Condensational Heating Research Articles

Zonal shift of the South Asian High on the subseasonal time‐scale and its relation to the summer rainfall anomaly in China

By using daily National Centers for Environmental Prediction‐National Center for Atmospheric Research (NCEP‐NCAR) reanalysis and observed rainfall data, we investigated the east–west shift of the South Asian High (SAH) on the subseasonal time‐scale and its relationship with the rainfall anomaly in China. It is found that the zonal shift of the SAH at 200 hPa displays a dominant periodicity of 10–50 days, with two preferred locations, one over the northeast Tibetan Plateau (eastern location) and the other over the northeast Iranian Plateau (western location). The zonal shift of the SAH is closely related to the southward movement of intraseasonal perturbations originating in middle latitudes. A vorticity budget analysis reveals that the advection of mean vorticity by the perturbation of meridional wind primarily contributes to the vorticity tendency over both the eastern and western locations. The zonal shift of the SAH closely connects to the summer rainfall anomalies over China. An eastern (a western) location of the SAH corresponds to generally positive (negative) rainfall anomalies in northwestern China and negative (positive) anomalies in southern China. A further diagnosis reveals that the strengthening of the intraseasonal perturbation during the southward journey in the eastern location is attributed to a positive convection–circulation feedback. On the one hand, a positive geopotential height anomaly in the upper troposphere and associated upper‐level divergence induce anomalous ascending motion and condensational heating in the middle troposphere. On the other hand, the positive heating anomaly increases mid‐tropospheric temperature and strengthens upper‐level geopotential height. The southward propagation leads to the zonal shift of the SAH.

Estimation of low-potential heat recuperation efficiency of smoke fumes in a condensation heat utilizer under various operation conditions of a boiler and a heating system

For enhancement of the natural gas utilization efficiency in boilers, condensation heat utilizers of low-potential heat, which are constructed based on a contact heat exchanger, can be applied. A schematic of the contact heat exchanger with a humidifier for preheating and humidifying of air supplied in the boiler for combustion is given. Additional low-potential heat in this scheme is utilized for heating of the return delivery water supplied from a heating system. Preheating and humidifying of air supplied for combustion make it possible to use the condensation utilizer for heating of a heat-transfer agent to temperature exceeding the dewpoint temperature of water vapors contained in combustion products. The decision to mount the condensation heat utilizer on the boiler was taken based on the preliminary estimation of the additionally obtained heat. The operation efficiency of the condensation heat utilizer is determined by its structure and operation conditions of the boiler and the heating system. The software was developed for the thermal design of the condensation heat utilizer equipped by the humidifier. Computation investigations of its operation are carried out as a function of various operation parameters of the boiler and the heating system (temperature of the return delivery water and smoke fumes, air excess, air temperature at the inlet and outlet of the condensation heat utilizer, heating and humidifying of air in the humidifier, and portion of the circulating water). The heat recuperation efficiency is estimated for various operation conditions of the boiler and the condensation heat utilizer. Recommendations on the most effective application of the condensation heat utilizer are developed.

MJO Moisture Budget during DYNAMO in a Cloud-Resolving Model

Abstract Contributions by different physical processes and cloud types to the sum of the large-scale vertical moisture advection and apparent moisture sink observed by the DYNAMO field campaign northern sounding array during the passage of a Madden–Julian oscillation (MJO) event are estimated using a cloud-resolving model. The sum of these two moisture budget terms is referred to as the column-confined moisture tendency MC. Assuming diabatic balance, the contribution of different physical processes and cloud types to the large-scale vertical velocity and MC can be estimated using simulated diabatic tendencies and the domain-averaged static stability and vertical moisture gradient. Low-level moistening preceding MJO passage is captured by MC and dominated by the effects of shallow clouds. Because of the large vertical moisture gradient at this level, condensational heating in these clouds generates ascent and vertical moisture advection overwhelming the removal of water vapor by condensation. Shallow convective eddy transport also contributes to low-level moistening during this period. Eddy transport by congestus and deep convective clouds contributes to subsequent mid- and upper-level moistening, respectively, as well as low-level drying. Because the upper-level vertical moisture gradient is small, ice deposition within stratiform clouds has a net drying effect. The weak eddy transport in stratiform clouds is unable to compensate for this drying. Nonprecipitating clouds mainly modulate MC through their effects on radiation. During the enhanced phase, reduced longwave cooling results in less subsidence and drying; the opposite occurs during the suppressed phase. Large-scale horizontal advection, which is not included in MC, is responsible for much of the drying during the dissipating phase.

