Variation In Tb Research Articles

Improvement of the Rain/No-Rain Classification Method for Microwave Radiometers Over the Tibetan Plateau

This letter identifies causes of the deterioration of the Global Satellite Mapping of Precipitation rain detection over the Tibetan Plateau during the summer monsoon season. Using the rain/no-rain classification (RNC) method over the Plateau, observed brightness temperature (Tb) at 21 (23) GHz from the Tropical Rainfall Measuring Mission Microwave Imager (the Defense Meteorological Satellite Program Special Sensor Microwave Imager) [Tb(21 V) and Tb(23 V)], and surface emissivity ( $\varepsilon )$ was substituted for surface temperatures (Ts) to exclude areas of low Ts as snow cover because it is difficult to distinguish between the scattering signals of precipitation and snow cover. A case study demonstrates that rain systems are excluded because Ts is often below the threshold for snow cover due to the use of an inadequate value for $\varepsilon $ (constant value throughout the year), even though a rain scattering signal at high-frequency channels under no snow cover is evident. After $\varepsilon $ is replaced with values from a monthly mean satellite observation-based land surface emissivity database, rainfall detection is improved. In addition, it is suggested that a database of RNCs should also consider diurnal variations in Tb(21 V) and Tb(23 V) due to large diurnal differences over the Plateau.

An extended global Earth system data record on daily landscape freeze–thaw status determined from satellite passive microwave remote sensing

Abstract. The landscape freeze–thaw (FT) signal determined from satellite microwave brightness temperature (Tb) observations has been widely used to define frozen temperature controls on land surface water mobility and ecological processes. Calibrated 37 GHz Tb retrievals from the Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave Imager (SSM/I), and SSM/I Sounder (SSMIS) were used to produce a consistent and continuous global daily data record of landscape FT status at 25 km grid cell resolution. The resulting FT Earth system data record (FT-ESDR) is derived from a refined classification algorithm and extends over a larger domain and longer period (1979–2014) than prior FT-ESDR releases. The global domain encompasses all land areas affected by seasonal frozen temperatures, including urban, snow- and ice-dominant and barren land, which were not represented by prior FT-ESDR versions. The FT retrieval is obtained using a modified seasonal threshold algorithm (MSTA) that classifies daily Tb variations in relation to grid-cell-wise FT thresholds calibrated using surface air temperature data from model reanalysis. The resulting FT record shows respective mean annual spatial classification accuracies of 90.3 and 84.3 % for evening (PM) and morning (AM) overpass retrievals relative to global weather station measurements. Detailed data quality metrics are derived characterizing the effects of sub-grid-scale open water and terrain heterogeneity, as well as algorithm uncertainties on FT classification accuracy. The FT-ESDR results are also verified against other independent cryospheric data, including in situ lake and river ice phenology, and satellite observations of Greenland surface melt. The expanded FT-ESDR enables new investigations encompassing snow- and ice-dominant land areas, while the longer record and favorable accuracy allow for refined global change assessments that can better distinguish transient weather extremes, landscape phenological shifts, and climate anomalies from longer-term trends extending over multiple decades. The dataset is freely available online (doi:10.5067/MEASURES/CRYOSPHERE/nsidc-0477.003).

Specialist-generalist model of body temperature regulation can be applied at the intraspecific level.

According to theoretical predictions, endothermic homeotherms can be classified as either thermal specialists or thermal generalists. In high cost environments, thermal specialists are supposed to be more prone to using facultative heterothermy than generalists. We tested this hypothesis at the intraspecific level using male laboratory mice (C57BL/cmdb) fasted under different thermal conditions (20 and 10°C) and for different time periods (12-48 h). We predicted that variability of body temperature (Tb) and time spent with Tb below normothermy would increase with the increase of environmental demands (duration of fasting and cold). To verify the above prediction, we measured Tb and energy expenditure of fasted mice. We did not record torpor bouts but we found that variations in Tb and time spent in hypothermia increased with environmental demands. In response to fasting, mice also decreased their energy expenditure. Moreover, animals that showed more precise thermoregulation when fed had more variable Tb when fasted. We postulate that the prediction of the thermoregulatory generalist-specialist trade-off can be applied at the intraspecific level, offering a valid tool for identifying mechanistic explanations of the differences in animal responses to variations in energy supply.

