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IAP - mesopause temperatures   (Site not responding. Last check: 2007-10-17) The mesopause, the upper boundary of the mesosphere, is characterized by a pronounced minimum in the temperature profile. The altitude if the mesopause is, again at polar latitudes, close to 88 km in summer and close to 100 km at all other times. The mesopause is the three-dimensional surface above 80 km that exhibits the local minimum with the lowest temperature on an average of 24 hours. www.iap-kborn.de /optik/mesotemp/mesotemp_e.htm   (234 words)

Climatology of winds   (Site not responding. Last check: 2007-10-17) Climatology of winds at the midlatitude mesopause region With aid of the measurements we are able to estimate the influence of lower and middle atmosphere variability on the mesopause dynamics, which in turn can be taken as an indicator for atmospheric variability. Climatology of prevailing horizontal winds at mesopause heights in the course of the year, taken from a joint analysis of Collm and Juliusruh measurements. www.uni-leipzig.de /~gasse/geo/climat_e.html   (269 words)

[10.10] Observational Definition of the Venus Mesopause: Vertical Structure, Diurnal Variation, and Short-term ...   (Site not responding. Last check: 2007-10-17) Combined 12CO and 13CO isotope spectral line measurements at 345 gHz and 330 gHz frequencies, respectively, provided enhanced sensitivity and vertical coverage for simultaneous retrievals of atmospheric temperatures and CO mixing ratios over the 75-105 km altitude region. Implementation of these retrievals for the dayside (superior conjunction) and nightside (inferior conjunction) periods yields a first-time definition of the vertical structure and diurnal variation of a low-to-mid latitude mesopause within the Venus atmosphere. At the times of the 1999-2001 observations, the Venus mesopause was located at a slightly lower level in the nightside (0.4 mbar, ~ 88 km) versus the dayside (0.2 mbar, ~ 91 km) atmosphere. www.aas.org /publications/baas/v33n3/dps2001/246.htm   (299 words)

The Atmosphere The mesosphere is the next layer above the stratopause and extends to its upper boundary (the Mesopause), at 50 miles(80 km) above the ground. The temperatures in the mesosphere drop to -184 ºF(-120 ºC) at the mesopause. The Thermosphere is the layer above the mesopause. library.thinkquest.org /C003124/en/atmos.htm   (733 words)

Further evidence of a two-level mesopause and its variations from UARS high-resolution Doppler imager temperature data During December solstice (1992), the mesopause is at the high level of 100 km in the Northern Hemisphere with a temperature of 190 K, and around 40°S, the mesopause changes to a low level of 88 km with a cool temperature (150 K) of 40 K less than the high-level mesopause. This kind of two-level mesopause structure is consistently seen during all solstices at the same height and the transition occurring at the same latitudes. The high-level mesopause with temperatures of 180–190 K and the low-level mesopause with temperatures of 140–150 K are observed. www.agu.org /pubs/crossref/2002/2000JD000118.shtml   (408 words)

[No title]   (Site not responding. Last check: 2007-10-17) The mesopause is one of these, and therefore the investigation and understanding of this strategic region is of central importance in our understanding of the factors involved in atmospheric variability. To determine the large-scale dynamics of the mesopause region by decomposition of the observations into the mean flow, planetary scale perturbations, tides and gravity waves, and to study the interactions between these dynamical components. Airglow emissions near the mesopause characterize the thin altitude layers within which they originate, but the method has the disadvantage that the altitude is not independently measured. stpl.cress.yorku.ca /~gordon/psmos_pr.html   (4261 words)

Climatology of the SKYHI Troposphere-Stratosphere-Mesosphere General Circulation Model The simulated summer polar mesopause temperatures decrease with increasing horizontal resolution, although even at 1-degree resolution the predicted temperatures are still warmer than observed. There is also a second peak in the amplitude of the semiannual wind oscillation at the top model level (0.0096 mb) corresponding to the observed mesopause semiannual oscillation. This simulated mesopause oscillation is weaker (by a factor of ~3) than that observed. www.soest.hawaii.edu /~kph/abs3.html   (724 words)

