scholarly journals On the Relations of the Spatial Standard Deviations of Contour Height and Temperature to the Spatial Mean Temperature over the Northern Hemisphere

1958 ◽  
Vol 9 (1) ◽  
pp. 35-39 ◽  
Author(s):  
E. Suzuki
Keyword(s):  
Northern Hemisphere ◽  
Mean Temperature ◽  
Standard Deviations

scholarly journals Impact of solar vs. volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

2013 ◽  
Vol 9 (6) ◽  
pp. 6179-6220 ◽  
Author(s):  
J. G. Anet ◽  
S. Muthers ◽  
E. V. Rozanov ◽  
C. C. Raible ◽  
A. Stenke ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Solar Irradiance ◽  
Energetic Particle ◽  
Volcanic Eruptions ◽  
Hadley Cell ◽  
Particle Spectrum ◽  
Volcanic Aerosol ◽  
Mean Temperature ◽  
The Impact ◽  
Dalton Minimum

Abstract. The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles vs. volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, 1780–1840 AD). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ < 250 nm, (ii) irradiance at wavelengths λ > 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere-ocean chemistry-climate-model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decrease global mean temperature by up to 0.5 K for 2–3 yr after the eruption. However, while the volcanic effect is clearly discernible in the southern hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree-ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ < 250 nm and in energetic particle spectra have only insignificant impact on the climate during the Dalton Minimum. This downscales the importance of top-down processes (stemming from changes at λ < 250 nm) relative to bottom-up processes (from λ > 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease of the ocean heat content (OHC) between the 0 and 300 m of depth, whereas the changes in irradiance at λ < 250 nm or in energetic particle have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8–15 yr after volcanic eruption, while the solar signal and the different volcanic eruptions dominate the OHC changes in the deeper ocean and prevent its recovery during the DM. Finally, the simulations suggest that the volcanic eruptions during the DM had a significant impact on the precipitation patterns caused by a widening of the Hadley cell and a shift of the intertropical convergence zone.

scholarly journals Climate of the last millennium: ensemble consistency of simulations and reconstructions

2012 ◽  
Vol 8 (3) ◽  
pp. 2409-2444 ◽  
Author(s):  
O. Bothe ◽  
J. H. Jungclaus ◽  
D. Zanchettin ◽  
E. Zorita
Keyword(s):  
Northern Hemisphere ◽  
Temperature Fields ◽  
Data Sets ◽  
Last Millennium ◽  
Max Planck ◽  
Simulation Data ◽  
Central European ◽  
Spatial And Temporal Scales ◽  
Mean Temperature ◽  
Ensemble Mean

Abstract. Are simulations and reconstructions of past climate and its variability comparable with each other? We assess if simulations and reconstructions are consistent under the paradigm of a statistically indistinguishable ensemble. Ensemble consistency is assessed for Northern Hemisphere mean temperature, Central European mean temperature and for global temperature fields for the climate of the last millennium. Reconstructions available for these regions are evaluated against the simulation data from the community simulations of the climate of the last millennium performed at the Max Planck Institute for Meteorology. The distributions of ensemble simulated temperatures are generally too wide at most locations and on most time-scales relative to the employed reconstructions. Similarly, an ensemble of reconstructions is too wide when evaluated against the simulation ensemble mean. Probabilistic and climatological ensemble consistency is limited to sub-domains and sub-periods. Only the ensemble simulated and reconstructed annual Central European mean temperatures for the second half of the last millennium demonstrates consistency. The lack of consistency found in our analyses implies that, on the basis of the studied data sets, no status of truth can be assumed for climate evolutions on the considered spatial and temporal scales and, thus, assessing the accuracy of reconstructions and simulations is so far of limited feasibility in pre-instrumental periods.

scholarly journals Proxy-Based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Method, Predictor Network, Target Season, and Target Domain

2005 ◽  
Vol 18 (13) ◽  
pp. 2308-2329 ◽  
Author(s):  
S. Rutherford ◽  
M. E. Mann ◽  
T. J. Osborn ◽  
K. R. Briffa ◽  
P D. Jones ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Warm Season ◽  
Cold Season ◽  
Target Domain ◽  
Proxy Data ◽  
Mean Temperature ◽  
Reconstructed Temperature ◽  
Temperature Reconstructions ◽  
Methodological Considerations