Body temperature patterns of a small endotherm in an extreme desert environment

Most desert small mammals use mechanisms to avoid overheating or dehydration during summer (e.g. nocturnality or torpor), but some are apparently able to cope with higher body temperatures (Tb) than normally recorded for mammals (i.e. hyperthermia). In winter, some small desert mammals use torpor to conserve energy during cool periods. Still, surprisingly few studies have reported field body temperature patterns in small terrestrial mammals inhabiting deserts, so it is unclear how common hyperthermia and torpor are in desert mammals. We measured Tb of a murid rodent, the Libyan jird (Meriones libycus), during both summer and winter in Saudi Arabia. Modal, minimum, and maximum Tbs were higher in summer than in winter, with maximum Tbs near 42 °C during summer, among the highest Tbs ever recorded in wild mammals. Variation in Tb was significantly higher during summer than winter, which was mostly related to passive warming throughout the day as ambient temperatures regularly exceeded 45 °C during summer. Conversely, during winter, Tbs were highest during the nocturnal active period. While the summer Tbs we recorded are among the highest ever for either murids or small desert mammals, we suspect this represents a lack of data on free-ranging small mammals more than unique adaptations by this species.

Base temperature as a function of genotype: a foundation for modeling phenology of temperate fruit species

To complete each phase of the growing season, plants must accumulate thermal time at lower base temperature (Tb). Little information exists on Tb variation between either fruit species or cultivars of the same species. We therefore aimed to determine the lower base temperature for contrasting genotypes in precocity of peach, plum, grape, pear, and kiwi. Twigs 25-35 cm long for the following cultivars: peach, Tropic Beauty (TB) and Eragil (ER); plum, Gulf Blaze (GB) and Letícia (LE); grape, Chardonnay (CH) and Cabernet Sauvignon (CS); pear, Smith (SM) and Packham’s (PA); and kiwi, Golden King (GK) and Hayward (HA) were collected in orchards in Veranópolis, RS Estate, on 06/13/2014, with 0 h at temperatures ? 7.2°C (chilling hours; HC) in the field. Intact twigs packed in black plastic film were subjected to 1,008 HC at 0°C in incubators to overcome dormancy and then transferred to temperatures of 2, 4, 6, 8, 10, and 12°C on single-node cuttings planted in phenolic foam to define effective heat temperature for the genotypes. Over 110 d, budburst of the buds was evaluated in 2-3-d intervals in the green-tip stage. The resulting inverse data of number of days to budburst (1/days to budburst) was inserted into regression curves to estimate Tb for each genotype. Historical phonological series comprised of 10 years for the analyzed cultivars and meteorological data of the cultivation sites were used to determine thermal time (degree-days) for the fruit trees during the growing season, considering different phenological phases. Temperate fruit species exhibited different Tb behaviors: Tb was lower for early cultivars (TB and GB = 2.2°C; CH = 2.1°C; SM = 4.4°C; GK = 4.3°C) and higher for late cultivars (ER = 6.3°C; LE = 6.2°C; CS = 4.3°C; HA and PA = 8.2°C) for all cultures. The Tb f fruit cultivars related directly with genotype chilling requirements: the higher the chilling requirement, the higher the Tb of the cultivar. Cultivars of the same fruit species yielded a sum of degree-days almost equal to finalize the growing season, regardless of the degree of precocity (TB = 1720; ER = 1801; GB = 1680; LE = 1718; CH = 2310; CS = 2369; SM = 2096; PA = 2003 GD; GK = 2775; HA = 2691). Regarding phenological phases, 82% of the assessed cases responded more to thermal time (degree-days) than to chronological time (d) to complete phenological steps. Differences in Tb between genotypes are a relevant factor for improving the accuracy and applicability of phenology models in agriculture.

