Mean and stdev of the year 2015: 46.9 +/- 34.4   

Mean +/- stdev:
1998 to 2015: 39.0 +/- 6.8 ug/m³
2002 to 2015: 36.0 +/- 6.1

Trends 1998 - 2015: -2.8 per decade
             2002 - 2015:  0.1 per decade (flat trend line)  

Watch the left scale to note that trends are very small!

See [1] [2] [3] [17]

Trendlines (start year is x = 1):
1998 to 2014: 312.08 +1.24*x  (+12.4 DU/decade)
2002 to 2014: 332.04 - 0.26*x  (- 2.6 DU/decade  )

(Uccle  gives +0.95DU*y^-1  for the 1998-2010 period) (see also [16])

Calibration multiplier to apply if Uccle Brewer #178 is the reference:
2015              : * 1.033 (provisional, many Uccle data not yet available)

2015 common 107 days measurements results:
Diekirch   = 326.2 DU
Uccle DS = 337.6 DU (update when all Uccle data are available)


See [4] [8] ([8] shows strong positive trend starting 1990 for latitudes 45°-75° North, Europe): [27] give +1.32 DU/y at the Jungfraujoch for 1995-2004.
See also recent EGU2009 poster [16].

Mean and stdev of the year 2015: 407.6 +/- 4.9

The 1998-2001 data are too unreliable to be retained for the trend analysis.

Trendlines (1998 is x = 1):
2002 to 2015: 403.0 + 0.40*x    (+   4.0 ppmV/decade)
2002 to 2012: 394.9 + 1.35*x   (+ 13.5 ppmV/decade)
2013 to 2015: 372.9 + 1.87*x    (+ 18.7 ppmV/decade)
 

The sharp plunge in 2013 should be taken with caution; there also was a change in the calibration gas the 21 Jan. 2014
The Mauna Loa 2015 average is 400.83 ppmV, the trend for the 2013 to 2015 period is about 15 ppmV/decade [34]
The German Hohenpeissenberg trend for the 2010 to 2015 period is 17 ppmV/decade, very close to the 2013-2015 meteoLCD trend of 18.7[48]
                                       

The second picture shows the asymptotic CO2 values (CO2wind) derived from the model published in [21] .
The blue upper curve shows the yearly mean values at Diekirch; the middle red curve the asymptotic CO2 values that would exist if wind velocity was infinite, and the lower green curve the yearly averages at Mauna Loa, augmented by +1.8 ppmV to respect the latitudinal gradient of approx. 0.06 ppm per degree.
The yearly trends calculated from the yearly mean and the asymptotic values at Diekirch are very similar to the MLO trend of 2.08 for the last 3 years:

MLO:                    +2.08 ppmV/year
Diekirch CO2:        +1.87 ppmV/year
Diekirch CO2wind: +1.90 ppmV/year

Trends are also similar for the period 2009 to 2012 (see the thin trend lines).
 

The CO2 data (monthly averages) clearly show the summer-time lows and winter highs, which reflect the impact of variable seasonal photo-synthesis (see here). This simple 12 month periodic sinus pattern was also found in 2014. Actually, as shown in addendum 3, the CO2 lowering intensity of wind speed seems to be an important modifier of this pattern  (as visible from the low CO2 values during the Jan and Feb months), possibly masking the effect (or better: the non-effect) of photosynthesis.
 

If we omit the Jan and Feb months, we find the "classic" sine wave, with an amplitude of 11 ppmV (or a total swing of 22 ppmV), which is close to the 20 ppmV found at the stations Hohenpeissenberg (HPB) and Ochsenkopf (OXK) in 2013. The 12 month periodic sinus model is rather good, with an R2=0.66.

.

Mean and stdev of the year 2015 (from monthly averages):
Diekirch: 10.15 +/- 5.72  (10.20 from all half-hour readings)
Findel:     10.36 +/- 6.48

Mean temperatures (+/- stdev):

1998 to 2015 : 10.33 +/- 0.46 °C                
2002 to 2015 : 10.37 +/- 0.49 °C
2006 to 2015 : 10.40 +/- 0.56 °C (last decade)

The sensor location has not been moved since 2002! The old thermistor sensor has been replaced by a PT100 (see comments in 2015_only.xls).

