Temperature changes in the mid‐ and high‐ latitudes of the Southern Hemisphere

Abstract

A Hierarchical Ascending Classification is used to regionalize monthly temperature anomalies measured at 24 weather stations in Antarctica and the Sub‐Antarctic and mid‐latitude southern islands from 1973 to 2002. Three principal regions are identified that are geographically coherent: Eastern Antarctica, the Antarctic Peninsula and the Sub‐Antarctic and mid‐latitude islands. Within each region, consistent trends are observed: namely, stationary temperatures in ‘East‐Antarctica’; a robust warming in the ‘Sub‐Antarctic and mid‐latitude islands’, most pronounced in austral summer (nearly 0.5 °C per decade); and a strong but more recent warming in the ‘Antarctic Peninsula’. Austral summer temperature anomalies are related to (1) the Southern Annular Mode (SAM) indexes computed using two reanalysis products (20th Century Reanalyses and ERA40) over two periods (1958–2002 and 1973–2002), (2) the seasonal frequencies of four recurrent daily weather regimes identified with a k‐means algorithm applied on the 500hPa geopotential height (DJF 1958–2002) and (3) HadSST2 sea surface temperature (SST) anomalies (DJF 1958–2002). East‐Antarctica interannual temperature anomalies are associated with the SAM variability. In the Antarctic Peninsula, only the long‐term trend is common with the SAM. The SAM does impact significantly the temperature anomalies of the Sub‐Antarctic and mid‐latitude islands. Trend and interannual variability of the islands' temperatures are associated with the nearby SST. For the Indian Ocean stations, warming in the Agulhas Current system could also have led to these changes. Copyright © 2012 Royal Meteorological Society

Wind speed trends over the southwestern Atlantic Ocean, between 33° and 50°S

“…A homogeneous area of warming (approximately +0.2 °C per decade) can be clearly appreciated at the Argentinean continental shelf and the adjacent ocean. On the contrary, Richard et al () obtained a negative annual trend of approximately −0.2 °C per decade at the northern Patagonian continental shelf estimated from UK Meteorological Office Hadley Centre's SST data set version 2 (period: 1958–2002). Considering these dissimilar SST trend patterns, computed from different databases and periods, it is difficult to conclude whether or not the wind speed trend pattern computed from CFSR data set could be related to a possible change in the SST at this region of the southwestern Atlantic Ocean.…”

“…SST and wind speed trend patterns, both of them computed from CFSR database, seem to be quite consistent. But, taking into account the different SST global trend patterns shown in previous works (Casey and Cornillon, 2001;Good et al, 2007;Richard et al, 2012), it was rather difficult to conclude whether or not the wind speed trend pattern computed from CFSR data set could be connected to a possible change of the SST at the study region. Sea surface wind speed values compiled from multiple satellite observations were also used to compute the spatial distribution of wind speed trends at the study region.…”

Global and regional evaluation of a global model simulated AODs with AERONET and MODIS observations

“…During December–February, the temperature in the Southern Hemisphere generally remains higher than Northern Hemisphere (Richard et al, ), shifting winds from equatorial regions towards the Southern Hemisphere (Husar et al, ). Figure shows a seasonal shift in wind pattern analysed using NCEP (National Center for Environmental Prediction) reanalysis wind data (http://www.esrl.noaa.gov/).…”

“…During December-February aerosol plume shifts towards the Gulf of Guinea and seems more intense due to the accumulation of anthropogenic aerosol, as this region is characterized with extensive biomass burning (Levinson and Lawrimore, 2009). During December-February, the temperature in the Southern Hemisphere generally remains higher than Northern Hemisphere (Richard et al, 2013), shifting winds from equatorial regions towards the Southern Hemisphere (Husar et al, 1997). Figure 5 shows a seasonal shift in wind pattern analysed using NCEP (National Center for Environmental Prediction) reanalysis wind data (http://www.esrl.noaa.gov/).…”

New Reconstruction of Antarctic Near-Surface Temperatures: Multidecadal Trends and Reliability of Global Reanalyses*,+

“…Poleward of 608S, a mere 15 research stations have temperature records extending from the IGY (or immediately thereafter) to the present. Despite their small number, these records have been used to reveal and investigate important aspects of Antarctic climate change (e.g., Thompson and Solomon 2002;Vaughan et al 2003;Turner et al 2005;Marshall et al 2013;Richard et al 2013). The main limitation of these investigations is that 1) they rely on stations mostly located on the coast, thus providing little insight into the vast Antarctic interior, and 2) they largely leave aside West Antarctica, owing to the lack of long-term continuous instrumental records in the region (here and throughout the paper, West Antarctica is meant as separate from the Antarctic Peninsula; see Fig.…”