Surface Temperature Difference Research Articles

A multicity analysis of daytime Surface Urban Heat Islands in India and the US.

• In the US, urban land surface temperature (LST) was higher compared to rural LST. • Despite urbanization, urban LST in India was lower compared to rural LST. • Non-photosynthetic vegetation (NPV) and barren land types influence the results. • Built-up indices used here do not differentiate sparse vegetation and built-up surfaces. • New methods are needed for quantifying urbanization's impact on LST in India. Daytime surface UHI (SUHI) and the factors influencing it across highly populated cities in India and the United States (US) were evaluated. Urban-rural mean land surface temperature (LST) differences (ΔT S ) were calculated and correlated with vegetation and built-up surface densities, quantified using the Normalized Difference Vegetation Index (NDVI) and Index Based Built-Up Index (IBI) respectively. The results from the US show a conventional SUHI phenomenon, and LST decrease with increasing vegetation and decreasing built-up surfaces. However, in India, despite existing urban densities, urban areas are cooler than the rural surroundings. The average LST was higher and NDVI was lower compared to the US, and NDVI and LST correlations were weak. Furthermore, in India, the average IBI values calculated for built-up areas, cropland, and other sparse vegetation land covers were approximately equal. The prevalence of non-photosynthetic vegetation (NPV) and barren soil in India are impacting spectral indices and the correlations. Differences in ΔT S and spectral indices trends between India and US highlight the shortcomings of the indices used in appropriately identifying Indian LULC types and establish the need for localized SUHI research methods that can specifically analyze the impact of urbanization on SUHI in India.

Hydrothermal Dynamics of Seasonally Frozen Soil With Different Vegetation Coverage in the Tianshan Mountains

The hydrothermal relationship between vegetation and seasonal frozen soil is one of the key research contents in the fields of permafrost ecological environment, hydrology and climate change in alpine mountainous areas. Based on the monitoring data of air temperature, precipitation and soil hydrothermal conditions at the depth of 0–5 m from site TS-04 (with high vegetation coverage) and site TS-05 (with low vegetation coverage) in the alpine grassland of the Tianshan Mountains, this study compared and analyzed the characteristics of freezing-thawing process, temperature and moisture changes of seasonal frozen soil with different vegetation coverage. The results show that the maximum seasonal freezing depth of the two sites is almost comparable, but site TS-04 has a smaller freezing and thawing rate, and a shorter duration of freeze-thaw at all depths. TS-04 also has a smaller annual range of surface temperature and ground-air temperature difference. The analysis indicates that vegetation acts as a thermal buffer and has a good thermal insulation effect on the ground surface. Site TS-04 had high unfrozen water content in the unfrozen period and the water content increased with depth, while the unfrozen water content was low in site TS-05. In addition, the thresholds of soil water content response to rainfall events at 5 cm depth of site TS-04 and site TS-05 were 5 and 11 mm precipitation respectively, which indicated that the high vegetation coverage is conducive to rainwater infiltration, and the underlying soil of the site has a faster response to rainfall events.

고층건축물의 높이에 따른 대류열전달률이 실내표면결로에 미치는 영향에 관한 이론적 연구

Although the temperature coefficient between outdoor air temperature and indoor air temperature is used to determine whether condensation occurs, it is reasonable to predict surface condensation using the surface temperature difference between outdoor and indoor. This study is conducted to determine whether condensation occurs by not using the air temperature difference between indoor and outdoor (the existing methods) but by applying the surface temperature difference between indoor and outdoor surfaces. The outdoor surface temperature is affected by air velocity on the building height, thus the convection heat transfer coefficient is different depending on the building height. The indoor surface temperature distribution is 21.4℃～21.5℃ when the existing equation is applied. But by applying the proposed equation, the indoor surface temperature distribution for the lower floor is 13.0～17.8℃, for the middle floor is 12.3℃～ 17.1℃, and for the top floor is 12.0℃～16.8℃. As the indoor surface temperature can be lower than indoor air dew point temperature, surface condensation is possible.

Distinct impacts of major El Niño events on Arctic temperatures due to differences in eastern tropical Pacific sea surface temperatures.

