA-55), and the latest Modern-Era Retrospective Analysis for Research and Applications (version 2; MERRA-2). The 2- and 30-yr return levels of daily PCP are estimated from a generalized extreme value (GEV) distribution fitted by the method of L moments, and their systematic errors are analyzed. JRA-55 and MERRA-2 generally outperform ERA-Interim and CFSR across all metrics. Biases are largely explained by poor reanalysis representation of terrain characteristics such as steepness, exposure, elevation, location of barriers, and wind speed and direction. Statistical stationarity of precipitation intensity and frequency over the 30-yr period is assessed by using confidence intervals and GEV distributions fitted with and without time-dependent parameters. It is determined that stationary distributions are sufficient to represent the climate of daily PCP for this region and time period.

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The Reliability of Antarctic Tropospheric Pressure and Temperature in the Latest Global Reanalyses

Journal of Climate ◽

10.1175/jcli-d-11-00685.1 ◽

2012 ◽

Vol 25 (20) ◽

pp. 7138-7146 ◽

Cited By ~ 155

Author(s):

Thomas J. Bracegirdle ◽

Gareth J. Marshall

Keyword(s):

Surface Energy Balance ◽

Surface Air Temperature ◽

Radiosonde Data ◽

Positive Trend ◽

Forecast System ◽

Climate Forecast System ◽

Sea Level Pressure ◽

Climate Forecast System Reanalysis ◽

Near Surface ◽

Modern Era

Abstract In this study, surface and radiosonde data from staffed Antarctic observation stations are compared to output from five reanalyses [Climate Forecast System Reanalysis (CFSR), 40-yr ECMWF Re-Analysis (ERA-40), ECMWF Interim Re-Analysis (ERA-Interim), Japanese 25-year Reanalysis (JRA-25), and Modern Era Retrospective-Analysis for Research and Applications (MERRA)] over three decades spanning 1979–2008. Bias and year-to-year correlation between the reanalyses and observations are assessed for four variables: mean sea level pressure (MSLP), near-surface air temperature (Ts), 500-hPa geopotential height (H500), and 500-hPa temperature (T500). It was found that CFSR and MERRA are of a sufficiently high resolution for the height of the orography to be accurately reproduced at coastal observation stations. Progressively larger negative Ts biases at these coastal stations are apparent for reanalyses in order of decreasing resolution. However, orography height bias cannot explain large winter warm biases in CFSR, JRA-25, and MERRA (11.1°, 10.2°, and 7.9°C, respectively) at Amundsen–Scott and Vostok, which have been linked to problems with representing the surface energy balance. Linear trends in the annual-mean T500 and H500 averaged over Antarctica as a whole were found to be most reliable in CFSR, ERA-Interim, and MERRA, none of which show significant trends over the period 1979–2008. In contrast JRA-25 shows significant negative trends over 1979–2008 and ERA-40 gives significant positive trends during the 1980s (evident in both T500 and H500). Comparison to observations indicates that the positive trend in ERA-40 is spurious. At the smaller spatial scale of individual stations all five reanalyses have some spurious trends. However, ERA-Interim was found to be the most reliable for MSLP and H500 trends at station locations.

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Recent Advances in the Development of Nano-Sculpted Films by Magnetron Sputtering for Energy-Related Applications

Nanomaterials ◽

10.3390/nano10102039 ◽

2020 ◽

Vol 10 (10) ◽

pp. 2039 ◽

Cited By ~ 1

Author(s):

Adriano Panepinto ◽

Rony Snyders

Keyword(s):

Thin Films ◽

Magnetron Sputtering ◽

Recent Progress ◽

Dye Sensitized Solar Cells ◽

Dye Sensitized ◽

New Generation ◽

Recent Experimental Work ◽

Sensitized Solar Cells ◽

Theoretical Results ◽

Made In

In this paper, we overview the recent progress we made in the magnetron sputtering-based developments of nano-sculpted thin films intended for energy-related applications such as energy conversion. This paper summarizes our recent experimental work often supported by simulation and theoretical results. Specifically, the development of a new generation of nano-sculpted photo-anodes based on TiO2 for application in dye-sensitized solar cells is discussed.

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Multi-decadal Records of Stratospheric Composition and their Relationship to Stratospheric Circulation Change

10.5194/acp-2017-401 ◽

2017 ◽

Author(s):

Anne R. Douglass ◽

Susan E. Strahan ◽

Luke D. Oman ◽

Richard S. Stolarski

Keyword(s):

Transport Model ◽

Atmospheric Composition ◽

Model Driven ◽

Earth Observing System ◽

Circulation Change ◽

Decadal Scale ◽

Stratospheric Circulation ◽

Transport And Mixing ◽

Stratospheric Composition ◽

Modern Era

Abstract. Constituent evolution for 1990–2015 simulated using the Global Modeling Initiative Chemistry and Transport Model driven by meteorological fields from the Modern Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) is compared with three sources of observations: ground based column measurements of HNO3 and HCl from two stations in the Network for Detection of Atmospheric Composition Change (NDACCC, ~ 1990–ongoing); profiles of CH4 from the HALogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS, 1992–2005); profiles of N2O from the Microwave Limb Sounder on the Earth Observing System satellite Aura (2015–ongoing). The differences between observed and simulated values are shown to be time dependent, with better agreement after ~2000 compared with the prior decade. Furthermore, the differences between observed and simulated HNO3 and HCl columns are shown to be correlated with each other, suggesting that issues with the simulated transport and mixing cause the differences during the 1990s and these issues are less important during the later years. Because the simulated fields are related to mean age in the lower stratosphere, we use these comparisons to evaluate the time dependence of mean age. We use these relationships to account for dynamical variability when determining decadal scale trends in constituents and mean age. The ongoing NDACC column observations provide critical information necessary to substantiate trends in mean age obtained using fields from MERRA-2 or any other reanalysis products.

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War Economy in the Contemporary Wars: In the Context of Central African Republic

Khulna University Business Review ◽

10.35649/kubr.2018.13.12.5 ◽

2019 ◽

Author(s):

Sabbir Ahmed

Keyword(s):

Civil War ◽

Civil Wars ◽

Design Methodology ◽

Central African Republic ◽

Work Experiences ◽

Recent Past ◽

War Economy ◽

War Production ◽

Modern Era ◽

Made In

Purpose: Ideally, the war economy is a set of contingencies undertaken by a state to mobilize its economy for war production or to support the war. However, the existing explanation of war economy does not fit in the conflicts of the modern era. In modern days ‘new war’ or ‘contemporary war’ are mostly intrastate and fought amongst the brutal unregulated non-state actors. This paper discussed different aspects of contemporary war economy focusing on the ongoing civil war of Central African Republic. Design/Methodology/Approach: This paper is developed on the basis of published literature and authors own work experiences in the Central African Republic. A qualitative analytical method has been followed to develop this paper. Findings: This paper identifies the economic system that has been developed in the Central African Republic amidst the civil war for the last two decades. Findings of this analysis show that this war economy is self- financing and parasitic in nature where there is ‘more to war than winning’. Limitations: Due to political unrest and several civil wars for more than two decades, no actual survey could be done in the recent past. Therefore, further study can be conducted to statistically prove the points made in this study. Implications: By studying the war economy of any contemporary war, one can understand the nature of the war as well as the types of trade that govern the war. Originality/Value: There are few works of literature on the war economy, contemporary wars and also conflicts of Central African Republic. The paper tries to view the said civil war from the economic perspective and identifies a different aspect of the contemporary war economy.

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