Weather Matrix User Guide

What is a Weather Matrix?

A weather matrix is a 2D lookup table that dynamically determines operational limits based on the current combination of weather conditions. The matrix defines relationships between three weather parameters:

• Column parameter: Forms the columns of your matrix (e.g., wind speed)
• Row parameter: Forms the rows of your matrix (e.g., wave height)
• Cell value: The operational limit for that specific combination of conditions

When the simulation encounters a particular weather scenario, it looks up the corresponding cell in the matrix to find the applicable limit. This allows the restriction to adapt dynamically rather than applying a single static threshold.

Example: How Lookup Works

Consider a wave height limit matrix where columns represent wind speed and rows represent wave period:

                Wind Speed (m/s)
                5      10     15     20
Wave Period  5  2.5m   2.0m   1.5m   1.0m
(s)          7  3.0m   2.5m   2.0m   1.5m
             9  3.5m   3.0m   2.5m   2.0m
            11  4.0m   3.5m   3.0m   2.5m

If the current weather shows 10 m/s wind and 7 second wave period, the simulation looks up that cell and finds the operational limit is 2.5m wave height. As weather conditions change, so does the applicable limit.

Supported Weather Parameters

Weather matrices support the following parameters:

Creating a Weather Matrix

Step 1: Define Matrix Structure

When creating a weather matrix, you need to specify:

1. Column Parameter: The weather parameter for columns (e.g., Wind Speed)
2. Row Parameter: The weather parameter for rows (e.g., Significant Wave Height)
3. Cell Parameter: The weather parameter that represents the operational limit

Step 2: Define Matrix Dimensions

Specify the header values for your matrix:

• Column headers: The discrete values for your column parameter (e.g., 5, 10, 15, 20 m/s for wind speed)
• Row headers: The discrete values for your row parameter (e.g., 1, 2, 3, 4 m for wave height)

Step 3: Populate Matrix Cells

Fill in each cell with the operational limit value that applies when conditions match that row and column combination. Each cell must contain a numeric value representing the limit for your chosen cell parameter.

Complete Example

Marine Transfer Operation Matrix

Objective: Limit significant wave height based on wind speed and wave period

Matrix Configuration:
- Column Parameter:  Wind Speed (m/s)
- Row Parameter: Mean Wave Period (seconds)
- Cell Parameter: Maximum Allowed Significant Wave Height (m)

                Wind Speed (m/s)
                5      10     15     20     25
Wave Period  4  1.5    1.2    1.0    0.8    0.5
(seconds)    6  2.0    1.8    1.5    1.2    0.8
             8  2.5    2.2    2.0    1.6    1.2
            10  3.0    2.8    2.5    2.0    1.5
            12  3.5    3.2    3.0    2.5    2.0

How it works: When wind speed is 10 m/s and wave period is 8 seconds, the lookup returns 2.2m as the maximum allowable significant wave height for this operation.

Using Weather Matrices in Weather Restrictions

Weather matrices provide an alternative to simple threshold restrictions. When you attach a matrix to a weather restriction:

1. Without Matrix (Static): "Don't operate when wind speed exceeds 15 m/s"
2. With Matrix (Dynamic): "Don't operate when wind speed exceeds the limit determined by the current wind speed, wave period, and their interaction"

You can choose to use either a simple threshold or a matrix for each weather parameter in your restriction. Matrices are particularly valuable when:

• Two weather parameters interact to affect operations
• Operational limits depend on multiple conditions
• Real-world experience shows varying limits under different scenarios

Technical Notes

Data Structure

Weather matrices are stored in the database with:

• Matrix metadata defining the three parameters
• Cells indexed by row and column position
• Numeric limit values within each cell

Matrix Resolution

When weather conditions fall between defined matrix values, the simulation uses interpolation to determine the applicable limit. Linear interpolation is typically applied between adjacent cells.