Response of the Baiu Rainband to Northwest Pacific SST Anomalies and Its Impact on Atmospheric Circulation

Abstract The Pacific–Japan (PJ) teleconnection pattern leads to a meridional precipitation dipole between the subtropics and East Asia in the summer of El Niño decaying years. However, observational analysis and model experiments indicate that increased sea surface temperature (SST) in the Kuroshio–Oyashio Extension (KOE) region, where a strong northward-decreasing SST gradient occurs, induces a northward shift of baiu rainfall with the subtropical jet, forming a tripolar precipitation anomaly pattern over the northwest Pacific. In July, the leading empirical orthogonal function (EOF) mode for precipitation represents the meridional dipole between subtropical and baiu rainfalls, while EOF-2 features the northward-shifted baiu rainband. The PJ atmospheric forcing increases KOE SST, which enhances northward shifts in the subtropical jet and baiu rainband, resulting in oceanic forcing over the KOE. In experiments using a regional climate model the subtropical jet response to KOE SST forcing explains about 20% of the anomalies in the control experiment. The northward-shifted baiu condensational heating also enhances the northward shift of the subtropical jet with a northeastward extension. In August when the baiu rainband disappears, the northward shift of the subtropical jet is enhanced mainly by KOE SST variability. During the summer, as a result of increased KOE SST and the northward-shifted baiu heating, cyclonic anomalies intensify over the Sea of Okhotsk and anticyclonic anomalies intensify over the northwest Pacific, affecting the western Pacific subtropical high. The results suggest that air–sea interaction over the KOE must be considered to better understand the summer northwest Pacific climate.

Nucleus factory on cavitation bubble for amyloid β fibril.

Structural evolution from monomer to fibril of amyloid β peptide is related to pathogenic mechanism of Alzheimer disease, and its acceleration is a long-running problem in drug development. This study reveals that ultrasonic cavitation bubbles behave as catalysts for nucleation of the peptide: The nucleation reaction is highly dependent on frequency and pressure of acoustic wave, and we discover an optimum acoustical condition, at which the reaction-rate constant for nucleation is increased by three-orders-of magnitudes. A theoretical model is proposed for explaining highly frequency and pressure dependent nucleation reaction, where monomers are captured on the bubble surface during its growth and highly condensed by subsequent bubble collapse, so that they are transiently exposed to high temperatures. Thus, the dual effects of local condensation and local heating contribute to dramatically enhance the nucleation reaction. Our model consistently reproduces the frequency and pressure dependences, supporting its essential applicability.

Comparative study on proper thermocouple attachment for vapour phase soldering profiling

Purpose – The paper aims to present a comparative study of various thermocouple (TC) attaching methods for the proper measurement of soldering temperature profiling during vapour phase soldering (VPS). The heat transfer process during VPS is different from common methods, while the required heat for reflow is provided by the condensation. The condensate is a flowing layer on the board, where the dynamic behaviour also affects the local conditions on the surfaces. Temperature measurements based on TCs are also affected this way; it is important to investigate the process for deeper understanding. Design/methodology/approach – Bare printed circuit boards (PCBs) were prepared for standard K-Type TCs attachment with industry standard materials: kapton polyimide tape, aluminium tape, SMD adhesive and high-temperature solder (HTS). Heating experiments were performed in a batch-type VPS oven with Galden LS240 fluid and fixed oven parameters. Findings – According to the specific attachment requirements, HTS and Alu-tape are the suggested methods for better profiling reliability and repeatability. Alu-tape is the preferred all-around method, for fast, exchangeable, cheap, reliable and repeatable profiling in a VPS oven. It was presented that the heating factor (Q?) gives more reliable comparison overview; the time period-based comparisons may be affected by the thermal inertia, while heating factor also includes temperature conditions at the given time points. Originality/value – The paper presents the reliability of the presented methods for VPS and present suggestions for the use of different TC ends and attaching materials during condensation heating of the PCBs. Also a new approach on profiling data evaluation based on the heating factor is presented and suggested for wider use.

