Vertical Temperature Profiles Research Articles

The Coexistence of Gravity Waves From Diverse Sources During a SOUTHTRAC Flight

AbstractWe use observations from one of the SOUTHTRAC (Southern Hemisphere Transport, Dynamics, and Chemistry) Campaign flights in Patagonia and the Antarctic Peninsula during September 2019 to analyze possible sources of gravity waves (GW) in this hotspot during austral late winter and early spring. Data from two of the instruments onboard the German High Altitude and Long Range Research Aircraft (HALO) are employed: the Airborne Lidar for Middle Atmosphere research (ALIMA) and the Basic HALO Measurement and Sensor System (BAHAMAS). The former provides vertical temperature profiles along the trajectory, while the latter gives the three components of velocity, pressure, and temperature at the flight position. GW‐induced perturbations are obtained from these observations. We include numerical simulations from the Weather Research and Forecast (WRF) model to place a four‐dimensional context for the GW observed during the flight and to present possible interpretations of the measurements, for example, the orientation or eventual propagation sense of the waves may not be inferred using only data obtained onboard. We first evaluate agreements and discrepancies between the model outcomes and the observations. This allowed us an assessment of the WRF performance in the generation, propagation, and eventual dissipation of diverse types of GW through the troposphere, stratosphere, and lower mesosphere. We then analyze the coexistence and interplay of mountain waves (MW) and non‐orographic (NO) GW. The MW dominate above topographic areas and in the direction of the so‐called GW belt, whereas the latter waves are mainly relevant above oceanic zones. WRF simulates NOGW as mainly upward propagating entities above the lower stratosphere. Model runs show that deep vertical propagation conditions are in general favorable during this flight but also that in the upper stratosphere and lower mesosphere and mainly above topography there is some potential for wave breaking. The numerical simulations evaluate the GW drag for the whole flight area and find that the strongest effect is located in the zonal component around the stratopause. The general behavior against height resembles that obtained with a local fixed lidar data. According to WRF results, up to 100 km horizontal wavelength MW account for about half of the force opposing the circulation of the atmosphere.

Pipeline leak jet fire thermal characteristic induced by hydrogen-blended natural gas: Physical modeling of temperature profile based on virtual origin theory

Hydrogen-blended natural gas has widely used in energy fuel systems in industrial and domestic applications. During storage, transportation and usage of the fuel, temperature characteristics make a key contribution to energy leak gas fire accidents. In this manuscript experimentally, the buoyant turbulent diffusion axial temperature profile of a hydrogenated methane jet fire is experimentally investigated under free fire and wall fire. Different hydrogen addition ratios, nozzle diameters, and fire heat release rates were considered in the experimental conditions. Temperature profiles and virtual origins were recorded and analyzed. It is found that the wall fire temperature is somewhat higher than that in the free fire at a fixed height. And the vertical temperature of the jet fire increases with the increase of the hydrogen addition ratio, while the flame height decreases. With the addition of hydrogen, the virtual origin is increased, and virtual origin of wall fire is clearly larger than that of the free fire. Due to the restriction of air entrainment from the sidewall and the hydrogen addition, the physical mechanism of restricted air entrainment was analyzed. In addition, a non-dimensional model of the virtual origin was proposed and analyzed for different conditions. Finally, the normalized vertical temperature profile in the continuous flame region, intermittent flame region and buoyant plume region based on the virtual origin and mirror-approach are still well characterized for air entrainment under all conditions. The results of this paper may demonstrate the potential for the risk assessment of hydrogen-blended natural gas fire.

A large-scale, long-term experimental campaign for the investigation of wind turbine noise fluctuations and amplitude modulation phenomena.

The understanding and prediction of wind turbine noise (WTN) remain a subject on which progress is needed to better address the concerns of residents of some wind farms and to help wind farm operators to better optimize their wind farms. A large-scale and long-term measurement campaign was conducted by partners of the PIBE project (https://www.anr-pibe.com/en) near a French wind farm during 430 days, in order to study the emission and propagation of WTN. The campaign provided 100ms sound levels and acoustic spectra, together with periodically recorded 2 min audio samples, at 5 locations ranging from 350m to 1.3km from the wind farm, in different propagation directions. Meteorological data were simultaneously collected by a 80m meteorological mast, one or two Lidars and sonic anemometers, in order to characterize vertical profiles of wind speed, wind direction, temperature, and wind turbulence. 2 distinct weeks of intensive measurements (one in summer and one in winter) completed the data by including 15 additional acoustic points at other locations. The database will mainly be used within the project for the investigation of an uncertainty model of WTN, and of WTN amplitude modulations. This communication presents the database and first results about temporal variabilities of WTN.

