...
| Panel | ||||||
|---|---|---|---|---|---|---|
| ||||||
The idea of the exercise would be to show probabilities of precipitation by two different ways: 1 : CDF The exercise would be to plot the CDF at a specific location (maybe different forecast times), ask if the CDF caracterise a gaussian distribution (answer is not) and answer simple questions by reading the CDF : probability (1-p) that the precipitation exceeds 10mm, 20mm, 30mm, ... 2 : Probability map Probability map give a spatialized information of the precipitation exceeding a specific threshold (i.e. 1-p spatialized) but for just one p value. We can add a question where they set different thresholds and comment the probability maps over the Cevenes. |
In the next tasks, we will look at probabilities of the total precipitation in different ways, highlighting the differences between the two forecast ensembles.
Task 1: Plot
...
probabilities and percentiles of total precipitation
Probabilities
Enter the folder Probabilities in the openifs_2018 folder.
...
The prob_tp_compare.mv icon will produce maps over France showing the probability total 6-hourly precipitation exceeds a threshold expressed in mm, for both the 2012 and 2016 forecast ensembles.
Maps are produced for 3 forecast times: +90, +96 and +102 hours.
Edit prob_tp_compare.mv and set the probability to 10mm:
| Code Block | ||
|---|---|---|
| ||
#The probability of precipitation greater than (mm)
prob=10 |
Leave the location as an empty string for now:
| Code Block |
|---|
location="" |
Run the macro and view the map.
Use the cursor data icon 
an
...
Right-click, select 'Edit' and then plot a CDF for Toulouse:
| Code Block | ||
|---|---|---|
| ||
param="tp"
station="TOU"
expID="ens_oper" |
Make sure useClusters='off'.
Do the same for the 2016 operational ensemble reforecast:
| Code Block |
|---|
expID="ens_2016" |
...
| Panel | ||||
|---|---|---|---|---|
| ||||
Q. What can you say about the spreadWhere are the highest rainfall areas? |
...
What are the differences between the two ensembles? |
Percentiles
| Panel | ||
|---|---|---|
| ||
Q. Using these two macros, compare the 2012 and 2016 forecast ensemble. Which was the better forecast for HyMEX flight planning? |
Task 1. Plot percentiles of total precipitation
...
Run the macro and compare the percentiles from both the forecasts. Change the percentiles to see how the forecasts differ.
Task 2: Plot
...
the CDF
This exercise uses the cdf.mv icon.
Right-click, select 'Edit' and then plot a CDF for Toulouse:
| Code Block | ||
|---|---|---|
| ||
param="tp"
station="TOU"
expID="ens_oper" |
Make sure useClusters='off'.
Do the same for the 2016 operational ensemble reforecast:
| Code Block |
|---|
expID="ens_2016" |
Compare the CDF from the different forecast ensembles
This macro will produce maps showing the probability of 6-hourly precipitation for the same area as in Task 1.
In this case, the maps show the probability that total precipitation exceeds a threshold expressed in mm.
Edit the prob_tp_compare.mv and set the probability to 20mm:
| Code Block | ||
|---|---|---|
| ||
#The probability of precipitation greater than
prob=20 |
...
.
| Panel | ||
|---|---|---|
| ||
Q. Using these two macros, compare the 2012 and 2016 forecast ensemble. Which was the better forecast for HyMEX flight planning? | ||
| Warning | ||
What can you say about the spread? Q. Why does the CDF not look like Figure 2 above? |
- Find a latitude/longitude point in the area of intense precipitation on 12Z 24/9/2012 and plot the CDF for MSLP (set station=[lat,lon] in the macro cdf.mv)
Exercise 5: Cluster analysis
...