Microscale-Meteorology-Presentation.pdf

Microscale Meteorology Group Presentation by: Adlaon, Cominador, Dali-on, Pilapil, & Ruiz Microscale meteorology Microscale meteorology is a fascinating branch of atmospheric science that focuses on the study of atmospheric phenomena on the smallest spatial and temporal scales. This field de...

Microscale Meteorology Group Presentation by: Adlaon, Cominador, Dali-on, Pilapil, & Ruiz Microscale meteorology Microscale meteorology is a fascinating branch of atmospheric science that focuses on the study of atmospheric phenomena on the smallest spatial and temporal scales. This field delves into the intricate processes occurring within the atmospheric boundary layer, the lowest part of the atmosphere that directly interacts with the Earth's surface.  The atmospheric boundary layer (ABL) is the lowest part of the Earth's atmosphere, directly influenced by its interaction with the surface. This layer typically extends from the ground up to about 1 to 2 kilometers, although its thickness can vary widely depending on the time of day, weather conditions, and geographic location. The atmospheric boundary layer (ABL) is a crucial component of the Earth's atmosphere, characterized by its direct interaction with the Earth's surface. Its structure and characteristics are essential for comprehending various weather phenomena and climate processes. 1. Surface Layer: Lowest part of the ABL, up to 10% of its height, where surface effects are strongest. Mixed Layer (Convective Boundary Layer): Above the surface layer; during the day, it's well-mixed due to solar heating. Residual Layer: Remains from the previous day's mixed layer, above the nocturnal boundary layer at night. Stable Boundary Layer (Nocturnal Boundary Layer): Forms at night with surface cooling, leading to a temperature inversion and less turbulence. Daytime: Solar heating causes vertical mixing and the formation of the convective boundary layer. Nighttime: Surface cooling leads to a stable boundary layer with reduced turbulence. Turbulence: Driven by wind shear and thermal buoyancy, enhancing the mixing of heat, moisture, and momentum. Eddies: Swirling motions of varying sizes that aid in the transport of atmospheric properties. Roughness: Surface features affect wind flow and turbulence in the ABL. Heat and Moisture Fluxes: Surface exchanges impact ABL characteristics, such as increased moisture from wet surfaces. Weather Phenomena: The ABL affects local weather events like fog and thunderstorms. Climate Modeling: Essential for accurate climate models, impacting energy and matter transfer between the surface and atmosphere.  Diurnal Cycle of the Atmospheric Boundary Layer (ABL) 1. E ar l y M or ni n g (Sunr i se) o Sur face H eat ing B egin s: Sol ar radiation warms the E arth's surface. o F or m at ion of t h e C on vect ive B ou n dar y L ayer (C B L ): R ising warm air starts creating convecti ve turbul ence. 2. M i d-M or n i ng t o A ft er noon (D ayt i m e) o D ev el opm en t of t h e M ixed L ayer : C ontinuous heati ng l eads to a wel l -dev el oped mi xed l ay er wi th strong v ertical mixi ng. o I ncr eased T u r bu l en ce: Peak turbul ence due to thermal buoyancy and wi nd shear, l eading to uniform properties wi thi n the l ayer. o R i si ng B oun dar y L ay er H ei gh t: A B L hei ght i ncreases, reaching i ts max imum by mid to l ate afternoon. 3. L at e A ft er noon t o E ar l y E v eni n g (Sunset) o D ecr easin g Sol ar R adi ati on : Surface heati ng di mi nishes as the sun sets. o T r ansit ion to t he Stabl e B oun dar y L ay er : M ix ed l ayer decays, turbul ence decreases, and a stabl e boundary l ay er forms.  