MetEd: Meteorology Education and Training. Operated by the COMET Program

Description:
This Webcast covers the ocean surface wind retrieval process, the basics of microwave polarization as it relates to wind retrievals, and several operational examples. Information on the development of microwave sensors used to retrieve ocean surface wind speed and the ocean surface wind vector (speed and direction) is also included.

Objectives:
State some key meteorological applications for ocean surface winds

• Describe the benefits of using microwave remote sensing to observe ocean winds
• Describe the differences between active and passive microwave remote sensing
• Describe in general terms, the emission, transmission, and scattering of microwave energy within the Earth-atmosphere system
• State the key assumptions for derivation of wind speed and direction from passive observation of microwave radiation
• Describe the limitations of passive microwave remote sensing and impacts on deriving wind speed and direction (this applies to both product limits and accuracy)
• Use cloud liquid water imagery to help assess the validity of the wind speed and direction vector

Estimated time to complete: 45 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2005-11-28

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Description:
This module starts with a forecast scenario that occurs along the California coast. The module then proceeds to describe the structure and climatology of these disturbances, as well as their synoptic and mesoscale evolution. The instruction concludes with a section on forecasting coastally trapped wind reversals. The module also includes a concise summary for quick reference and a final exam to test your knowledge. Like other modules in the Mesoscale Meteorology Primer, this module comes with audio narration, rich graphics, and a companion print version.

Objectives:
At the end of the module you should be able to do the following things:

With regard to characteristics of CTWRs

• Describe how pressure, temperature, and wind change with passage of a coastally trapped wind reversal (CTWR)
• Recall how quickly CTWRs propagate up the U.S. West Coast
• Recall why SLP rises after passage of a CTWR
• Locate areas likely to experience CTWRs on a physical map of the world
• Recall the frequency of CTWRs along the California coast
• Explain why CTWRs are best explained as a Kelvin wave, rather than a gravity wave

With regard to the structure of CTWRs

• Describe how the MBL changes with passage of a CTWR
• Recognize how a cross-coast profile of the MBL changes during a CTWR
• Recognize a CTWR on a wind profiler record
• Recall the height at which wind first reverses direction as a CTWR propagates
• Recall the association of stratus formation with CTWRs

With regard to the synoptic evolution of CTWRs

• Describe how MSLP, 850-mb heights, and 500-mb heights depart from climatologic norms during a CTWR
• Describe how changes in MSLP and 850-mb pressure force low-level offshore winds, and how this affects sensible weather along the coast
• Describe how variations in MSLP affect along-shore pressure gradients
With regard to the mesoscale evolution of CTWRs
• Recall how the synoptic setup forces the mesoscale offshore low
• Recall how the offshore low moves during a CTWR
• Describe how coastal mountains force ageostrophic flow
• Recall how coastal mountains contribute to warming of offshore winds
• Describe how and why a mesoscale high forms along the coast
• Recall the factors that cause northward propagation of the CTWR

With regard to forecasting CTWRs

• Recall the 3 best synoptic clues for forecasting a CTWR
• Recall where the offshore low forms with respect to the low-level offshore flow
• Recall where the stratus surge initiates with respect to the offshore low
• Describe the use and limitations of mesoscale NWP models in predicting CTWRs

Estimated time to complete: 1.5-2 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2002-08-06

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Description:
Fog frequently forms in response to dynamically forced changes in the boundary layer. This module examines dynamically forced fog in the coastal and marine environment, focusing on advection fog, steam fog, and west coast type fog. The focus of the module is on the boundary layer evolution of air parcels as they traverse trajectories over land and water. The module also examines mesoscale effects that impact the distribution of fog and low-level stratus over short distances. A general discussion of forecast products and methodologies concludes the module.

