scholarly journals Recent mean temperature trends in Pakistan and links with teleconnection patterns

2012 ◽  
Vol 33 (2) ◽  
pp. 277-290 ◽  
Author(s):  
S. del Río ◽  
M. Anjum Iqbal ◽  
A. Cano-Ortiz ◽  
L. Herrero ◽  
A. Hassan ◽  
...  
Keyword(s):  
Teleconnection Patterns ◽  
Temperature Trends ◽  
Mean Temperature

Climate Variability and Trend Analyses of Rainfall and Temperature Data of Imphal, Manipur

2021 ◽  
Vol 14 (11) ◽  
pp. 57-63
Author(s):  
Abujam Manglem Singh
Keyword(s):  
Climate Variability ◽  
Monsoon Season ◽  
Temperature Data ◽  
Climate Mitigation ◽  
Climate Data ◽  
Local Climate ◽  
Mitigation And Adaptation ◽  
Temperature Trends ◽  
Mean Temperature ◽  
Maximum Minimum

Understanding local climate variability and change is necessary for improving future climate forecasts and also aids preparation of informed area specific climate mitigation and adaptation strategies. Climate change at local scale is best revealed by studying observed variabilities and trends in rainfall and temperature data through statistical techniques. Therefore, this study employed standard deviation and coefficient of variability and Mann-Kendall test and Sen slope determination non-parametric techniques to perform variability and trends analyses across multiple temporal scales on climate data obtained at Imphal (Tulihal) station. The results indicate prevalence of different patterns between rainfall and temperature trends. Except for the positive trends in the month May (2mm/yr) and in the pre-monsoon season (9.49mm/yr), no other discernable patterns in rainfall data were observed. Temperature trends, on the other hand, witnessed significant positive increase in maximum, minimum and mean values. For mean temperature, all months registered significant increasing trends. At the annual and seasonal scales also, maximum, minimum and mean temperatures have increased although with varying rates. It is noteworthy to mention that temperature change has occurred at two distinct phases; before 1993 slow warming and after 1993 rapid warming. Temporal distribution of annual mean temperature captures this pattern more vividly as warming rate before 1993 was less than 0.01 compared to 0.450c/year in the latter phase. Overall, it can be said that rainfall has higher variability with very little or no pattern but temperature distribution suggests existence of strong trends in the observed data.

Dynamic Contribution to Hemispheric Mean Temperature Trends

Science ◽  
1995 ◽  
Vol 270 (5237) ◽  
pp. 780-783 ◽  
Author(s):  
J. M. Wallace ◽  
Y. Zhang ◽  
J. A. Renwick
Keyword(s):  
Temperature Trends ◽  
Mean Temperature

scholarly journals Effect of atmospheric circulation on surface air temperature trends in years 1979–2018

2021 ◽  
Author(s):  
Jouni Räisänen
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Coupled Model ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Mean Square ◽  
Temperature Trends ◽  
Mean Temperature ◽  
The Mean ◽  
Mean Square Difference

AbstractThe effect of atmospheric circulation on monthly, seasonal and annual mean surface air temperature trends in the years 1979–2018 is studied by applying a trajectory-based method on the European Centre for Medium-Range Weather Forecasts ERA5 reanalysis data. To the extent that the method captures the effects of atmospheric circulation, the results suggest that circulation trends only had a minor impact on observed annual mean temperature trends in most areas. Exceptions include, for example, a decrease in annual mean warming by about 1 °C in western Siberia, and increased warming in central Europe and the Arctic Ocean. However, the effect of circulation trends on seasonal and particularly monthly temperature trends is more substantial. Subtracting the effect of circulation changes from the ERA5 temperature trends leaves residual trends with a smoother annual cycle than the original trends. The residual monthly mean temperature trends also tend to agree better with the multi-model mean temperature trends from models in the 5th Coupled Model Intercomparison Project (CMIP5) than the original ERA5 trends do, with a 42% decrease in the mean square difference over the global land area. However, the corresponding decrease in the mean square difference of the annual mean temperature trends is only 6%.

scholarly journals Stratospheric and tropospheric SSU/MSU temperature trends and compared to reanalyses and IPCC CMIP5 simulations in 1979–2005

2013 ◽  
Vol 13 (2) ◽  
pp. 3957-3992 ◽  
Author(s):  
A. M. Powell ◽  
J. Xu ◽  
C.-Z. Zou ◽  
L. Zhao
Keyword(s):  
Spatial Correlation ◽  
Cmip5 Model ◽  
Model Simulations ◽  
Middle Troposphere ◽  
Global Mean Temperature ◽  
Temperature Trends ◽  
Mean Temperature ◽  
Microwave Sounding ◽  
Stratospheric Cooling ◽  
Global Mean

