Producing small scale temperature fluctuations in an airstream

1978 ◽  
Vol 49 (10) ◽  
pp. 1432-1434 ◽  
Author(s):  
G. E. Schacher ◽  
C. W. Fairall
Keyword(s):  
Temperature Fluctuations ◽  
Small Scale ◽  
Scale Temperature

Small-Scale Temperature Fluctuations in Perfused Tissue During Local Hyperthermia

1986 ◽  
Vol 108 (3) ◽  
pp. 246-250 ◽  
Author(s):  
J. W. Baish ◽  
P. S. Ayyaswamy ◽  
K. R. Foster
Keyword(s):  
Scaling Laws ◽  
Temperature Fluctuations ◽  
Small Scale ◽  
Adjacent Tissue ◽  
Local Hyperthermia ◽  
Thermal Equilibration ◽  
Scale Temperature ◽  
Tissue Region ◽  
Significant Temperature ◽  
Analytical Expressions

We develop analytical expressions (scaling laws) for the local temperature fluctuations near isolated and countercurrent blood vessels during hyperthermia. These scaling laws relate the magnitude of such fluctuations to the size of the heated region and to the thermal equilibration length of the vessels. A new equilibration length is identified for countercurrent vessels. Significant temperature differences are predicted between the vessels and the immediately adjacent tissue when the equilibration length is comparable to or longer than the size of the heated tissue region. Countercurrent vessels are shown to have shorter equilibration lengths and produce smaller temperature fluctuations than isolated vessels of the same size.

scholarly journals Balloon-borne match measurements of mid-latitude cirrus clouds

2013 ◽  
Vol 13 (10) ◽  
pp. 25417-25479 ◽  
Author(s):  
A. Cirisan ◽  
B. P. Luo ◽  
I. Engel ◽  
F. G. Wienhold ◽  
U. K. Krieger ◽  
...  
Keyword(s):  
Temperature Fluctuations ◽  
Cloud Microphysics ◽  
Cirrus Clouds ◽  
Climate Feedback ◽  
Small Scale ◽  
Model Parameters ◽  
Air Mass ◽  
Upper Troposphere ◽  
Weather Model ◽  
Scale Temperature

Abstract. Observations of persistent high supersaturations with respect to ice inside cirrus clouds are challenging our understanding of cloud microphysics and of climate feedback processes in the upper troposphere. Single measurements of a cloudy air mass provide only a snapshot from which the persistence of ice supersaturation cannot be judged. We introduce here the "cirrus match technique" to obtain information of the evolution of clouds and their saturation ratio. The aim of these coordinated balloon soundings is to analyze the same air mass twice. To this end the standard radiosonde equipment is complemented by a frost point hygrometer "SnowWhite" and a particle backscatter detector "COBALD" (Compact Optical Backscatter Aerosol Detector). Extensive trajectory calculations based on regional weather model COSMO forecasts are performed for flight planning and COSMO analyses are used as basis for comprehensive microphysical box modeling (with grid scale 2 km and 7 km, respectively). Here we present the results of matching a cirrus cloud to within 2–15 km, realized on 8 June 2010 over Payerne, Switzerland, and a location 120 km downstream close to Zurich. A thick cirrus was detected over both measurement sites. We show that in order to quantitatively reproduce the measured particle backscatter ratios, the small-scale temperature fluctuations not resolved by COSMO must be superimposed on the trajectories. The stochastic nature of the fluctuations is captured by ensemble calculations. Possibilities for further improvements in the agreement with the measured backscatter data are investigated by assuming a very slow mass accommodation of water on ice, the presence of heterogeneous ice nuclei, or a wide span of (spheroidal) particle shapes. However, the resulting improvements from microphysical refinements are moderate and comparable in magnitude with changes caused by assuming different regimes of temperature fluctuations for clear sky or cloudy sky conditions, highlighting the importance of a proper treatment of subscale fluctuations. The model yields good agreement with the measured backscatter over both sites and reproduces the measured saturation ratios with respect to ice over Payerne. Conversely, the 30% in-cloud supersaturation measured in a massive, 4-km thick cloud layer over Zurich cannot be reproduced, irrespective of the choice of meteorological or microphysical model parameters. The measured supersaturation can only be explained by either resorting to an unknown physical process, which prevents the ice particles from consuming the excess humidity, or – much more likely – by a measurement error, such as a contamination of the sensor housing of the SnowWhite hygrometer by a precipitation drop from a mixed phase cloud just below the cirrus layer or from some very slight rain in the boundary layer. This uncertainty calls for in-flight checks or calibrations of hygrometers under the extreme humidity conditions in the upper troposphere.