A Modeling Study of a Low-Level Jet along the Yun-Gui Plateau in South China

AbstractIn this study, the three-dimensional structures and diurnal evolution of a typical low-level jet (LLJ) with a maximum speed of 24 m s−1 occurring in the 850–800-hPa layer are examined using both large-scale analysis and a high-resolution model simulation. The LLJ occurred on the eastern foothills of the Yun-Gui Plateau in south China from 1400 LST 29 June to 1400 LST 30 June 2003. The effects of surface radiative heating, topography, and latent heat release on the development of the LLJ case are also studied. Results show that a western Pacific Ocean subtropical high and a low pressure system on the respective southeast and northwest sides of the LLJ provide a favorable large-scale mean pressure pattern for the LLJ development. The LLJ reaches its peak intensity at 850 hPa near 0200 LST with wind directions veering from southerly before sunset to southwesterly at midnight. A hodograph at the LLJ core shows a complete diurnal cycle of the horizontal wind with a radius of 5.5 m s−1. It is found that in an LLJ coordinates system the along-LLJ geostrophic component regulates the distribution and 65% of the intensity of LLJ, whereas the ageostrophic component contributes to the clockwise rotation, thus leading to the formation and weakening of the LLJ during night- and daytime, respectively. Numerical sensitivity experiments confirm the surface radiative heating as the key factor in determining the formation of the nocturnal LLJ. The existence of the Yun-Gui Plateau, and the downstream condensational heating along the mei-yu front play secondary roles in the LLJ formation.

Impact of East Asian Summer Monsoon Heating on the Interannual Variation of the South Asian High

Abstract Occupying the upper troposphere over subtropical Eurasia during boreal summer, the South Asian high (SAH) is thought to be a regulator of the East Asian summer monsoon (EASM), which is particularly important for regional climate over Asia. However, there is feedback of the condensational heating associated with EASM precipitation to SAH variability. In this study, interannual variation of SAH intensity and the mechanisms are investigated. For strong SAH cases, the high pressure system intensifies and expands. Significant positive anomalies of the geopotential height and upper-tropospheric temperature were found over the Middle East and to the east of the Tibetan Plateau (TP), namely, the western and the eastern flanks of the SAH. The dynamical diagnosis and the numerical experiments consistently show that the interannual variation of SAH intensity is strongly affected by EASM precipitation over the eastern TP–Yangtze River valley. The feedback of the condensational heating anomaly to the SAH is summarized as follows: Excessive EASM heating excites a local anticyclone in the upper troposphere and warms the upper troposphere, leading to the eastward extension of the SAH’s eastern edge and reinforcing geopotential height anomalies over East Asia. Furthermore, the monsoonal heating excites a westward-propagating Rossby wave that increases the upper-tropospheric geopotential height and warms the upper troposphere over the Middle East. In conclusion, this study suggests a mechanistic paradigm in which the EASM may also be a modulator of SAH variation rather than just a passive result of the latter as traditionally thought. The results suggest that the EASM and the SAH are a tightly interactive system.

The Role of Moisture in Summertime Low-Level Jet Formation and Associated Rainfall over the East Asian Monsoon Region

Abstract The southwesterly low-level jet (LLJ) located to the east of the Tibetan Plateau in southern China plays an important role in summertime convective initiation over north China. This study adopts a novel perspective and uses hindcast experiments in order to investigate the role of moisture in LLJ and associated heavy rainfall formation, employing a global atmospheric general circulation model (AGCM). In the sensitivity experiments, an increase of humidity in the inflow region leads to a weaker LLJ but stronger diurnal wind oscillations. The weaker LLJ is due to a decreased lower-tropospheric east–west pressure gradient resulting from a low pressure anomaly over southeastern China induced by deep convection and related condensational heating. On the other hand, the stronger diurnal variation of the LLJ originates from stronger day-and-night thermal differences over the sloping terrain, which is related to drier conditions over the mountain range. Moreover, the increased humidity and decreased LLJ counteract one another to impact precipitation in the outflow region. The change of precipitation is mainly determined by the altered moisture flux divergence. If the increase in humidity dominates, then the moisture flux convergence is enhanced and favors more precipitation over north China. Otherwise, if the decreased LLJ dominates, then the moisture flux convergence is reduced, which constrains precipitation. It is highlighted that the moist diabatic and dynamic processes are intimately coupled, and that a correct simulation of moisture flux convergence is vital for AGCMs to reproduce the LLJ-related precipitation, particularly the nocturnal precipitation peak, which is a deficiency in many current models.

