Turbulence Measurements in a Young Cyclone Over the Ocean1

1957 ◽  
Vol 38 (1.1) ◽  
pp. 13-16 ◽  
Author(s):  
Andrew F. Bunker
Keyword(s):  
Heat Flow ◽  
Transition Zone ◽  
Thermal Structure ◽  
Air Mass ◽  
Cold Air ◽  
Turbulence Measurements ◽  
Heat Flows ◽  
Low Level ◽  
Strong Turbulence ◽  
Warm Sector

A flight was made through a young coastal storm with a PBY-6A aircraft equipped to measure both mean temperatures and rapid variations of the temperature and turbulent gust velocities. Low level observations were obtained which show the thermal structure of the cyclone and the magnitude of the turbulence, the shearing stresses and the heat flows. Particularly strong turbulence was noted in the transition zone between the cool air of the anticyclone and the faster moving air of the warm sector. Stable air and downward heat flow was observed in the cold air mass.

scholarly journals The role of nocturnal Low-Level-Jet in nocturnal convection and rainfalls in the west Mediterranean coast: the episode of 14 December 2010 in northeast of Iberian Peninsula

2012 ◽  
Vol 8 (1) ◽  
pp. 27-31 ◽  
Author(s):  
J. Mazón ◽  
D. Pino
Keyword(s):  
Iberian Peninsula ◽  
Mesoscale Model ◽  
Return Flow ◽  
Inertial Oscillation ◽  
Air Mass ◽  
Cold Air ◽  
Low Level ◽  
Radar Images ◽  
Synoptic Wind ◽  
Low Level Jet

Abstract. The night of 14 December 2010 radar images of the Spanish Weather Agency recorded a large rain band that moved offshore at the Northeast coast of the Iberian Peninsula. MM5 mesoscale model is used to study the atmospheric dynamics during that day. A Nocturnal Low Level Jet (NLLJ) generated by an inertial oscillation that brings cold air to the coast from inland has been simulated in the area. This cold air interacts with a warmer air mass some kilometers offshore. According to the MM5 mesoscale model simulation, the cold air enhances upward movements of the warm air producing condensation. Additionally, there is a return flow to the coastline at 600–900 m high. This warm air mass interacts again with the cold air moving downslope, also producing condensation inland. The simulation for the night before this episode shows large drainage winds with a NLLJ profile, but no condensation areas. The night after the 14th the simulation also shows drainage winds but without a NLLJ profile. However, an offshore convergence area was produced with a returned flow, but no condensation inland occurred. This fact is in agreement with radar observations which reported no precipitation for these two days. Consequently, NLLJ in combination with a synoptic wind over the sea could enhance condensation and eventually precipitation rates in the Mediterranean Iberian coast.

scholarly journals Budgets of rotational and divergent kinetic energy in the warm-sector torrential rains over South China: a case study

2021 ◽  
Author(s):  
Shui-Xin Zhong ◽  
Wei-Guang Meng ◽  
Fu-You Tian
Keyword(s):  
Kinetic Energy ◽  
Energy Budget ◽  
South China ◽  
Extreme Precipitation ◽  
Flux Divergence ◽  
Low Level ◽  
Warm Sector ◽  
Kinetic Energy Budget ◽  
Rotational Components ◽  
The Pearl River

AbstractThe contributions of divergent and rotational wind components to the kinetic energy budget during a record-breaking rainstorm on 7 May 2017 over South China are examined. This warm-sector extreme precipitation caused historical maximum of 382.6 mm accumulated rainfall in 3 h over the Pearl River Delta (PRD) regions in South China. Results show that there was a high low-level southerly wind-speed tongue stretching into the PRD regions from the northeast of the South China Sea (SCS) during this extreme precipitation. The velocity potential exhibited a low-value center as well as a low-level divergence-center over the SCS. The rotational components of the kinetic energy (KR)-related terms were the main contribution-terms of the kinetic energy budget. The main contribution-terms of KR and the divergent component of kinetic energy (KD) were the barotropical and baroclinic processes-related terms due to cross-contour flow and the vertical flux divergence.

scholarly journals A 7-Year Climatology of Warm-Sector Heavy Rainfall over South China during the Pre-Summer Months

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 914
Author(s):  
Tao Chen ◽  
Da-Lin Zhang
Keyword(s):  
South China ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Convective Available Potential Energy ◽  
Potential Temperature ◽  
Vertical Wind Shear ◽  
Precipitable Water ◽  
Atmospheric Parameter ◽  
Low Level ◽  
Warm Sector