Abstract Results are presented from a set of experiments designed to investigate factors that may influence proxy-based reconstructions of large-scale temperature patterns in past centuries. The factors investigated include 1) the method used to assimilate proxy data into a climate reconstruction, 2) the proxy data network used, 3) the target season, and 4) the spatial domain of the reconstruction. Estimates of hemispheric-mean temperature are formed through spatial averaging of reconstructed temperature patterns that are based on either the local calibration of proxy and instrumental data or a more elaborate multivariate climate field reconstruction approach. The experiments compare results based on the global multiproxy dataset used by Mann and coworkers, with results obtained using the extratropical Northern Hemisphere (NH) maximum latewood tree-ring density set used by Briffa and coworkers. Mean temperature reconstructions are compared for the full NH (Tropics and extratropics, land and ocean) and extratropical continents only, withvarying target seasons (cold-season half year, warm-season half year, and annual mean). The comparisons demonstrate dependence of reconstructions on seasonal, spatial, and methodological considerations, emphasizing the primary importance of the target region and seasonal window of the reconstruction. The comparisons support the generally robust nature of several previously published estimates of NH mean temperature changes in past centuries and suggest that further improvements in reconstructive skill are most likely to arise from an emphasis on the quality, rather than quantity, of available proxy data.

scholarly journals Impact of solar versus volcanic activity variations on tropospheric temperatures and precipitation during the Dalton Minimum

2014 ◽  
Vol 10 (3) ◽  
pp. 921-938 ◽  
Author(s):  
J. G. Anet ◽  
S. Muthers ◽  
E. V. Rozanov ◽  
C. C. Raible ◽  
A. Stenke ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Solar Irradiance ◽  
Energetic Particle ◽  
Volcanic Eruptions ◽  
Energetic Particles ◽  
Hadley Cell ◽  
Particle Spectrum ◽  
Volcanic Aerosol ◽  
Mean Temperature ◽  
Dalton Minimum

Abstract. The aim of this work is to elucidate the impact of changes in solar irradiance and energetic particles versus volcanic eruptions on tropospheric global climate during the Dalton Minimum (DM, AD 1780–1840). Separate variations in the (i) solar irradiance in the UV-C with wavelengths λ < 250 nm, (ii) irradiance at wavelengths λ > 250 nm, (iii) in energetic particle spectrum, and (iv) volcanic aerosol forcing were analyzed separately, and (v) in combination, by means of small ensemble calculations using a coupled atmosphere–ocean chemistry–climate model. Global and hemispheric mean surface temperatures show a significant dependence on solar irradiance at λ > 250 nm. Also, powerful volcanic eruptions in 1809, 1815, 1831 and 1835 significantly decreased global mean temperature by up to 0.5 K for 2–3 years after the eruption. However, while the volcanic effect is clearly discernible in the Southern Hemispheric mean temperature, it is less significant in the Northern Hemisphere, partly because the two largest volcanic eruptions occurred in the SH tropics and during seasons when the aerosols were mainly transported southward, partly because of the higher northern internal variability. In the simulation including all forcings, temperatures are in reasonable agreement with the tree ring-based temperature anomalies of the Northern Hemisphere. Interestingly, the model suggests that solar irradiance changes at λ < 250 nm and in energetic particle spectra have only an insignificant impact on the climate during the Dalton Minimum. This downscales the importance of top–down processes (stemming from changes at λ < 250 nm) relative to bottom–up processes (from λ > 250 nm). Reduction of irradiance at λ > 250 nm leads to a significant (up to 2%) decrease in the ocean heat content (OHC) between 0 and 300 m in depth, whereas the changes in irradiance at λ < 250 nm or in energetic particles have virtually no effect. Also, volcanic aerosol yields a very strong response, reducing the OHC of the upper ocean by up to 1.5%. In the simulation with all forcings, the OHC of the uppermost levels recovers after 8–15 years after volcanic eruption, while the solar signal and the different volcanic eruptions dominate the OHC changes in the deeper ocean and prevent its recovery during the DM. Finally, the simulations suggest that the volcanic eruptions during the DM had a significant impact on the precipitation patterns caused by a widening of the Hadley cell and a shift in the intertropical convergence zone.

What Is Fever?