The Thermodynamic and Microphysical Evolution of an Intense Snowband during the Northeast U.S. Blizzard of 8–9 February 2013

Abstract An intense snowband developed across Long Island, New York, to the north and west of the surface cyclone center on 8–9 February 2013. The snowband evolved through three distinct phases during its 12-h lifetime. During phase 1 the band developed in an area of low-to-midlevel frontogenesis and pivoted over central Long Island and southern Connecticut, where it remained for approximately 10 h. The environment surrounding the snowband cooled to <0°C; however, the band was collocated with a 900–700-hPa layer that remained above 0°C for ~5 h. During phase 2 the band exhibited heavy snowfall rates exceeding 7.5–10 cm h−1 with large and aggregated snow, wet-growth hail-like particles, and a radar reflectivity of ~55 dBZ. About 1 h later during phase 3, the snowband reflectivity decreased to near 30 dBZ and was characterized by less dense snow in a colder environment while still maintaining heavy snowfall rates (6.5–6.7 cm h−1). The Weather Research and Forecasting (WRF) Model was used to analyze the band and temperature evolution. Model trajectories terminating within the warmer snowband environment underwent rapid ascent on the east side of the band during which condensation and deposition enhanced the warming before undergoing rapid descent within the band. Analysis of the thermodynamic equation within the band environment revealed that this subsidence warming and upstream condensational heating for trajectories entering the band partially offset the diabatic cooling term, which supported a warmer layer and mixed precipitation during phase 2. Finally, model sensitivity tests showed that melting helped cool low levels and change the microphysical character to all snow during phase 3.

Synergistic contribution of precipitation anomalies over northwestern India and the South China Sea to high temperature over the Yangtze River Valley

This study explores the characteristics of high temperature anomalies over eastern China and associated influencing factors using observations and model outputs. Results show that more long-duration (over 8 days) high temperature events occur over the middle and lower reaches of the Yangtze River Valley (YRV) than over the surrounding regions, and control most of the interannual variation of summer mean temperature in situ. The synergistic effect of summer precipitation over the South China Sea (SCS) region (18°–27°N, 115°–124°E) and the northwestern India and Arabian Sea (IAS) region (18°–27°N, 60°–80°E) contributes more significantly to the variation of summer YRV temperature, relative to the respective SCS or IAS precipitation anomaly. More precipitation (enhanced condensational heating) over the SCS region strengthens the western Pacific subtropical high (WPSH) and simultaneously weakens the westerly trough over the east coast of Asia, and accordingly results in associated high temperature anomalies over the YRV region through stimulating an East Asia-Pacific (EAP) pattern. More precipitation over the IAS region further adjusts the variations of the WPSH and westerly trough, and eventually reinforces high temperature anomalies over the YRV region. Furthermore, the condensational heating related to more IAS precipitation can adjust upper-tropospheric easterly anomalies over the YRV region by exciting a circumglobal teleconnection, inducing cold horizontal temperature advection and related anomalous descent, which is also conducive to the YRV high temperature anomalies. The reproduction of the above association in the model results indicates that the above results can be explained both statistically and dynamically.

North Atlantic Storm-Track Sensitivity to Warming Increases with Model Resolution

Abstract Mesoscale condensational heating can increase the sensitivity of modeled extratropical cyclogenesis to horizontal resolution. Here a pseudo global warming experiment is presented to investigate how this heating-enhanced sensitivity to resolution changes in a warmer and thus moister atmosphere. The Weather Research and Forecasting (WRF) Model with 120- and 20-km grid spacing is used to simulate current and future climates. It is found that the North Atlantic storm-track response to global warming is amplified at the higher model resolution. The most dramatic changes occur over the northeastern Atlantic, where resolution typical of current general circulation models (GCMs) results in a smaller global warming response in comparison with that in the 20-km simulations. These results suggest that caution is warranted when interpreting projections from coarse-resolution GCMs of future cyclone activity over the northeastern Atlantic.

