Note: HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control Forecast (ex-HRES) output is equivalent to HRES output where shown in the diagrams.   At the time of the diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.

Vertical profiles window

Vertical profiles window supplements the tools already available (Probe, Time-series, Cities, EPSgram) on ecCharts and elsewhere.  It provides information about the vertical structure of the forecast model atmosphere for any location (as selected by the Probe Tool) and any time (as selected by the Time Navigator).  Currently validity times are limited to 6 hour steps up to T+120.

There are 137 model levels for medium range ensemble members and the Ensemble Control Forecast.  Every model level is used in the lower troposphere up to about 700mb, and only every other level higher up.


 

Fig8.1.8-1: To display Vertical Profile.

  1. From Charts menu, select All points based products.
  2. Select Medium Range and Point based products. Select Vertical Profiles icon.
  3. Select date/time of forecast base time and date/time of forecast valid time.
  4. Select location, either by name or by lat/long.

Vertical Profile display

A single display comprises the following elements:

Temperature, dew point and dew point Depression on (most) model levels

  • The vertical structure of temperature (red) and moisture (dew point, green) in tephigram format, and also dew point depression (blue).  Shaded bands denote for the ensemble the minimum, 25th and 75th percentiles and maximum for each of temperature, dew point and dew point depression distributions at each level, with the median value shown by a thin solid line.  This display strategy mirrors the use of box-and-whisker plots on meteograms.  A thick solid line represents Ensemble Control Forecast (ex-HRES) (as on meteogram products).
    • dew point depressions are first computed from each ensemble member output at each level, and then the spread and median are derived in the same way as for temperatures and dew point.  So maximum dew point depression shown is not derived from the highest temperature on any ensemble member and the lowest dew point on any ensemble member at that level.
    • Wind arrows from Ensemble Control Forecast (ex-HRES) standard level output are shown on the dew point depression diagram (5m/s per full barb).  This plotting position was chosen for convenience, and not because of any direct or implied relationship with the dew point depression information itself.
    • Note that whilst the Ensemble Control Forecast (ex-HRES) traces for each thermal variable all represent plausible solutions, the same cannot be said for the median traces because they will very probably comprise data from different runs at different levels.


Fig8.1.8-2: An example of ecCharts vertical profile output.  With effect from Cy49r1, HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical and their results are a single solid trace on the vertical profile.  The feint solid lines are the median value of the ensemble (not including the ensemble control (ex-HRES).  The maximum dew point temperature among the ensemble members can be greater than the minimum temperature among the ensemble members.  Of course, these are not from the same ensemble member.  The breadth of the coloured regions give an indication of uncertainty in a similar manner to box and whisker plots. The darker shades (within 25th to 75th percentiles) correspond to the box.  The lighter shades (the total range) correspond to the extent of the whiskers.  The dew point depression range is 0C-20C to show moist environments in more detail.  In this example, at 800hPa, the total dew point depression spread (light shading) is from 0C to more than 20C suggesting great uncertainty, but the large majority of ensemble members (dark shading) and the ensemble control (ex HRES) suggest dew point depression only some 2C-4C giving more confidence.  Note also In this example, at 400hPa, the ensemble control (ex-HRES) lies outside the 25th to 75th percentile (dark shading) and therefore may not be the most probable result. 

  


Fig8.1.8-3: Magnified portion of Fig8.1.8-2 showing the possible overlap between temperatures and dew points among the ensemble members.  At some levels (here 860hPa taken for illustration) some ensemble members forecast dew points are higher than the temperature forecast by other ensemble members.  The dew point depression is 0C-20C to show moist environments in more detail. 

Note: The diagram is output from Cy48r when the resolution of HRES (~9km) differed from the resolution of medium range ensemble (~18km).  With effect from Cy49r1, HRES and Ensemble Control Forecast (ex-HRES) are scientifically, structurally and computationally identical and their results are a single trace on the vertical profile.


