scholarly journals Towards a more reliable historical reanalysis: Improvements for version 3 of the Twentieth Century Reanalysis system

2019 ◽  
Vol 145 (724) ◽  
pp. 2876-2908 ◽  
Author(s):  
Laura C. Slivinski ◽  
Gilbert P. Compo ◽  
Jeffrey S. Whitaker ◽  
Prashant D. Sardeshmukh ◽  
Benjamin S. Giese ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Twentieth Century Reanalysis

On the performance of twentieth century reanalysis products for Antarctic snow accumulation

2019 ◽  
Vol 54 (1-2) ◽  
pp. 435-455 ◽  
Author(s):  
Yetang Wang ◽  
Shugui Hou ◽  
Minghu Ding ◽  
Weijun Sun
Keyword(s):  
Twentieth Century ◽  
Snow Accumulation ◽  
Antarctic Snow ◽  
Twentieth Century Reanalysis

scholarly journals Global Identification of Previously Undetected Pre-Satellite-Era Tropical Cyclone Candidates in NOAA/CIRES Twentieth-Century Reanalysis Data

2013 ◽  
Vol 52 (10) ◽  
pp. 2243-2259 ◽  
Author(s):  
Ryan E. Truchelut ◽  
Robert E. Hart ◽  
Briana Luthman
Keyword(s):  
Twentieth Century ◽  
Tropical Cyclones ◽  
Historical Record ◽  
Reanalysis Data ◽  
Ocean Basin ◽  
Candidate Event ◽  
Filtering Algorithm ◽  
Global Identification ◽  
Time Required ◽  
Twentieth Century Reanalysis

AbstractPrior to the satellite era, limited synoptic observation networks led to an indefinite number of tropical cyclones (TCs) remaining undetected. This period of decreased confidence in the TC climatological record includes the first two-thirds of the twentieth century. While prior studies found that this undersampling exists, disagreement regarding its magnitude has caused difficulties in interpreting multidecadal changes in TC activity. Previous research also demonstrated that reanalyses can be used to extend TC climatology, utilizing the NOAA/Cooperative Institute for Research in Environmental Sciences (CIRES) Twentieth-Century Reanalysis to manually identify previously unknown Atlantic Ocean basin potential TCs. This study expands the spatiotemporal scope of the earlier work by presenting a filtering algorithm that dramatically improves the efficiency with which candidate events are identified in the reanalysis. This algorithm was applied to all tropical basins for the years 1871–1979, resulting in the first quantitative and objective global TC candidate event counts for the decades prior to formal recordkeeping. Observational verification performed on a subset of these events indicates that the algorithm identifies potential missing TCs at a success rate approximating that of earlier work with a significant decrease in the amount of time required. Extrapolating these proportions to all of the candidate events identified suggests that this method may help to locate hundreds of previously unknown TCs worldwide for future study and cataloging. As such, the dataset produced by this research is a source of independent guidance for use in ongoing and future TC climatology revision efforts to produce a more complete historical record more quickly than with current methods.

scholarly journals The Representation of the South Pacific Convergence Zone in the Twentieth Century Reanalysis

2019 ◽  
Vol 147 (3) ◽  
pp. 841-851 ◽  
Author(s):  
Thomas Harvey ◽  
James A. Renwick ◽  
Andrew M. Lorrey ◽  
Arona Ngari
Keyword(s):  
Twentieth Century ◽  
Southern Oscillation ◽  
South Pacific ◽  
South Pacific Convergence Zone ◽  
Past Century ◽  
Convergence Zone ◽  
The South ◽  
Southwest Pacific ◽  
Surface Observations ◽  
Twentieth Century Reanalysis

Abstract The South Pacific convergence zone (SPCZ) is the largest rainfall feature in the Southern Hemisphere, and is a critical component of the climate for South Pacific island nations and territories. The small size and isolated nature of these islands leaves them vulnerable to short- and long-term changes in the position of the SPCZ. Its position and strength is strongly modulated by El Niño–Southern Oscillation (ENSO), leading to large interannual variability in rainfall across the southwest Pacific including seasonal droughts and pluvials. Currently much of the analysis about SPCZ activity has been restricted to the satellite observation period starting in 1979. Here, the representation of the SPCZ in the Twentieth Century Reanalysis (20CR), which is a three-dimensional atmospheric reconstruction based only on surface observations, is discussed for the period since 1908. The performance of two versions of the 20CR (version 2 and version 2c) in the satellite era is compared with other reanalyses and climate observation products. The 20CR performs well in the satellite era. Extra surface observations spanning the SPCZ region from the longitude of the Cook Islands has improved the representation of the SPCZ during 1908–57 between 20CRv2 and 20CRv2c. The well-established relationship with ENSO is observed in both the representation of mean SPCZ position and intensity, and this relationship remains consistent through the entire 1908–2011 period. This suggests that the ENSO–SPCZ relationship has remained similar over the course of the past century, and gives further evidence that 20CRv2c performs well back to 1908 over the southwest Pacific region.

scholarly journals Classifications of Winter Euro-Atlantic Circulation Patterns: An Intercomparison of Five Atmospheric Reanalyses

2017 ◽  
Vol 30 (19) ◽  
pp. 7847-7861 ◽  
Author(s):  
Jan Stryhal ◽  
Radan Huth
Keyword(s):  
Twentieth Century ◽  
Mediterranean Region ◽  
Large Scale ◽  
Climate Models ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Synoptic Climatology ◽  
Cmip5 Models ◽  
Circulation Patterns ◽  
Twentieth Century Reanalysis

Abstract Atmospheric reanalyses have been widely used to study large-scale atmospheric circulation and its links to local weather and to validate climate models. Only little effort has so far been made to compare reanalyses over the Euro-Atlantic domain, with the exception of a few studies analyzing North Atlantic cyclones. In particular, studies utilizing automated classifications of circulation patterns—one of the most popular methods in synoptic climatology—have paid little or no attention to the issue of reanalysis evaluation. Here, five reanalyses [ERA-40; NCEP-1; JRA-55; Twentieth Century Reanalysis, version 2 (20CRv2); and ECMWF twentieth-century reanalysis (ERA-20C)] are compared as to the frequency of occurrence of circulation types (CTs) over eight European domains in winters 1961–2000. Eight different classifications are used in parallel with the intention to eliminate possible artifacts of individual classification methods. This also helps document how substantial effect a choice of method can have if one quantifies differences between reanalyses. In general, ERA-40, NCEP-1, and JRA-55 exhibit a fairly small portion of days (under 8%) classified to different CTs if pairs of reanalyses are compared, with two exceptions: over Iceland, NCEP-1 shows disproportionately high frequencies of CTs with cyclones shifted south- and eastward; over the eastern Mediterranean region, ERA-40 and NCEP-1 disagree on classification of about 22% of days. The 20CRv2 is significantly different from other reanalyses over all domains and has a clearly suppressed frequency of zonal CTs. Finally, validation of 32 CMIP5 models over the eastern Mediterranean region reveals that using different reanalyses can considerably alter errors in the CT frequency of models and their rank.

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