Martian Atmospheric Temperature and Density Profiles During the First Year of NOMAD/TGO Solar Occultation Measurements

AbstractWe present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in‐house pre‐processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth‐tested retrieval scheme to Mars conditions. Both pre‐processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re‐analysis are briefly discussed.

ВЛИЯНИЕ СПОСОБОВ УСВОЕНИЯ СПУТНИКОВЫХ ДАННЫХ O ТЕМПЕРАТУРЕ ПОВЕРХНОСТИ МОРЯ НА ВОСПРОИЗВЕДЕНИЕ ГИДРОФИЗИЧЕСКИХ ПОЛЕЙ ЧЕРНОГО, АЗОВСКОГО И МРАМОРНОГО МОРЕЙ В МОДЕЛИ INMOM

The results are analyzed of the simulation of hydrophysical fields of the Black, Azov, and Marmara seas with the Institute of Numerical Mathematics Ocean Model (INMOM) implemented with a spatial resolution of 4 km, with various assimilation technique for sea surface temperature (SST) data from the SEVIRI sensor installed on MSG satellites. The relaxation (so called nudging) and the ensemble optimal interpolation (EnOI) with various assimilation time frequencies (3-, 6-, 12-, and 24-hour assimilation windows) were used as assimilation methods. It was shown that the assimilation of SST data via the EnOI made it possible to reproduce hydrophysical fields more accurately than via nudging or without assimilation at all. Even with the assimilation of SST data irregularly distributed over space and time, a decrease in the calculation error was observed over the entire sea area, and the structures of the zones of temperature rise or drop were more correctly simulated. The best results were achieved with via the EnOI assimilation with an increasing assimilation frequency over time. When SST data were assimilated using the EnOI, the mean error decreased from 0.16°C (24-hour assimilation window) to 0.08°C (3-hour assimilation window); accordingly, the absolute mean error decreased from 1.03 to 0.33°C, and the standard deviation decreased from 1.33 to 0.42°C. In addition, assimilation using the EnOI 3-hour window improved the reproduction of SST during the period of convection cooling. The assimilation of SST data also led to changes in the structure of the surface sea circulation. In some areas, the direction of currents varied within 5°-10°, and the velocity modulus changed by 3-5%. The assimilation of SST data only slightly reduced errors in the structure of the model vertical temperature profile, which can reach 2°C at depths of 30-40 m. At depths greater than 100 m, deviations did not exceed 0.05°C.

Ocean responses to Shaheen, the first cyclone to hit the north coast of Oman in 2021

On October 3rd, 2021, cyclone Shaheen made landfall on the northeast coast of Oman as a first-category cyclone after crossing the Sea of Oman. It is the first time in more than 130 years that a storm has made such extraordinary landfall on the northeast coast of Oman. This study intends to examine the effects of cyclone Shaheen on ocean cooling and biological response in the Sea of Oman (SO) and the the Arabian Sea (AS) using satellite remote sensing data, an Argo float, and the HYCOM model. The validation analysis of the HYCOM model and the Argo float showed strong correlations between vertical temperature profiles (R = 0.99) and vertical salinity profiles (R = 0.89). Furthermore, winds during the cyclone caused mixing and upwelling leading to Sea Surface Temperatures (SST) dropping 2.5 °C along southern Iranian coastlines, decreasing 5 °C along northern Oman's coastlines, and rising 1 °C across the Arabian Sea. As a result of the exitance of the cyclonic eddies in the Sea of Oman, a significant drop of 5 °C in SST was observed along the coastline of Oman caused by cold upwelled water from southern Iranian coastlines. Cyclone Shaheen's heavy rainfall caused the Sea Surface Salinity (SSS) in the Sea of Oman to drop from 36.7 to 36.8 psu. According to the results, Ekman pumping and upwelling processes predominated along the southern Iranian coast resulting in nutrient uplift and phytoplankton blooms (3 mg/m3). In contrast, strong stratification near the coast of Oman prevented nutrient uplift and led to low Chl-a concentrations. Due to the unique nature of cyclone Shaheen, it is essential to examine the complex dynamic and interaction between the ocean and atmosphere in the Sea of Oman and the Arabian Sea.

