On the cooccurrence of wintertime temperature anomalies over eastern Asia and eastern North America

Abstract

The cooccurrence of wintertime temperature anomalies over eastern Asia and eastern North America is examined. The winter days during 1948–2014 are assigned to nine regimes by applying the self‐organizing map clustering method to the area‐averaged land surface temperature anomalies over these two regions. About half of the winter days are associated with concurrent temperature anomalies. The occurrence of the concurrent/nonconcurrent regimes is closely related to the large‐scale circulation conditions. The Eurasian teleconnection pattern and the Pacific‐North American teleconnection pattern are two dominant large‐scale circulation modes associated with the cooccurrence of the temperature anomalies, through their impacts on the intensities of the corresponding troughs. The precursor analysis reveals that the lead time of the early signals for the concurrent cold anomalies is about 4 days longer than that for the concurrent warm anomalies. In addition, the average lead time of the precursor signals for the wintertime temperature anomalies over eastern Asia is longer than that over eastern North America.

Exploring the combined effects of the Arctic Oscillation and ENSO on the wintertime climate over East Asia using self‐organizing maps

“…The SOM technique and its variations have been successfully applied in climate science to identify representative circulation patterns. Here are four examples: The SOM technique was used by Mills and Walsh [] to categorize the spatial patterns of daily SLP over the Arctic during the period of 1979–2013 and allow for the study of the relationship between the variations in synoptic activity and the recent rapid sea ice reduction; by applying the SOM technique to the daily geopotential height anomaly fields, Horton et al [] studied the major circulation patterns and their trends over the Northern Hemisphere and identified the possible causes for the recent increases of some extreme weather phenomena; Huang et al [] applied the SOM technique to the potential vorticity on the 300 K isentropic surface and identified nine distinct wintertime circulation patterns over East Asia; Chen et al [] used the SOM algorithm to identify the circulation patterns favorable for the cooccurrence of wintertime temperature extremes over eastern Asia and eastern North America. While these three studies exclusively applied the SOM method to a single variable in the specific region under analysis, it should be noted that there have been studies where the SOM method was applied to multiple variables in one specific region.…”

Dynamic and Thermodynamic Factors Associated with Different Precipitation Regimes over South China during Pre-Monsoon Season

“…In this study, a neural network-based classification technique, i.e., Self-Organizing Map (SOM) technique proposed by Kohonen [25], is used to classify the AMJ sub-daily precipitation over South China into different precipitation regimes. Up to date, SOM was widely used in the climate community [26][27][28][29][30][31][32][33]. In addition, the previous studies have pointed out that the persistence and transformation characteristics among different regimes benefit the weather forecast [34][35][36].…”

Association between Arctic Circulation and Indian Summer Monsoon Rainfall

“…There are many clustering algorithms available and have been used in climate science e.g. the hard clustering methods like map-tomap method [13,14], the distance-based k-means method [14][15][16][17][18], soft clustering methods like fuzzy c-menas method [19,20], machine learning techniques like self-organizing maps [21,22], and stochastic weather generators using time series resampling algorithms [23].…”