The El Niño Southern Oscillation (ENSO) is a climate mode in the tropical Pacific. The ENSO teleconnections are known to affect Arctic temperature; however, the robustness of this relationship remains debated. We find that Arctic surface temperatures during three major El Niño events are remarkably well simulated by a state-of-the-art model when nudged to the observed pantropical sea surface temperatures (SSTs). SST perturbation experiments show that the 1982–1983 warm pan-Arctic and the 1997–1998 cold pan-Arctic during winter can be explained by far eastern equatorial Pacific SSTs being higher during 1997–1998 than 1982–1983. Consistently, during the 2017–2018 La Niña, unusually low SSTs in the same region contributed to pan-Arctic warming. These pan-Arctic responses to the SSTs are realized through latent heating anomalies over the western and eastern tropical Pacific. These results highlight the importance of accurately representing SST amplitude and pattern for Arctic climate predictions.

Influence of architectural features of buildings on heat losses from their facades

In the heat balance of buildings, the main heat loss occurs through enclosing structures. Determining the heat transfer coefficients on the exterior facades of buildings is not an easy procedure, as they depend on a wide range of parameters: wind speed in the surface atmosphere, wind direction relative to the orientation of facades, surface orientation relative to wind, surface angle relative to the ground plane, type terrain, the impact of adjacent buildings, surface texture, surface and air temperature differences, surface size and aspect ratio, etc. The paper presents the results of a numerical study of heat transfer from the outer surfaces of separately located structures in the surface layer of the atmosphere. Schematic models of the building have the same heat transfer surface area, but different heights and lengths. CFD-modeling of heat transfer of buildings in the wind flow in a three-dimensional setting allowed to establish some features of heat transfer of enclosing structures depending on the height of the building and the characteristics of the wind flow. In particular, it is shown that the average surface values of heat flux density increase with increasing building height. The results of the calculation of the average heat flux density on the surface of buildings indicate its dependence on the height of this building. This dependence is observed only for houses with a height of less than 30 m. For taller houses, this dependence is insignificant. The local values of heat transfer coefficients on the windward and leeward facades of the building obtained as a result of modeling indicate incorrect application of heat transfer coefficient values αк = 23 W / (m2 ∙ K) for construction practice for external surfaces of enclosing structures. For windward facades, a polynomial model for the heat transfer coefficient is more suitable, and for leeward ones, the Frank formula for αk.

Experimental evaluation of the thermal performance of cool pavement materials in cold regions of China.

The local thermal property evaluation of pavement materials has not received enough attention, making the implementation of cool material measures to alleviate the urban heat island difficult. This study aims to conduct a control experiment on cool pavement bricks selection from the local market. The surface temperature difference and change characteristics of 28 bricks with different physical properties (i.e. colour, thickness, size and internal structure) were recorded by an infrared thermal imager and thermometers. Comparative analysis shows that the maximum surface temperature of the light-yellow brick is 7.3 °C lower than that of the ash black one, and the maximum surface temperature of hollow bricks is 5.6 °C lower than that of solid bricks. Thick bricks have a slightly low mean and maximum surface temperatures, and large bricks also have a low maximum surface temperature, but only deep coloured bricks. The analysis of variance revealed that for the maximum surface temperature, the three factors (i.e. colour, thickness and internal structure) have an interactive effect; for the mean surface temperature, only the colour and internal structure factors have a significant independent effect. This paper provides a feasible bottom-up cooling scheme for urban underlying surface.

Difference of body surface temperature in stable chronic obstructive pulmonary disease patients with different degree of airflow limitation

