Search Results

You are looking at 1 - 10 of 19 items for :

  • Decadal variability x
  • Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) x
  • Refine by Access: All Content x
Clear All
Gloria L Manney, Michelle L Santee, Zachary D Lawrence, Krzysztof Wargan, and Michael J Schwartz


A comprehensive investigation of the climatology of and interannual variability and trends in the Asian summer monsoon anticyclone (ASMA) is presented, based on a novel area and moments analysis. Moments include centroid location, aspect ratio, angle, and “excess kurtosis” (measuring how far the shape is from elliptical) for an equivalent ellipse with the same area as the ASMA. Key results are robust among the three modern reanalyses studied. The climatological ASMA is nearly elliptical, with its major axis aligned along its centroid latitude and a typical aspect ratio of ~5–8. The ASMA centroid shifts northward with height, northward and westward during development, and in the opposite direction as it weakens. New evidence finding no obvious climatological bimodality in the ASMA reinforces similar suggestions from previous studies using modern reanalyses. Most trends in ASMA moments are not statistically significant. ASMA area and duration, however, increased significantly during 1979–2018; the 1958–2018 record analyzed for one reanalysis suggests that these trends may have accelerated in recent decades. ASMA centroid latitude is significantly positively (negatively) correlated with subtropical jet core latitude (altitude), and significantly negatively correlated with concurrent ENSO; these results are consistent with and extend previous work relating monsoon intensity, ENSO, and jet shifts. ASMA area is significantly positively correlated with the MEI ENSO index two months previously. These results improve our understanding of the ASMA using consistently defined diagnostics of its size, geometry, interannual variability, and trends that have not previously been analyzed.

Restricted access
Natalie P. Thomas, Michael G. Bosilovich, Allison B. Marquardt Collow, Randal D. Koster, Siegfried D. Schubert, Amin Dezfuli, and Sarith P. Mahanama

( Meehl and Tebaldi 2004 ; Wang et al. 2020 ). Over the United States, trends in heat-wave frequency have been generally positive in recent decades ( Oswald and Rood 2014 ; Schoof et al. 2017 ; Oswald 2018 ; Shafiei Shiva et al. 2019 ), although regional trends vary based on the index used ( Smith et al. 2013 ). Several studies have noted the greater increase in nighttime (Tmin) versus daytime (Tmax) heat waves over the United States ( Lyon and Barnston 2017 ; Rennie et al. 2019 ), specifically

Restricted access
Mohar Chattopadhyay, Will McCarty, and Isaac Moradi

. The intermittency in the data can be mitigated by homogenization process that is used in production of long-term continuous sonde data. The data can range from multiple years to multiple decades from a particular instrument, which is affected by artificial shifts. The homogenization process provides spatiotemporal consistency for radiosonde data. The Radiosonde Observation Correction Using Reanalyses (RAOBCORE) and Radiosonde Innovation Composite Homogenization (RICH) software package ( Haimberger

Restricted access
Franklin R. Robertson, Michael G. Bosilovich, and Jason B. Roberts

Halpert 1987 ; Dai and Wigley 2000 ; Gu et al. 2007 ; Robertson et al. 2014 ). Midlatitude storm-track changes embodying teleconnections with tropical forcing also have significant variations at higher latitudes. Over longer time scales Pacific decadal variability [PDV or Pacific decadal oscillation (PDO); e.g., Power et al. 1999 ; Dai 2013 ; Lyon et al. 2014 ] and other basin-scale phenomena [e.g., the Atlantic multidecadal oscillation (AMO); Enfield et al. 2001 ; Sutton and Hodson 2005

Full access
Krzysztof Wargan, Gordon Labow, Stacey Frith, Steven Pawson, Nathaniel Livesey, and Gary Partyka

an added value brought to satellite observations of ozone through data assimilation. In particular, work done at the GMAO over the past decade has shown that assimilation of retrieved ozone data from the Microwave Limb Sounder (MLS) along with total ozone observations from the Ozone Monitoring Instrument (OMI), both onboard the Earth Observing System (EOS) Aura satellite, produces realistic global distributions of ozone in the stratosphere and upper troposphere ( Stajner et al. 2008 ; Wargan

Full access
Gloria L. Manney and Michaela I. Hegglin

preclude those changes being related to climate change impacts that may themselves be correlated with ENSO changes. Several other modes of natural variability, such as the North Atlantic Oscillation, Arctic Oscillation, southern annular mode, quasi-biennial oscillation, Pacific decadal oscillation, and Madden–Julian oscillation, may also be associated with changes in the upper-tropospheric jets on decadal or longer time scales (e.g., Thompson et al. 2000 , 2011 ; Overland and Wang 2005 ; Woollings

Open access
Michael G. Bosilovich, Franklin R. Robertson, Lawrence Takacs, Andrea Molod, and David Mocko

(not shown) are less obviously affected by observing system changes. We suspect that short-term climate fluctuations such as Pacific decadal variability ( Power et al. 1999 ; Ogata et al. 2013 ), the Atlantic multidecadal oscillation ( Enfield et al. 2001 ; Zhang and Delworth 2006 ), or other modes of natural climate variability are likely sources of significant hydrologic cycle variations over this period. While spatial patterns of these modes may be present, these signals are masked in global

Full access
Richard I. Cullather and Sophie M. J. Nowicki

and the full time series shown in Fig. 4 are associated with the region to the north of the Canadian Arctic Archipelago. The patterns shown in Fig. 15 suggest a correlation with high pressure in the area, while the regression for the full available time period shown in Fig. 4 indicates regression values near zero and of no significance. These differences may be due to interannual variability and the overall lack of melt events in these basins prior to the most recent decade. Similar Arctic

Full access
Ronald Gelaro, Will McCarty, Max J. Suárez, Ricardo Todling, Andrea Molod, Lawrence Takacs, Cynthia A. Randles, Anton Darmenov, Michael G. Bosilovich, Rolf Reichle, Krzysztof Wargan, Lawrence Coy, Richard Cullather, Clara Draper, Santha Akella, Virginie Buchard, Austin Conaty, Arlindo M. da Silva, Wei Gu, Gi-Kong Kim, Randal Koster, Robert Lucchesi, Dagmar Merkova, Jon Eric Nielsen, Gary Partyka, Steven Pawson, William Putman, Michele Rienecker, Siegfried D. Schubert, Meta Sienkiewicz, and Bin Zhao

late 1990s, banned the release of the main ozone-depleting substances. Because the rate of the springtime polar ozone depletion depends on temperature and the strength of the Antarctic polar vortex in a given year, the size of the ozone hole exhibits a dynamically driven interannual variability superimposed on decadal-scale trends. This dynamical modulation is also evident in Fig. 24 . The extremely small (less than 3 × 10 6 km 2 ) ozone hole in 2002 occurred in conjunction with the only major

Full access
Lawrence Coy, Paul A. Newman, Steven Pawson, and Leslie R. Lait

1. Introduction The quasi-biennial oscillation (QBO) consists of downward descending easterly and westerly zonal wind regimes that dominate the zonal mean wind variability in the tropical lower stratosphere (100–10 hPa, ~18–30 km in altitude) with a varying (~28 month) period [see Baldwin et al. (2001) and references therein]. The QBO has been a persistent characteristic of the tropical lower stratosphere since observations began in 1953. However, a significant disruption of the QBO occurred

Full access