Thermal physiology of a reproductive female marsupial, Antechinus flavipes

Reproduction is an energetically costly, but necessary, process for animals. Small mammals in particular are at a disadvantage as they experience high heat losses to their environment, substantially increasing their energetic costs. However, many small mammals save energy by using torpor, a reduction in metabolic rate and body temperature (Tb). Antechinus flavipes is a small dasyurid marsupial endemic to Australia that uses torpor during adverse conditions. Females usually produce only one litter in their life. In our study, we aimed to quantify the thermal physiology of reproductive female A. flavipes held under natural ambient conditions in an outdoor aviary, and also under stable conditions indoors, during gestation, parturition and lactation. Throughout gestation, A. flavipes displayed similar variations in torpor use and Tb to reproductively unsuccessful females (did not produce young). Torpor use increased with decreasing ambient temperature in the outdoor aviary and ceased when held under stable ambient conditions indoors. Interestingly, during parturition/early lactation, Tb was tightly controlled and daily Tb variation decreased by ≥2.3 °C in comparison to all other reproductive states. Additionally, daily Tb variations during lactation were slightly smaller than those of gestating and reproductively unsuccessful females; however, this conclusion is only preliminary. Our results reveal that the flexibility of the thermal physiology of female A. flavipes is important throughout the reproductive period, except during parturition/early lactation when a stable Tb is likely beneficial to the early stages of development.

Long-term ground-based microwave radiometric measurements of atmospheric brightness temperature in SKYNET Hefei (31.90N, 117.17E) site

A dual-frequency, ground-based microwave radiometer (WVR-1100) is used to investigate the behavior of the atmosphere in terms of zenith brightness temperature (TB) at 23.8 and 31.4GHz respectively. Some experimental findings in SKYNET Hefei site from September 2002 to August 2012 are presented. The cumulative distributions of TB at both frequencies for all sky conditions show four different regions, while only two regions can be identified for clear, lightly cloudy and cloudy condition. Annual cycle of TB at 23.8GHz is apparently remarkable, indicating the large annual cycle of atmospheric water vapor. Regular seasonal variations of TB are observed with the strongest value in summer and the weakest in winter.

MICROWAVE IMAGING OF A HOT FLUX ROPE STRUCTURE DURING THE PRE-IMPULSIVE STAGE OF AN ERUPTIVE M7.7 SOLAR FLARE

ABSTRACT Corona structures and processes during the pre-impulsive stage of solar eruption are crucial to understanding the physics leading to the subsequent explosive energy release. Here we present the first microwave imaging study of a hot flux rope structure during the pre-impulsive stage of an eruptive M7.7 solar flare, with the Nobeyama Radioheliograph at 17 GHz. The flux rope is also observed by the SDO/AIA in its hot passbands of 94 and 131 Å. In the microwave data, it is revealed as an overall arcade-like structure consisting of several intensity enhancements bridged by generally weak emissions, with brightness temperatures (T B) varying from ∼10,000 K to ∼20,000 K. Locations of microwave intensity enhancements along the structure remain relatively fixed at certain specific parts of the flux rope, indicating that the distribution of emitting electrons is affected by the large-scale magnetic configuration of the twisted flux rope. Wavelet analysis shows a pronounced 2 minute period of the microwave T B variation during the pre-impulsive stage of interest. The period agrees well with that reported for AIA sunward-contracting loops and upward ejective plasmoids (suggested to be reconnection outflows). This suggests that both periodicities are controlled by the same reconnection process that takes place intermittently at a 2 minute timescale. We infer that at least a part of the emission is excited by non-thermal energetic electrons via the gyro-synchrotron mechanism. The study demonstrates the potential of microwave imaging in exploring the flux rope magnetic geometry and relevant reconnection process during the onset of solar eruption.

Qualitative Verification of CE-2's Microwave Measurement: Relative Calibration Based on Brightness Temperature Model and Data Fusion