Trends  from 2002 to 2015:
meteoLCD:      -0.03°C/decade
Findel:              +0.11°C/decade

Latest Global temperature anomaly trends for same period:
UAH (satellite)   : + 0.05°C/decade   [45]
RSS (satellite)   : - 0.062°C/decade
CRU (Hadcrut4): + 0.013°C/decade

Highest decadal Central England warming trend from 1691 to 2009: +1.86°C/decade for 1694-1703!
See also [15] (which may be obsolete)

DTR = daily max - daily min temperature

Mean and stdev of the year 2015 (from monthly averages):
Diekirch: 8.76 +/- 3.36  (8.79 from all half-hour readings)
Findel:     7.75 +/- 2.81

Mean DTR ( +/- stdev):
1998 to 2015:  8.53 +/- 0.55
2002 to 2015:  8.65 +/- 0.57
2006 to 2015:  8.59 +/- 0.47 (last decade)

For 2002 to 2015: all trends are practically flat.
Findel DTR trend is  flat from 2004 to 2015.


A fingerprint of climate warming is that daily minima increase more rapidly than daily maxima so that the DTR trend should become negative. Clearly the data do not show this neither at Diekirch nor at the Findel.

The BEST data set for Luxembourg [29] stops at 2013.

See [5], [13] and [30]

Diekirch:   +0.5 °C/decade since 2002
Findel:       +0.1 °C/decade
Germany:  +0.3  °C/decade [46]
NOA:         +0.5 °C/decade (NOA normalized index)

The plot shows the mean temperatures of December (from previous year), January and February. It also shows in brown the NAO index for the months Dec to Feb [47]

The North Atlantic Oscillation clearly influences our winters (but note the 2014 year exception!); the correlations between the 3 different DJF temperature series and NAO normalized index are 0.54, 0.40 and 0.60, all except the second (Findel) significant at the 5% level. The NAO index trend is equal to the Diekirch trend.

1998 to 2015 mean +/- stdev: 700.7 +/- 138.4 mm 
2002 to 2015 mean +/-stdev:  655.1 +/_108.9 mm
 

The negative trend from 1998 to 2015 seems spectacular: -123.5 mm/decade, which comes from the very high values of 2000 and 2001.
The 2002-2015 period suggests a more constant pattern and shows a much lower trend of -28.5 mm/decade.

Clearly precipitation shows an oscillation pattern, so linear trends should be taken with precaution.. A good model for the Diekirch data is a sinus function of 5.38 years period (R² = 0.54) (see lower graph).

The same model  suggests a similar period of 5.78 years for the Findel precipitation pattern (R² = 0.43)

[6] gives short term periods of 6 to 7 years for the Western European region.

Values of total solar energy of the year 2015:
Diekirch: 1127.3 KWh/m²
Uccle:      1111.7    [49]

1998 to 2015 mean: 123.92 W/m2 = 1085.5 kWh/m2
2002 to 2015 mean: 124.02 W/m2 = 1086.4 kWh/m2

Visible negative trend: 1998 to 2015: -17.6 kWhm^-2/decade
(not surprising with exceptional 2003 peak!)
Nearly flat trend from 2004 to 2015   : -1.8 kWhm^-2/decade
(actual solar cycle #24 begins Jan. 2009).

(see Addendum 1 for calculations of radiative forcing and solar sensitivity, addendum 2 for detecting a solar influence on temperature and moist enthalpy)

Helioclim satellite measurements show ongoing solar dimming over Luxembourg for 1985 to 2005  [33] (see graph)
[14] finds 0.7 Wm^-2y^-1 for West-Europe 1994-2003 , meteoLCD +1 Wm^-2y^-1 for 1998-2003.See also [9]

Values of sunshine hours of the year 2015:
Diekirch:     1550 hours (215m asl)
Findel:         1796 hours (365m asl, Campbell- Stokes)
Trier:            1652 hours (279m asl) [40] (Diekirch total used for missing May data)
Uccle:          1734 hours (100m asl)

Negative trends:
1998 to 2015: - 116 hours/decade
2004 to 2015: -   35 hours/decade

Note that negative trend has diminished (nearly flat since 2004).

The decline from 2012 to 2013 is -10.8%, to be compared to the data from the Fraunhofer Institut which give a decline of -10.6 % of the German PV "Volllasttunden" [37]

See paper [23] by F. Massen comparing 4 different methods to compute sunshine duration from pyranometer
 

The next graph shows the plots of the four above-mentioned stations. It should be noted that meteoLCD (Diekirch) is located in a valley, Findel and Trier on top of a plateau. The Findel totals are much higher than those of the other stations, which certainly is also partially caused by the use of the Campbell-Stokes instrument known to give too high readings (in July and August the excess of Findel readings was highest). The 2006 and 2007 Uccle values should be taken with caution!