Assessing Climate and Human Activity Effects on Hypersaline Lake Ecosystem: Case Study of Saki Lake, Crimea

In the Crimean Peninsula, there are several hypersaline lakes that have hydromineral and biological resources. However, they are under a significant anthropogenic load, which together with the climate change leads to negative consequences for the ecosystems. The aim of the work was to study the seasonal changes of physicochemical parameters of water (temperature, pH, oxygen content, salinity, redox potential Eh, optical density and transparency) and Artemia population in Saki Lake in 2022. For the daily fluctuations of temperature, O2, CH4 and CO2, a vertical temperature profile measuring system was installed at the boundaries of the air, water and bottom at a depth of 4 m and with a spatial discreteness of 0.2 m. The drive sensors for the content of gases assay in the air were installed. The increase in salinity and Eh in summer was accompanied by an increase in air and water temperature. Simultaneously, decreases in oxygen content and pH in brine have been observed. Artemia cysts were found throughout the year, nauplii were mostly available during spring and autumn, and the adults were shown in summer. The obtained results demonstrated the seasonal fluctuations in the hypersaline ecosystem within the ongoing climate change, and they can be used for the development of the optimal management of the mineral and biological resources of such water bodies.

Dimensional Characterization of Groundwater Oblique Flow Problems with Heat Transport.

A dimensional study of two problems in which the groundwater flow is oblique has been carried out in order to characterize the vertical profiles of temperature along the domain affected by the flow, determining an input region in which the profiles depend on the horizontal position follow by a region in which profiles only depend on the vertical component of the flow. In the first problem, the horizontal and vertical components of velocity are constant. In the second scenario, the oblique flow of groundwater is generated because in the boundary conditions, the hydraulic potentials present a constant value. From the discriminated dimensional analysis of the mathematical model (governing equations and boundary conditions), the dependencies of the unknowns of greatest interest, characteristic lengths for the development of temperature-depth profiles and velocity profiles and the temperature field, with the dimensionless groups deduced are established. Once these dependencies have been verified, they are graphically represented by means of curves and surfaces as universal solutions to these problems. Based on these universal solutions an inverse problem protocol for estimating water flows from temperature measurements is proposed. The use of universal graphs of the two proposed scenarios avoids the large number of numerical simulations that this type of problem required.

Triple diffusive Marangoni convection in a fluid-porous structure: Effects of a vertical magnetic field and temperature profiles

In this study, the triple diffusive Marangoni convection (TDMC) problem when a steady heat source is present in both layers and a vertical uniform magnetic field in a fluid-porous structure is investigated in closed form. The horizontally infinite fluid-porous structure, which is horizontally surrounded by adiabatic boundaries and subjected to basic uniform and non-uniform temperature profiles. For all three temperature profiles (TP), linear, parabolic and inverted parabolic, the eigenvalues, the thermal Marangoni numbers (TMNs) are determined in closed form for lower rigid and upper free boundaries with surface tension, depending on both temperature and concentrations. The effects of relevant parameters on the eigenvalues, hence on TDMC, against depth ratio are attempted for all TPs. It is noticed that, the inverted parabolic TP on TDMC in a composite layer is the most stable of all the three TPs, the linear TP is the most unstable one and the parabolic TP is the moderate one. The relevant physical parameters considered in the study are effective for porous layer dominant fluid-porous structures.

Plant–atmosphere heat exchange during wind machine operation for frost protection

To mitigate spring frost damage, fruit farmers use wind machines to mix warm overlying air down to the vegetation. Up to this point, studies on wind machine efficiency have focused on air temperatures. The temperature of different plant organs during operation remains unknown, while critical for the actual degree of frost damage. With Distributed Temperature Sensing we measured vertical in-canopy air temperature profiles in a pear orchard in the Netherlands and thermistors were installed to determine the plant tissue temperatures. We found that to optimize wind machine operation, it is important to consider two effects of a wind machine: (1) mixing of stratified air above and into the canopy layer and (2) erosion of the leaf boundary layer to facilitate plant–air heat exchange. We show how foliage reduces plume penetration to the ground with distance to the wind machine. Due to this blocking at least 15 rotations (∼ 75 min) are needed for optimal mixing. Leaf temperatures lag behind air temperatures, due to strong radiative cooling. We found that over the rotation cycle of a wind machine the temperature difference between leaf and air is variable as convective warming repeatedly dominates over radiative cooling. This is different for flowers and shoots due to different heat capacities. Thin flower petals store little heat and are almost in direct equilibrium with air temperature changes. Shoots, with their higher heat capacity and lower surface/volume ratio, store more heat during the day that is slowly released at night. This discrepancy between plant and air temperature should be considered for frost damage prediction.