The calibration quality of the Chang'E-2 (CE-2) microwave radiometer (MRM) and the accuracy of brightness temperature (TB) data should be adequately addressed. The quality of CE-2 MRM data can be demonstrated by the analysis and simulation of TB data with the microwave transfer model and by the relative comparison between the TB and other data sets. To calibrate the TB data in a relative way, we calculated the variation of TB with respect to the latitude over certain typical regions theoretically. Three types of areas in the Moon, including the old crater, the fresh crater, and the Apollo region, are chosen as examples. A detailed method incorporating the topographic effect is employed to compute the TB. The Lunar Reconnaissance Orbiter's Diviner infrared measurement is used to ensure the accuracy of the simulated physical temperature. The consistency of the TB undulation between simulations and observations along the profile of these regions verifies the reasonability of CE-2's TB data partly. Our simulation also confirms the topographic effect of sloping walls at the crater rims on the solar heat flux received per unit surface area and reproduces the TB undulation observed by CE-2. Rock abundance and topography data are used for qualitative comparison with the CE-2 TB data. General similarity between the diurnal TB difference and the altitude profile over most craters and the similarity between the diurnal TB difference and the rock abundance profile over fresh craters can prove the relative qualification of CE-2 MRM data to a certain degree.

Evaluation of two methods for minimally invasive peripheral body temperature measurement in birds

Body temperature (Tb) is a valuable parameter when assessing the physiological state of animals, but its widespread measurement is often constrained by methods that are invasive or require frequent recapture of animals. Alternatives based on automated remote sensing of peripheralTbshow promise, but little is known about their strengths and limitations. We measured peripheralTbin great titsParus majorwith subcutaneously implanted passive integrated transponders (PIT tags) and externally attached radio transmitters to determine repeatability of measurements, sensitivity of each method to variation in ambient temperature (Ta) and wind speed, the relationship between methods, and their ability to capture circadian variation inTb. Repeatability of measurements by radio transmitters was high (> 80%) when readings were taken within 20 min, but reduced to 16% when measures were spaced 3.5 h apart. PIT tag data for the 3.5 h interval were more repeatable (33%) and less variable (cv). Data were affected byTawith a stronger effect on the externally attached transmitters, but the influence of wind speed was small for both methods. There was a significant positive relationship between transmitter‐ and PIT tag temperature during both days and nights. Both methods were equally suited to detect diel changes in peripheralTb. However, transmitters offered longer detection distance and better temporal resolution. These qualities should be considered when deciding how to collectTbdata remotely. If properly deployed, both methods allow measurement of peripheralTbover a wide range of natural systems and conditions in small, free‐ranging, birds.

Thermal biology of the toad Rhinella schneideri in a seminatural environment in southeastern Brazil

The toad, Rhinella schneideri, is a large-bodied anuran amphibian with a broad distribution over South America. R. schneideri is known to be active at night during the warm/rainy months and goes into estivation during the dry/cold months; however, there is no data on the range of body temperatures (Tb) experienced by this toad in the field, and how environmental factors, thermoregulatory behaviors or activity influence them. By using implantable temperature dataloggers, we provide an examination of Tb variation during an entire year under a seminatural setting (emulating its natural habitat) monitored with thermosensors. We also used data on preferred Tb, allowing us to express the effectiveness of thermoregulation quantitatively. Paralleling its cycle of activity, R. schneideri exhibited differences in its daily and seasonal profile of Tb variation. During the active season, toads spent daytime hours in shelters and, therefore, did not explore microhabitats with higher thermal quality, such as open areas in the sun. At nighttime, the thermal suitability of microhabitats shifted as exposed microhabitats experienced greater temperature drops than the more insulated shelter. As toads became active at night, they were driven to the more exposed areas and, as a result, thermoregulatory effectiveness decreased. Our results, therefore, indicate that, during the active season, a compromise between thermoregulation and nocturnal activity may be at play. During the estivation period, R. schneideri spent the entire day cycle inside the shelter. As toads did not engage in nocturnal activity in those areas with low thermal quality, the overall effectiveness of thermoregulation was, indeed, elevated. In conclusion, we showed that daily and seasonal variation in Tb of an anuran species is highly associated with their respective pattern of activity and may involve important physiological and ecological compromises.