scholarly journals Extreme-Value Statistics for Testing Dark Energy

2014 ◽  
Vol 10 (S306) ◽  
pp. 54-56
Author(s):  
Simone Aiola ◽  
Arthur Kosowsky ◽  
Bingjie Wang
Keyword(s):  
Dark Energy ◽  
Null Hypothesis ◽  
Temperature Fluctuations ◽  
Extreme Value Statistics ◽  
Small Scale ◽  
Complementary Approach ◽  
Scale Temperature ◽  
Λcdm Model ◽  
The Universe ◽  
Cmb Temperature

AbstractThe integrated Sachs-Wolfe effect was recently detected at a level of 4.4σ by [Granett et al. (2008)], by stacking compensated CMB temperature patches corresponding to superstructures in the universe. We test the reported signal using realistic gaussian random realizations of the CMB sky, based on the temperature power spectrum predicted by the concordance ΛCDM model. Such simulations provide a complementary approach to the largely used N-body simulations and allow to include the contaminant effects due to small-scale temperature fluctuations. We also apply our pipeline to foreground-cleaned CMB sky maps using the [Granett et al. (2008)] voids/clusters catalog. We confirm the detection of a signal, which depart from the null hypothesis by 3.5σ, and we report a tension with our theoretical estimates at a significance of about 2.5σ.

Anisotropy of small-scale scalar turbulence

2001 ◽  
Vol 448 ◽  
pp. 279-288 ◽  
Author(s):  
SUSAN KURIEN ◽  
KONSTANTINOS G. AIVALIS ◽  
KATEPALLI R. SREENIVASAN
Keyword(s):  
Reynolds Number ◽  
Spherical Harmonics ◽  
High Reynolds Number ◽  
Temperature Fluctuations ◽  
Small Scale ◽  
Surface Layers ◽  
Isotropic Part ◽  
Scalar Turbulence ◽  
Scale Temperature ◽  
High Reynolds

The anisotropy of small-scale temperature fluctuations in shear flows is analysed by making measurements in high-Reynolds-number atmospheric surface layers. A spherical harmonics representation of the moments of scalar increments is proposed, such that the isotropic part corresponds to the index j = 0 and increasing degrees of anisotropy correspond to increasing j. The parity and angular dependence of the odd moments of the scalar increments show that the moments cannot contain any isotropic part (j = 0), but can be satisfactorily represented by the lowest-order anisotropic term corresponding to j = 1. Thus, the skewnesses of scalar increments (and derivatives) are inherently anisotropic quantities, and are not suitable indicators of the tendency towards isotropy.

Small-scale temperature fluctuations seen by the VeRa Radio Science Experiment on Venus Express

Icarus ◽  
2012 ◽  
Vol 221 (2) ◽  
pp. 471-480 ◽  
Author(s):  
S. Tellmann ◽  
B. Häusler ◽  
D.P. Hinson ◽  
G.L. Tyler ◽  
T.P. Andert ◽  
...  
Keyword(s):  
Temperature Fluctuations ◽  
Small Scale ◽  
Radio Science ◽  
Scale Temperature ◽  
Venus Express

scholarly journals Heterogeneous formation of polar stratospheric clouds – Part 2: Nucleation of ice on synoptic scales

2013 ◽  
Vol 13 (21) ◽  
pp. 10769-10785 ◽  
Author(s):  
I. Engel ◽  
B. P. Luo ◽  
M. C. Pitts ◽  
L. R. Poole ◽  
C. R. Hoyle ◽  
...  
Keyword(s):  
Heterogeneous Nucleation ◽  
Temperature Fluctuations ◽  
Ice Nucleation ◽  
Solid Particles ◽  
Small Scale ◽  
Synoptic Scale ◽  
Polar Stratospheric Clouds ◽  
Ice Nuclei ◽  
Scale Temperature ◽  
Stratospheric Clouds

