scholarly journals Urban-Induced Changes on Local Circulation in Complex Terrain: Central Mexico Basin

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 904
Author(s):  
Lourdes P. Aquino-Martínez ◽  
Arturo I. Quintanar ◽  
Carlos A. Ochoa-Moya ◽  
Erika Danaé López-Espinoza ◽  
David K. Adams ◽  
...  
Keyword(s):  
Large Scale ◽  
Meridional Circulation ◽  
Circulation Pattern ◽  
Heat Fluxes ◽  
Local Circulation ◽  
Pressure System ◽  
Near Surface ◽  
Zonal Circulation ◽  
Downslope Wind ◽  
Mexico Basin

Land use land cover (LULC) significantly impacts local circulation in the Mexico Basin, particularly wind field circulations such as gap winds, convergence lines, and thermally induced upslope/downslope wind. A case study with a high-pressure system over the Mexico Basin isolates the influence of large-scale synoptic forcing. Numerical simulations reveal a wind system composed of meridional circulation and a zonal component. Thermal pressure gradients between the Mexico basin and its colder surroundings create near-surface convergence lines as part of the meridional circulation. Experiments show that the intensity and organization of meridional circulations and downslope winds increase when LULC changes from natural and cultivated land to urban. Zonal circulation exhibits a typical circulation pattern with the upslope flow and descending motion in the middle of the basin. Large values of moist static energy are near the surface where air parcels pick up energy from the surface either as fluxes of enthalpy or latent heat. Surface heat fluxes and stored energy in the ground are drivers of local circulation, which is more evident in zonal circulation patterns.

scholarly journals Local climate, circulation and surface-energy balance of an Antarctic blue-ice area

1994 ◽  
Vol 20 ◽  
pp. 160-168 ◽  
Author(s):  
R. Bintanja ◽  
M. R. van den Broeke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Weddell Sea ◽  
Wave Radiation ◽  
Local Circulation ◽  
Night Time ◽  
Pressure System ◽  
Continental Scale

Results of measurements performed on and around an Antarctic blue-ice field are presented in this paper. The measurements were carried out in a valley of Heimefrontfjella, Dronning Maud Land, during a 2 month field season in the austral summer of 1992–93. A simple model is used to evaluate the surface-energy balance from measured meteorological quantities. The large differences in the surface-energy-balance values between snow and blue ice are mainly caused by differences inalbedo, surface roughness, thermal conductivity and short-wave radiation extinction coefficient. Taking into account uncertainties in the calculations, it appears that the calculated sublimation rates over ice and snow do not differ much.Furthermore, typical circulation patterns are described. The large continental-scale katabatic flow is forced by radiative cooling of the surface (night-time) and the mesoscale horizontal temperature gradient (daytime). The latter penetrates to the surface due to enhanced mixing in an unstable stratified boundary layer. At night, shallow katabatic layers form along local fall lines. On some occasions the large-scale katabatic winds decrease through the presence of a high-pressure system in the weddell Sea and a local circulation can develop inside the valley.

scholarly journals Potential climatic impacts and reliability of very large-scale wind farms

2010 ◽  
Vol 10 (4) ◽  
pp. 2053-2061 ◽  
Author(s):  
C. Wang ◽  
R. G. Prinn
Keyword(s):  
Wind Power ◽  
Wind Turbines ◽  
Energy Demand ◽  
Large Scale ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Surface Cooling ◽  
Long Distance ◽  
Near Surface

Abstract. Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled substantial interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability, including backup generation capacity, very long distance power transmission lines, and onsite energy storage, each with specific economic and/or technological challenges.

scholarly journals The Okhotsk-Japan Circulation Pattern and the Heavy Rainfall in Beijing in 2012 Summer

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yafei Wang ◽  
Jianzhao Qin ◽  
Lijuan Zhu
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Circulation Pattern ◽  
Northern China ◽  
Reanalysis Data ◽  
Heavy Rainfall Event ◽  
Baikal Lake ◽  
Ural Mountains ◽  
Pressure System ◽  
Blocking High