BackgroundThis study aimed to investigate the changes of body surface temperature of stable chronic obstructive pulmonary disease (COPD) patients and explore its clinical significance for the progression of COPD. ObjectivesThe aim of this study was to explore the correlation between body surface temperature and disease severity in COPD patients. MethodsFrom May 2015 to May 2016, the patients who were diagnosed as COPD at stable phase (n = 148) were enrolled in this study. The subjects in control group (n = 49) were healthy people. The patients’ general condition modified Medical Research Council (mMRC) dyspnea scale and the COPD assessment test (CAT) score were recorded, and pulmonary function of patients was determined. Back average temperature measurement was made using a thermal infrared imager (DT-9875, CEM, China). ResultsPatients in the COPD group had significantly lower mean temperatures of the back than those in the control group. The mean temperature of the back presented a decreased tendency with the aggravation of airflow limitation. Correlation analysis revealed that in the COPD group, the back temperature was negatively correlated with smoking index and mMRC score. FEV1%, FVC% and FEV1/FVC were positively correlated with pulmonary function. Smoking showed a tendency to lower the back temperature of COPD patients. ConclusionsThis study preliminarily suggested that the body surface temperature of COPD patients decreased compared with that of healthy people, which may be associated with the dysfunction of autonomic nerve, increased basal metabolic rate, metabolic syndrome and peripheral nerve injury in COPD patients.

The thermal profile of self-tapping screws: The effect of insertion speed, power insertion, and screw geometry on heat production at the bone-screw interface.

IntroductionPower insertion of screws using high-speed saves time during operative fixation of fractures compared to manual insertion. Heat production during screw insertion may cause thermal damage at the critical bone-screw interface, reducing fixation strength, delaying healing, or increasing infection risk. Currently, the thermal impact of screw insertion is incompletely understood. This study investigated the thermal profiles of self-tapping screws at varying insertion speeds, utilizing manual versus power insertion, and with differing cutting flute geometries to determine which variables may save time while mitigating thermal injury. MethodsThermal and mechanical force profiles were obtained during insertion of 24 mm length, 3.5 mm stainless steel screws into 50 PCF polyurethane after pre-drilling. Power insertion at low (30RPM) and high (300RPM) speed, manual screwdriver insertion versus high-speed power insertion, and two different cutting flute geometries were compared. Infrared thermography was used to measure maximum surface temperatures and mean temperature change (°C). Time (s) was measured to compare manual and power insertion. Means were compared using a two-tailed independent t-test. ResultsMaximum surface temperature of high-speed insertion (55.42 ± 5.58 °C) was significantly greater (p < 0.001) than low-speed (41.07 ± 2.33 °C). Similarly, mean temperature rise of high-speed insertion (29.52 ± 5.39 °C) was greater than that of low-speed (15.13 ± 2.63 °C) (p < 0.001). There was no statistical difference in maximum surface temperature between manually inserted screws (56.58 ± 5.53 °C) and high-speed power inserted screws (55.42 ± 5.58 °C) (p = 0.155), while insertion speeds were almost 5 times faster with high-speed power insertion (6.75 ± 1.84 s) than with manual insertion (30.3 ± 4.06 s) (p < 0.001). There were no differences detected between the geometry groups in any outcome measure tested. ConclusionHigh speeds for screw insertion generate significantly greater maximum temperatures and greater temperature rise than slower speeds. Surprisingly, the thermal profile of manual insertion was similar to high-speed insertion, while requiring significantly longer for insertion. Low-speed insertion generated significantly lower maximal temperatures and temperature rise. Surgeons could consider utilizing low-speed when inserting orthopaedic screws with a power driver to minimize thermal impact to bone while optimizing efficiency.