Hurricane Sandy before 1900 and after 2100

Abstract To what extent did large-scale thermodynamic climate change contribute to the intensity and unusual track of Hurricane Sandy, which affected the U.S. mid-Atlantic region in late October 2012? How much of an impact would projected future climate change have on a storm such as Sandy? These questions are investigated using an ensemble of high-resolution numerical simulations in conjunction with analyzed and projected changes from a suite of general circulation models (GCMs). Simulations initialized with current analyses from the midpoint of Sandy’s life cycle, while the system was centered near the Bahamas, adequately replicate the observed intensity and track of Sandy. Initial and boundary condition data are then altered with thermodynamic change fields obtained from a five-member GCM ensemble, allowing hypothetical replication of the synoptic weather pattern that accompanied Hurricane Sandy, but for large-scale thermodynamic conditions corresponding to the 1880s and for projections to the twenty-second century. The past ensemble produces a slightly weaker storm that makes landfall south of the observed location. The future ensemble depicts a significantly more intense system that makes landfall farther north, near Long Island, New York. Within the limitations of the methods used, it is suggested that climate change to date exerted only a modest influence on the intensity and track of Sandy. The strengthening in the simulations run with projected future warming is consistent with increased condensational heating; changes in the synoptic steering flow also appear to result from diabatic processes. The questions of how climate change affected Sandy’s genesis and early life cycle, changes in the frequency of this type of synoptic pattern, and changes in impacts related to coastal development and sea level rise are not considered here.

Mediterranean Summer Climate and the Importance of Middle East Topography*

Abstract In summer, the atmospheric circulation over the Mediterranean is characterized by localized intense subsidence and low-level northerlies over the central to eastern portion of the basin. Here, simulations with the Community Atmosphere Model, version 5 are used to investigate the influence of the elevated terrain of North Africa and the Middle East on this summertime circulation. This builds on previous work that recognized a role for North African topography in localizing the Mediterranean subsidence. By flattening the two regions of elevated terrain in the model, it is demonstrated that, while they both conspire to produce about 30% of the summertime subsidence, contrary to previous work, the mountains of the Middle East dominate in this topographic contribution by far. This topography, consisting primarily of the Zagros mountain range, alters the circulation throughout the depth of the troposphere over the Mediterranean and farther east. The model results suggest that about 20% of the Mediterranean summertime moisture deficit can be attributed to this mountain-induced circulation. This topography, therefore, plays an important role in the climate of the Mediterranean and the large-scale circulation over the rest of Eurasia during the summer. Further stationary wave modeling reveals that the mountain influence is produced via mechanical forcing of the flow. The greatest influence of the topography occurs when the low-level incident flow is easterly, as happens during the summer, primarily because of the presence of condensational heating over Asia. During other seasons, when the low-level incident flow is westerly, the influence of Middle East topography on the Mediterranean is negligible.

Asian summer monsoon onset barrier and its formation mechanism

The onset process of Asian summer monsoon (ASM) is investigated based on diagnostic analysis of observations of precipitation and synoptic circulation. Results show that after the ASM commences over the eastern Bay of Bengal (BOB) around early May, the onset can propagate eastwards towards the South China Sea and western Pacific but is blocked on its westward propagation along the eastern coast of India. This blocking, termed the “monsoon onset barrier (MOB)”, presents a Gill-type circulation response to the latent heating released by BOB monsoon convection. This convective condensation heating generates summertime (wintertime) vertical easterly (westerly) shear to its east (west) and facilitates air ascent (descent). The convection then propagates eastward but gets trapped on its westward path. To the east of the central BOB, the surface air temperature (SAT) cools faster than the underlying sea surface temperature (SST) due to monsoon onset. Thus more sensible heat flux supports the onset convection to propagate eastward. To the west of the central BOB, however, the land surface sensible heating over the Indian Peninsula is strengthened by the enhanced anticyclone circulation and air descent induced by the BOB monsoon heating. The strengthened upstream warm horizontal advection then produces a warm SAT center over the MOB region, which together with the in situ cooled SST reduces the surface sensible heating and atmospheric available potential energy to prevent the occurrence of free convection. Therefore, it is the change in both large-scale circulation and air–sea interaction due to BOB summer monsoon onset that contributes to the MOB formation.