Objectives:
After completing this module, the learner should be able to do the following things:

With regard to the general features of dynamically forced fog and stratus:

• Describe the differences in boundary layer characteristics and evolution for advection, West Coast, and steam fog in a marine environment
• Describe the differences in synoptic environments for advection, West Coast, and steam fog in a marine environment
• Describe the relationship of sea surface temperature to fog formation for advection, West Coast, and steam fog in a marine environment
With regard to advection fog:
• Describe the general synoptic environment that is conducive to fog formation
• List at least 2 ways that subtropical high-pressure systems contribute to the formation of advection fog
• Describe the evolution of the boundary layer along an air parcel trajectory that leads to advection fog
• Describe how sea surface temperature changes along an air parcel trajectory that leads to advection fog
• Recall the origins of strong sea surface temperature gradients
• On a world map, identify areas prone to advection fog
• Recall the seasonality of advection fog

With regard to West Coast fog and low stratus:

• Describe the general synoptic environment that is conducive to fog formation
• List at least 2 ways that subtropical high-pressure systems contribute to the formation of West Coast fog and low stratus
• Describe the evolution of the boundary layer along an air parcel trajectory that leads to West Coast fog and low stratus
• List at least 2 ways that the boundary layer cools to saturation in a West Coast fog/stratus event.
• Recall the role of upwelling in the formation of West Coast fog and low stratus
• On a world map, identify areas prone to West Coast fog and low stratus
• Recall the seasonality of West Coast fog and low stratus
With regard to steam fog:
• Describe the general synoptic environment that is conducive to fog formation
• Describe the characteristics and evolution of the boundary layer along an air parcel trajectory that leads to steam fog
• On a world map, identify areas prone to steam fog
• Recall the seasonality of steam fog events

With regard to mesoscale influences upon dynamically forced fog:

• Describe the effects of coastal topography in fog formation
• Describe how coastal jets affect fog formation and dissipation
• Describe how sea breezes affect fog formation and dissipation
• Describe the impact of local variations in sea surface temperature on fog formation and dissipation

With regard to forecasting dynamically forced fog:

• Describe the general approach to forecasting fog
• List at least 4 critical atmospheric fields to monitor in plan view when forecasting fog
• List at least 4 critical atmospheric fields to monitor in vertical profiles when forecasting fog
• Describe the limitations of NWP models in fog forecasting

Estimated time to complete: 3 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2005-03-01

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Description:
This module provides a basic understanding of why gap winds occur, their typical structures, and how gap wind strength and extent are controlled by larger-scale, or synoptic, conditions. You will learn about a number of important gap flows in coastal regions around the world, with special attention given to comprehensively documented gap wind cases in the Strait of Juan de Fuca and the Columbia River Gorge. Basic techniques for evaluating and predicting gap flows are presented. The module reviews the capabilities and limitations of the current generation of mesoscale models in producing realistic gap winds. By the end of this module, you should have sufficient background to diagnose and forecast gap flows around the world, and to use this knowledge to understand their implications for operational decisions. Other features in this module include a concise summary for quick reference and a final exam to test your knowledge. Like other modules in the Mesoscale Meteorology Primer, this module comes with audio narration, rich graphics, and a companion print version.

Objectives:
After completing this module, the learner should be able to do the following:

With regard to the description of gap winds:
• Recall where in a gap the strongest wind speeds are typically observed.
• Describe the different kinds of topographic gaps and their effect on gap flow.
• List at least 3 natural hazards that may be associated with gap winds.

With regard to the structure of gap winds:
• Describe how wind speed varies through the gap during a gap flow event.
• Describe the temperature profile through a gap during a gap flow event.
• Describe the pressure profile through a gap during a gap flow event.

With regard to the origin of gap flows:
• Describe the conditions required for geostrophic flow.
• Recall that gap winds are typically non-geostrophic.
• Describe the origin of the pressure gradients that occur across gaps.
• Recall that the thinning of low-level cool air at a gap exit can increase the pressure gradient across a gap.
• Recall that adiabatic warming of downslope winds can increase the pressure gradient across a gap.

With regard to forecasting gap winds:
• Qualitatively describe how varying the following factors affects wind speed through a gap:
   * Pressure gradient
   * Surface roughness
   * Gap length
   * Temperature
• Describe the horizontal resolution of a mesoscale model required to accurately forecast flow through a gap.

Estimated time to complete: 1.5-2 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2003-03-20

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Description:
Landfalling cyclones and their attendant fronts significantly impact the structure of mesoscale wind and precipitation fields along the west coast of North America. This module focuses on the complex interaction of the wind field with topography and the resulting effects on nearshore winds and precipitation. For example, prefrontal conditions may lead to flow blocking, development of a barrier jet, and seaward displacement of the maximum precipitation. Postfrontal conditions tend to promote windward ridging and lee troughing, which enhance along-coast flow.

Objectives:

Performance Objectives

After completing the module, the learner should be able to do the following tasks:

• Describe the conditions under which flow becomes blocked by topography.