Growth Patterns and AMS-14C Age Dates of Fossil Corals from Northwest Pacific

This study aims to evaluate the controlling factor/s of coral growth in the northwest Pacific during the Holocene. Here, we present newly acquired growth data and radiocarbon age dates of fossil Porites corals collected from Holocene uplifted marine terraces in Kikaijima, southern Japan and northwest Luzon, Philippines. Carbonate mineral identification using X-ray diffraction (XRD) and scanning electron microscope (SEM) was conducted to screen for any diagenetic alteration in the fossil corals. We used accelerator mass spectrometer (AMS) – 14C dating to determine the absolute age dates of the fossil corals. Well-preserved fossil corals yielded radiocarbon age dates of 3235 ± 20 and 5712 ± 24 cal. yr BP for Kikaijima and 6285 ± 79, 6144 ± 77, 4336 ± 21, 4277 ± 19, 4200 ± 20, and 2972 ± 70 cal. yr BP for northwest Luzon. X-ray imaging of a 5-mm thick coral slab was utilized to measure growth variables. Linear extension rate, skeletal density, and calcification rate of Kikaijima corals are 3.77–8.72 mm/ yr, 1.71–1.87 g/cm3, and 0.70–1.56 g/cm2yr, respectively. Linear extension rate, skeletal density, and calcification rate from northwest Luzon corals are 10.17–17.6 mm/yr, 0.66–1.67 g/cm3, and 0.91–2.81 g/cm2yr, respectively. Average linear extension rate from both sites was significantly and positively related to average calcification rate (r = 0.72, p = 0.019, n = 10). Skeletal density and linear extension rate measured from both sites were inversely related with each other (r = –0.56, p = 0.09, n = 10). Our data suggest that the variations in linear extension rates of fossil corals were influenced by the sea surface temperature (SST) difference between the study sites. However, data from modern corals are still needed to establish the local linear extension rate- SST relationship and to quantitatively evaluate how coral growth changes with respect to SST. Geomorphological, sedimentological, and geochronological studies of Holocene uplifted marine terraces should be conducted to provide the timing of emergence and coral reef development during Holocene.

Cooling of neutron stars with quark-hadron continuity

Neutron stars are high-density objects formed by the gravitational collapse of massive stars, and the whole star can be likened to a giant nucleus. The interior of a neutron star is considered to contain exotic particles and states which do not appear in a normal nucleus. The internal states are constrained by observations of masses and radii via the equation of state of highly dense nuclear matter. Within these constraints, a variety of exotic states have been discussed. The internal state of neutron stars is closely related to its neutrino emission process, which cools the star from the inside. This effect can be compared with observations of the surface temperature of neutron stars. However, despite the wide range of observations of neutron stars, the nature of the neutron star matter remains uncertain. We consider quark matter as an exotic state and perform cooling calculations for neutron stars, incorporating the effects of nucleon superfluidity and quark colour superconductivity.We take into account the “quark-hadron continuity”, in which the neutron superfluidity is succeeded by thedquark pairing. Furthermore, we obtained the range of the neutron star cooling curve, taking into account the difference in surface temperature due to the composition of the surface layer. We found that the existence of quark matter causes strong neutrino emission from quarks, which is moderately suppressedbysuperfluidity and superconductivity, and canexplain the cold surface temperature of neutron stars.

Changes in the Eastward Movement Speed of the Madden–Julian Oscillation with Fluctuation in the Walker Circulation

Abstract The eastward movement of a convectively active region is a distinguishing characteristic of the Madden–Julian oscillation (MJO). However, knowledge about the mechanisms that determine the eastward movement speed remains limited. This study investigates how the background environment modulates the speed of the boreal winter MJO and describes an intrinsic relationship between the MJO and background atmospheric circulation. We calculated the speed of the MJO events from the daily tracking of the locations of the minimum values of the outgoing longwave radiation anomaly in the time–longitude space. These speeds were then used to analyze systematic differences in the sea surface temperature (SST) distribution associated with the MJO speed. The analysis revealed a deceleration of the MJO under low-frequency (&gt;90 days) SST distributions that increased toward the western Pacific from both the Indian Ocean and the eastern Pacific. In contrast, the dependency on SST variability in intraseasonal frequencies (20–90 days) was small. Subsequently, the relationship between the MJO speed and background circulation, which is largely determined by the lower boundary condition set by the low-frequency SST distribution, was analyzed. The analysis counterintuitively revealed that the MJO tends to decelerate when the large-scale zonal circulation with low-level westerlies and upper-level easterlies from the Indian Ocean to the Maritime Continents is strong. The results suggest a novel view that the MJO is an integral component of the Walker circulation and that its eastward movement is modulated by the state of the large-scale flow of the Walker circulation.

