The mean depth–time curves and the mean density–time curves are given in
Figure 5 (below 1,400 m a.s.l.) and
Figure 6 (1,400–2,000 m a.s.l.). Mean and
σ of
ρ are calculated using the moving window averaging technique (±16 days) including all data from the respective elevation zone. When the number of records drops below 50 in May (see
Figures 5(b) and
6(b)) no mean
HS and
ρ values are given after 7 May (below 1,400 m a.s.l.) and after 25 May (1,400–2,000 m a.s.l.). In the lower elevation zone, mean
HS starts with 0.23 m and the peak of the mean
HS curve (0.5 m) is reached at the end of February. Mean
ρ starts with 160 kg m
−3 and rises up to 350 kg m
−3 in mid-April. After that, mean
ρ decreases due to late season records with ephemeral snow covers (
Figure 5). In contrast, data from above 1,400 m a.s.l. result in a rising
ρ until mid-May. While
ρ below 1,400 m a.s.l. rises in an almost linear manner throughout the season, densification shifts to a higher rate in the upper elevation zone in March. The shift of the densification rate goes hand in hand with a flattening of the mean
HS curve at approximately 0.9 m (
Figure 6). Simultaneously, the range of mean
HS ±1
σ becomes largest. Daily densification rates show a large noise and, therefore, monthly mean values are calculated (Table 2). Below 1,400 m a.s.l., densification rates have a low variability, with monthly values ranging from 0.9 kg m
−3 d
−1 in January to 1.35 kg m
−3 d
−1 in March. Above 1,400 m a.s.l., densification rates are around 0.6 kg m
−3 d
−1 from November to January. After a transition phase in February, densification reaches its maximum rates in March and April (1.8–1.89 kg m
−3 d
−1).
Table 2Monthly mean values of daily densification rates of the Tyrolean station data
. | Densification kg m−3 d−1
. |
---|
. | < 1,400 m a.s.l.
. | > 1,400 m a.s.l.
. |
---|
Nov | 0.96 | 0.61 |
Dec | 1.06 | 0.59 |
Jan | 0.93 | 0.62 |
Feb | 1.12 | 1.20 |
Mar | 1.35 | 1.89 |
Apr | 0.84* | 1.80 |
May | – | 1.34 |
. | Densification kg m−3 d−1
. |
---|
. | < 1,400 m a.s.l.
. | > 1,400 m a.s.l.
. |
---|
Nov | 0.96 | 0.61 |
Dec | 1.06 | 0.59 |
Jan | 0.93 | 0.62 |
Feb | 1.12 | 1.20 |
Mar | 1.35 | 1.89 |
Apr | 0.84* | 1.80 |
May | – | 1.34 |
Figure 5
Long-term mean (1952–2010) of (a) snow depth–time curves and (c) density–time curves of Tyrolean station data of the elevation zone below 1,400 m a.s.l. The number of records available for calculating the mean values is given in (b).
Figure 5
Long-term mean (1952–2010) of (a) snow depth–time curves and (c) density–time curves of Tyrolean station data of the elevation zone below 1,400 m a.s.l. The number of records available for calculating the mean values is given in (b).
Close modalFigure 6
Long-term mean (1952–2010) of (a) snow depth–time curves and (c) density–time curves of Tyrolean station data of the elevation zone 1,400 m a.s.l. to 2,000 m a.s.l. The number of records available for calculating the mean values is given in (b).
Figure 6
Long-term mean (1952–2010) of (a) snow depth–time curves and (c) density–time curves of Tyrolean station data of the elevation zone 1,400 m a.s.l. to 2,000 m a.s.l. The number of records available for calculating the mean values is given in (b).
Close modal