12 research outputs found
NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere
Meteorological Uncertainty of atmospheric Dispersion model results (MUD):Final Report of the NKS-B MUD activity
Enviro-HIRLAM online integrated meteorology-chemistry modelling system:strategy, methodology, developments and applications (v7.2)
Trends and annual cycles in soundings of Arctic tropospheric ozone
Ozone soundings from nine Nordic stations have been homogenized and
interpolated to standard pressure levels. The different stations have very
different data coverage; the longest period with data is from the end of the
1980s to 2014.
At each pressure level the homogenized ozone time series have been
analysed with a model that includes both low-frequency variability in
the form of a polynomial, an annual cycle with harmonics, the possibility
for low-frequency variability in the annual amplitude and phasing,
and either white noise or noise given by a first-order autoregressive
process. The fitting of the parameters is performed with a Bayesian
approach not only giving the mean values but also confidence intervals.
The results show that all stations agree on a well-defined annual cycle in
the free troposphere with a relatively confined maximum in the early summer.
Regarding the low-frequency variability, it is found that Scoresbysund,
Ny Ă
lesund, Sodankylä, Eureka, and Ărland show similar, significant
signals with a maximum near 2005 followed by a decrease. This change is
characteristic for all pressure levels in the free troposphere. A significant
change in the annual cycle was found for Ny Ă
lesund, Scoresbysund, and
Sodankylä. The changes at these stations are in agreement with the
interpretation that the early summer maximum is appearing earlier in the
year.
The results are shown to be robust to the different settings of the
model parameters such as the order of the polynomial, number of harmonics in
the annual cycle, and the type of noise