Abstract. Using the satellite temperature measurements from the Stratospheric Sounding Units (SSU) and Microwave Sounding Units (MSU including the advanced microwave sounding unit, AMSU) since 1979, the trends and uncertainties in the fifth Coupled Model Intercomparison Project (CMIP5) model simulations from the middle troposphere to the upper stratosphere (5–50 km) have been explored. The temperature trend discrepancies between the new generation reanalyses are investigated. Both the temporal character of the global mean temperature and the regional spatial pattern of the temperature trends are discussed. The results show that the CMIP5 model simulations reproduced common stratospheric cooling and tropospheric warming features although a significant discrepancy among the selected models was observed. For the temporal variation of the global mean temperature, the CMIP5 simulations reproduce the volcanic signal and were highly consistent with the SSU measurements in the upper stratosphere. In contrast, the CFSR and MERRA reanalyses (excluding ERA-I) exhibit a different result from the CMIP5 simulations. For the spatial variation of the temperature trends, the CMIP5 simulations displayed a different latitudinal-longitudinal pattern from SSU/MSU measurements in all six layers from the middle troposphere to the upper stratosphere. The CFSR reanalysis shows a good spatial correlation with satellite observations in the troposphere but poor spatial correlation in the stratosphere. The ERA-I and MERRA reanalyses have good spatial correlation in the upper stratosphere and an even better spatial correlation in the troposphere. Generally, the CMIP5 simulations significantly underestimated the stratospheric cooling in the tropics and substantially overestimated the cooling over the Antarctic in the MSU observations. The largest trend spread among the seven CMIP5 simulations is seen in both the south- and north-polar regions in the stratosphere and troposphere. The tropospheric spread values are generally smaller than the stratospheric spread values.

scholarly journals Revisiting Whether Recent Surface Temperature Trends Agree with the CMIP5 Ensemble

2016 ◽  
Vol 29 (24) ◽  
pp. 8673-8687 ◽  
Author(s):  
Marena Lin ◽  
Peter Huybers
Keyword(s):  
Surface Temperature ◽  
Linear Trend ◽  
Coupled Model ◽  
Global Trends ◽  
Global Mean Temperature ◽  
Temperature Trends ◽  
Mean Temperature ◽  
Intercomparison Project ◽  
Slope Estimator ◽  
Global Mean

Abstract In an earlier study, a weaker trend in global mean temperature over the past 15 years relative to the preceding decades was characterized as significantly lower than those contained within the phase 5 of the Coupled Model Intercomparison Project (CMIP5) ensemble. In this study, divergence between model simulations and observations is estimated using a fixed-intercept linear trend with a slope estimator that has one-third the noise variance compared to simple linear regression. Following the approach of the earlier study, where intermodel spread is used to assess the distribution of trends, but using the fixed-intercept trend metric demonstrates that recently observed trends in global mean temperature are consistent () with the CMIP5 ensemble for all 15-yr intervals of observation–model divergence since 1970. Significant clustering of global trends according to modeling center indicates that the spread in CMIP5 trends is better characterized using ensemble members drawn across models as opposed to using ensemble members from a single model. Despite model–observation consistency at the global level, substantial regional discrepancies in surface temperature trends remain.

scholarly journals Spatial analysis of mean temperature trends in Spain over the period 1961–2006

2011 ◽  
Vol 78 (1-2) ◽  
pp. 65-75 ◽  
Author(s):  
S. del Río ◽  
L. Herrero ◽  
C. Pinto-Gomes ◽  
A. Penas
Keyword(s):  
Spatial Analysis ◽  
Temperature Trends ◽  
Mean Temperature

scholarly journals Radiosonde stratospheric temperatures at Dumont d'Urville (Antarctica): trends and link with polar stratospheric clouds

2010 ◽  
Vol 10 (8) ◽  
pp. 3813-3825 ◽  
Author(s):  
C. David ◽  
P. Keckhut ◽  
A. Armetta ◽  
J. Jumelet ◽  
M. Snels ◽  
...  
Keyword(s):  
Significant Trend ◽  
Positive Trend ◽  
International Geophysical Year ◽  
Stratospheric Temperature ◽  
Temperature Trends ◽  
Mean Temperature ◽  
Climate Evolution ◽  
Data Gap ◽  
Using Data ◽  
Stratospheric Clouds

Abstract. Temperature profiles measurements are performed daily (00:00 UT) in Dumont d'Urville (66°40' S, 140°01' E) by Météo-France, using standard radiosondes, since the International Geophysical Year in 1957. Yet, due to a 16 years data gap between 1963 and 1978, the entire dataset is only used for a qualitative overview. Only the most recent series, between 1979 and 2008, is used to investigate the inter-annual stratospheric temperatures variability. Over Dumont d'Urville, at the edge of the vortex, the annual mean temperature cooling of about 1 K/decade at 20 km is the result of the cooling trends between 0.5 and 1.4 K/decade, in summer and autumn and a warming of about 1.1 K/decade in spring. These values are consistent with values obtained using data from inner vortex stations, but with smaller amplitude. No statistically significant trend is detected in winter. We propose here the first attempt to link stratospheric temperature trends to Polar Stratospheric Cloud (PSC) trends in Antarctica based on the only continuous 20 years database of PSC lidar detection. Despite the absence of mean temperature trend during winter, the occurrence of temperatures below the NAT threshold between 1989 and 2008 reveals a significant trend of about +6%/decade. The PSCs occurrences frequency exhibits a concomitant trend of about +3%/decade, although not statistically significant. Yet, this is consistent with results obtained in the Northern Hemisphere. Such a possible positive trend in PSC occurrence has to be further explored to be confirmed or invalidated. If confirmed, this PSC trend is likely to have strong impacts, both on ozone recovery and climate evolution in Antarctica. The study also reveals the importance of trends on extreme temperatures, and not only on mean temperatures.

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