How will the summer 2016 be in Jena? What is your forecast? Submit your forecast and you can win a bottle of good wine! Below are the two metrics described for which you can submit your forecasts. Both are related to the meteorological “summer”, i.e. are based on the data observed at the weather station of our institute roof from the time period June 1, 2016 until August 31, 2016. Send your entry by email to me (firstname.lastname@example.org). It should contain your forecast for one or the other metric or for both and a few words/lines explaining how you got to your forecast (statistical model, grandma’s guess, reading of coffee grounds, whatever).
The deadline for entries is: June 30, 2016, 23:59:59 GMT
Note that the deadline is already one month in summer, hence you can potentially profit from the observations that are made during June…
Metric 1: Maximum temperature recorded and the number of “tropical nights”
This metric consists of two numbers: (1) the maximum 10′ temperature recorded on the institute weather station and (2) the number of tropical nights during the summer of 2016. Tropical nights are defined as nights with a minimum temperature larger than 20°C. Statistics for both metrics are given below.
Maximum temperature recorded on the institute weather station
The following figure shows the summer maximum temperature recorded in Jena since 1833. The data before 2004 are from the weather station in the Schillergässchen, the more recent data are from the institute weather station with a small adjustment explained here.
There are some caveats regarding this graphic. Daily maximum temperatures were recorded from analogue Tmin/Tmax thermometers until 2003. Since 2004 the maximum temperature is determined from the 10′ digital recordings of our institute weather station. The red linear trend line has a slope of 2.3 °C/century, which is above the long-term mean summer temperature trend in Jena (1.2 °C/century). If we take the distribution of the individual years around the trend curve and project it with the trend to the year 2006, we obtain:
Thus you can choose your guess based on this statistic…
The annual number of tropical nights in summer since the year 2000 is shown below:
Prior to 2000 there is practically no year with a tropical night. It is likely that this partially reflects a measurement bias; I think that the continuous measurements on our institute weather station are more accurate to pick the daily minimum temperature than the analogue minimum thermometers used at the Schillergässchen weather station. The different local conditions might also introduce some bias.
Metric 2: Minimum of the 15-day median of the daily lowermost 5% quantile of the recorded CO2 concentration
This metric tries to capture the seasonal trough of the CO2 concentration. The figure below shows the lowermost 5% quantile measurements of each day (dots) and the running 15-day median (black curve). The vertical lines in each year bracket the meteorological summer. Also shown for comparison is the monthly measurement from Mauna Loa (orange dots).
A table with the values of the annual summer minima of the black curve and the annual monthly minimum recorded at Mauna Loa is shown here:
and in graphical form:
The required metric more or less follows the Mauna Loa record. The value for 2016 is based on the observations until June 15, 2016.