Australian Antarctic Division - Looking Up: Atmospheric Sciences The Atmospheric and Space Physics group are looking at the mesosphere and the mesopause (the transition region between the mesosphere and the thermosphere) to see if things are changing due to natural or human made effects. The Antarctic mesopause is the coldest part of the atmosphere (-150 to 130ºC), and physicists suspect that it is very sensitive to climate change. Scientists have attributed this to a decrease in mesopause temperature and an increase in the gas methane in the middle atmosphere. www.aad.gov.au /default.asp?casid=747   (765 words)

Mysterious clouds caused by cosmoids? Science News - Find Articles These clouds, which are seen from the ground in summer after sunset or before sunrise at high latitudes, are unusual because they form in the mesopause, at altitudes of 80 kilometers or more--far above where scientists expect water vapor and other cloud material from the earth to be able to reach. Moreover, the theories require that the mesopause be cold enough for condensation to occur. In Dubin's model, extremely cold and icy cosmoids approach the dark side of the earth, become electrically charged and disintegrate into a stream of small particles, which are funneled by the geomagnetic field into a polar region. findarticles.com /p/articles/mi_m1200/is_v129/ai_4258422?...   (383 words)

[No title]   (Site not responding. Last check: 2007-10-17) The coldest place on earth is at the top of the mesosphere, AKA the mesopause. On an annual average, the 100 km mesopause altitude is observed over 83% of the planet. I will present a hand-waving explanation of this phenomenon, that will introduce concepts of atmospheric circulation from the ground to the mesopause as well as gravity waves, which are the drivers of the circulation that produces the refrigerator effect. www.naic.edu /~astro/talks/abstracts/friedman_20jun05.htm   (134 words)

Joe She For the past 20 years, he has made a series of innovations in two high-spectral-resolution lidars: Rayleigh-Mie lidar and narrowband sodium lidar for atmospheric temperature and wind measurements, respectively in the lower and upper atmosphere. The narrowband sodium lidar, now capable of measuring mesopause region (80-110 km in altitude) temperature and wind on a 24-hour continuous basis, has enjoyed considerable success with continued NSF funding for upper atmospheric research since 1989. She and D. Krueger, "Impact of natural variability in the 11-year mesopause region temperature observation over Fort Collins, CO," Adv. www.physics.colostate.edu /People/faculty/JoeShe   (352 words)

- en On the connection between upper atmospheric dynamics and tropospheric parameters: Correlation between mesopause region winds and the North Atlantic Oscillation. The middle- and high-latitude stratospheric and mesospheric wind field in winter is dominated by the stratospheric polar vortex, which reaches up into the mesopause region and leads to westerly winds there in winter. Thus also the mesopause region winds are positively correlated to the Central European winter surface temperatures. www.knmi.nl /publications/showAbstract.php?id=736   (159 words)

Australian Antarctic Division - The mesopause The mesopause is the coldest region of the Earth's atmosphere. The altitude of the mesopause varies with season and latitude. In the polar regions, the altitude of the mesopause ranges between 90 kilometres in summer and 110 kilometres in winter, when minimum temperatures typically reach 130 K (-140°C) and 180 K (-90°C) respectively. www.aad.gov.au /default.asp?casid=11553   (100 words)

IAP Mesopause   (Site not responding. Last check: 2007-10-17) The mesopause altitude is on an upper level around 100 km throughout the winter hemisphere and the tropics, jumping down immediately at a certain subtropical latitude on the summer hemisphere to the lower level at about 85 km and increasing slightly towards the summer pole. of the mesopause altitude is shown to the right for 54° N. It again implies the notion of a steady variation with the season going from the high winter mesopause down to the low summer mesopause and back. The mesopause altitude is on an upper level around 100 km throughout most of the year (8-9 month) so this should be called the normal mesopause state. www.iap-kborn.de /optik/mesotemp/twolevel_d.htm   (310 words)