Diurnal Cycle of the Atmospheric Boundary Layer (ABL) 4. N i gh t ti m e (N octu r nal P er i od) o D evelopm en t of t h e N oct u r n al B ou ndar y L ayer (N B L ): C haracterized by a temperature i nversi on and reduced turbul ence. o R esi du al L ayer : A bove the stabl e l ayer, remnants of the dayti me mi x ed l ayer persi st wi th weak turbul ence. 5. E ar l y M or n i n g (Pr e-dawn ) o C ol dest T emper atu r es: Surface i s cool est j ust before sunrise wi th the strongest temperature i nversi on. o P oten t i al for F og an d D ew F or mat i on : C ool i ng may l ead to fog and dew i f the ai r i s moi st. 1. R adi ativ e H eati ng and C ool i n g o D aytime: Sol ar radi ation heats the surface, driv ing the formation of the conv ective boundary l ayer (C B L ). o N i gh ttime: R adi ativ e cool ing of the surface l eads to the devel opment of a stabl e boundary l ayer (SB L ) wi th reduced turbul ence. 2. T u r bu l en ce an d M i xi ng o D aytime: H eating generates turbul ence and strong vertical mix ing. o N i gh ttime: C ool ing reduces turbul ence, l eadi ng to a more stabl e atmosphere. 3. Su r face F l u xes o H eat, M oistu r e, an d M om en tu m E xch an ges: C ruci al for A B L dynamics, infl uenci ng temperature, moisture, and wi nd patterns. K ey Pr ocesses D u r i n g th e D i u r n al C ycl e W eath er P r edi cti on : A ffects l ocal weather condi ti ons, such as temperature changes, wi nd patterns, and fog or frost li keli hood. C l i mat e Stu dies: E ssenti al for cli mate model ing and predi cting l ong-term changes. E n v ir onm en tal A ppl i cati on s: I mportant for managi ng ai r quali ty , agri culture, and urban planni ng. I mpl i cati on s of t he D i ur n al C ycl e  Key Points on ABL Formation, Evolution, and Impact: 1. Surface Heating and Cooling: Daytime: Solar heating creates thermal buoyancy, forming a convective boundary layer (CBL). Nighttime: Radiative cooling leads to a stable boundary layer (SBL) with a temperature inversion. 2. Turbulence and Mixing: Thermal Buoyancy: Warm air rises, creating convection cells and enhancing vertical mixing. Mechanical Turbulence: Wind shear and surface obstacles increase turbulence.  Key Points on ABL Formation, Evolution, and Impact: 3. Surface Characteristics: Albedo: Affects heat absorption; low albedo surfaces absorb more heat, creating a deeper CBL. Surface Roughness: Influences mechanical turbulence; rougher surfaces create more friction. Moisture Content: Affects boundary layer humidity and energy partitioning. 4. Radiative Processes: Solar Radiation: Drives daytime heating and impacts ABL stability. Radiative Cooling: Causes nighttime inversions and the formation of a stable boundary layer.  Key Points on ABL Formation, Evolution, and Impact: 5. Atmospheric Stability: Lapse Rate: Determines stability; steep lapse rates promote instability, while gentle rates or inversions promote stability. 6. Synoptic-Scale Influences: Weather Systems: High-pressure systems promote stability; low-pressure systems enhance convection. Advection: Brings different thermal and moisture characteristics, altering the ABL. 7. Geographical and Seasonal Variability: Latitude, Season, Topography: Affect ABL characteristics through variations in solar radiation, heating/cooling cycles, and local wind patterns.  Interactions and Feedback Mechanisms D i u r nal C ycl e: T u r bu l ence B oun dar y L ayer Surface heati ng and G ener at i on: H ei ght : cool i ng create dail y T hermal and V ari es wi th heati ng, vari ati ons i n A B L mechanical processes cool i ng, and stabi l ity; structure; heati ng contri bute to i ncreases duri ng the l eads to a turbulence; surface day wi th heati ng and wel l -mi x ed heati ng causes thermal decreases at ni ght w ith convective l ayer, turbulence, whi l e wi nd cool i ng. whi l e cool i ng creates shear creates a stabl e strati fied mechanical turbul ence. l ayer.  Implications for Weather and Climate W eat h er A i r Q u al i t y : C l i m ate M odel in g: P henom en a: Stabi l i ty affects A ccurate I nfl uences cl oud representati on of A B L pol l utant formati on, fog, frost, processes i s cruci al for di spersi on; stabl e and thunderstorms; cl i mate model s, condi ti ons can i mpacti ng energy strong heati ng can l ead to cumul us worsen ai r qual i ty , bal ance, surface cl ouds and storms, whi l e unstabl e temperature, and whi l e cool i ng can atmospheri c condi ti ons i mprov e promote fog. ci rcul ati on. i t. 1.Surface Albedo: 1.Heating/Cooling: Low-albedo surfaces (e.g., forests) absorb more heat, creating a deeper CBL; high-albedo surfaces (e.g., snow) absorb less heat. 2.Surface Roughness: 1.Mechanical Turbulence: Rough surfaces increase turbulence and vertical mixing within the ABL. 3.Soil Moisture and Vegetation: 1.Soil Moisture: Affects evaporation and heat capacity, influencing the ABL's diurnal cycle. 