Ice thickness effects on Aquarius brightness temperatures over Antarctica

AbstractThe Dome‐C region, in the East Antarctic Plateau, is regarded as an ideal natural laboratory for calibration/validation of space‐borne microwave radiometers. At L‐band, the thermal stability of this region has been confirmed by several experimental campaigns. However, its use as an independent external calibration target has recently been questioned due to some spatial inhomogeneities and seasonal effects revealed in the brightness temperatures (TB) acquired in this area. This paper shows the observed relationship, from exploratory research, between the Antarctic ice thickness spatial variations and the measured Aquarius TB changes. A 3‐months no‐daylight period during the Austral winter has been analyzed. Four transects have been defined over East Antarctica covering areas with different ice thickness variations and ranges. The theoretical L‐band penetration depth has been estimated to understand the possible contributions to the measured signal. A good agreement has been observed between Aquarius TB and ice thickness variations over the whole Antarctica, with correlations of ∼0.6–0.7. The two variables show a linear trend with slopes of ∼8.3–9.5 K/km. No correlation has been observed with the subglacial bedrock. The maximum L‐band penetration depth has been estimated to be ∼1–1.5 km. Results are therefore consistent: the spatial variations found on Aquarius TB are not related to the emissivity of the bedrock, which lies deeper. This study provides evidence that new L‐band satellite observations could contribute to further our understanding of Antarctic geophysical processes.

Effect of Snow Surface Metamorphism on Aquarius L-Band Radiometer Observations at Dome C, Antarctica

The Antarctic Plateau presents ideal characteristics to study the relationship between microwave observations and snow/ice properties. It is also a promising target for radiometer calibration and sensor intercalibration, which are critical for applications requiring subkelvin accuracy, such as sea surface salinity retrievals. This paper presents the spaceborne Aquarius L-band radiometric observations collected since August 2011 over the Antarctic Plateau, and it focuses on their temporal evolutions at Dome C (75.1 $^{\circ} \hbox{S}$ , 123.35 $^{\circ} \hbox{E}$ ). Aquarius operates three radiometers with a sensitivity of 0.15 K (over the oceans), allowing us to analyze small variations in brightness temperature (TB) and changes with incidence angles. Over the Antarctic Plateau, Aquarius TBs have a relatively low annual standard deviation (0.2–0.9 K) where melting never occurs. However, the analysis of the TB time series at Dome C revealed significant variations (up to 2.5 K) in summer. First, these variations are compared with a remote sensing grain index (GI) based on high-frequency (89 and 150 GHz) shallow-penetration TB channels. Variations in the ratio of TBs observed at horizontal and vertical polarizations are synchronous with GI changes. Second, Aquarius TB variations are compared with the presence of hoar crystals on the surface identified using surface-based near-infrared photographs. The largest and longest changes in TBs correspond to periods with hoar crystals on the surface. Therefore, in spite of the deep penetration of the L-band radiation, evolutions of the snow properties near the surface, which usually change rapidly and irregularly, do influence L-band observations. Collection of accurate snow surface measurements and thorough analyses of the L-band observations are thus needed to use the Antarctic Plateau as a calibration/inter-calibration target.

Body temperature regulation during acclimation to cold and hypoxia in rats

Extreme environmental conditions present challenges for thermoregulation in homoeothermic organisms such as mammals. Such challenges are exacerbated when two stressors are experienced simultaneously and each stimulus evokes opposing physiological responses. This is the case of cold, which induces an increase in thermogenesis, and hypoxia, which suppresses metabolism conserving oxygen and preventing hypoxaemia. As an initial approach to understanding the thermoregulatory responses to cold and hypoxia in a small mammal, we explored the effects of acclimation to these two stressors on the body temperature (Tb) and the daily and ultradian Tb variations of Sprague-Dawley rats. As Tb is influenced by sleep-wake cycles, these Tb variations reflect underlying adjustments in set-point and thermosensitivity. The Tb of rats decreased precipitously during initial hypoxic exposure which was more pronounced in cold (Tb=33.4±0.13) than in room temperature (Tb=35.74±0.17) conditions. This decline was followed by an increase in Tb stabilising at a new level ~0.5°C and ~1.4°C below normoxic values at room and cold temperatures, respectively. Daily Tb variations were blunted during hypoxia with a greater effect in the cold. Ultradian Tb variations exhibited daily rhythmicity that disappeared under hypoxia, independent of ambient temperature. The adjustments in Tb during hypoxia and/or cold are in agreement with the hypothesis that an initial decrease in the Tb set-point is followed by its partial re-establishment with chronic hypoxia. This rebound of the Tb set-point might reflect cellular adjustments that would allow animals to better deal with low oxygen conditions, diminishing the drive for a lower Tb set-point. Cold and hypoxia are characteristic of high altitude environments. Understanding how mammals cope with changes in oxygen and temperature will shed light into their ability to colonize new environments along altitudinal clines and increase our understanding of how Tb is regulated under stimuli that impose contrasting physiological constraints.