Thermal Variations   (Site not responding. Last check: 2007-10-17) The mesopause altitude is near 100 km in winter during Nov-Feb and near 86 km in summer during May-Jul. The mesopause temperature varies from 190 K in mid-winter to 175 K in mid-summer. The transitions between winter and summer mesopause structures occur rapidly in Mar-Apr and Aug-Sep. The temperature differences between the two sites are less than 15 K and appear to be the result of atmospheric planetary, tidal and gravity wave perturbations. Comparison of mesopause region temperature structure between composite of Lidar measurements in Urbana, IL and Ft. Collins, CO and MF Radar measurements in Urbana, IL. conrad.ece.uiuc.edu /home/Seasonal_variations.htm   (147 words)

The potassium density and temperature structure in the mesopause region (80–105 km) at a low latitude (28°N) By means of a groundbased lidar we have measured potassium layer parameters and the temperature structure in the mesopause region during 55 nights in 1999 at Tenerife (28°N). We also study the nocturnal mean temperatures and their seasonal variations and derive new evidence for the global two-level structure of the mesopause. About midsummer we observed the mesopause close to 86 km with about 183 K for a period of four weeks. www.agu.org /pubs/crossref/2002/2002GL015578.shtml   (221 words)

The Atmosphere The chemicals are in an excited state, as they absorb energy from the Sun. The mesopause separates the mesophere from the thermosphere. The regions of the stratosphere and the mesosphere, along with the stratopause and mesopause, are called the middle atmosphere by scientists. liftoff.msfc.nasa.gov /academy/space/atmosphere.html   (568 words)

Summer polar mesopause region temperatures measured in 2001 by the ALOMAR Weber Sodium Lidar Temperature profiles in the mesopause region over Andoya, Norway (69N, 16E)were measured on 18 days during summer 2001, as weather permitted, by the Weber sodium resonance lidar. The summer polar mesopause is the coldest part of the atmosphere, with temperatures reaching below 130K, in spite of being continuously sunlight. The mesopause altitude measured by the lidar moves from 89 km in June to 85 km at the end of August. www.cora.nwra.com /~biff/AL2001tempfinal/AL2001tempfinal.html   (1498 words)

AIM - Education and Public Outreach Thayer, J.P., G.E. Thomas, and F.-J. Lukens, Foreword: Layered phenomena in the mesopause region, Thomas, G. Mesospheric clouds and the physics of the mesopause region. Thomas, G. E., Olivero, J. J., Jensen, E. J., Schröder, W., Toon, O. Relation between increasing methane and the presence of ice at the mesopause. aim.hamptonu.edu /library/1library.html   (2796 words)

RAND | Papers | On the Role of the Mesopause in Interaction Studies. A demonstration that the spatial and temporal behavior of the mesosphere and lower thermosphere can be depicted in a way consistent with empirical data only if they are considered as separate entities. Attempts to derive quantitatively plausible connections between them failed until it was assumed that the mesopause itself was not only a schematic boundary, but also a region exerting a dominant effect on the atmosphere above and below. It thus appears that the mesopause region is the center of interactions between lower and upper atmosphere, where direct solar influences from above combine with the periodic phenomena from below. www.rand.org /pubs/papers/P3346   (363 words)

Colloquium Schedule   (Site not responding. Last check: 2007-10-17) The mesopause region is the coldest and least accessible part of the earth's atmosphere. Nighttime studies by airglow techniques present their own uncertainties and are unable to resolve either the vertical spatial or the temporal structure of this dynamic region. Resonance lidars have been applied to the study of the thermal structure of the earth's mesopause region for about a decade, and only in the past year at Arecibo. www.naic.edu /~astro/talks/abstracts/mary.html   (127 words)