In view of the limited predictability of heavy rainfall (HR) events and the limited understanding of the physical mechanisms governing the initiation and organization of the associated mesoscale convective systems (MCSs), a composite analysis of 58 HR events over the warm sector (i.e., far ahead of the surface cold front), referred to as WSHR events, over South China during the months of April to June 2008~2014 is performed in terms of precipitation, large-scale circulations, pre-storm environmental conditions, and MCS types. Results show that the large-scale circulations of the WSHR events can be categorized into pre-frontal, southwesterly warm and moist ascending airflow, and low-level vortex types, with higher frequency occurrences of the former two types. Their pre-storm environments are characterized by a deep moist layer with >50 mm column-integrated precipitable water, high convective available potential energy with the equivalent potential temperature of ≥340 K at 850 hPa, weak vertical wind shear below 400 hPa, and a low-level jet near 925 hPa with weak warm advection, based on atmospheric parameter composite. Three classes of the corresponding MCSs, exhibiting peak convective activity in the afternoon and the early morning hours, can be identified as linear-shaped, a leading convective line adjoined with trailing stratiform rainfall, and comma-shaped, respectively. It is found that many linear-shaped MCSs in coastal regions are triggered by local topography, enhanced by sea breezes, whereas the latter two classes of MCSs experience isentropic lifting in the southwesterly warm and moist flows. They all develop in large-scale environments with favorable quasi-geostrophic forcing, albeit weak. Conceptual models are finally developed to facilitate our understanding and prediction of the WSHR events over South China.

scholarly journals Present-day geothermal regime of the Uliastai Depression, Erlian Basin, North China

2018 ◽  
Vol 37 (2) ◽  
pp. 770-786 ◽  
Author(s):  
Wei Xu ◽  
Shaopeng Huang ◽  
Jiong Zhang ◽  
Ruyang Yu ◽  
Yinhui Zuo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Structure ◽  
Rheological Characteristic ◽  
Rheological Parameter ◽  
Lithospheric Thickness ◽  
Terrestrial Heat Flow ◽  
Geothermal Regime ◽  
Mantle Heat Flow ◽  
Erlian Basin

In this study, we calculated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin by using systematical steady-state temperature data obtained from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes. Then, we calculated the lithospheric thermal structure, thermal lithospheric thickness, and lithospheric thermo-rheological structure by combining crustal structure, thermal conductivity, heat production, and rheological parameter data. Research from the Depression shows that the present-day terrestrial heat flow ( qs) is 86.3 ± 2.3 mW/m2, higher than the average of 60.4 ± 12.3 mW/m2 of the continental area of China. Mantle heat flow ( qm) in the Depression ranges from 33.7 to 39.3 mW/m2, qm/ qs ranges from 40 to 44%, show that the crust plays the dominant position in the terrestrial heat flow. The thermal thickness of the lithosphere is about 74–88 km and characterized by a “strong crust–weak mantle” rheological characteristic. The total lithospheric strength is 1.5 × 1012 N/m under wet mantle conditions. Present-day geothermal regime indicates that the Uliastai Depression has a high thermal background, the activity of the deep-seated lithosphere is relatively intense. This result differs significantly from the earlier understanding that the area belongs to a cold basin. However, a hot basin should be better consistent with the evidences from lithochemistry and geophysical observations. The results also show the melts/fluids in the study area may be related to the subduction of the Paleo-Asian Ocean. The study of the geothermal regime in the Uliastai Depression provides new geothermal evidence for the volcanic activity in the eastern part of the Central Asian Orogenic Belt and has significant implications for the geodynamic characteristics.

An air mass-derived cool season climatology of synoptically forced Appalachian cold-air damming

2017 ◽  
Vol 38 (2) ◽  
pp. 530-542 ◽  
Author(s):  
Andrew W. Ellis ◽  
Michael L. Marston ◽  
Daniel A. Nelson
Keyword(s):  
Cool Season ◽  
Air Mass ◽  
Cold Air

scholarly journals Processes contributing to cloud dissipation and formation events on the North Slope of Alaska

2021 ◽  
Vol 21 (5) ◽  
pp. 4149-4167
Author(s):  
Joseph Sedlar ◽  
Adele Igel ◽  
Hagen Telg
Keyword(s):  
Cloud Formation ◽  
North Slope ◽  
Near Surface ◽  
Air Mass ◽  
Low Level ◽  
Clear Sky ◽  
The North ◽  
Synoptic Conditions ◽  
North Slope Of Alaska ◽  
Low Cloud