Genesis and Development Mechanisms of a Polar Mesocyclone over the Japan Sea

Abstract A polar mesocyclone (PMC) observed over the Japan Sea on 30 December 2010 was studied using a nonhydrostatic mesoscale numerical model with a horizontal resolution of 2 km. The numerical simulation successfully reproduced the observed life cycle of the PMC. The results of the numerical simulation suggest that the life cycle of the PMC may be divided into three stages: an early development stage, in which a number of small vortices appear in a shear zone; a late development stage, which is characterized by the merger of vortices and the formation of a few larger vortices; and a mature stage, in which only a single PMC is present. During the early development stage, vortices are generated in the shear zones of strong updrafts in discrete cumulus convection cells. In contrast, during the late development stage, the vortices develop as a result of barotropic instability in the shear zone. A cloud-free eye and spiral cloud bands accompany the mature stage of a simulated PMC. A warm core structure also forms at the center of the PMC on account of adiabatic warming associated with downdrafts. The structures in the PMC during the mature stage resemble those of a tropical cyclone. Sensitivity experiments, in which sensible and latent heat fluxes from the sea surface and condensational heating were switched on/off, demonstrate that condensational heating is critical to the development of the PMC at all stages, and that sensible and latent heat fluxes play secondary roles.

Diurnal variation in the occurrence frequency of the Tibetan Plateau vortices

A diagnostic study is made on the diurnal variation in the occurrence frequency of the Tibetan Plateau vortices (TPVs) in four local time (LT) periods of a day (06–12 LT, 12–18 LT, 18–00 LT, 00–06 LT) using the data from May to September in 2006–2008. The occurrence frequency of the TPVs shows a robust diurnal variation with its maximum from evening to midnight (18–00 LT) and minimum from early morning to noon (06–12 LT). The physical processes in association with the diurnal variation of the TPVs are revealed. Both large-scale circulations and condensational latent heat induced by the precipitation system have important effect on the diurnal variation of the TPVs’ occurrence. In the evening at 18 LT, there are strongest convergence at 500 hPa and divergence at 200 hPa. Meanwhile, the largest water vapor is transported to the main body of the Tibetan Plateau, and the stratification is unstable, which are conducive to the strongest convection and condensational latent heat release accompanied with the largest precipitation system. All these conditions are responsible for the maximum occurrence of the TPVs in 18–00 LT. On the contrary, at 06 LT the weakest convergence at 500 hPa and divergence at 200 hPa as well as the stable stratification result in little latent heat release, and the minimum occurrence of the TPVs is observed in 06–12 LT.

Calibration of a convective parameterization scheme in the WRF model and its impact on the simulation of East Asian summer monsoon precipitation

Reasonably modeling the magnitude, south–north gradient and seasonal propagation of precipitation associated with the East Asian summer monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain–Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved. The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years. Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. By using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.

Equatorward shift of the South Asian high in response to anthropogenic forcing

The South Asian high (SAH) is a huge anticyclone in the upper troposphere. It influences the climate and the distribution of trace constituents and pollutants. The present study documents the change in the SAH and precipitation under global warming, as well as the possible link between the changes, based on 17 Coupled Model Intercomparison Project Phase 5 (CMIP5) model simulations. The CMIP5 historical simulation reproduces reasonably the tropospheric circulation (including the SAH), precipitation, and moisture. Under global warming, more than 75 % of the CMIP5 models project a southward shift of the SAH. The southward shift is more significant in the models with stronger anticyclonic circulation in the south part of the climatological SAH. The precipitation response displays a contrasting feature: negative over the southeastern equatorial Indian Ocean (IO) and positive over the tropical northern IO, the Bay of Bengal, and the equatorial western Pacific. The results of a linear baroclinic model (LBM) show that the regional rainfall changes over the Bay of Bengal and the equatorial western Pacific have a main contribution to the southward shift of the SAH. In addition, the precipitation and the surface wind responses over the Indo-Pacific region are well coupled. On one hand, the surface wind anomaly affects the rainfall response through altering the SST and moisture. On the other hand, the condensational heating released by regional rainfall changes sustains the surface wind response.

Modeling method of heat transfer during Vapour Phase Soldering based on filmwise condensation theory

The paper presents a practical method for calculating the heat transfer during Vapour Phase Soldering (VPS) process. VPS is a reflow soldering method based on condensation heating and used in the electronics manufacturing. The presented explicit model describes solutions for filmwise condensation heat transfer based on the Nusselt theory. Different approaches on describing the filmwise condensation were investigated, compared and modified in order to determine a proper heat transfer coefficient for the VPS process – where the heated assembly can be considered as a horizontal plate. For the verification, measurements were done in an experimental soldering oven. The results of the calculations show a proper approximation with the measured temperature data. Finally the results were compared with a solution obtained from complex multi-physics simulation. The results point out, that the application of filmwise condensation model for VPS can be more practical than a complex multi-physics model, from the aspect of calculation error and computation time.