2.Vegetation: Adds moisture and generates additional turbulence, affecting humidity and cloud formation. 4. Urbanization: Urban Heat Island (UHI): Urban areas are warmer, creating a deeper, more turbulent CBL and reduced nighttime cooling. Surface Impermeability: Reduces moisture and evaporation, leading to drier urban ABL conditions. 5.Topography: Elevation and Slope: Affect temperature gradients and create orographic effects influencing cloud formation and precipitation. Local Wind Systems: Topography creates valley and mountain breezes, affecting the ABL’s dynamics. 6. Land-Water Interactions: Coastal Areas: Sea breezes and differing heating rates between land and water affect ABL characteristics. Combined Effects and Feedback Mechanisms: Energy Balance: Surface characteristics impact how energy is partitioned into sensible and latent heat fluxes. Climate and Weather Patterns: Influence local and regional climates, affecting weather events. Feedback Loops: Changes in land surfaces (e.g., deforestation) can impact regional rainfall and climate patterns Note: Understanding these factors is crucial for accurate weather prediction, climate modeling, and environmental management. Key Points on the Atmospheric Boundary Layer (ABL): 1.Weather Prediction: 1.Local Weather: The ABL affects wind patterns, temperature, and humidity, crucial for forecasting wind storms, heatwaves, frost, and fog. 2.Clouds and Precipitation: It influences cloud formation and precipitation, impacting forecasts of thunderstorms and rainfall. 3.Air Quality: The ABL affects pollutant dispersion and urban weather patterns, influencing air quality predictions. Key Points on the Atmospheric Boundary Layer (ABL): 2. Climate Modeling: Energy Exchange: The ABL mediates energy transfer between the surface and atmosphere, affecting global climate patterns. Moisture Transport: It plays a key role in transporting moisture, influencing cloud formation and precipitation. Feedback Mechanisms: The ABL contributes to climate feedbacks and is impacted by land use changes, affecting climate models. Key Points on the Atmospheric Boundary Layer (ABL): 3. Interactions with Larger-Scale Processes: Energy and Moisture: The ABL influences and is influenced by energy exchange and moisture transport, impacting regional and global climate. Turbulence and Mixing: Turbulent mixing in the ABL affects heat and momentum exchange, influencing larger atmospheric dynamics. Synoptic Features: It interacts with weather systems like fronts and convective systems, affecting regional weather patterns. Key Points on the Atmospheric Boundary Layer (ABL): 4. Challenges and Advances: Challenges: Complex processes and limited data make accurate modeling difficult. Advances: High-resolution models and improved observational techniques enhance ABL representation in weather and climate models. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 1. Radiative Processes: Surface Radiation Budget: Clouds and Radiation: The ABL mediates the exchange of Clouds in or near the ABL, such as radiative energy between the Earth's stratocumulus, can affect the energy surface and the atmosphere. During budget by reflecting solar radiation the day, solar radiation heats the and trapping longwave radiation. surface, which then heats the ABL. This influences both local and At night, the surface and ABL cool regional climates by altering surface via longwave radiation, potentially temperatures and energy fluxes. forming temperature inversions. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 2. Moisture Transport Evaporation and Transpiration: Surface Moisture Fluxes: Boundary Layer Moistening: The ABL is essential for Moisture transported from the transporting moisture from the surface can extend upwards surface through evaporation and through convection, impacting transpiration, which contributes to upper layers of the ABL and humidity and supports cloud potentially influencing formation and precipitation. larger-scale weather systems. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 3. Turbulence and Mixing Vertical Mixing: Turbulent Exchange: Entrainment Processes: Turbulent mixing within the ABL Entrainment, or the mixing of facilitates the exchange of heat, air from the free atmosphere moisture, and momentum into the ABL, can affect the between the surface and the ABL's depth and properties, atmosphere. This mixing can impacting cloud development influence stability and dynamics at and boundary layer phenomena. larger scales. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 4. Synoptic and Mesoscale Interactions Fronts and Airmasses: Boundary Layer Modification: Boundary Layer Response: Conversely, the state of the The passage of fronts and air ABL can influence the behavior masses can significantly impact of larger-scale features. For the ABL's temperature and instance, a well-mixed humidity profiles. For example, boundary layer can facilitate air cold fronts can sharply alter ABL mass mixing, while a stable conditions, while warm fronts can layer can sharpen frontal destabilize the boundary layer. boundaries. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 4. Synoptic and Mesoscale Interactions Mesoscale Convective Systems (MCS): Initiation and Maintenance: Outflow Boundaries: The ABL's instability and moisture content are crucial for MCS MCS outflow boundaries can development. Intense precipitation interact with the ABL, triggering and downdrafts from MCS can new convection and creating modify the ABL, influencing local feedback mechanisms that and regional weather patterns. affect weather patterns. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 5. Planetary Boundary Layer (PBL) Dynamics Boundary Layer Depth: Diurnal Variation: Seasonal and Regional Variations: The depth of the ABL changes throughout the day, with a shallower, Seasonal and regional stable layer at night and a deeper, differences in ABL depth and more convective layer during the structure can impact day. These variations affect the larger-scale circulation patterns, interaction between the surface and such as tropical convection and larger atmospheric processes. the Hadley circulation. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 6. Global Climate Systems Monsoons: ABL Influence: The ABL regulates heat and moisture fluxes during monsoon systems. The heating of land and changes in the ABL help establish monsoon circulations, while monsoon rainfall can modify surface properties, influencing the ABL and feedback mechanisms. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 6. Global Climate Systems El Niño-Southern Oscillation (ENSO): Teleconnections: Feedback Loops: ENSO events alter sea surface temperatures and influence the ENSO can create feedback loops ABL’s properties, affecting through alterations in surface regional weather patterns. The energy and moisture fluxes, ABL's response to ENSO events impacting the ABL and broader includes changes in precipitation climate systems. and temperature anomalies. THE INFLUENCE OF THE ABL ON LOCAL WEATHER PHENOMENA 7. Pollution and Aerosols Pollutant Dispersion: Boundary Layer Height: Aerosol Interactions: The height and stability of the ABL Aerosols in the ABL can influence are crucial for pollutant dispersion. radiative processes and cloud A well-mixed ABL can disperse formation, impacting local and pollutants over a larger volume, regional climates. Understanding whereas a stable, shallow ABL can aerosol-ABL interactions is key to lead to high pollutant studying air quality and climate concentrations near the surface. dynamics  Summary The interactions between the ABL and larger-scale atmospheric processes are complex and multifaceted. The ABL affects and is affected by energy exchanges, moisture transport, turbulence, synoptic