Brightness Temperature Calculation of Lunar Crater: Interpretation of Topographic Effect on Microwave Data From Chang'E

In order to quantitatively interpret topographic effect on Chang'E (CE) microwave data, a detailed method to compute brightness temperature (TB) over a lunar crater is proposed, which incorporated the effect of surface tilts. The method improves the effective solar irradiance model of the lunar surface to obtain the temperature profile of the lunar crater. The calculated TB at 37 GHz with the proposed computation method, which is based on three digital elevation models (DEMs) from different sources, are consistent with the observed TB from the CE-2 microwave radiometer. The simulated behavior of TB across crater Hercules reproduces the TB undulation observed by CE in a single swath. TB is significantly affected by the lunar dust of a lunar crater and affected by albedo and emissivity in a lesser degree. Based on the explanation with simplified models, the TB variation over a crater is proved to be significantly affected, through physical temperature, by the crater shape described by DEMs. With the simplified crater model, the amplitude of the TB oscillatory curves is proved to depend on the crater shape.

Behavioral and metabolic contributions to thermoregulation in freely swimming leatherback turtles at high latitudes.

Leatherback turtles in the Northwest Atlantic Ocean have a broad geographic range that extends from nesting beaches near the equator to seasonal foraging grounds as far north as Canada. The ability of leatherbacks to maintain core body temperature (Tb) higher than that of the surrounding water is thought to be a key element of their biology that permits them to exploit productive waters at high latitudes. We provide the first recordings of Tb from freely swimming leatherbacks at a northern foraging ground, and use these data to assess the importance of behavioral adjustments and metabolic sources of heat for maintenance of the thermal gradient (Tg). The mean Tb for individual leatherbacks ranged from 25.4 ± 1.7 to 27.3 ± 0.3 °C, and Tg ranged from 10.7 ± 2.4 to 12.1 ± 1.7 °C. Variation in mean Tb was best explained by the amount of time that turtles spent in the relatively warm surface waters. A diel trend in Tb was apparent, with daytime cooling suggestive of prey ingestion and night-time warming attributable to endogenous heat production. We estimate that metabolic rates necessary to support the observed Tg are ~3 times higher than resting metabolic rate, and that specific dynamic action is an important source of heat for foraging leatherbacks.

Evaluating the thermal effects of translocation in a large-bodied pitviper.

Acute stressors can be costly, often requiring alteration of normal physiological processes to mitigate their effects. Animal translocation may be a very stressful event and result in a reduced ability to maintain homeostasis. The impacts of translocation on the thermal ecology of ectothermic vertebrates, which may rely on preferred habitats for thermoregulation, are currently unknown. In this study, 22 adult male Northern Pacific rattlesnakes (Crotalus oreganus oreganus) were implanted with automated temperature loggers and radio-tracked. Snakes were assigned to one of three treatments: translocation, handling control, and undisturbed control. Short-distance translocation (SDT) and handling treatments were applied weekly for 6 weeks. Hourly body temperature (Tb ) was recorded during the course of the study. Mean Tb was impacted in a time-dependent fashion, where translocated snakes had lower mean Tb than handled controls during the first week of the study only, especially the first 24 hr after translocation. Separating the dataset into day and night revealed that this effect was localized to Tb variation during the day only. Variance in temperature was not impacted by translocation or handling. Snake body mass and time of year were the major factors influencing the thermal profiles of these rattlesnakes. Thermal ecology in male rattlesnakes is resilient to SDT, suggesting that they quickly resume normal behaviors following repeated bouts of acute capture stress and disturbance of their spatial ecology. This study provides support for SDT as a safe measure for mitigating human-snake interactions and facilitating conservation practices regarding male snakes, which are the most frequently encountered sex.

