Ice Winter Severity in the Western Baltic Sea in the Period 1301-1500 
49 
3: The reconstruction of ice winter severity in the Western Baltic for the period 1501- 
1700 is based on seven ice winter severity types (Koslowski and Glaser, 1999) 
T— 
CD 
h- 
LO 
CO 
T— 
CD 
h- 
LO 
CO 
^— 
CD 
h- 
LO 
CO 
^— 
CD 
h- 
LO 
co 
^— 
CD 
h- 
LO 
co 
o 
O 
CM 
CO 
-M- 
■M" 
LO 
CO 
h- 
CO 
OO 
CD 
O 
CM 
CM 
co 
■M" 
LO 
CO 
CO 
h- 
OO 
CD 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
LO 
CO 
CO 
co 
co 
co 
CO 
co 
CO 
CO 
co 
CO 
CO 
-i— 
-i— 
-i— 
-i— 
-1— 
-1— 
-1— 
-i— 
-i— 
-1— 
-i— 
-i— 
-i— 
-i— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
-1— 
Fig. 4. Ice winter index numerals 1501 - 1700 
In the meantime, ice winter severity in the Western Baltic has been reconstructed for the period 
1301-1500 on the basis of seven ice winter severity types. The method used to reconstruct and 
analyse ice conditions during 1301-1500 is similar to that applied to the 1501-1700 period. 
Reliability of reconstructed data 
While the reconstruction of only a few winters is insecure in the 1501-1700 time series, the 
number of such winters in the period 1301-1500 is larger and, especially in the period 1301- 
1400, the number of winters with insufficient data availability is too large for an acceptable 
analysis by the usual method. 
Table 1. Degrees of reliability of reconstructed ice winters 
(*) Data from Koslowski and Glaser, 1999 
Time 
Reconstruction 
Fully secured 
Approximately secured 
Weakly secured 
Insecure 
1501-1550 (*) 
23 
9 
16 
2 
1551-1600 (*) 
36 
8 
5 
1 
1601-1650 (*) 
34 
11 
3 
2 
1651-1700 (*) 
42 
7 
1 
0 
1301-1350 
5 
8 
37 
1351-1400 
8 
14 
28 
1401-1451 
24 
8 
18 
1451-1500 
25 
19 
6