and mesoscale phenomena, and global climate systems. Understanding these interactions is essential for improving weather forecasts, climate models, and our grasp of the Earth's atmospheric system. Advances in observational techniques and modeling continue to enhance our ability to predict and manage weather and climate impacts influenced by the ABL  Turbulence and its Characteristics 1. Irregular and Chaotic Motion Unpredictability: Turbulent flow is marked by irregular and unpredictable variations in velocity and pressure. Fluctuations: There are rapid and random fluctuations in velocity and pressure at various scales. These fluctuations can be difficult to predict and model due to their complexity. 2. Presence of Eddies and Vortices: Eddies: Turbulent flow is characterized by the presence of swirling motions known as eddies. These can vary in size from large-scale vortices to small, localized swirls. Vortices: Vortices are rotational flow patterns that contribute to the mixing Turbulence and its Characteristics 3.Enhanced Mixing and Transport: Efficient Mixing: Turbulence mixes fluids more effectively than smooth flow, speeding up the transfer of momentum, heat, and mass. Dispersion: Turbulent flow spreads pollutants and substances more rapidly and widely compared to laminar flow. 4. Wide Range of Scales: Large-Scale Eddies: Big swirling vortices in turbulence carry most of the flow’s energy and affect the overall behavior. Small-Scale Eddies: These large eddies break into smaller ones, eventually reaching tiny scales where energy is dissipated due to viscosity. Turbulence and its Characteristics 5. Energy Cascade Process: Transfer of Energy: In turbulence, energy moves from large vortices to smaller ones through interactions and breakdowns. Dissipation: The smallest vortices, at Kolmogorov scales, convert energy into heat due to viscosity. 6. High Reynolds Number: Reynolds Number (Re): This dimensionless number helps determine the flow regime of a fluid. Transition: As the Reynolds number increases and surpasses a critical threshold, flow transitions from smooth (laminar) to turbulent. Turbulence and its Characteristics 7. Complexity and Modelling Challenges: Difficulty in Modelling: Due to its chaotic and irregular nature, turbulence is challenging to model accurately. Nonlinear Interactions: Turbulence involves nonlinear interactions between different scales and components of the flow, further complicating its analysis.  Laminar and Turbulent Flow 1. Flow Characteristics: Laminar Flow: Turbulent Flow: Smooth and Ordered: Fluid moves in Chaotic and Irregular: Fluid motion is parallel layers with minimal mixing. characterized by swirling, unpredictable patterns. Velocity Profile: Parabolic in pipes; Velocity Profile: Flatter in pipes; highest at the center and zero at the higher average velocity near the wall boundary due to viscosity. with increased mixing.  Laminar and Turbulent Flow 2. Reynolds Number: Laminar Flow: Turbulent Flow: Reynolds Number (Re): Occurs at Reynolds Number (Re): Occurs at low Re (Re < 2000), where viscous high Re (Re > 4000), where forces are dominant. inertial forces are dominant.  Laminar and Turbulent Flow 3. Predictability: Laminar Flow: Turbulent Flow: Predictable: Described by simple Unpredictable: Exhibits complex, equations, such as the chaotic behavior making it harder Navier-Stokes equations in their to model. laminar form.  Laminar and Turbulent Flow 4. Energy Dissipation: Laminar Flow: Turbulent Flow: Lower Energy Dissipation: Mainly Higher Energy Dissipation: Due to due to viscosity. the creation and interaction of eddies and vortices  Laminar and Turbulent Flow 5. Mixing and Transport: Laminar Flow: Turbulent Flow: Limited Mixing: Minimal Enhanced Mixing: Greater inter-layer mixing. mixing and more efficient transport of momentum, heat, and pollutants.  Laminar and Turbulent Flow 6. Examples Laminar Flow: Turbulent Flow: Examples: Honey flowing through a thin Examples: Water flowing in a river, air pipe, slow-moving water in a narrow turbulence behind an aircraft wing, channel, or smooth air flow over a or smoke rising from a chimney. streamlined wing at low speeds.  