Weather: Theory & Practical Applications

Transcription

1 Weather: Theory & Practical Applications Thursday, January 24 th 1:00 p.m. 2:30p.m. PRESENTED BY: Brian Boothe & Chris Algee Schedulers & Dispatchers Conference San Antonio, TX January 22 25, 2013

2 The Basics Air Masses and Fronts Air Mass Large body of air which has similar moisture & temperature in any horizontal direction 4 Main Categories Continental (c) Maritime (m) Tropical (t) Polar (p) Source: fuelberg.met.fsu.edu 2

3 Fronts Areas of transition between air masses Source: fuelberg.met.fsu.edu 3

4 Jet stream Jet stream - fast flowing, narrow, currents of air located at the boundary between air masses and just below the tropopause

5 Turbulence Boeing 777 Wake Turbulence 5

6 What is Turbulence? A state of fluid flow in which the instantaneous velocities exhibit irregular and apparently random fluctuations."

7 Causes of Turbulence Jet stream Clear Air Turbulence Thunderstorms Mountain Turbulence

8 Different types of Turbulence Mechanical - Disruption to the smooth horizontal flow of air. Thermal - Turbulence caused by vertical currents of air in an unstable atmosphere

9 Clear Air Turbulence (CAT) Strong turbulence in an otherwise cloudless region that effects aircraft to violent updrafts or downdrafts Common at high altitudes Invisible because not associated with clouds Difficult to detect even with convection radars Photo: Kent Meireis

10 Area of highest Turbulence The CAT is strongest on the cold air side of the jet, next to and just underneath the axis of the jet.

11 Thunderstorms The strength of Vertical wind shear is important of factor in the strength and in the duration of a storm

12 Turbulence in a Thunderstorm

13 Mountain Turbulence Strong winds are forced over and around large mountains Turbulence is often severe Characteristic cloud patterns often present

14 When are Mountain Waves formed? Atmospheric conditions needed: The wind flow at around ridge height is nearly perpendicular to the ridge line and at least 25 kts Wind speed increases with height There is a stable layer at around ridge height. Altocumulus Standing Lenticular Clouds

15 Forecasting Turbulence - Ellrod Index Uses numerical modeling to examine vertical wind shear, horizontal deformation, and convergence

16 Turbulence Intensity Light chop - slight, rapid and somewhat rhythmic bumpiness without noticeable changes in altitude or attitude. Moderate turbulence - similar to light turbulence, but greater intensity. Changes in altitude/attitude occur. Aircraft remains in control at all times. Variations in indicated air speed. Moderate chop - similar to light chop, but greater intensity. Rapid bumps or jolts without obvious changes in altitude or attitude. Severe turbulence - large, abrupt changes in altitude/attitude. Large variation in indicated airspeed. Aircraft may be temporarily out of control. Extreme turbulence - aircraft is violently tossed about and is impossible to control. May cause structural damage.

17 Thunderstorms Photo: Caren s Photo Trip on Flickr 17

18 Thunderstorm Life Cycle Developing Stage Mature Stage Dissipating Stage Source: aviationweather.gov/general/pubs/front/docs/jul-11.pdf 18

19 Types of Thunderstorms Single Cell Multicell Cluster Multicell Line (Squall Line) Supercell Source: NOAA NSSL 19

20 Thunderstorm Impacts to Aviation Hail Turbulence Rapid-Onset Icing Lightning Microbursts Rapid Vertical Acceleration Lightning strikes a plane on takeoff from Kamatzu Air Force Base in Japan Source: 20

21 Thunderstorm Hazards Downbursts Microburst and Macroburst are localized column of fast moving sinking air Source: CRH.NOAA.GOV

22 Aircraft Icing 22

23 Why is icing bad? It destroys the smooth flow, increasing drag while decreasing the ability to create lift. Ice and snow accumulation no thicker or coarser than a piece of sandpaper can decrease lift by 30% and increase drag by 40%. In moderate to severe icing, light aircraft can become so iced that continued flight is impossible. Icing can cause engine stoppage by either icing up the carburetor, or blocking airflow in fuel-injected engines. Can cause instrumentation to be come inoperable: antennas, pitot tube icing. Source: 23

24 Types of Icing Rime icing Has a rough milky white appearance, and generally follows the contours of the surface closely Clear icing Ice is usually clear and smooth, contains air pockets which results in a lumpy translucent appearance. Most of the time clear ice is denser and harder than rime ice, making it more difficult to remove with deicing systems. Mixed icing Mixed icing is a combination of both rime and clear icing. Combines the worst characteristics of both, can form a rough surface rapidly when ice particles become imbedded in clear ice 24

25 Types of Icing Rime Mixed Clear Photo (left): Photo (right): 25

26 Where to find icing Can occur any time liquid water is present below 32 F Typically occurs along frontal boundaries. Possible between October and March in cumulus and stratiform clouds. Most common on decent but also possible on climb. Also possible during the summer in strong vertically robust thunderstorms. 26

27 Icing probability Common in eastern US due to availability of moisture. The Great Lakes are also a good source of winter moisture. Even though temperatures in the west are primarily colder during the winter, clouds tend to be much drier than those in the eastern US. 27

28 Temperature breakdown Icing can occur any time liquid water is present below 0 C. Temperature dewpoint spread of 2 C or less with OAT between 0 C - 20 C icing is likely. Severe icing usually occurs between 0 C - 10 C Temperatures lower that -40 C liquid water turns to solid crystals therefore icing is not possible. 28