Using station precipitation and reanalysis data, we examined the evolution of the large-scale circulations associated with the heavy rainfall event that occurred around July 21, 2012 (721 heavy rainfall). This study focuses on a role that the large-scale circulations named “the Okhotsk-Japan (OKJ) circulation pattern” played in causing the heavy rainfall case. We found that the 721 heavy rainfall occurred under a background of the OKJ circulation that persisted for about 10 days. However, the pattern was different from the normal OKJ circulation, for this circulation pattern accompanied a blocking high between the Ural Mountains and the Baikal Lake. This difference resulted from the seasonal change of the basic flow. The related Rossby wave propagated eastward during the persisting period of the dominated OKJ pattern. This caused the development of a low-pressure system around the Baikal Lake and the weakening of a ridge around the Okhotsk Sea. The slow evolution of the OKJ circulation created a favorable environment for the moisture transport to northern China, assisting in the generation of the 721 heavy rainfall.

scholarly journals Decomposition of Random Errors Inherent to HOAPS-3.2 Near-Surface Humidity Estimates Using Multiple Triple Collocation Analysis

2016 ◽  
Vol 33 (7) ◽  
pp. 1455-1471 ◽  
Author(s):  
Julian Kinzel ◽  
Karsten Fennig ◽  
Marc Schröder ◽  
Axel Andersson ◽  
Karl Bumke ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Large Scale ◽  
Heat Fluxes ◽  
Specific Humidity ◽  
Random Errors ◽  
Bias Analysis ◽  
Data Set ◽  
Near Surface ◽  
Ocean Atmosphere

AbstractLatent heat fluxes (LHF) play an essential role in the global energy budget and are thus important for understanding the climate system. Satellite-based remote sensing permits a large-scale determination of LHF, which, among others, are based on near-surface specific humidity . However, the random retrieval error () remains unknown. Here, a novel approach is presented to quantify the error contributions to pixel-level of the Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data, version 3.2 (HOAPS, version 3.2), dataset. The methodology makes use of multiple triple collocation (MTC) analysis between 1995 and 2008 over the global ice-free oceans. Apart from satellite records, these datasets include selected ship records extracted from the Seewetteramt Hamburg (SWA) archive and the International Comprehensive Ocean–Atmosphere Data Set (ICOADS), serving as the in situ ground reference. The MTC approach permits the derivation of as the sum of model uncertainty and sensor noise , while random uncertainties due to in situ measurement errors () and collocation () are isolated concurrently. Results show an average of 1.1 ± 0.3 g kg−1, whereas the mean () is in the order of 0.5 ± 0.1 g kg−1 (0.5 ± 0.3 g kg−1). Regional analyses indicate a maximum of exceeding 1.5 g kg−1 within humidity regimes of 12–17 g kg−1, associated with the single-parameter, multilinear retrieval applied in HOAPS. Multidimensional bias analysis reveals that global maxima are located off the Arabian Peninsula.

scholarly journals Tropical Transition of the 2001 Australian Duck

2010 ◽  
Vol 138 (6) ◽  
pp. 2038-2057 ◽  
Author(s):  
Luke Andrew Garde ◽  
Alexandre Bernardes Pezza ◽  
John Arthur Tristram Bye
Keyword(s):  
Potential Vorticity ◽  
Large Scale ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
Heat Fluxes ◽  
Pressure System ◽  
Surface Heat Fluxes ◽  
Warm Core ◽  
Tasman Sea ◽  
Upper Level

Abstract In March 2001, a hybrid low pressure system, unofficially referred to as Donald (or the Duck), developed in the Tasman Sea under tropical–extratropical influence, making landfall on the southeastern Australian coast. Here, it is shown that atmospheric blocking in the Tasman Sea produced a split in the subtropical jet, allowing persistent weak vertical wind shear to manifest in the vicinity of the developing low. It is hypothesized that this occurred through sustained injections of potential vorticity originating from higher latitudes. Hours before landfall near Byron Bay, the system developed an eye with a short-lived warm core at 500 hPa. Cyclone tracking revealed an erratic track before the system decayed and produced heavy rains and flash flooding. A three-dimensional air parcel backward-trajectory scheme showed that the air parcels arriving in the vicinity of the mature cyclone originated from tropical sources at lower levels and from the far extratropics at higher levels, confirming the hybrid characteristics of this cyclone. A high-resolution (0.15°) nested simulation showed that recent improvements in the assimilation scheme used by the Australian models allowed for accurately simulating the system’s trajectory and landfall, which was not possible at the time of the event. Compared to the first South Atlantic hurricane of March 2004, the large-scale precursors were similar; however, the Duck was exposed to injections of upper-level potential vorticity and favorable surface heat fluxes for a shorter period of time, resulting in it achieving partial tropical transition only hours prior to landfall.