1993 ◽  
Vol 32 (3) ◽  
pp. 142-146 ◽  
Author(s):  
Lynn W. Herzog ◽  
Lauren J. Coyne
Keyword(s):  
Significant Rise ◽  
Mean Temperature ◽  
Healthy Infants ◽  
Electronic Thermometer ◽  
The Mean ◽  
Standard Deviations ◽  
Definition Of

To determine the normal temperature of healthy infants, we studied 691 infants less than 3 months of age being seen for regularly scheduled well-baby visits. All temperatures were taken rectally with an electronic thermometer. The mean temperature was 37.5°C ± 0.3°C. Using a cutoff of 2 standard deviations (SD) above the mean, fever would be defined as a temperature ≥ 38.1°C. The 95th percentile was 38.0°C, and ≥38.1°C would correspond to values above the 95th percentile. The most widely used definition of fever at present is a temperature ≥38.0°C; by this definition, 6.5% of these well infants would be considered to have a fever. A significant rise in temperature with age was noted. For infants from birth to 30 days old, 2 SD above the mean was 38.0°C; for those 31 to 60 days old, it was 38.1°C; and for those 61 to 91 days old, it was 38.2°C. Similarly, the 95th percentile was 37.9°C, 38.0°C, and 38.1°C, respectively. Temperature also varied significantly with the season of the year, being higher in the summer (2 SD above a mean = 38.3°C) than in the winter (2 SD above a mean = 38.0°C). Fever should be defined as a temperature ≥38.0°C in infants less than 30 days of age, ≥38.1°C in 1-month-olds, and ≥38.2°C in 2-month-olds.

scholarly journals Radiosondes stratospheric temperatures from 1957 to 2008 at Dumont d'Urville (Antarctica): trends and link with Polar Stratospheric Clouds

2009 ◽  
Vol 9 (6) ◽  
pp. 25687-25722 ◽  
Author(s):  
C. David ◽  
P. Keckhut ◽  
A. Armetta ◽  
J. Jumelet ◽  
M. Marchand ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Significant Trend ◽  
Positive Trend ◽  
Temperature Profiles ◽  
International Geophysical Year ◽  
Mean Temperature ◽  
Data Gap ◽  
Using Data ◽  
Stratospheric Clouds ◽  
International Geophysical

Abstract. Temperature profiles measurements are performed daily (00:00 UT) in Dumont d'Urville by Météo-France, using standard radiosondes, since the International Geophysical Year in 1957. A significant cooling of about 2.3 K/decade at 20 km appears between 1957 and 2008, consistent with other Antarctic studies. Due to a 16 years data gap between 1963 and 1978, 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 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. 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.

scholarly journals The climate impact of COVID-19-induced contrail changes

2021 ◽  
Vol 21 (12) ◽  
pp. 9405-9416
Author(s):  
Andrew Gettelman ◽  
Chieh-Chieh Chen ◽  
Charles G. Bardeen
Keyword(s):  
Surface Temperature ◽  
Northern Hemisphere ◽  
Land Surface ◽  
Radiative Forcing ◽  
Climate Impact ◽  
Climate Impacts ◽  
Infrared Heating ◽  
Boreal Summer ◽  
Surface Temperature Change ◽  
Standard Deviations

Abstract. The COVID-19 pandemic caused significant economic disruption in 2020 and severely impacted air traffic. We use a state-of-the-art Earth system model and ensembles of tightly constrained simulations to evaluate the effect of the reductions in aviation traffic on contrail radiative forcing and climate in 2020. In the absence of any COVID-19-pandemic-caused reductions, the model simulates a contrail effective radiative forcing (ERF) of 62 ± 59 mW m−2 (2 standard deviations). The contrail ERF has complex spatial and seasonal patterns that combine the offsetting effect of shortwave (solar) cooling and longwave (infrared) heating from contrails and contrail cirrus. Cooling is larger in June–August due to the preponderance of aviation in the Northern Hemisphere, while warming occurs throughout the year. The spatial and seasonal forcing variations also map onto surface temperature variations. The net land surface temperature change due to contrails in a normal year is estimated at 0.13 ± 0.04 K (2 standard deviations), with some regions warming as much as 0.7 K. The effect of COVID-19 reductions in flight traffic decreased contrails. The unique timing of such reductions, which were maximum in Northern Hemisphere spring and summer when the largest contrail cooling occurs, means that cooling due to fewer contrails in boreal spring and fall was offset by warming due to fewer contrails in boreal summer to give no significant annual averaged ERF from contrail changes in 2020. Despite no net significant global ERF, because of the spatial and seasonal timing of contrail ERF, some land regions would have cooled slightly (minimum −0.2 K) but significantly from contrail changes in 2020. The implications for future climate impacts of contrails are discussed.

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