From 2007 on all 4 stations give totals that vary in the same manner (synchronous increase and decrease)

All trends are practically flat!
 

See [10] and [22] (poster finds slight positive trend in June (+2%) and negative trend in August (-1%), no trend for other months, for period 1991 to 2008)

(The slight negative trend in biologically effective UVB is not consistent with the slight negative trend of the total ozone column [28], [50] , but consistent with the small  decrease of solar irradiance since 2004).

mean +/- stdev:
1998 to 2015  53.8 +/- 4.6 kWh*m^-2*y^-1
2004 to 2015: 53.9 +/- 4.2

Overall trend is flat, from 2004 to 2015 slightly negative.
 

^{The 3 independent measures of solar energy, UVB and UVA doses all point to a slight solar dimming since 2004.}

Mean moist enthalpy of 2015: 26.01+/- 11.32 kJ/kg

See [24] on how the energy content of moist air is calculated. Several authors, (e.g. Prof. Roger Pielke Sr.) insist that air temperature is a poor metric for global warming/cooling, and that the energy content of the moist air and/or the Ocean Heat Content (OHC) are better metrics
Mean yearly moist enthalpy values are very close, but they may change from zero up to 60 KJ/kg during a year. Moist enthalpy can not be calculated for temperatures <= 0 °C.

mean +/- stdev:
2002 to 2015  27.78 +/- 0.96 kJ/kg
2004 to 2015: 27.60 +/- 0.92

                       
Both trends are clearly negative which is consistent with the trends in temperature and solar energy. during the 14 years.

The 1998-1999 data are too unreliable to be retained.

2000 to 2013: trend: - 0.3 ug*m^-3*y^-1
2004 to 2013 rend:   idem

mean +/- stdev:
2000 to 2013: 9.2 +/- 1.8 ug/m³
2004 to 2014: 8.5 +/- 1.5

Many missing data from 2011 to 2013 ( 25%, 21% , 8%) so be careful! All these concentrations are very low! Luxembourg-City has a background of 25-30 and rural Vianden (Niklausberg) one of 2.5 (approx. 2013 values from [39])

see [11] which gives ~30% reduction from 1990 to 2005 for the EU-15 countries.

The 1998-1999 data are too unreliable to be retained.

2000 to 2013: trend: + 0.3 ug*m^-3*y^-1
2004 to 2013 rend:   + 0.6

mean +/- stdev:
2000 to 2013: 22.5 +/- 3.9 ug/m³
2004 to 2014: 22.7 +/- 4.5

Many missing data from 2011 to 2013 ( 25%, 21% , 8%) so be careful! All these concentrations are low! Luxembourg-City has a background of 58 and rural Vianden (Niklausberg) one of 9.4 (average since 1988) [38]

The mean monthly CO2 data show an oscillatory pattern which can be modeled by a 6 month period sine wave. This is not consistent with the commonly admitted explication that the summer lows and winter highs are a fingerprint of changing photosynthesis, which should lead to a single annual sinus wave (as in 2013).

The 6 month period is essentially caused by the low Jan, Feb and Dec values, and is replaced by the usual 12 period if these months are omitted.

The right figure shows the monthly mean CO2 and monthly mean wind speeds. Clearly low wind goes with high CO2, independent of the seasons (significant correlation R = -0.86 !)

The next figure gives the CO2 mixing ratios versus the monthly mean wind speed; the usual exponential model beautifully describes this pattern. The horizontal asymptote of 395.5 ppmV should correspond to the background CO2 level, as shown in [21].

There is some debate about the (global) changes of the seasonal CO2 amplitude, which seems to increase due to global greening [41], agricultural green revolution [43], changing air trans-continental circulation [42] and possibly other unknown factors. Look also at the presentation [44].

Locally it seems that the effects of higher/lower wind speeds and photosynthesis are difficult to untangle. If we restrict our data to those days where the mean wind speed is less than 1, the correlation between CO2 and wind speed is lower (-0.76) but still significant.

Curiously all the papers studying this seasonal amplitude problem seem to ignore the influence of changing wind speeds.

Here again higher wind speeds usually go together with lower CO2 levels (notice the exception on March!), but the monthly mean values do not follow the usual model well.

If we take all 17520 individual measurements, the picture becomes clearer, and we find that our "bumerang" model follows reasonably well the overall pattern. The horizontal asymptote suggest a background CO2 level of about 389 ppmV, which seems a bit low.