Manual of Ice (MANICE): chapter 6
Chapter 6: Ice Thickness Measurements and Reports
- 6.1: Weekly Ice Thickness Reports
- 6.2: Ice Thickness Monthly Reports
- 6.3: Examples of Ice thickness Reports
This chapter deals with the measurement and reporting of ice thickness and snow depth. The depth of snow is important to know because it has a direct bearing on the ice thickness due to it's insulating qualities. These measurements are important operationally since they provide a means to estimate the general thickness of the ice cover around the area. They are also important climatological records that users need for ice modeling, building infrastructures and, most recently, studies in climate change. Annual data summaries are produced from these measurements.
The observer shall ensure that the site selected has a depth of water greater than the maximum ice thickness expected for the year. The ice thickness and snow depth shall be measured, as near as practicable, at the same location throughout the ice season, and from one season to the next. The site should be on undeformed (level) and undisturbed ice. When the auger is used, a new hole shall be drilled for each measurement made in order to obtain the thickness of the entire ice layer. If a tidal crack is a permanent feature at the station, the site selected should be slightly seaward of the crack.
6.1 Weekly Ice Thickness Reports
Weekly reports are used in near real-time as validation of fast ice growth and to estimate the rate of growth of drifting sea ice. The reports are to be forwarded to a designated collection station on the meteorological communication system, where they are to be entered on the circuit in bulletins under the heading "ITCN01"with the collection station's identifier. MANTRANS (cf. 3) gives a listing of ITCN bulletin headings, including the stations contained in the bulletins and prescribes the relays which provide the desired distribution.
The weekly ice thickness and snow depth measurements are coded as follows:
ITCN01 CXXX YYGGgg
(CXXX) YYItI tIt StS tWtd
Table 6.1: Weekly Ice Thickness Message Heading
| Symbol | Description |
| ITCN01 | Message Identifier |
| CXXX | Transmission station identifier |
| YY | Day of month of message transmission |
| GG | Hour of message transmission |
| gg | Minute of message transmission |
Table 6.2: Weekly Ice Thickness Message Body
| Symbol | Description | Code Table |
| CXXX | Observation station identifier(if different than transmission station) | |
| YY | Day of month of measurement | |
| ItI tIt | Ice thickness in whole centimetres | |
| StS t | Average depth of snow in whole centimetres at measurement site | |
| T | Surface topography | 6.3 |
| Wt | Cracks and leads | 6.4 |
| d | Measurement method used | 6.5 |
Table 6.3: Surface Topography (T)
| Symbol | Concentration | Code |
| Smooth | 0 | |
| Rafted | 0 - 1/10 | 1 |
| 2/10 - 3/10 | 2 | |
| 4/10 - 10/10 | 3 | |
| Ridged | 0 - 1/10 | 4 |
| 2/10 - 3/10 | 5 | |
| 4/10 - 10/10 | 6 | |
| Hummocked | 0 - 1/10 | 7 |
| 2/10 - 3/10 | 8 | |
| 4/10 - 10/10 | 9 |
Table 6.4: Cracks and Leads (Wt)
| Description | Code |
| No cracks or leads | 0 |
| Few Cracks | 1 |
| Numerous cracks | 2 |
| Few leads | 3 |
| Numerous leads | 4 |
Table 6.5: Measurement Method Used (d)
| Description | Code |
| Visually | 0 |
| Ice Auger Kit | 1 |
| Hot Wire | 2 |
| Other Means | 3 |
Ice Service Specialist measuring ice thickness.
Photo: Jan-Andrej Skopalik © Environment Canada, 2013
6.2 Ice Thickness Monthly Report
Weekly ice thickness measurements are recorded on Form 0063-2317. Figure 6.1 ("Ice Thickness Form 0063-2317", p. 6-7) shows an example of a completed form. The completed forms constitute the official record of ice thickness and snow depth reports from network stations. The Officer-In-Charge (OIC) is responsible for ensuring that each form has been carefully checked and signed by himself or his/her deputy. This signature is a certification of the accuracy and completeness of the record.
The form shall be forwarded by mail to the Canadian Ice Service at the end of each month. One copy should be retained for station files. One form should be used for each month's observations.
The station name in full, the month and year shall be entered neatly on each sheet in the appropriate spaces provided at the top of the form.
The form has four (4) categories of information to be entered:
- measurement site
- measurements
- leads
- remarks
Table 6.6: Ice Thickness Monthly Report
| Item # | Item | Description |
| 1 | Measurement Site | The bearing and distance from a significant landmark and report any change of the site, should a change become necessary |
| 2a | Date of Measurement | The date (a two-figure number) when the ice measurement is taken |
| 2b | Ice Thickness | Measured ice thickness to the nearest whole centimetre |
| 2c | Depth of Snow | Average snow depth to the nearest whole centimetre |
| 2d | Surface Topography | Surface features at the measurement site and seaward (Table 7.3) |
| 2e | Cracks/Leads | The presence and orientation of cracks and leads (Table 7.4) |
| 2f | Method Used | The method used to measure or estiamte the ice thickness (Table 7.5) |
| 2g | Transmitted by Message | Y (yes) or N (no) whether or not the weekly report was transmitted |
| 3 | Leads | The presence and when possible the location orientation, length and width (in metres or kilometres) of leads shall be noted |
| 4 | Remarks | Additional information (include the date ice first appears and the date the ice is unsafe for measurement) |
6.3 Examples of Ice Thickness Reports
Example 1
ITCN01 CYFB 072200
07112 15611
Heading
ITCN01 CYFB 072200
ITCN01 message identifier
CYFB station identifier (Iqaluit)
072200 time of filing report for transmission was 7th day of the month at 2200UTC
Body
07112 15611
07 date of measurement was 7th day of the month
112 ice thickness is 112 centimetres
15 average depth of snow is 15 centimetres at measurement site
6 surface topography = 4/10 - 10/10 ridging
1 few cracks
1 measurement made with ice auger kit
Example 2
ITCN01 CYVN 072100\
07095 08401
Heading
ITCN01 CYVN 072100
ITCN01 message identifier
CYVN station identifier (Cape Dyer)
072100 time of filing report for transmission was 7th day of the month at 2100UTC
Body
07095 08401
07 date of measurement was 7th day of the month
095 ice thickness is 95 centimetres
08 average depth of snow is 8 centimetres at measurement site
4 surface topography = 0 - 1/10 ridging
0 no cracks or leads
1 measurement made with ice auger kit
The above examples would be assembled into a bulletin by YFB, the designated collection station, in the following form:
ITCN01 CYFB 072230
YFB 07112 15611
YVN 07095 08401
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