The vertical profile uses every model level in the lower troposphere up to about 700mb, and every other level at higher levels.  The model levels from each ensemble member are all set to the ensemble mean pressure values before the spread metrics (e.g. 25th and 75th percentiles etc) are computed. 

Hodograph

Horizontal Winds on Pressure levels

  • The vertical structure of winds (m/s) is shown by a wind hodograph that uses one line for each ensemble member and one colour for each of a range of levels (warmer colours for low levels and colder ones for upper levels).  Only data from standard pressure levels are shown.  The radial wind speed scale varies to span the value range represented, with certain values (20, 50, 100 m/s) highlighted to aid quick interpretation.  A solid line shows Ensemble Control Forecast (ex-HRES).  This should be identical to the winds on the dew point depression plot).
  • To avoid plot clutter:


Fig8.1.8-4: An example of ensemble and winds plotted as hodographs.  Depending on the case, these can be very informative (e.g. the consistency of significant shear among ensemble members).  This example shows significant shear from SE'ly winds at low levels to SW'ly winds at mid-tropospheric levels to W'ly winds in the upper troposphere.

MUCAPE and MUCIN diagram

The MUCAPE and MUCIN diagram shows the distribution of the most unstable Convective Available Potential Energy (MUCAPE) for three different categories of Convective Inhibition (MUCIN) in box and whisker format.   

Fig8.1.8-5: An example of box and whisker plot of the distribution among ensemble members of MUCIN and MUCAPE.

These diagrams indicate the variation among ensemble members of the intensity of convection that may occur (MUCAPE) together with the likelihood of attaining the release of that convection (i.e. overcoming MUCIN).  Three arbitrary ranges of MUCIN are shown: MUCIN <50J/kg representing a fairly low energy requirement before release of convection,  MUCIN >200J/kg representing a more substantial energy requirement, and an intermediate value range of MUCIN.  The vertical scale shows the MUCAPE energy in J/kg if convection is released.  Box and whisker symbols have their normal meanings.  Black filled circles are shown where there are five or fewer ensemble members where convection is released.  The numbers of ensemble members within each MUCIN category are given at the top of each column.  The number of members without release of MUCAPE is shown in the top right hand corner (e.g. MUCAPE=0: 13 meaning 13 ensemble members failed to identify any MUCAPE in the forecast ensemble ascent).

Note: At present these diagrams are annotated as CIN but should be shown as MUCIN as shown above in Fig:8.1.8-5.  This will be corrected on output in the near future.



It should be remembered that the MUCIN and MUCAPE values indicated are diagnostic.  The diagrams show the general state of the model atmosphere as forecast for that time.  MUCIN does not indicate whether convective instability will be released, but rather provides an indication of the potential for that release.  It is important the user to assesses the likelihood of MUCIN values being overcome during the following hours, either by diurnal heating, by dynamically induced uplift of the airmass, or by mechanical uplift caused by flow over mountains etc. 

In principle, MUCIN, the convective inhibition, can be computed from any model level.  In practice the temperature structure of the forecast atmosphere is scanned in the vertical, working out what MUCIN is for parcels rising from each level, and then the minimum of the values that correspond to levels in the lowest 350hPa of the atmosphere is stored in MARS (and used in ecCharts etc.).   Conceptually, MUCIN is always zero or a positive value.  However in practice where the parcel curve (from any of the levels tested) never even reaches the environment curve (i.e. it lies always to the left of it) then MUCIN is in effect infinite.  Infinite values of MUCIN is stored as a missing value indicator whenever the (minimum) MUCIN encountered exceeds a pre-defined very large threshold (e.g. in strong inversions).

MUCAPE is different in that it is bounded between 0 and some large, non-infinite, value that depends on atmospheric structure.  So MUCAPE is stored in a different manner that does not include missing values.


Additional Sources of Information

(Note: In older material there may be references to issues that have subsequently been addressed)

Read more information on “Using ECMWF's new ensemble vertical profiles”.

Read about the vertical profile product (P39-44).



(FUG Associated with Cy49r1)