Surface-based temperature inversion characteristics and impact on surface air temperatures in northwestern Canada from radiosonde data between 1990 and 2016

Assumptions of linear lapse rates in regions prone to surface-based inversions (SBIs) can generate biases in the prediction of surface air temperature. Although studies of Arctic inversions are common, few regional studies of their characteristics exist in high-latitude regions with mountainous topography. To address this gap, vertical atmospheric temperature profiles for five sites in northwestern Canada were analysed using archived radiosonde data from 1990 to 2016. We present monthly, seasonal, and annual SBI characteristics including the occurrence of transient and persistent SBIs. A novel metric, surface-based inversion impact (SBIimp), was developed by combining the traditional inversion characteristics of depth, strength, and frequency, and was used to quantify the impact of SBIs on cooling the surface air temperature. SBIimp values of >5 °C yr−1 and ∼10 °C winter−1 occur locally. A weak linear relationship between sea ice coverage in the Beaufort Sea and SBIimp manifests across parts of the study area, though this relationship does not persist after detrending the datasets. Topographic analysis of areas surrounding each radiosonde location reveals highly variable SBIimp in complex mountain areas and more consistent SBIimp across areas of low relief. Our results can help interpret the role of inversions in climatic conditions maintaining cryospheric elements such as permafrost.

Mixing regimes in a cluster of seven maar lakes in tropical monsoon Asia

ABSTRACT The 7 maar lakes of San Pablo are a cluster of small volcanic lakes on Luzon Island, Philippines. These lakes, which are heavily utilized for aquaculture and ecotourism, usually experience fish kills that coincide with the northeast monsoon (NEM). This study explores limnophysical processes, particularly mixing regimes, in the lakes in relation to prevailing monsoons. We monitored monthly vertical and seasonal profiles of water temperature, salinity, conductivity, and dissolved oxygen from October 2016 to December 2018. Three types of mixing regimes were observed among the lakes, which have similar surface areas but different depths: polymixis in the shallowest; warm monomixis in lakes with intermediate depth; and meromixis in the deepest. A boundary between monomixis and meromixis was identified between 36 and 62 m depth. Monthly monitoring showed seasonal mixing occurred exclusively during the NEM (Nov–Apr). We also incorporated meteorological data into the model and performed multiple regression analysis for each lake to determine the best predictor: lake stability, as indicated by the Schmidt stability (ST ). A between-lake comparison showed lake stability was strongly correlated with both air temperature and wind speed, suggesting these 2 meteorological variables are involved in establishing thermal stratification in the lakes during the southwest monsoon. This study provides insights for adaptive lake management and projections of climate impacts on these understudied tropical lake ecosystems in Southeast Asia.

Experimental Investigation on the Vertical Temperature Profile of Spilled Plume from a Compartment-Facade Fire with a Horizontal Projection

Experimental Investigation on the Vertical Temperature Profile of Spilled Plume from a Compartment-Facade Fire with a Horizontal Projection

Effects of microforms on the evaporation of peat‐bryophyte‐litter column in a montane peatland in Canadian Rocky Mountain

AbstractPeatland microtopography contains hummocks (local high points) and hollows (local low points). Little is known about how the evaporation of peat (P), peat‐bryophyte (BP), peat‐litter (LP) and peat‐bryophyte‐litter (LBP) columns varies with peatland microforms. That is, whether there are fine‐scale variations in peatland evaporation, and if they are critical when being upscaled to the entire peatland ecosystem is yet to be answered. This study found that evaporation was significantly affected by cover type (P, BP, LP or LBP) and the interaction effect of the cover type and microform, based on the field evaporation experiments in a montane peatland in the Canadian Rocky Mountains, during the growing season of 2021. Mean daily evaporation of P‐Hummock and P‐Hollow is 14.16 and 11.76 g day−1, respectively; BP‐Hummock and BP‐Hollow is 9.57 and 14.38 g day−1, respectively; LBP‐Hummock and LBP‐Hollow is 9.44 and 9.91 g day−1, respectively; and evaporation of LP‐Hummock and LP‐Hollow is 5.68 and 7.64 g day−1, respectively. Peatland microform indirectly affected evaporation through interactions with cover type, modifying the vertical profile of soil temperature and changing key environmental drivers of evaporation. Moreover, the ability of two widely used models in modelling the spatial variation of peatland evaporation was also tested. It was found that Penman–Monteith (P–M) model and the bryophyte layer model in the Atmosphere‐Plant Exchange Simulator (APES) were able to yield satisfactory results based on field measurements of soil temperature and soil moisture. This study supports developing more practical evaluation tools on the hydrological state of peatland ecosystems.