• Given the wind speed, stability (Brunt-Vaisala Frequency), and mountain height, determine whether flow will be blocked by topography.


• Describe how the angle between a landfalling front and the coastline
  affects the flow/topography interaction.


• Describe how the prefrontal environment may experience enhanced stability.


• Describe the conditions that lead to formation of a barrier jet.


• Describe the change in the pressure field as cold fronts make landfall.


• Given a landfalling front under conditions conducive to flow blocking,
  describe the anticipated effects on the motion of the cold front, the
  wind field, and the precipitation field.


• Given a landfalling front under conditions that are not conducive
  to flow blocking, describe the anticipated effects on the motion of
  the cold front, the wind field, and the precipitation field.


• Describe the advantages in using a high-resolution model to forecast the
  effects of landfalling fronts, compared to lower-resolution models.

Estimated time to complete: 1.5 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2006-05-24

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Description:
Low-level coastal jets occur along many coastlines. Winds may exceed 35 knots and lead to high waves and significant low-level vertical wind shear. Thus, low-level coastal jets present a hazard to both marine and aviation operations in the coastal zone. This core module describes the features of coastal jets and explores the conditions under which they form. Like other foundation modules in the Mesoscale Primer, this module starts with a forecast scenario and concludes with a concise summary and a final exam. By the end of this module, you should have sufficient background to diagnose and forecast coastal jets around the world and to use this knowledge to understand the implications for operational decisions.

Objectives:
After completing this module, the learner should be able to do the following things.

With regard to the features of coastal jets:

• Describe a coastal jet; its location, size, strength, and operational impacts
• Describe the synoptic conditions that lead to a coastal jet
• Describe the boundary layer structure that results in a coastal jet
• Describe the role of coastal mountains in the formation of coastal jets

With regard to the thermal structure and forcing of coastal jets:

• Describe how a cool, well-mixed marine boundary layer leads to a baroclinic structure
• Identify an appropriate baroclinic structure for a coastal jet in a vertical cross section of potential temperature
• Given a global plot of sea level pressure, identify locations that are prone to coastal jets
• Recall the difference in conditions that lead to a coastal jet as opposed to a sea breeze
• Recall the origins of cool sea surface temperatures (SSTs)
• On a world map, identify areas prone to cold ocean currents and coastal upwelling

With regard to along-coast variations of coastal jets:

• Given a map of California or Oman, identify local regions of maximum and minimum wind speeds within a coastal jet
• Recall the correlation of wind speed with mesoscale variations in sea level pressure and thickness of the marine boundary layer
• Describe how hydraulic theory can explain variations in the thickness of the marine boundary layer

With regard to forecasting coastal jets:

• On a synoptic scale, recognize the structure that leads to a coastal jet at the surface and at 850 hPa
• On the mesoscale, recognize areas that are prone to local wind maxima within a coastal jet
• Recall which satellite sensors will help detect coastal jets

Estimated time to complete: 1-2 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2004-08-16

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Description:
This module introduces forecasters to the use of microwave image products for observing and analyzing tropical cyclones. Microwave data from polar-orbiting satellites is crucial to today’s operational forecasters, and particularly for those with maritime forecasting responsibilities where in situ observations are sparse. This module includes information on storm structure and techniques for improved storm positioning using the 37 and 85-91 GHz channels from several satellite sensors. Information on current sensors and on the product availability in the NPOESS era is also presented.

Objectives:
• Explain how single channel and multispectral microwave imagery can be used to locate centers of circulation and other features within tropical cyclones
• Explain how parallax error affects imagery from different microwave channels
• Identify satellites that carry microwave imagers and sounders
• Contrast active and passive microwave remote sensing strategies
• Contrast conical and cross-track scanning strategies
• Explain how clouds, precipitation, and the ocean surface interact with microwave
energy at different frequencies
• Associate storm characteristics with features observed in microwave imagery

Estimated time to complete: 60 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2004-11-10