scholarly journals Local climate, circulation and surface-energy balance of an Antarctic blue-ice area

1994 ◽  
Vol 20 ◽  
pp. 160-168
Author(s):  
R. Bintanja ◽  
M. R. van den Broeke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Weddell Sea ◽  
Wave Radiation ◽  
Local Circulation ◽  
Night Time ◽  
Pressure System ◽  
Continental Scale

Results of measurements performed on and around an Antarctic blue-ice field are presented in this paper. The measurements were carried out in a valley of Heimefrontfjella, Dronning Maud Land, during a 2 month field season in the austral summer of 1992–93. A simple model is used to evaluate the surface-energy balance from measured meteorological quantities. The large differences in the surface-energy-balance values between snow and blue ice are mainly caused by differences inalbedo, surface roughness, thermal conductivity and short-wave radiation extinction coefficient. Taking into account uncertainties in the calculations, it appears that the calculated sublimation rates over ice and snow do not differ much.Furthermore, typical circulation patterns are described. The large continental-scale katabatic flow is forced by radiative cooling of the surface (night-time) and the mesoscale horizontal temperature gradient (daytime). The latter penetrates to the surface due to enhanced mixing in an unstable stratified boundary layer. At night, shallow katabatic layers form along local fall lines. On some occasions the large-scale katabatic winds decrease through the presence of a high-pressure system in the weddell Sea and a local circulation can develop inside the valley.

scholarly journals Potential climatic impacts and reliability of very large-scale wind farms

2009 ◽  
Vol 9 (5) ◽  
pp. 19081-19102 ◽  
Author(s):  
C. Wang ◽  
R. G. Prinn
Keyword(s):  
Wind Power ◽  
Wind Turbines ◽  
Large Scale ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Surface Cooling ◽  
Long Distance ◽  
Near Surface ◽  
Legitimate Interest

Abstract. Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled legitimate interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1°C over land installations. In contrast, surface cooling exceeding 1°C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability, including backup generation capacity, very long distance power transmission lines, and onsite energy storage, each with specific economic and/or technological challenges.

scholarly journals Structure of the Western Tibetan Vortex inconsistent with a thermally-direct circulation

2021 ◽  
Author(s):  
Xiao-Feng Li ◽  
Jingjing Yu ◽  
Shaofeng Liu ◽  
Jingzhi Wang ◽  
Lei Wang
Keyword(s):  
Large Scale ◽  
Surface Air Temperature ◽  
Circulation Model ◽  
Circulation Pattern ◽  
Net Radiation ◽  
Near Surface ◽  
Radiative Balance ◽  
Air Temperatures ◽  
Western Tibetan Plateau ◽  
Global Atmospheric Circulation

AbstractThe Western Tibetan Vortex (WTV) is a large-scale circulation pattern identified from year-to-year circulation variability, which was used to understand the causal mechanisms for slowdown of the glacier melting over the western Tibetan Plateau (TP). A recent argument has suggested the WTV is the set of wind field anomalies resulting from variability in near-surface air temperatures over the western TP (above 1500 m), which, in turn, is likely driven by the surface net radiation. This study thereby evaluates the above putative thermal-direct mechanism. By conducting numerical sensitivity experiments using a global atmospheric circulation model, SAMIL, we find a WTV-like structure cannot be generated from a surface thermal forcing imposed on the western TP. A thermally-direct circulation generated by the surface or near surface heating is expect to cause upward motions and a baroclinic structure above it. In contrast, downward motions and a quasi-barotropic are observed in the vertical structure of the WTV. Besides, we find variability of the surface net radiation (sum of the surface shortwave and longwave net radiation) over the western TP can be traced back to the WTV variability based on ERA5 data. The anticyclonic (cyclonic) WTV reduces (increases) the cloudiness through the anomalous downward (upward) motions, causes more (less) input shortwave net radiation and thereby more (less) surface net radiations, resulting in the warmer (cooler) surface and near-surface air temperature over the western TP. The argument is constructive in encouraging examination of the radiative balance processes that complements previous studies.