Abstract. This paper provides compelling evidence for the importance of heterogeneous nucleation, likely on solid particles of meteoritic origin, and of small-scale temperature fluctuations, for the formation of ice particles in the Arctic stratosphere. During January 2010, ice PSCs (polar stratospheric clouds) were shown by CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) to have occurred on a synoptic scale (~1000 km dimension). CALIPSO observations also showed widespread PSCs containing NAT (nitric acid trihydrate) particles in December 2009, prior to the occurrence of synoptic-scale regions of ice PSCs during mid-January 2010. We demonstrate by means of detailed microphysical modeling along air parcel trajectories that the formation of these PSCs is not readily reconciled with expectations from the conventional understanding of PSC nucleation mechanisms. The measurements are at odds with the previous laboratory-based understanding of PSC formation, which deemed direct heterogeneous nucleation of NAT and ice on preexisting solid particles unlikely. While a companion paper (Part 1) addresses the heterogeneous nucleation of NAT during December 2009, before the existence of ice PSCs, this paper shows that also the large-scale occurrence of stratospheric ice in January 2010 cannot be explained merely by homogeneous ice nucleation but requires the heterogeneous nucleation of ice, e.g. on meteoritic dust or preexisting NAT particles. The required efficiency of the ice nuclei is surprisingly high, namely comparable to that of known tropospheric ice nuclei such as mineral dust particles. To gain model agreement with the ice number densities inferred from observations, the presence of small-scale temperature fluctuations, with wavelengths unresolved by the numerical weather prediction models, is required. With the derived rate parameterization for heterogeneous ice nucleation we are able to explain and reproduce CALIPSO observations throughout the entire Arctic winter 2009/2010.

scholarly journals Heterogeneous formation of polar stratospheric clouds – Part 2: Nucleation of ice on synoptic scales

2013 ◽  
Vol 13 (4) ◽  
pp. 8831-8872 ◽  
Author(s):  
I. Engel ◽  
B. P. Luo ◽  
M. C. Pitts ◽  
L. R. Poole ◽  
C. R. Hoyle ◽  
...  
Keyword(s):  
Heterogeneous Nucleation ◽  
Temperature Fluctuations ◽  
Ice Nucleation ◽  
Solid Particles ◽  
Small Scale ◽  
Synoptic Scale ◽  
Polar Stratospheric Clouds ◽  
Ice Nuclei ◽  
Scale Temperature ◽  
Stratospheric Clouds

Abstract. This paper provides unprecedented evidence for the importance of heterogeneous nucleation, likely on solid particles of meteoritic origin, and of small-scale temperature fluctuations, for the formation of ice particles in the Arctic stratosphere. During January 2010, ice PSCs (Polar Stratospheric Clouds) were shown by CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) to have occurred on a synoptic scale (~ 1000 km dimension). CALIPSO observations also showed widespread PSCs containing nitric acid trihydrate (NAT) particles in December 2009, prior to the occurrence of synoptic-scale regions of ice PSCs during mid-January 2010. We demonstrate by means of detailed microphysical modeling along air parcel trajectories that the formation of these PSCs is not readily reconciled with expectations from the conventional understanding of PSC nucleation mechanisms. The measurements are at odds with the previous laboratory-based understanding of PSC formation, which deemed direct heterogeneous nucleation of NAT and ice on preexisting solid particles unlikely. While a companion paper (Part 1) addresses the heterogeneous nucleation of NAT during December 2009, before the existence of ice PSCs, this paper shows that also the large-scale occurrence of stratospheric ice in January 2010 cannot be explained merely by homogeneous ice nucleation but requires the heterogeneous nucleation of ice, e.g. on meteoritic dust or preexisting NAT particles. The required efficiency of the ice nuclei is surprisingly high, namely comparable to that of known tropospheric ice nuclei such as mineral dust particles. To gain model agreement with the ice number densities inferred from observations, the presence of small-scale temperature fluctuations, with wavelengths unresolved by the numerical weather prediction models, is required. With the derived rate parameterization for heterogeneous ice nucleation we are able to explain and reproduce CALIPSO observations throughout the entire Arctic winter 2009/2010.

scholarly journals Small-scale temperature fluctuations associated with gravity waves cause additional radiative cooling of mesopause the region

2007 ◽  
Vol 34 (24) ◽  
Author(s):  
Alexander A. Kutepov ◽  
Artem G. Feofilov ◽  
Alexander S. Medvedev ◽  
Adalbert W. A. Pauldrach ◽  
Paul Hartogh
Keyword(s):  
Gravity Waves ◽  
Temperature Fluctuations ◽  
Small Scale ◽  
Radiative Cooling ◽  
Scale Temperature
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