Sea Breeze Geoengineering to Increase Rainfall over the Arabian Red Sea Coastal Plains

Abstract The Red Sea (RS) has a high evaporation rate, exceeding 2 m of water per year. The water vapor is transported from the shorelines by sea breezes as far as 200 km landward. Relative humidity in the vicinity of the RS exceeds 80% in summer. Nevertheless, precipitation is scarce in most of the Arabian RS coastal plain. In this work we use the Weather Research and Forecasting (WRF) regional model to assess how deliberate changes (geoengineering) in the surface albedo or conversion of bare land to wide-leaf forests over a vast coastal plain region affect precipitation over the Arabian RS coast. Our simulations show that geoengineering of land surface characteristics perturbs coastal circulation; alters temperature, moisture, and momentum exchange between the land surface and atmosphere; and changes the breeze intensity, cloud cover, and eventually the amount of precipitation. We find that extended afforestation and increased surface albedo are not effective in triggering rainfall over the RS coastal plains. Conversely, decreasing surface albedo to 0.2, assuming installation of solar panels over the coastal plains, increases surface air temperature by 1–2 K, strengthens horizontal surface temperature differences between sea and land, intensifies breezes, increases water vapor mixing ratio in the boundary layer above 3 km by about 0.5 g kg−1, enhances vertical mixing within the planetary boundary layer, and generates 1.5 Gt of extra rainwater, equivalent to the annual consumption of five million people. Thus, this form of regional land surface geoengineering, along with advanced methods of collection and underground storage of freshwater, provides a feasible solution to mitigation of the existing water crisis in the arid coastal regions.

OCULAR SURFACE TEMPERATURE DIFFERENCES IN RETINAL VASCULAR DISEASES.

To define the effect of age-related macular degeneration (AMD) and diabetic retinopathy (DR) on the ocular thermographic profile. This retrospective cross-sectional study included subjects diagnosed with DR or AMD between January and April 2019. Individuals without ocular disease served as controls. A thermal imaging camera was used for ocular surface temperature (OST) acquisition. The mean temperatures of the medial cantus, lateral cantus, and cornea were calculated. Thermographic images were obtained from 133 subjects (260 eyes, 97 DR and 163 AMD) and 48 controls (55 eyes). Ocular surface temperature was higher among patients with AMD and lowest among patients with DR (P < 0.001). A subgroup analysis revealed that eyes with diabetic macular edema had significantly higher OSTs than DR eyes without diabetic macular edema. Moreover, the OST in eyes with diabetic macular edema was similar to the measurements of the AMD group. There were no differences in OSTs between neovascular and nonneovascular AMD eyes. Although AMD and DR are considered posterior segment conditions, their effect on OST implies that the entire globe is involved. Although both conditions result from similar multifactorial pathophysiologic changes, the differences in OST between DR and AMD might be due to dissimilarity in the balance of pathologic processes involved in each condition. Further research is required to better understand the pathophysiology of these diseases and their effect on OST as well as to determine the effect of vasculature, circulation, and tissue metabolism on ocular temperature.

Laterality of Skin Temperature and Magnetic Resonance Imaging in Patients with Wallenberg Syndrome

Background: Recently, lateral differences in body surface temperature (BST) have been reported as a symptom of Wallenberg syndrome (WS), resulting from disturbances in the sympathetic nerve pathway. This study aimed to investigate the relationship between the laterality of BST and brain magnetic resonance imaging (MRI) findings in 12 patients with WS.Methods: BST was measured using an infrared thermal camera at 7±3 days and 90±30 days after symptom onset. The MRI findings were categorized as rostral, middle, and caudal medulla rostrocaudally and typical, ventral, large, dorsal, and lateral types in the horizontal direction.Results: MRI revealed medullary lesions on the right in five patients and on the left in seven patients. Two patients without lateralized BST had lateral caudal medullary infarction, and one patient had a dorsal middle medullary infarction. One patient with lateralized BST had a rostral medullary infarction and the other had a typical or large middle medulla infarction. Lateralized BST in patients with WS may disturb the sympathetic nervous system pathway that descends from the rostral ventrolateral medulla oblongata. Deficits in sweating and skin blood flow may cause BST laterality.Conclusion: This study showed that lateralized BST in patients with WS may be associated with disturbances in the sympathetic nervous pathway descending from the rostral ventrolateral medulla. These results support the assumption that autonomic dysfunction may be related to abnormal sensory symptoms in patients with WS.