High frequency thermal emission from the lunar surface and near surface temperature of the Moon from Chang’E-2 microwave radiometer

Near surface temperature of the Moon and thermal behaviors of the lunar regolith can provide important information for constraining thermal and magmatic evolution models of the Moon and engineering constrains for in situ lunar exploration system. In this study, China’s Chang’E-2 (CE-2) microwave radiometer (MRM) data at high frequency channels are used to investigate near surface temperature of the Moon given the penetration ability of microwave into the desiccated and porous lunar regolith. Factors that affect high frequency brightness temperature (TB), such as surface slope, solar albedo and dielectric constant, are analyzed first using a revised Racca’s temperature model. Radiative transfer theory is then used to model thermal emission from a semi-infinite regolith medium, with considering dielectric constant and temperature profiles within the regolith layer. To decouple the effect of diurnal temperature variation in the uppermost lunar surface, diurnal averaged brightness temperatures at high frequency channels are used to invert mean diurnal surface and subsurface temperatures based on their bilinear profiles within the regolith layer. Our results show that, at the scale of the spatial resolution of CE-2 MRM, surface slope of crater wall varies typically from about 20° to 30°, and this causes a variation in TB about 10–15K. Solar albedo can give rise to a TB difference of about 5–10K between maria and highlands, whereas a ∼2–8K difference can be compensated by the dielectric constant on the other hand. Inversion results indicate that latitude (ϕ) variations of the mean diurnal surface and subsurface temperatures follow simple rules as cos0.30ϕ and cos0.36ϕ, respectively. The inverted mean diurnal temperature profiles at the Apollo 15 and 17 landing sites are also compared with the Apollo heat flow experiment data, showing an inversion uncertainty <4K for surface temperature and <1K for subsurface temperature.

Body Temperature Predicts the Direction of Internal Desynchronization in Humans Isolated from Time Cues

This publication presents a new analysis of experiments that were carried out in human subjects in isolation from time cues, under supervision of Jürgen Aschoff and Rütger Wever at the Max Planck Institute for Behavioural Physiology (Erling-Andechs, Germany, 1964-1974). Mean rectal temperatures (tb) were compared between subjects who showed internal desynchronization (ID) and internal synchronization (IS) of the endogenous rhythms of sleep-wakefulness and of body temperature. The results showed that tb was reduced in long ID (circadian sleep-wake cycle length [τ(SW)] > 27 h) and increased in short ID (τ(SW) < 22 h) relative to IS. In subjects with both ID and IS sections in the complete record, these differences were also found when comparing only the IS sections: Low tb during IS predicts the later occurrence of long ID, and high tb predicts the incidence of short ID. While this association is associated with sex differences in tb, it also occurs within each sex. To the extent that the variation in tb reflects the variation in heat production (metabolic rate), the results are consistent with the proposition that the spontaneous frequency of the human sleep-wake oscillator is associated with the metabolic rate, as suggested on the basis of the proportionality of meal frequency and sleep-wake frequency. The finding thus has implications for our views on spontaneous sleep timing.

Seasonal variations in behaviour of thermoregulation in juveniles and adults Liolaemus lutzae (Squamata, Liolaemidae) in a remnant of Brazilian restinga

Adaptations of lizards inhabiting hot arid environments should include mechanisms of behavioural thermoregulation. In contrast, in environments with lower temperatures lizards tend to behave as thermoconformers. Herein we aim to infer thermoregulatory behaviours exhibited by Liolaemus lutzae (a lizard species endemic to restingas in the coast of the state of Rio de Janeiro, Brazil) in two different seasonal thermal environments. In the dry season, the body temperatures (Tb) of the lizards were higher than air temperature (Ta) and similar to substrate temperature (Ts), suggesting thermoconformer thermoregulatory behaviour using Ts. During the rainy season, the higher percentage of negative values of ΔTs (=Tb−Ts) and ΔTa (=Tb−Ta) and the tendency for lower Tb compared to Ts suggest a more active behavioural thermoregulation in that season. The ΔTs was higher for juveniles in the rainy season, suggesting that youngest lizards tended to thermoregulate more actively regarding to Ts than adults. L. lutzae probably survives under high Ts due to the behaviour of the individuals sheltering inside burrows or under detritus and burying themselves into the sand. This behavioural flexibility may potentially reduce variations in Tb of active lizards in changing thermal environments both during the daily cycle and between seasons.