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Description:
This is the third and final part in a training series on rip currents. The topic of forecasting daily rip current risk can be explored by operational forecasters, many of whom do not have a physical oceanography background. The hazards of rip currents and a review of the factors that contribute to rip current development are discussed. To demonstrate the process of a rip current forecast and as an example of what can locally be developed at the user’s station, the module presents a rip current worksheet that is used operationally at some forecast offices. Various parts of this worksheet require the use of observed data and model output. These resources range from NOS Detailed Wave Summary reports to NOAA WAVEWATCH III model polar plots of wave spectral energy. The usage of these products in terms of rip current forecasting using the worksheet is explained in detail. In particular, the issue of “wave masking” in the 2-D model plots is illustrated. In order to practice with the products presented, the user is provided two cases (East and West Coasts). Other factors discussed include tide and lake levels as well as situational awareness. Lastly, a summary of important points from the module and experienced forecast offices is provided. Users are encouraged to examine the state of their office’s rip current program and develop a plan for improvement based on concepts and ideas presented in this module.

Objectives:
1. Describe the important elements that determine rip current risk.
2. Describe a process and resources that can be used to develop a local rip current forecast scheme.
3. Given wave data, determine whether wave masking is occurring and what the appropriate swell or wave components are to assess rip current risk.
4. Describe factors, other than swell and wind waves, that can alter rip current risk.

Estimated time to complete: 2-3 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2006-08-11

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Description:
The Rip Currents: Nearshore Fundamentals module provides insight into how nearshore circulation and wave dynamics are involved in rip current formation. Topics covered in this module include: nearshore terminology, circulation and waves, rip current characteristics, and rip current forcing mechanisms. This module is the second of three modules covering the forecasting of rip currents.

Objectives:
After completing the module users will be able to:
- Describe the various zones, bathymetry features, and currents of the near shore environment.
- Describe shallow water, near shore process.
- Describe rip current characteristics.
- Describe rip current forcing mechanisms.

Estimated time to complete: 40 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2004-12-13

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Description:
This 20-minute webcast by Timothy Schott of the National Weather Service's Marine and Coastal Weather Services Branch discusses the basics of rip current formation and detection and the partnerships between the National Weather Service, National Sea Grant College Program, and the United States Lifesaving Association as they relate to rip current safety. Rip Currents is one of three modules on forecasting rip currents.

Estimated time to complete: 20 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2004-08-16

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Description:
This is the fourth module in our series on open water waves. As deep-water
waves approach the coastline, they encounter shallower water and begin to
interact with the sea floor while evolving into shallow water waves. This
module uses an interactive wave calculator to look at a variety of shallow-water wave behaviors, including shoaling, refraction, reflection, breaking, attenuation, and coastal
run-up and set-up. All are important considerations when forecasting for
small craft and other recreational interests in the near-shore
environment.

Objectives:
By the end of this module, you will have learned:

* What transformations waves undergo as they move from deep water into shallow water

* How to describe and predict the effects of shallow-water processes such as shoaling, refraction, and attenuation

* How to identify and distinguish between the various breaker types, matching them with their corresponding bathymetry

* How to predict the effects of interactions between waves and currents

* The difference between wave run-up and set-up, and how to estimate them

Estimated time to complete: 1.5 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2006-08-01

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Description:
This module describes the phenomena of the sea breeze. It examines factors that lead to the formation of a sea breeze, modifying effects on sea breeze development, how mesoscale NWP models handle sea breezes, and sea breeze forecast parameters. The module places instruction in the context of a sea breeze case from Florida and compares surface and satellite observations to a model simulation using the AFWA MM5. Like other modules in the Mesoscale Meteorology Primer, this module comes with audio narration, rich graphics, and a companion print version.

Objectives:
Terminal Objectives
By the end of this module you will be able to describe how and why, when and where sea breezes occur

Enabling Objectives
By the end of this module you will be able to do the following:
1. Describe when and where sea breezes form
2. Characterize the sea breeze in terms of strength and horizontal and vertical extent
3. List the principle factors that affect sea breeze formation
4. List the sensible weather associated with formation and passage of a sea breeze front
5. Describe the use and limitations of NWP model simulations of sea breezes.
6. Describe how satellite imagery can assist in detecting sea breezes

Estimated time to complete: 1 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2002-12-12

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Description:
This is the second in a series of training modules on marine wind and waves. The first module discussed wave types and characteristics and is a good primer to this next marine training topic. Wave Life Cycle I: Generation examines how wind creates waves and the inter-relationships between wind speed, wind duration, and fetch length during this process. These three factors are important to predicting wave height and what will limit wave growth. Additional topics include fully developed seas, observation sources, and various special wind events such as coastal jets and instability mixing in the marine boundary layer. While much of this instruction is at a basic level, all marine forecasters will find benefit in the more intermediate and advanced topics. These include the issue of dynamic or “trapped” fetch as well as the use of satellite-based observations of marine winds using the active microwave technique known as scatterometry. User interactions are included throughout the module and within the short case study. The next module in the series will look at propagation and dispersion as the waves leave the generation area.