Study on the Influence Law of Temperature Profile of Vertical Wells in Gas Reservoirs

Due to the lack of a robust temperature model and poor knowledge about the influence law of temperature profile, it is still highly challenging to interpret the production profile of vertical wells in layered gas reservoirs from distributed temperature sensing (DTS) quantitatively. In this paper, a coupled temperature prediction model for vertical wells in the layered gas reservoir is developed, considering several microthermal effects and non-isothermal seepage. Based on the theoretical simulation, several single factors' influence on the vertical well's temperature profile in a layered gas reservoir has been analyzed. The sensitivity of temperature profiles on different affecting factors has been evaluated through orthogonal test analysis. It has been found that the influence degree of each factor on the temperature profile of the vertical well in the layered gas reservoir is as follows: formation permeability > production rate >water saturation > wellbore inclination angle > relative density of natural gas > formation thermal conductivity > wellbore diameter (k >Qg > SW > θ > dg > Kt > D). The dominant factors affecting the temperature profile of vertical wells in layered gas reservoirs are formation permeability, production rate, and water saturation. The proposed temperature prediction model can serve as the forward model when developing the inversion system to interpret DTS measurement. The findings of this paper provide solid theoretical support for the quantitative interpretation of the flow rate profile for vertical wells in layered gas reservoirs.

A multi-scale temperature-based strategy to map hydrologic exchange flows in highly dynamic systems

Mapping and quantifying hydrologic exchange flows (HEFs) is critical to environmental monitoring and remediation at contaminated sites; however, these objectives are challenging in highly dynamic systems, e.g., along dam-regulated rivers, where HEFs vary rapidly. Direct seepage measurements are labor-intensive and difficult to automate, whereas indirect (e.g., thermal) and remote sensing methods have potential to allow continuous monitoring with limited field effort. We present a preliminary assessment of a multi-scale temperature-based strategy for monitoring HEFs along the Hanford Reach of the Columbia River, in eastern WA, United States. Five thermal methods were assessed. First, a vertical temperature profile (VTP) was installed into the streambed. The VTP data were analyzed using a data assimilation algorithm designed for automated real-time estimation in dynamic systems. Second, a thermal infrared (TIR) camera was used in roving surveys to identify seeps. Third, a TIR camera was stationed at the VTP site to collect images at 1-h intervals. Together, the two TIR datasets provided a basis to assess the potential for drone-based TIR. Fourth, temperature was measured at the sediment/water interface to assess fiber-optic distributed temperature sensing. Fifth, imagery from the ECOSTRESS satellite mission was acquired to assess the potential of spaceborne thermal monitoring. Based on our preliminary assessment, VTP, TIR, and bed temperature measurements provide complementary spatial coverage, temporal sampling, and resolution; these methods have potential for long-term, automated monitoring of HEFs. The publicly available spaceborne imagery, however, proved inadequate because of insufficient spatial resolution and data gaps resulting from cloud cover and revisit frequency.

Three-Dimensional Static Instability of Gravity Waves and a Possible Parameterization of the Associated Wave Breaking

Abstract Parameterizations of subgrid-scale gravity waves (GWs) in atmospheric models commonly involve the description of the dissipation of GWs. Where they dissipate, GWs have an increased effect on the large-scale flow. Instabilities that trigger wave breaking are an important starting point for the route to dissipation. Possible destabilizing mechanisms are numerous, but the classical vertical static instability is still regarded as a key indicator for the disposition to wave breaking. In this work, we investigate how the horizontal variations associated with a GW could alter the criterion for static instability. To this end, we use an extension of the common parcel displacement method. This three-dimensional static stability analysis predicts a significantly larger range of instability than does the vertical static stability analysis. In this case, the Lindzen-type saturation adjustment to a state of marginal stability is perhaps a less suitable ansatz for the parameterization of the GW breaking. To develop a possible ansatz for the GW dissipation due to three-dimensional instability, we apply the methods of irreversible thermodynamics, which are embedded in the Gibbs formalism of dynamics. In this way, the parameterization does not only satisfy the second law of thermodynamics, but it can also be made consistent with the conservation of energy and further (non-)conservation principles. We develop the parameterization for a discrete spectrum of GW packets. Offline computations of GW drag and dissipative heating rates are performed for two vertical profiles of zonal wind and temperature for summer and winter conditions from CIRA data. The results are compared to benchmarks from the literature.

