Two leading modes of the interannual variability in South American surface air temperature during austral winter

2017 ◽  
Vol 51 (5-6) ◽  
pp. 2141-2156 ◽  
Author(s):  
Yanjie Li ◽  
Jianping Li ◽  
Fred Kucharski ◽  
Jin Feng ◽  
Sen Zhao ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
South American ◽  
Austral Winter

Interannual variability of surface air temperature over mid-high latitudes of Eurasia during boreal autumn

2019 ◽  
Vol 53 (3-4) ◽  
pp. 1805-1821 ◽  
Author(s):  
Shangfeng Chen ◽  
Renguang Wu ◽  
Linye Song ◽  
Wen Chen
Keyword(s):  
Interannual Variability ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
High Latitudes

scholarly journals Potential Predictability of North American Surface Temperature. Part I: Information-Based versus Signal-To-Noise-Based Metrics

2014 ◽  
Vol 27 (4) ◽  
pp. 1578-1599 ◽  
Author(s):  
Y. Tang ◽  
D. Chen ◽  
X. Yan
Keyword(s):  
Surface Temperature ◽  
Interannual Variability ◽  
Air Temperature ◽  
North American ◽  
Southern Oscillation ◽  
Surface Air Temperature ◽  
Multiple Model ◽  
Signal To Noise ◽  
Potential Predictability ◽  
Geographical Variations

Abstract In this study, the potential predictability of the North American (NA) surface air temperature was explored using information-based predictability framework and Ensemble-Based Predictions of Climate Changes and their Impacts (ENSEMBLES) multiple model ensembles. Emphasis was put on the comparison of predictability measured by information-based metrics and by the conventional signal-to-noise ratio (SNR)-based metrics. Furthermore, the potential predictability was optimally decomposed into different modes by maximizing the predictable information (equivalent to the maximum of SNR), from which the most predictable structure was extracted and analyzed. It was found that the conventional SNR-based metrics underestimate the potential predictability, in particular in these areas where the predictable signals are relatively weak. The most predictable components of the NA surface air temperature can be characterized by the interannual variability mode and the long-term trend mode. The former is inherent to tropical Pacific sea surface temperature (SST) forcing such as El Niño–Southern Oscillation (ENSO), whereas the latter is closely associated with the global warming. The amplitude of the two modes has geographical variations in different seasons. On this basis, the possible physical mechanisms responsible for the predictable mode of interannual variability and its potential benefits to the improvement of seasonal climate prediction were discussed.

On the Possible Link between Tropical Convection and the Northern Hemisphere Arctic Surface Air Temperature Change between 1958 and 2001

2011 ◽  
Vol 24 (16) ◽  
pp. 4350-4367 ◽  
Author(s):  
Sukyoung Lee ◽  
Tingting Gong ◽  
Nathaniel Johnson ◽  
Steven B. Feldstein ◽  
David Pollard
Keyword(s):  
Arctic Ocean ◽  
Interannual Variability ◽  
Northern Hemisphere ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Convective Precipitation ◽  
Frequency Of Occurrence ◽  
Teleconnection Patterns ◽  
Polar Amplification ◽  
Trend Pattern

Abstract This study presents mechanisms for the polar amplification of surface air temperature that occurred in the Northern Hemisphere (NH) between the periods of 1958–77 (P1) and 1982–2001 (P2). Using European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40) reanalysis data, it is found that over the ice-covered Arctic Ocean, the winter surface warming arises from dynamic warming (stationary eddy heat flux and adiabatic warming). Over the ice-free Arctic Ocean between the Greenland and the Barents Seas, downward infrared radiative (IR) flux is found to dominate the warming. To investigate whether the difference in the flow between P1 and P2 is due to changes in the frequency of occurrence of a small number of teleconnection patterns, a coupled self-organizing map (SOM) analysis of the 250-hPa streamfunction and tropical convective precipitation is performed. The latter field was specified to lead the former by 5 days. The results of the analysis showed that the P2 − P1 trend arises from a decrease in the frequency of negative phase PNA-like and circumglobal streamfunction patterns and a corresponding increase in the frequency of positive PNA-like and circumglobal streamfunction patterns. The occurrence of the two strong 1982–83 and 1997–98 El Niño events also contributes toward this trend. The corresponding trend in the convective precipitation is from below average to above average values in the tropical Indo-western Pacific region. Each of the above patterns was found to have an e-folding time scale from 6 to 8 days, which implies that the P2 − P1 trend can be understood as arising from the change in the frequency of occurrence of teleconnection patterns that fluctuate on intraseasonal time scales. The link between intraseasonal and interannual variability was further examined by linearly regressing various quantities against trend patterns with interannual variability subtracted. It was found that enhanced convective precipitation is followed 3–6 days later by the occurrence of the P2 − P1 circulation trend pattern, and then 1–2 days later by the corresponding trend pattern in the downward IR flux. This finding suggests that an increased frequency of the above sequence of events, which occurs on intraseasonal time scales, can account for the NH winter polar amplification of the surface air temperature via increased dynamic warming and downward IR flux.

scholarly journals Response of Simulated Surface Air Temperature to the Interannual Variability of Leaf Area Index in Eastern China

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Xuezhen Zhang ◽  
Qiuhong Tang
Keyword(s):  
Leaf Area Index ◽  
Interannual Variability ◽  
Leaf Area ◽  
Air Temperature ◽  
Eastern China ◽  
Sensible Heat Flux ◽  
Model Performance ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Area Index

Using the coupled WRF-Noah model, we conducted two experiments to investigate impacts of the interannual variability of leaf area index (LAI) on the surface air temperature (SAT) in eastern China. The Moderate Resolution Imaging Spectroradiometer (MODIS) observed dynamic LAI data from 2002 to 2009 were used in one modeling experiment, and the climatological seasonal cycle of the MODIS LAI was used in the other experiment. The results show that the use of dynamic LAI improves model performance. Compared with the use of climatological LAI, the use of dynamic LAI may reduce the warm (cool) bias in the years with large positive (negative) LAI anomalies. The reduction of the warm bias results from the modeled cooling effect of LAI increase through reducing canopy resistance, promoting transpiration, and decreasing sensible heat flux. Conversely, the reduction of cool bias is a result of the warming effect of negative anomaly of LAI. The use of dynamic LAI can improve model performance in summer and to a lesser extent, spring and autumn. Moreover, the dynamic LAI exerts a detectable influence on SAT in the WRF model when the LAI anomaly is at least 20% of the climatological LAI.

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