Chiao-Yao (Joe) She We are demonstrating a ground-based lidar (laser radar) station that could monitor atmospheric temperatures from the earth's surface to the mesopause region some 100 km up. The existing lidar technique for temperature measurements relies on Rayleigh scattering for measuring air-density profile from which the atmospheric temperatures are calculated by assuming hydrostatic and local thermal equilibrium. For altitudes above 80 km, we use a narrowband tunable laser to induce fluorescence emission of natural Na atoms existed in the mesopause region (between 80 to 110 km, a region too high for airplane and balloon and too low for satellite) for temperature measurements. www.physics.colostate.edu /People/faculty/she   (507 words)

Atmosphere - Mesosphere   (Site not responding. Last check: 2007-10-17) In the mesopause over the North and South poles, the air temperature may drop as low as -109 °C. The coldest mesopause temperatures at a pole occur when it is summer there. The air in the mesosphere may mix, as it does in the troposphere. library.thinkquest.org /C005686/htmfiles/mesosphere.htm   (162 words)

Puzzling height of polar clouds linked to solar radiation The formation of polar mesospheric clouds is a complex process that depends on the temperature, water vapor and vertical wind structure of the mesopause region, Gardner said. Measurements taken during the austral summer of 2002-2003 revealed that the Rothera polar mesospheric clouds were much weaker, less frequent and not as high as those observed at the South Pole. The measurements also showed that in late January the temperatures in the mesopause were warmer at Rothera compared with the South Pole. www.news.uiuc.edu /news/04/0126gardner.html   (1091 words)

Wintertime mesopause temperatures observed by lidar measurements over Syowa station (69°S, 39°E), Antarctica Monthly averaged temperature profiles in the mesopause region in wintertime (June, July and August) are nearly 20 K lower than those in the northern hemisphere sites. The mesopause temperatures (∼175 K) in winter months however are about 20 K lower than those observed from a northern hemisphere conjugate site, Andøya. The lower winter mesopause temperatures measured at Syowa station, which are consistent with southern hemisphere mesopause temperatures measured by a shipborne lidar, suggest the existence of a hemispheric difference. www.agu.org /pubs/crossref/2002/2002GL015244.shtml   (258 words)

JetStream - An Online School for Weather: Layers of the Atmosphere As such, the effect of the warming by ultraviolet radiation also becomes less and less leading to a decrease in temperature with height. However, the gases in the mesosphere are thick enough to slow down meteorites hurtling into the atmosphere, where they burn up, leaving fiery trails in the night sky. The Thermosphere extends from the mesopause to 430 miles (690 km) above the earth. www.srh.noaa.gov /srh/jetstream/atmos/layers.htm   (565 words)

Meteorology Among Chapman's many papers applying diffusion theory to stellar and planetary atmospheres, special mention must be made of his and Kendall's theory of the origin of noctilucent clouds, published in 1965. This theory, based on a systematic investigation of the upward diffusion of water vapor and the downward diffusion of meteoric dust, attributes the appearance of these clouds to the simultaneous occurrence of a descent of the turbopause to the mesopause, a low mesopause temperature, and the presence of moist air below the mesopause. While acceptance of their theory will depend on the observation of the three required conditions when noctilucent clouds are present and absent, the theoretical discussion of the diffusion and convection and of their effect on the formation of noctilucent clouds will remain a guide for future studies. www.gi.alaska.edu /chapman/meteorology.html   (976 words)

NAIC Arecibo Observatory Lidar Capabilities Page   (Site not responding. Last check: 2007-10-17) The diode laser is frequency modulated by a dual-pass acousto- optic modulation setup developed by the lidar group at Colorado State University in order to get the spectral information necessary to measure potassium temperature in the mesopause. The receiver consists of an 800 mm diameter Cassegrain telescope that is fiber-optically coupled to receiver optics made up of an optical chopper to block low-altitude return, a narrow-band interference filter to reduce background, and an electronically gated GaAs photomultiplier detector. Mesopause Climatology: Long-term seasonal studies of the climatology of the mesopause. www.naic.edu /~lidar/capabilities.html   (694 words)

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