Effect of Waveform Channel on the Cooling Performance of Hybrid Microchannel

To improve comprehensive hydrothermal performance of microfluidic cooling, a new type of hybrid microchannel is proposed. In this paper, turbulent flow and heat transfer characteristics of rectangular cross section straight hybrid microchannel, trapezoidal cross section straight hybrid microchannel, and trapezoidal cross section waveform hybrid microchannel (TWHM) are compared numerically by a realizable turbulence model under different pump power and heat flux. The results show that TWHM has a greater pressure drop at the same Reynolds number but has the best heat dissipation performance at the same pump power, in which temperature difference can be reduced up to 55.01%. The effect of arc height and chord length on the cooling performance of TWHM is also studied. As increases or decreases under the same pump power, the friction factor increases, while the total thermal resistance and bottom surface temperature difference decrease gradually. The cooling performance of channels becomes closer as the pump power increases. In addition, with the same cross-sectional area, the cooling performance of the waveform hybrid microchannel can be further improved by optimizing cross-sectional shape . The best cooling performance can be obtained at .

Experimental investigation on thermal characteristics of a novel mesh flat-plate heat receiver in a solar power tower system

In solar power tower systems, the heating surface of a heat receiver is prone to local overheating, thermal fatigue, and thermal ratcheting under nonstationary, nonuniform, and high-heat-flow-density loads, resulting in failure of the heat receiver. Therefore, this paper proposes a novel high-temperature, mesh, flat-plate heat receiver (FPHR) comprising multiple micro heat pipe loops. A series of tests were conducted to investigate the heat transfer characteristics and cooling start-up performance of the mesh FPHR. The results indicate that the larger cooling rates can reduce successful start-up times by more than 12%, and the FPHR has excellent isothermal performance (<35.05 °C) and heat transfer performance, which can withstand high-heat-flow-density loads and effectively prevent the harm caused by thermal stress. In addition, the nonuniform heating condition has a greater impact on the isothermal performance of FPHR, and the maximum temperature difference of the heat absorption surface with the change of the tilt angle is only reduced by 2.03 °C. The efficiency of the FPHR can exceed 83.98% and the air outlet temperature can exceed 714.5 °C. The results will contribute to the further development of heat receivers used in solar power tower systems.

Heat transfer in a rarefied gas between profiled surfaces moving relative to each other

The heat transfer in a rarefied gas between two solid surfaces moving relative to each other was studied. The problem was solved for nitrogen using the event-driven molecular dynamics (EDMD) method under the following conditions: (1) а wide range of flow regimes (Kn=0.05−20), (2) high relative velocity of surfaces, comparable to the thermal velocity of gas molecules, (3) significant difference in surface temperatures, (4) rotational degrees of freedom in gas molecules and (5) complex geometry of solid surfaces. Special attention was paid to the heat removal from the hot surface, namely the quantitative assessment of the reduction of heat removal due to viscous friction and effect of the transverse profiling of surfaces on the heat transfer between them.

Thermal effusivity of different tabletop materials in relation to users’ perception

Tactile interaction between humans and elements in the built environment, such as furniture, is often underappreciated. The aim of this study was to objectively evaluate thermal properties of ten tabletop materials as well as user perceptions of those materials after use. Sixteen participants tested ten materials in a randomised order. Infrared thermography was used to determine tabletop temperature distribution and change. Materials with lower thermal effusivity (wood-based materials) in general reached higher surface temperature differences after 15 min of contact and were rated as more pleasant to touch, more suitable for writing, and more liked for everyday use. Participants’ sex and forearm mass had no effect on the temperature after contact. Participants gave the highest ratings to the appearance of oak-based materials. Surface treatment affected subjective evaluation of the materials. The tabletop made of lacquered solid wood had the most favourable thermal and user-rated characteristics.

