Comparative study of multiple measures on temporal irreversibility of daily air temperature anomaly variations over China

2019 ◽  
Vol 523 ◽  
pp. 1387-1399
Author(s):  
Boer Zhang ◽  
Fenghua Xie ◽  
Zunhai Fu ◽  
Zuntao Fu
Keyword(s):  
Comparative Study ◽  
Air Temperature ◽  
Temperature Anomaly ◽  
Multiple Measures ◽  
Air Temperature Anomaly

scholarly journals Discriminating Developing versus Nondeveloping Tropical Disturbances in the Western North Pacific through Decision Tree Analysis

2015 ◽  
Vol 30 (2) ◽  
pp. 446-454 ◽  
Author(s):  
Wei Zhang ◽  
Bing Fu ◽  
Melinda S. Peng ◽  
Tim Li
Keyword(s):  
Decision Tree ◽  
Air Temperature ◽  
North Pacific ◽  
Western North Pacific ◽  
Temperature Anomaly ◽  
Relative Vorticity ◽  
Precipitation Rate ◽  
C4.5 Algorithm ◽  
Air Temperature Anomaly

Abstract This study investigates the classification of developing and nondeveloping tropical disturbances in the western North Pacific (WNP) through the C4.5 algorithm. A decision tree is built based on this algorithm and can be used as a tool to predict future tropical cyclone (TC) genesis events. The results show that the maximum 800-hPa relative vorticity, SST, precipitation rate, divergence averaged between 1000- and 500-hPa levels, and 300-hPa air temperature anomaly are the five most important variables for separating the developing and nondeveloping tropical disturbances. This algorithm also unravels the thresholds of the five variables (i.e., 4.2 × 10−5 s−1 for maximum 800-hPa relative vorticity, 28.2°C for SST, 0.1 mm h−1 for precipitation rate, −0.7 × 10−6 s−1 for vertically averaged convergence, and 0.5°C for 300-hPa air temperature anomaly). Six rules are derived from the decision tree. The classification accuracy of this decision tree is 81.7% for the 2004–10 cases. The hindcast accuracy for the 2011–13 dataset is 84.6%.

scholarly journals What Drives the North Atlantic Oscillation’s Temperature Anomaly Pattern? Part I: The Growth and Decay of the Surface Air Temperature Anomalies

2019 ◽  
Vol 77 (1) ◽  
pp. 185-198 ◽  
Author(s):  
Joseph P. Clark ◽  
Steven B. Feldstein
Keyword(s):  
Skin Temperature ◽  
Air Temperature ◽  
Temperature Anomaly ◽  
Surface Air Temperature ◽  
Temperature Changes ◽  
Temperature Anomalies ◽  
The North ◽  
Temperature Advection ◽  
Anomaly Pattern ◽  
Air Temperature Anomaly

Abstract Composite analysis is used to examine the physical processes that drive the growth and decay of the surface air temperature anomaly pattern associated with the North Atlantic Oscillation (NAO). Using the thermodynamic energy equation that the European Centre for Medium-Range Weather Forecasts implements in their reanalysis model, we show that advection of the climatological temperature field by the anomalous wind drives the surface air temperature anomaly pattern for both NAO phases. Diabatic processes exist in strong opposition to this temperature advection and eventually cause the surface air temperature anomalies to return to their climatological values. Specifically, over Greenland, Europe, and the United States, longwave heating/cooling opposes horizontal temperature advection while over northern Africa vertical mixing opposes horizontal temperature advection. Despite the pronounced spatial correspondence between the skin temperature and surface air temperature anomaly patterns, the physical processes that drive these two temperature anomalies associated with the NAO are found to be distinct. The skin temperature anomaly pattern is driven by downward longwave radiation whereas stated above, the surface air temperature anomaly pattern is driven by horizontal temperature advection. This implies that the surface energy budget, although a useful diagnostic tool for understanding skin temperature changes, should not be used to understand surface air temperature changes.

scholarly journals On Weak Zonally Symmetric ENSO Atmospheric Heating and the Strong Zonally Symmetric ENSO Air Temperature Response

2005 ◽  
Vol 62 (6) ◽  
pp. 2012-2022 ◽  
Author(s):  
Allan J. Clarke ◽  
Kwang-Y. Kim
Keyword(s):  
Air Temperature ◽  
Vertical Velocity ◽  
Temperature Anomaly ◽  
Southern Oscillation ◽  
Temperature Response ◽  
Surface Friction ◽  
Significant Loss ◽  
The Earth ◽  
Symmetric Heating ◽  
Air Temperature Anomaly

Abstract Observations show that regions of anomalous deep convective El Niño–Southern Oscillation (ENSO) heating tend to be balanced by anomalous ENSO cooling elsewhere so that, averaged around the globe from (say) 10°S to 10°N, the net anomalous heating is nearly zero. The zonally symmetric heating is weak because it is approximately proportional to vertical velocity that, when averaged over a constant pressure surface S around the earth from 10°S to 10°N, is nearly zero. The horizontally averaged vertical velocity over S is small because the net horizontal geostrophic convergent flow across 10°S and 10°N is zero. Although the zonally symmetric ENSO heating is weak, the observed ENSO tropospheric air temperature anomaly has a large zonally symmetric component. Past work has shown that with weak momentum and thermal damping, Kelvin and Rossby waves can travel around the earth without significant loss of amplitude so that a zonally symmetric response is favored. This physical interpretation depends on knowing temperature and momentum anomaly damping times over the depth of the troposphere. Such times are not well known. Here a Gill tropical atmospheric model is generalized to include realistic surface friction and so theoretically estimate a frictional spindown time. Using this spindown time (approximately 3 weeks), together with an estimate of the Newtonian cooling time (1 month) the authors show, in agreement with observations, that the extremely weak zonally symmetric heating anomaly generates a symmetric air temperature anomaly comparable to the asymmetric one.

scholarly journals The Response Time of the Temperature of the Equatorial Troposphere to ENSO Heating

2005 ◽  
Vol 62 (12) ◽  
pp. 4412-4422 ◽  
Author(s):  
Allan J. Clarke ◽  
Kwang-Y. Kim
Keyword(s):  
Heat Loss ◽  
Air Temperature ◽  
Temperature Anomaly ◽  
Southern Oscillation ◽  
Sensible Heat Flux ◽  
Meridional Flow ◽  
Latent Heating ◽  
Adiabatic Cooling ◽  
Air Temperature Anomaly ◽  
The Tropics

Abstract Air temperature anomalies, averaged over the troposphere to 200 mb and around the earth from 10°S to 10°N, lag the similarly averaged El Niño–Southern Oscillation (ENSO) atmospheric latent heating anomalies by about one month. Most of the latent heating is balanced by vertical adiabatic cooling although the zonally averaged imbalance is larger than is typical locally in the Tropics. The excess latent heating heats the atmosphere and generates a temperature anomaly. As the temperature anomaly rises, the atmosphere loses heat until the residual heating is balanced by anomalous cooling. By then the temperature anomaly is typically about 0.4°C. Analysis of the thermodynamic energy equation shows that the ENSO heat loss is highly linearly correlated with the air temperature anomaly averaged over the equatorial troposphere; that is, the adjustment to the residual anomalous heating (or cooling) is Newtonian. Consistent with the observed one-month lag, the Newtonian e-folding time is about 35 days. Similar results apply for latitude bands 5°S–5°N and 15°S–15°N (Newtonian cooling times of 29 and 46 days, respectively). The heat loss is mainly through meridional sensible heat flux rather than radiation. Much of the anomalous cooling is due to the mean meridional flow that diverges more temperature anomaly aloft than it converges near the surface.

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