scholarly journals Sensitivity of the regional European boreal climate to changes in surface properties resulting from structural vegetation perturbations

2015 ◽  
Vol 12 (10) ◽  
pp. 3071-3087 ◽  
Author(s):  
J. H. Rydsaa ◽  
F. Stordal ◽  
L. M. Tallaksen
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Structural Changes ◽  
Mixed Forest ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Energy Partitioning ◽  
The Arctic ◽  
Surface Model ◽  
Near Surface

Abstract. Amplified warming at high latitudes over the past few decades has led to changes in the boreal and Arctic climate system such as structural changes in high-latitude ecosystems and soil moisture properties. These changes trigger land–atmosphere feedbacks through altered energy partitioning in response to changes in albedo and surface water fluxes. Local-scale changes in the Arctic and boreal zones may propagate to affect large-scale climatic features. In this study, MODIS land surface data are used with the Weather Research and Forecasting model (WRF V3.5.1) and Noah land surface model (LSM), in a series of experiments to investigate the sensitivity of the overlying atmosphere to perturbations in the structural vegetation in the northern European boreal ecosystem. Emphasis is placed on surface energy partitioning and near-surface atmospheric variables, and their response to observed and anticipated land cover changes. We find that perturbations simulating northward migration of evergreen needleleaf forest into tundra regions cause an increase in latent rather than sensible heat fluxes during the summer season. Shrub expansion in tundra areas has only small effects on surface fluxes. Perturbations simulating the northward migration of mixed forest across the present southern border of the boreal forest, have largely opposite effects on the summer latent heat flux, i.e., they lead to a decrease and act to moderate the overall mean regional effects of structural vegetation changes on the near-surface atmosphere.

scholarly journals Evaluation of the near-surface evolution of Foehn events in COSMO-1

2021 ◽  
Author(s):  
Yue Tian ◽  
Juerg Schmidli ◽  
Julian Quimbayo-Duarte
Keyword(s):  
Land Surface ◽  
Monitoring Network ◽  
Automatic Monitoring ◽  
Bare Soil ◽  
Heat Fluxes ◽  
Grid Spacing ◽  
Surface Evolution ◽  
Near Surface ◽  
Model Biases ◽  
Downslope Wind

<p>Foehn is a downslope wind with a large impact on society due to its gusty nature and the associated high-temperature extremes. It is influenced by and interacts with near-surface processes, such as the cold air pool (CAP), an important phenomenon that is often present in the foehn valleys during the cold season. Therefore, it is challenging to accurately forecast the foehn characteristics, in terms of the onset, strength, and decay as the near-surface evolution is the result of multi-scale interactions between the larger atmosphere and the mountain/local valley topography. From a meso-/micro-scale perspective, this study investigates the skill of the COSMO model (v5.7) at 1.1 km grid spacing in simulating the near-surface foehn evolution for a set of south foehn events, representative of different foehn types around the Alps. The evaluation is based on a comparison to station data from the automatic monitoring network of MeteoSwiss, with a focus on the Rhine Valley. Significant cold and moist biases are found in the model during foehn hours in all the chosen cases. Biases in Foehn duration and spatial extent are also studied. The sensitivity of these biases to several land-surface parameterization choices, e.g., skin layer, bare soil evaporation, and resistance for heat fluxes, are investigated and presented. Simulations for the same foehn events with COSMO at 500 m grid spacing are also evaluated for a better understanding of the model biases. Further studies from the perspective of climatological statistics are needed to establish the relationships between model biases and foehn types.</p>

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