Hierarchical Bayesian modeling of ocean heat content and its uncertainty

The accurate quantification of changes in the heat content of the world’s oceans is crucial for our understanding of the effects of increasing greenhouse gas concentrations. The Argo program, consisting of Lagrangian floats that measure vertical temperature profiles throughout the global ocean, has provided a wealth of data from which to estimate ocean heat content. However, creating a globally consistent statistical model for ocean heat content remains challenging due to the need for a globally valid covariance model that can capture complex nonstationarity. In this paper, we develop a hierarchical Bayesian Gaussian process model that uses kernel convolutions with cylindrical distances to allow for spatial nonstationarity in all model parameters while using a Vecchia process to remain computationally feasible for large spatial datasets. Our approach can produce valid credible intervals for globally integrated quantities that would not be possible using previous approaches. These advantages are demonstrated through the application of the model to Argo data, yielding credible intervals for the spatially varying trend in ocean heat content that accounts for both the uncertainty induced from interpolation and from estimating the mean field and other parameters. Through cross-validation, we show that our model outperforms an out-of-the-box approach as well as other simpler models. The code for performing this analysis is provided as the R package BayesianOHC.

Experimental investigation on RP‐3 aviation kerosene large‐scale pool fires at high altitude

AbstractRP‐3 aviation kerosene is a standard fuel that is used in civil aircraft and is a substitute for Jet‐A fuel. This paper investigates the combustion behaviour of RP‐3 aviation kerosene in an open space in the low‐pressure environment of a plateau. A series of large‐scale pools with diameters ranging from 0.4 m to 2.82 m combustion experiments are performed. Typical combustion characteristic parameters, including combustion rate, flame height and axial plume temperature distribution is measured. Results show that a low‐pressure environment significantly affects pool fires. With combustion rate, there is a linear variation law between oil pool size and combustion rate. The experimental data are fitted as a means of obtaining the large‐scale combustion rate relationship equation at low pressure. Experimental flame height data is compared using classical prediction models. Prediction model coefficients at low pressure are determined. The axial plume temperature distribution is greater than in the literature findings due to flames becoming longer in a low‐pressure environment. The three regimes in McCaffery's model are redefined and correlate well with the vertical temperature profile of the pool centreline. The results of the experimental investigation will help research fire hazards in low‐pressure environments while also contributing to the provision of basic data for the development of firefighting operation strategies.

Synergistic retrieval and complete data fusion methods applied to simulated FORUM and IASI-NG measurements

Abstract. In the frame of Earth observation remote-sensing data analysis, synergistic retrieval (SR) and complete data fusion (CDF) are techniques used to exploit the complementarity of the information carried by different measurements sounding the same air mass and/or ground pixel. While more difficult to implement due to the required simultaneous access to measurements originating from different instruments, the SR method is sometimes preferred over the CDF method as the latter relies on a linear approximation of the retrieved states as functions of the true atmospheric and/or surface state. In this work, we study the performance of the SR and CDF techniques when applied to simulated measurements of the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) and the Infrared Atmospheric Sounding Interferometer – New Generation (IASI-NG) missions that will be operational in a few years, from two polar-orbiting satellites. The study is based on synthetic measurements generated for the two missions in clear-sky atmospheres. The target parameters of the inversion are the vertical profiles of temperature, water vapor and ozone mixing ratios, surface temperature, and spectral emissivity. We find that for exact matching of the measurements, the results of the SR and CDF techniques differ by less than 1/10 of their errors estimated through the propagation of measurement noise. For measurements with a realistic mismatch in space and time, the two methods provide more different results. Still in this case, however, the differences between the results are within the error bars due to measurement noise. We conclude that, when applied to FORUM and IASI-NG missions, the two methods are equivalent from an accuracy point of view.