Stable Atmosphere Unstable Atmosphere Mixing Height Definition The

Stable Atmosphere Unstable Atmosphere Mixing Height Definition The mixed layer can be defined as the altitude

above ground level to which pollutants vertically disperse. Fearon Mixing Height Definition The height of the layer adjacent to the ground over which an

emitted inert non-buoyant tracer will be mixed (by turbulence) with a time scale of about one hour or less. Beyrich Mixing Height Definition The thickness Z, of the mixed layer,

defined as the location of a capping temperature inversion or statically stable layer of air. Glossary of Meteorology Reasons for Capping Inversion Because of summertime Pacific High,

average inversion ht along California coast is about 400 meters Marine layer is usually 1500 to 2000 feet deep in Bay Area Rising air cools, and descending air warms, making the mixed layer adiabatic

Types of Mixing MECHANICAL MIXING Predominates at nighttime Turbulence due to wind shear Turbulence due to obstacles

Turbulence is proportional to wind speed (ie. H= 125 U) Types of Mixing Height CONVECTIVE MIXING HEIGHT Is a daytime phenomenon - due to heating by the sun

On sunny or partly cloudy days, is dominate from one hour after sunrise to one hour before sunset (13 deg above horizon). On overcast days, figure two hours. Convective VS Mechanical

Convective Mixing usually dominates over Mechanical Mixing During very windy conditions smoke plumes will stay close to the ground WHERE TO GET

INFORMATION ON MIXING HEIGHTS Holtzworth Techinque Model-Based Soundings

NOAA models (such as ETA or SRI) can generate soundings for current time or future time for any location. www.arl.noaa.gov/ready/

cmet.html www.weather.nps.navy.mil/profiler/coastprof.html DRI Web Page with Mixing Hts www.cefa.dri.edu/Operational_Products/NCEP_Exp/exp_index.htm

Model Calculations Model being developed by EPA (AIRMET) will calculated hourly mixing ht values using Monin Obukhov length and friction velocity Need measurements of net radiation and heat flux, in addition to winds,

temperature and RH Complex Terrain Upper air data tend to be

collected over simple terrain Extrapolating mixing depths to elevated terrain is not straight forward Mixing Depth Observations at Flat-Land Sites in Bay Area

Issue #1 How to estimate mixing depth on site? Estimating Mixing Heights Most

plans say will use Oakland Sounding and test burns Burn elevation may be higher than Oakland mixing depth How is height of smoke determined during test burns

Issue #2 Burning before meeting the mixing height prescription.

TITLE 17, SECTION 80160, PART J Require the land manager or his/ her designee conducting a prescribed burn to ensure that all conditions and requirements stated in the smoke management

plan are met on the day of the burn event and prior to ignition. Meeting Prescription Many plans prescribe a mixing depth of 1500 feet agl There is a reference to this value in a

table in the Smoke Management Training Workshop Manual The problem is that this height is often the maximum mixing depth, and is not reached until 2 3 pm. END

Holtzworth Technique

Recently Viewed Presentations

  • New Systems: Eos and Rhea

    New Systems: Eos and Rhea

    Portable Programming Models - Wayne Joubert. User Driven Content. How can Users Share their Knowledge with the Community? -Suzanne Parete-Koon OLCF Allocation Programs - Ashley Barker. I/O Strategies - Sarp Oral. OLCF User Needs for New Data Services - Jack...
  • AFGHANISTAN by Don L. F. Nilsen and Alleen

    AFGHANISTAN by Don L. F. Nilsen and Alleen

    For higher numbers new letters were needed so we get L for fifty, C for 100, M for 1000 and so on. * ARABIC NUMBERS:٠١٢٣٤٥٦٧٨٩ We use a Roman alphabet for our writing system, but we don't use the Roman...
  • Evolution Unit - Mr. Walter's AP Biology(J.H. Rose)

    Evolution Unit - Mr. Walter's AP Biology(J.H. Rose)

    Evolution Unit AP Biology * * * * * * Anatomical evidence 1. These structures are called… homologous 2. These structures are evidence for…. common ancestry 3. similar internal structure = similar development 4. different function = different environment &...
  • Kmen: Porifera, Cnidaria - Masaryk University

    Kmen: Porifera, Cnidaria - Masaryk University

    Systém a evoluce bezobratlých 3. cvičení J. Schenková Metazoa - bazální mnohobuněční Porifera 2 - 4 vývojové linie spojené do 1 kmene
  • Introduction to Environmental Science

    Introduction to Environmental Science

    The Great Leap Forward. Starting in 1958, Mao Zedong, leader of the Communist Party of China, initiated a series of policies to transform the country into a modern, industrialized, communist society.
  • Lecture 3: IR System Elements (cont) Principles of

    Lecture 3: IR System Elements (cont) Principles of

    Relevance Relevance Relevance Relevance Research and Thought Saracevic Define your own relevance A. Gages B. Aspect C. Object judged D. Frame of reference E. Assessor Schamber, Eisenberg and Nilan Schamber, et al. Conclusions Froelich Janes' View Operational Definition of Relevance...
  • Access to Learning: Language and Academic Skills Support

    Access to Learning: Language and Academic Skills Support

    Access to Learning: Language and Academic Skills Support Available for International Students Gamu Matarira Siegrid Beck Xiangping Du HBS L&T Conference 2013
  • Image Formation & Optical Instruments - UCF Physics

    Image Formation & Optical Instruments - UCF Physics

    Object between c and f. Object between f and the mirror. The Mirror Equation The Mirror Equation Magnification Curved Mirrors Curved Mirrors Image With a Convex Mirror 13 12 8 8 8 8 9 13 Image Formation (the ray reaching...