An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

Discussed in a global context, the issue of scale is important to consider as it relates to climate change. As climatological studies utilize temporally and spatially static definitions of seasonal definitions, the understanding of seasonal change may be limited by the way in which seasons are defined. This research serves as a challenge to this perspective by examining the changes in seasons by incorporating variability into the way in which seasons are defined. Temporally and spatially variable seasons were defined based on thresholds of apparent temperature and upper-level circulation patterns for the period 1948-2012. Using 60 US surface stations, two apparent air temperature metrics were used to define seasons that vary spatially and temporally. Stations represented major cities found in the contiguous United States. A large-scale circulation approach utilized synoptic categorizations based on 250-mb geopotential heights from the NCEP-NCAR reanalysis (NNR) as a metric of seasonal delineation. In this method, seasons varied temporally but not spatially. Despite the different methodological approaches, consistent trends were found. Since 1948, late starts of autumn and winter have been observed while earlier onsets of spring and summer have taken place. For the individual stations, the largest shifts occurred along coasts and in larger, more urbanized environments. Individual locations also showed increased variability in start date, and significant changes were found for all four seasons in the circulation approach. Seasons have been shown to be important for a variety of processes including phenological responses and human adaptation to extreme temperature environments; therefore, the consideration of season variability may be appropriate for future climatological research.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating changes in season length, onset, and end dates across the United States (1948–2012)

Allen

Sheridan

2015

“…Zander et al . (2013) attempted to synoptically define the spring season in the NE United States based on the type (moist/dry, polar/moderate/tropical) and frequency of air masses and also studied the spring temporal characteristics (start, end, duration) over the area. They found that the spring season is dry through time but recently has also been warmer and the start of the season is arriving earlier.…”

Section: Introductionmentioning

confidence: 99%

“…It seems there is agreement on an earlier start date of spring in the works of Sparks and Menzel (2002) for Europe, Zander et al . (2013) and Allen and Sheridan (2015) for the United States. Cassou and Cattiaux (2016) studied the effects a warmer world would have on seasons over Europe and found that winter onset would be slightly delayed and summer would start about 25 days earlier, which would be explained by the reduced March east–west temperature gradient linked to snow cover decline.…”

Section: Introductionmentioning

confidence: 99%

An objective definition of seasons for the Mediterranean region

Kotsias

Lolis

Hatzianastassiou

et al. 2020

An objective definition of seasons for the Mediterranean region is performed using the mean intra-annual variations of 12 climatological parameters. The aim is to achieve a climatologically appropriate determination of the onset and cessation dates, as well as the duration, of each season, better than the conventional seasons (winter, spring, summer and autumn). Moreover, possible changes of the defined seasons during the 70-year study period 1949-2018 are investigated over the climatologically sensitive Mediterranean region. The data used are daily NCEP/NCAR Reanalysis grid point values of precipitation rate, convective precipitation rate, 2 m temperature, total cloud cover, 2 m zonal and meridional wind, 500 and 1,000 hPa geopotential height, 500 and 850 hPa temperature, 850 hPa specific humidity and precipitable water over the Mediterranean region, for the period 1949-2018. Firstly, Principal Component Analysis is applied to the mean intra-annual variations of the above parameters in order to reduce the dimensionality and then k-means Cluster Analysis is applied to the resultant Principal Components in order to group dates with similar regimes of the above parameters. This methodology is applied for the 70-year period 1949-2018 as well as for the five overlapping 30-year subperiods

Seventy‐year disruption of seasons characteristics in the Arabian Peninsula

Ajjur

Al-Ghamdi

2021

Climate change has significantly influenced the characteristics of seasons and negatively affected ecosystems and socio-economic life. This study presents a new, objective definition for seasons in the Arabian Peninsula. Specifically, the study determines disruptions in the onset, cessation, and duration of winter, spring, summer, and autumn based on mean intra-annual changes of 12 climatological parameters from 1950 to 2019. Data for climatological parameters were obtained from the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis. These data were analysed using two multivariate statistical methods: principal component analysis and cluster analysis. The results show that the characteristics of the four seasons differ from conventionally defined seasons. The differing characteristics of the four seasons are (a) that winter extends for 91 days, between 2 November (the previous year) and 31 January; (b) spring extends for 111 days, until 22 May; (c) summer extends for 106 days, until 5 September and, finally; (d) autumn completes the cycle, extending for 57 days. To investigate the decadal disruption of seasons' characteristics, the analysis was performed on the data collected during five overlapping 30-year periods: 1950-