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Latent heat
About: Latent heat is a research topic. Over the lifetime, 13503 publications have been published within this topic receiving 302811 citations.
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TL;DR: Using NASA scatterometer (NSCAT) wind vectors with high spatial resolution of 25 km, the role of the wind field over the Japan Sea in JSPW formation was investigated during the period of winter monsoon.
Abstract: It is known that wintertime air-sea interaction in the Japan Sea, enhanced by outbreaks of dry and cold air masses from the Eurasian continent, generates a characteristic water mass called Japan Sea Proper Water (JSPW) through deep convection. Using NASA scatterometer (NSCAT) wind vectors with high spatial resolution of 25 km, the role of the wind field over the Japan Sea in JSPW formation was investigated during the period of winter monsoon. It is revealed by NSCAT observations that the wintertime surface winds over the Japan Sea are strongly influenced by the upstream topography of the coastal region of the Eurasian continent. A strong wind area appears off Vladivostok, both in the snapshot and the monthly mean wind fields. The dynamics behind this strong wind flow may be attributed to the highly stratified surface wind being blocked by the coastal mountains and exiting through the narrow valley near Vladivostok into the Japan Sea. The NSCAT winds are coupled with European Centre for Medium-Range Weather Forecasts air temperature and humidity and Japan Meteorological Agency sea surface temperature (SST) data for turbulent flux estimation. Monthly mean wind speed, momentum flux, sensible heat flux, latent heat flux, and evaporation have peak values exceeding 9 m s -1 , 0.275 N m -2 , 170 W m -2 , 130 W m -2 , and 120 mm, respectively, in the strong wind area, which has a diameter of about 150 km. Multichannel sea surface temperature (MCSST) images of the Japan Sea for late January 1997 show that the cold SST (∼0°C) area extends from the coastal region to the outer sea off Vladivostok. The MCSSTs decreased by 1°C for January in this region. The cold SST region coincides with the strong wind area, and both locations agree well with the JSPW formation region, which, according to Sudo [1986], is north of 41°N between 132° and 134°E. The spatial agreement strongly suggests that the wind, enhanced by the topographic effect around Vladivostok, causes the large turbulent heat flux and evaporation in this area, which generates the coldest SST and dense water mass, i.e., JSPW. This may be a process of coastal topography-air-sea interaction that leads to deep-sea water formation in the Japan Sea. Because of the concentrated feature of turbulent fluxes and the inferred relation to the center of deep convection phenomenon, the strong wind area is called the flux center in this study.
110 citations
TL;DR: In this article, a two-leaf canopy model for predicting fluxes of net radiation, sensible heat, latent heat and CO2 between plant canopies and the atmosphere was tested against 228 half-hourly micrometeorological flux measurements spanning over two months during the vegetative growth of two wheat crops.
110 citations
01 Jan 1993
TL;DR: Kunkel et al. as discussed by the authors examined the effect of krypton density corrections on water vapor fluxes due to the flux of sensible heat in terms of the Bowen ratio and found that the correction due to latent heat is proportional only to the mole fraction of water vapor and is 5 times smaller than that for the sensible heat.
Abstract: The magnitude of the of the Webb et al. (1980) density corrections on water vapor fluxes due to the flux of sensible heat is examined in terms of the Bowen ratio. The correction due to latent heat is proportional only to the mole fraction of water vapor and is 5 times smaller than that for the sensible heat. The temperature regime within the path of the krypton hygrometer was measured to determine its effect in the Webb et al. (1980) corrections and the krypton O 2 absorption corrections. The results of this experiment are inconclusive, but confirm the need for additional measurements. Two methods for determining water vapor from krypton hygrometer measurements are reexamined. An approximate method endorsed by the manufacturer and having errors of less than 3 percent for fluctuation smaller than 2 gm -3 is shown to underestimate the vapor flux by 14% under specific conditions of light winds and irrigated surfaces in arid regions (K. Kunkel, 1992, personal communication).
110 citations
TL;DR: In this paper, the role of the radiation balance in driving the sensible and latent heat fluxes on a daily and seasonal basis, quantify magnitudes and rates of the LH fluxes and evaporation, and present a comprehensive picture of the seasonal and interannual thermal and energy regimes, their variability, and their most important controls.
Abstract: This paper addresses interannual and seasonal variability in the thermal regime and surface energy fluxes in central Great Slave Lake during three contiguous open-water periods, two of which overlap the Canadian Global Energy and Water Cycle Experiment (GEWEX) Enhanced Study (CAGES) water year. The specific objectives are to compare the air temperature regime in the midlake to coastal zones, detail patterns of air and water temperatures and atmospheric stability in the central lake, assess the role of the radiation balance in driving the sensible and latent heat fluxes on a daily and seasonal basis, quantify magnitudes and rates of the sensible and latent heat fluxes and evaporation, and present a comprehensive picture of the seasonal and interannual thermal and energy regimes, their variability, and their most important controls. Atmospheric and lake thermal regimes are closely linked. Temperature differences between midlake and the northern shore follow a seasonal linear change from 68C colder midlake in June, to 68C warmer in November‐December. These differences are a response to the surface energy budget of the lake. The surface radiation balance, and sensible and latent heat fluxes are not related on a day-to-day basis. Rather, from final lake ice melt in mid-June through to mid- to late August, the surface waters strongly absorb solar radiation. A stable atmosphere dominates this period, the latent heat flux is small and directed upward, and the sensible heat flux is small and directed downward into the lake. During this period, the net solar radiation is largely used in heating the lake. From mid- to late August to freeze up in December to early January, the absorbed solar radiation is small, the atmosphere over the lake becomes increasingly unstable, and the sensible and latent heat fluxes are directed into the atmosphere and grow in magnitude into the winter season. Comparing the period of stable atmospheric conditions with the period of unstable conditions, net radiation is 6 times larger during the period of stable atmosphere and the combined latent and sensible heat fluxes are 9 times larger during the unstable period. From 85% to 90% of total evaporation occurs after mid-August, and evaporation rates increase continuously as the season progresses. This rate of increase varies from year to year. The time of final ice melt exerts the largest single control on the seasonal thermal and energy regimes of this large northern lake.
109 citations
TL;DR: In this article, a method of thermal characterization of buildings materials including micro-encapsulated phase change materials (PCMs) incorporated into cement-mortars from simultaneous heat flux and temperature measurements is presented.
109 citations