Laminar and Turbulent Flow 7. Visual Appearance: Laminar Flow: Turbulent Flow: Visual Appearance: Smooth and Visual Appearance: Chaotic steady with well-defined with swirling patterns and streamlines. eddies. SCALES OF TURBULENCE AND THEIR SIGNIFICANCE 1. Integral scale refers to the largest scale of turbulence in a flow, typically associated with the size of the largest eddies or vortices 2. Energy Cascade the process by which turbulent kinetic energy is transferred from large eddies (large scales to smaller eddies through a series of interactions and breakdowns. 3. Kolmogorov Scales are the smallest scales of turbulence where viscous effects become significant. SCALES OF TURBULENCE AND THEIR SIGNIFICANCE 4. Taylor Microscale represents a characteristic length scale over which turbulence is still relatively isotropic and homogeneous. 5. Large Eddy Scales refer to the size of the largest turbulent eddies in a flow, which are responsible for most of the turbulence's energy and transport. 6. Intermediate Scales are the scales between the large eddies and the Kolmogorov scales. Summary Points of “THE ENERGY CASCADE PROCESS IN TURBULENT FLOWS” Energy Cascade: Turbulent energy moves from large eddies to smaller ones, eventually being dissipated as heat. Large-Scale Eddies: Initial sources of turbulence containing most energy. Intermediate Scales: Facilitate energy transfer between large and small eddies. Kolmogorov Scales: Smallest scales where energy dissipation occurs. Understanding the energy cascade is crucial for analyzing and modeling turbulent flows, as it explains how energy is distributed and dissipated across different scales. Key Points on Turbulence and Pollutant Dispersion 1.Enhanced Mixing and Diffusion: 1.Turbulent Diffusion: Turbulence causes rapid and effective mixing of pollutants through chaotic eddy motion, leading to more uniform distribution. 2.Eddy Diffusivity: Measures the efficiency of turbulent mixing; higher values indicate better pollutant dispersion. 2.Vertical and Horizontal Transport: 1.Vertical Transport: Turbulence moves pollutants up and down, affecting their altitude and improving air and water quality by dispersing pollutants. 2.Horizontal Transport: Facilitates the lateral spread of pollutants, reducing localized high concentrations. Key Points on Turbulence and Pollutant Dispersion 3. Interaction with Atmospheric Stability: Stable Atmosphere: Limits vertical mixing, leading to higher pollutant concentrations near the source. Unstable Atmosphere: Enhances vertical mixing, resulting in more uniform pollutant distribution. 4. Boundary Layer Effects: Atmospheric Boundary Layer (ABL): Turbulence here affects pollutant dispersion; daytime turbulence improves mixing, while nighttime stability can increase concentrations near the surface. Urban Boundary Layer: Urban structures create complex turbulence patterns, affecting pollutant dispersion and creating localized hot spots. Key Points on Turbulence and Pollutant Dispersion 5.Practical Implications: Air Quality Management: Accurate dispersion models help predict pollution levels and inform mitigation strategies. Environmental Impact Assessment: Turbulence models guide the assessment of industrial and traffic pollution impacts.  Weather Systems: Turbulence enhances the development and severity of weather phenomena like storms, cyclones, and frontal systems through improved mixing and energy transfer. Boundary Layer Processes: Within the atmospheric boundary layer, turbulence affects surface winds, temperature, moisture distribution, and pollutant dispersion, influenced by daily and urban effects. Larger-Scale Interactions: Turbulence interacts with broader atmospheric processes, affecting energy exchange and influencing weather patterns and climate dynamics Understanding turbulence in these contexts is essential for accurate weather prediction, climate modeling, and managing the impacts of weather and climate on human activities and the environment. Thank You For Listening!