29 Steps to Avoid Icing Try to minimize time between de-icing application and takeoff. Stay out of icing temperatures as long as possible if visible moisture (clouds) are present. Minimize exposure to frontal boundary. 29

30 Fog Source: Creative Commons glennharper 30

31 Fog Types Radiation Calm winds Clear skies Rapid cooling after sunset Advection Warm air mass moves over cooler ground Typically light winds Upslope Advection fog in San Francisco Warm moist air cools as it rises against sloping terrain Precipitation-Induced Warm rain evaporates in cool air Ice Most common in Arctic regions Source: CBS4 Weather San Francisco 31

32 Fog Types Figure 1: Radiation Fog Figure 2: Advection Fog Figure 1: Radiation Fog Figure 2: Advection Fog 32

33 Fog Average number of days of dense fog Dense fog Visibility ¼ statute mile or less 33

34 VOLCANIC ASH Source: Iceland Meteorological Office 34

35 VOLCANIC ASH Volcanic ash is made up of small pieces of rock and glass that can range in size from large, heavy rock fragments to small, fine particles (2mm in diameter or smaller). Ash can travel thousand of miles depending on the type of eruption and the upper level jet stream. 35

36 Volcanic Ash Advisory Centers Red shaded regions are areas without active volcanoes and therefore are not represented. 36

37 SPACE WEATHER Source: 37

38 SPACE WEATHER Space Weather systems have an adverse impact on operations in polar airspace, thereby reducing capacity of polar routes Can cause: Loss of communications capability Erroneous navigation information Crew and passenger radiation exposure Restrict or constrain polar routes resulting in: Flight Delays and/or diversions Less efficient routes flown Consequences are increased fuel consumption and higher operating costs 38

39 SPACE WEATHER Due to the substantial increase in polar aviation operations and the increased use of GNSS (global navigation satellite system), space weather events are more important than ever to the aviation community. AMS Forum Session 10 SWx Impacts Panel 39

40 Application -- Overview Let s take the knowledge & create a skill set Analysis Long range(5-3 days) Shorter range(48-24 hours) Day of flight(24-0 hours) Communication of impact Resources Charts Radar Websites Products 40

41 Step 1: Discovery Educate yourself with all the considerations Departure & Arrival Airport Runway characteristics Navigational support Notice to airmen(notam) FBO facilities & services available Hangar De-ice / Anti-ice Snow removal Surface treatments 41

42 Step 1: Discovery Departure & Arrival Airport Runway characteristics Length & Width Airport elevation Weight capacity Navigational support ILS, LOC, GPS more common Approach minimums Notice to Airmen(NOTAMs) Check throughout analysis Show stoppers 42

43 Step 1: Discovery FBO Facility & services available Hangar Heated hangar; radiant roof heating preferred De-ice(Type I) & Anti-ice(Type IV) Application methods Holdover tables Snow removal Equipment type Duration of maintenance Ramp maintenance Surface treatments Snow/Ice melt systems 43

44 Step 2A: Identification of potential impact Analysis: Long Range(5-3 days out) Surface forecast (right) High/Low Pressure areas Extended forecast(below) Paints general picture 44

45 Step 2B: Identification of potential impact Analysis: Shorter Range(48-24 hours out) Forecast is becoming more accurate Continue to utilize surface forecast & extended forecast Compare forecasts from long range analysis to predict pattern If there is delay potential action maybe necessary Include crewmembers to discuss potential impact Prepare statement of advisement to passenger for awareness if warranted Some contingency planning might be necessary 45

46 Step 2C: Identification of potential impact Analysis: Day of flight(24-0 hours out) Text weather Aviation Routine Weather Reports(METAR) Aerodrome forecasts(taf) National Airspace System(NAS) Radar / SIGMETS 46

47 Step 2C: Identification of potential impact METAR Text weather Observed every hour SPECI is issued for significant changes TAF Issued every 6 hours Generally apply to a 24 hour period with some exceptions 47

48 Step 2C: Identification of potential impact National Airspace System(NAS) Operational Information System(OIS) Ops Plans Terminal constraints En route constraints Ops Advisories Issued for information on the following ATC programs Airspace Flow Program(AFP) Ground Stop(GS) Ground Delay Program(GDP) General Aviation Arrival Program(GAAP) Programs define delay with issuance of EDCT Expected Departure Clearance Time Utilized within +/- 5 min of time issued NBAA Air Traffic Services is a valuable resource 48

49 Step 2C: Identification of potential impact Composite Radar Precipitation finder Return levels Level 1 Green/Light Level 2 Yellow/Moderate Level 3 Red/Severe Sigmets NWS product graphic & text Convective Issued every hour Valid for two hours Non-convective Relates to severe turbulence 49

50 Step 3: Communication of impact Goal #1: Create situational awareness Goal #2: Avoid panic Suggestions to satisfy goal #1 & goal #2 promise continuous monitoring and further advisements avoid aviation technical terminology maintain solid relationship during entire scheduling process to establish trust 50

51 Office Setup Source: Rockwell Collins Ascend Flight Information Solutions 51

52 Resources Websites Flight Delay Information NAS Status - Operational Information System(OIS) EDCT Look up Aviation Weather GFS Forecast Localized Aviation MOS Product(LAMP) 52

53 Resources More websites Seasonal Convective Forecast Historical query Seasonal - Tropical 53

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