Abstract. Clear-sky periods across the high latitudes have profound impacts on the surface energy budget and lower atmospheric stratification; however an understanding of the atmospheric processes leading to low-level cloud dissipation and formation events is limited. A method to identify clear periods at Utqiaġvik (formerly Barrow), Alaska, during a 5-year period (2014–2018) is developed. A suite of remote sensing and in situ measurements from the high-latitude observatory are analyzed; we focus on comparing and contrasting atmospheric properties during low-level (below 2 km) cloud dissipation and formation events to understand the processes controlling clear-sky periods. Vertical profiles of lidar backscatter suggest that aerosol presence across the lower atmosphere is relatively invariant during the periods bookending clear conditions, which suggests that a sparsity of aerosol is not frequently a cause for cloud dissipation on the North Slope of Alaska. Further, meteorological analysis indicates two active processes ongoing that appear to support the formation of low clouds after a clear-sky period: namely, horizontal advection, which was dominant in winter and early spring, and quiescent air mass modification, which was dominant in the summer. During summer, the dominant mode of cloud formation is a low cloud or fog layer developing near the surface. This low cloud formation is driven largely by air mass modification under relatively quiescent synoptic conditions. Near-surface aerosol particles concentrations changed by a factor of 2 around summer formation events. Thermodynamic adjustment and increased aerosol presence under quiescent atmospheric conditions are hypothesized as important mechanisms for fog formation.

scholarly journals Heat Flow, Geotherms, Density and Lithosphere Thickness in SW of Iberia (South of Portugal)

2018 ◽  
Vol 1 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Maria Rosa Alves Duque
Keyword(s):  
Heat Flow ◽  
Thermal Structure ◽  
Average Density ◽  
Ore Deposits ◽  
Flow Density ◽  
The South ◽  
Lithosphere Thickness ◽  
Structure Density ◽  
Using Data ◽  
Lateral Variations

Thermal structure, density distribution and lithosphere thickness in the SW part of the Iberian Peninsula are studied using data obtained in the South Portuguese Zone (SPZ) and SW border of the Ossa Morena Zone (OMZ) in the South of Portugal. Five different regions were defined, and models were built for each region. Geotherms were obtained using average density values from data published. The high values of heat flow density in these regions are attributed to occurrence of anomalous heat sources due to radioactivity content and exothermic chemical reactions associated to ore deposits in the zone. The results obtained with models based on isostasy in the region led to lithosphere thickness values between 95 and 96 km in the SPZ and a lower value of 94.5 km in the SW border of the OMZ. Analysis of geotherms shows lateral variations of temperature at the same depth. These lateral variations are compared with information obtained with seismic data.

scholarly journals Heat flow distribution and thermal structure of the Nankai subduction zone off the Kii Peninsula

2011 ◽  
Vol 12 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Hideki Hamamoto ◽  
Makoto Yamano ◽  
Shusaku Goto ◽  
Masataka Kinoshita ◽  
Keiko Fujino ◽  
...  
Keyword(s):  
Heat Flow ◽  
Subduction Zone ◽  
Thermal Structure ◽  
Flow Distribution ◽  
Kii Peninsula ◽  
Nankai Subduction Zone

scholarly journals Surface heat flow and lithosphere thermal structure of the Rhenohercynian Zone in the greater Luxembourg region

Geothermics ◽  
2015 ◽  
Vol 56 ◽  
pp. 93-109 ◽  
Author(s):  
Tom Schintgen ◽  
Andrea Förster ◽  
Hans-Jürgen Förster ◽  
Ben Norden
Keyword(s):  
Heat Flow ◽  
Thermal Structure ◽  
Surface Heat ◽  
Surface Heat Flow ◽  
Rhenohercynian Zone

scholarly journals Adjoint inversion of the thermal structure of Southeastern Australia

2019 ◽  
Vol 219 (3) ◽  
pp. 1648-1659 ◽  
Author(s):  
B Mather ◽  
L Moresi ◽  
P Rayner
Keyword(s):  
Thermal Properties ◽  
Heat Flow ◽  
Heat Production ◽  
Thermal Structure ◽  
Surface Heat ◽  
Flow Data ◽  
Data Set ◽  
Surface Heat Flow ◽  
Southeastern Australia ◽  
Curie Depth

SUMMARY The variation of temperature in the crust is difficult to quantify due to the sparsity of surface heat flow observations and lack of measurements on the thermal properties of rocks at depth. We examine the degree to which the thermal structure of the crust can be constrained from the Curie depth and surface heat flow data in Southeastern Australia. We cast the inverse problem of heat conduction within a Bayesian framework and derive its adjoint so that we can efficiently find the optimal model that best reproduces the data and prior information on the thermal properties of the crust. Efficiency gains obtained from the adjoint method facilitate a detailed exploration of thermal structure in SE Australia, where we predict high temperatures within Precambrian rocks of 650 °C due to relatively high rates of heat production (0.9–1.4 μW m−3). In contrast, temperatures within dominantly Phanerozoic crust reach only 520 °C at the Moho due to the low rates of heat production in Cambrian mafic volcanics. A combination of the Curie depth and heat flow data is required to constrain the uncertainty of lower crustal temperatures to ±73 °C. We also show that parts of the crust are unconstrained if either data set is omitted from the inversion.

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