1033. Skin Surface Thermal Imaging to Differentiate Cellulitis and Pseudocellulitis in the Emergency Department

Abstract Background Cellulitis is misdiagnosed in up to 30% of cases, resulting in overuse of antibiotics. This represents a threat to patient safety and public health. Surface thermal imaging has been proposed as a tool to reduce errors in diagnosing cellulitis. The study objective was to compare skin surface temperature measurements between patients with cellulitis and pseudocellulitis. Methods We prospectively enrolled patients presenting to the emergency department (ED) with dermatologic lower extremity complaints that involved visible erythema. Using a thermal imaging camera, the maximum temperature value (Tmax) for the affected area of skin and corresponding area on an unaffected limb were captured. The Tmax gradient between the affected and unaffected limb was calculated. Gold standard diagnosis (cellulitis versus pseudocellulitis) was determined by consensus of a blinded, multidisciplinary physician review panel (two infectious disease, two dermatologists and two emergency medicine). Differences in temperature variables (Tmax and Tmax gradient) between cellulitis and pseudocellulitis were compared using t-tests. Results The sample included 204 participants, 59% male with an average age of 57 years. Based on expert panel consensus diagnosis, 92 (45%) of the participants had cellulitis. The cellulitis group had an average Tmax of 33.2°C and 30.2°C for affected and unaffected skin respectively, which was a significant difference of 2.9°C (CI: 2.5 to 3.6; p&amp;lt; 0.001). The difference in the Tmax gradients between patients with cellulitis and pseudocellulitis was 2.08°C (CI: 1.46-2.70; p&amp;lt; 0.001). Conclusion This represents the largest validation study of skin surface temperature differences between cellulitis and pseudocellulitis. Significant difference in temperature gradients between cases of cellulitis and pseudocellulitis suggests thermal imaging could be a useful diagnostic adjunct that can help differentiate these conditions. Such a modality could be particularly helpful in the ED setting where providers must balance diagnostic uncertainty with antimicrobial stewardship principles. Future work will identify the best performing temperature variables and determine optimal cutoff values for use in diagnostic algorithms. Disclosures All Authors: No reported disclosures

Seasonal and interannual drought responses of vegetation in a California urbanized area measured using complementary remote sensing indices

The effects of drought can manifest in vegetation across an array of physiological responses and time scales. In metropolitan areas, vegetation provides shading and cooling during hot and dry conditions, but these benefits can be reduced with drought. While many studies have evaluated interannual vegetation drought responses, these responses to drought can be expressed diversely across seasons, especially in cities that regularly experience seasonal drought (e.g., in Mediterranean climates). Here, we evaluated seasonal and interannual drought responses across the dominant types of urban trees and grasses in the Santa Barbara, California, USA metropolitan area, primarily using Landsat imagery acquired from 2010 to 2019 as well as repeat Airborne Visible Infrared Imaging Spectrometer - Classic (AVIRIS-C) imagery acquired 2013–2015. To track vegetation types, we produced a random forest classification from 4 m AVIRIS-Next Generation (AVIRIS-NG) imagery acquired in June 2014 (overall accuracy = 86%; kappa = 0.85), thresholding to >90% pure pixels for most vegetation types in the coarser time series imagery. We monitored drought response from Landsat imagery using the Normalized Difference Vegetation Index (NDVI) and the difference in land surface temperature (ΔLST) between vegetation and developed/impervious surfaces. We used AVIRIS-C to measure equivalent water thickness (EWT), comparing it with NDVI. During drought years, NDVI was lower and ΔLST was closer to zero. Changes in EWT revealed seasonal adjustments by vegetation that were not readily apparent in the NDVI. To show how drought response expression in vegetation can vary by season, drought duration, and urban vegetation type, we examined the correlations of both NDVI and ΔLST to the Standardized Precipitation Evapotranspiration Index (SPEI) calculated over a range of time spans. For most vegetation types, the strongest correlations of NDVI to SPEI and ΔLST to SPEI were during the summer, except for annual grass and turfgrass NDVI, which had the strongest correlations in the winter. In general, NDVI and ΔLST for annual grass were most often correlated with SPEI at spans <12 months, particularly for NDVI. By contrast, NDVI and ΔLST for trees and turfgrass were commonly also correlated with SPEI at spans ≥12 months, in addition to seasonal time spans of <12 months. This study demonstrates the benefits of using functionally and seasonally distinctive remote sensing variables (NDVI, ΔLST, and EWT) together to quantify changes in vegetation canopy condition during droughts.