Objectives:
After completing the module users will be able to:
- Describe how wind generates waves, including how wind speed, fetch length, and duration interact to affect the wave growth process.
- Use a wave nomogram to manually estimate wave height.
- Describe the remote sensing and numerical prediction tools that aid forecasting of wave generation.
- Describe fully developed seas.
- List in situ as well as remote sensing sources of wind observations and describe their capabilities.
- Recall some of the various special wind events such as coastal jets and instability mixing in the marine boundary layer that affect wave generation.
- Describe the issue of dynamic or "trapped" fetch.

Estimated time to complete: 60-90 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2005-07-14

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Description:
The goal of the module is to enable a marine forecaster to manually predict how the wave height and period will change as the waves leave their generation area, become swell, and then propagate and disperse into the forecaster’s offshore coastal waters. While numerical wave prediction models can provide swell height and period forecasts, they are dependent on accurate wind forecasts by atmospheric prediction models. Therefore, manual skills in determining swell height and period are needed in order to cross-check or correct model predictions in cases of poor or unresolved model forecasts of winds. The module starts by discussing how swell propagate along great circle tracks and how these tracks will look different on various map projections. With this in mind the concept of developing a known “swell window” for a given location is introduced. Next, the module uses conceptual animations to demonstrate the effects of dispersion on the swell group as it propagates over a long distance. Also discussed are nonlinear processes, wave steepness, travel time, event duration, and opposing winds. Then the module explains how swell height changes due to angular spreading of wave energy and provides a simplified method to calculate this change. Finally, users are able to test their new understanding of these concepts through a short exercise where they are asked to determine swell height and period at multiple locations. User interactions are included throughout the module and within the short exercise. This is the third in a series of training modules on marine wind and waves. It follows the “Wave Types and Characteristics” and “Wave Generation” modules.

Objectives:
1.State the difference between seas and swell.
2.Recognize that waves propagate along great circle tracks and that these tracks look different on various 2-dimensional map projections.
3.Consider the effects of diffraction around barriers in forecasting swell heights.

4.Identify the effects of dispersion on a wave group, including:
a. waves become sorted by wave period
b. longer period waves outrun shorter period waves
c. swell height and steepness decrease
d. the wave group expands in space
e. the time it takes the entire wave group to pass a point increases

5.Explain how significant swell period can lengthen over time due to nonlinear interactions and dispersion, while individual swell period is conserved.

6.Given initial swell period, propagation distance, and fetch width, use a nomogram to forecast the change in significant swell period due to dispersion of a wave group.

7.Given initial or final swell period, propagation distance, and fetch width, use a swell travel time chart to forecast the time a swell to begin to impact a destination.

8.Using a swell travel time chart, forecast the length of time a wave group will affect a coastal area.

9.Given significant wave height for waves propagating in the central direction of a fetch area, forecast the decrease in significant wave height due to angular spreading for locations up to 70 degrees off the central direction of the wave group.

Estimated time to complete: 60 min

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2006-01-12

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Description:
This is the first in a series of new marine meteorology modules based on COMET’s old laser disk and CD-ROM modules on marine meteorology. This module is an introduction to waves and their associated characteristics. Several types of waves are presented, from the common wind wave to the rare tsunami wave. The basic physical, mathematical, and statistical traits of waves are discussed, along with how they change once waves become swell. This material serves as a building block to subsequent modules on wave generation, propagation, and dispersion.

Objectives:
After completing the module users will be able to:
- Recall the different wave types based on their different generation sources.
- Describe the physical characteristics of these different wave types, including anatomy and nomenclature
- Recall the mathematical expressions and equations that define physical characteristics
- Recall the statistical traits (i.e., wave spectrum and height
classifications) of waves.
- Describe the processes related to swell travel and dispersion.

Estimated time to complete: 1 h

Includes audio: yes

Required plug-ins:   Flash RealPlayer Java Adobe® Reader®
 * Plug-in information

Last published on: 2003-07-31

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