Figure 2
Four panels arranged in a two-by-two grid, where the top row is labeled “(a)” and the bottom row is labeled “(b)”. Each panel contains multiple line plots. In the top row “(a)”, four dual-axis line graphs are arranged in a two-by-two grid labeled “E 1”, “E 2”, “E 3”, and “E 4”. In all plots, the left vertical axis is labeled “E 1 (millimeters)”, “E 2 (millimeters)”, “E 3 (millimeters)”, and “E 4 (millimeters)” in blue and the right vertical axis is labeled “Temperature (degree Celsius)” in red from “5” to “25” in increments of 5. The horizontal axis in all plots represents dates: “2022-09-01”, “2023-03-01”, “2023-09-01”, “2024-03-01”, and “2024-09-01”, spaced evenly from left to right. In the left panel of “(a)”, “E 1” and “E 3” are stacked vertically. In “E 1”, the left vertical axis ranges from “negative 0.10” to “0.20” in increments of 0.05. The blue dashed line starts at (2022-09-01, 0.00), rises to (2023-03-01, 0.12), decreases to (2023-09-01, 0.03), then increases to (2024-03-01, 0.20), sharply drops to (2024-03-01, “negative 0.08”). The red temperature line fluctuates between (2022-09-01, 22), (2023-03-01, 20), (2023-09-01, 13), (2024-03-01, 25), and continues toward (2024-09-01, 18), with visible vertical red spikes. In “E 3”, the left vertical axis ranges from “negative 0.10” to “0.20” in increments of 0.05. The blue dashed line starts at (2022-09-01, 0.00), rises to (2023-03-01, 0.12), decreases to (2023-09-01, 0.02), then increases sharply to (2024-03-01, 0.20), drops to (2024-03-01, “negative 0.10”), continues downward to (2024-09-01, “negative 0.08”), and finally rises sharply to (2024-09-01, 0.20). The red temperature line fluctuates between (2022-09-01, 22), (2023-03-01, 20), (2023-09-01, 13), (2024-03-01, 25), and continues toward (2024-09-01, 18), with visible vertical red spikes. In the right panel of “(a)”, “E 2” and “E 4” are stacked vertically. In “E 2”, the left vertical axis ranges from “negative 0.05” to “0.10” in increments of 0.05. The blue dashed line starts near (2023-03-01, “negative 0.05”), rises sharply at (2023-03-01, 0.11), then immediately drops to (2024-03-01, “negative 0.05”), and remains nearly flat through (2024-09-01, “negative 0.05”). The red temperature line fluctuates between (2022-09-01, 21), (2023-03-01, 17), (2023-09-01, 13), (2024-03-01, 25), and continues toward (2024-09-01, 18), with visible vertical red spikes. In “E 4”, the left vertical axis ranges from “negative 0.05” to “0.20” in increments of 0.05. The blue dashed line starts at (2022-09-01, 0.00), rises to (2023-03-01, 0.12), decreases to (2023-09-01, 0.03), then increases to (2024-03-01, 0.20), drops to (2024-03-01, “negative 0.05”), continues downward to (2024-09-01, “negative 0.05”), and finally rises sharply to (2024-09-01, 0.20). The red temperature line fluctuates between (2022-09-01, 22), (2023-03-01, 20), (2023-09-01, 13), (2024-03-01, 25), and continues toward (2024-09-01, 18), with visible vertical red spikes. In the bottom row “(b)”, four dual-axis line graphs are arranged in a two-by-two grid labeled “E 1”, “E 2”, “E 3”, and “E 4”. In all plots, the left vertical axis is labeled “E 1 (millimeters)”, “E 2 (millimeters)”, “E 3 (millimeters)”, and “E 4 (millimeters)” in blue and the right vertical axis is labeled “Temperature (degree Celsius)” in red from “10” to “30” in increments of 10. The horizontal axis in all plots represents dates: “2022-10-01”, “2023-04-01”, “2023-10-01”, “2024-04-01”, and “2024-10-01”, spaced evenly from left to right. In the left panel of “(b)”, “E 1” and “E 3” are stacked vertically. In “E 1”, the left vertical axis ranges from “negative 0.025” to “0.000” in increments of 0.005. The blue dashed line starts at (2022-10-01, 0.000), drops to (2023-04-01, “negative 0.010”), fluctuates through (2023-10-01, “negative 0.012”), then decreases further to (2024-04-01, “negative 0.020”), and ends near (2024-10-01, “negative 0.022”). The red temperature line fluctuates between (2022-10-01, 22), (2023-04-01, 18), (2023-10-01, 30), (2024-04-01, 15), and continues toward (2024-10-01, 20), with visible vertical red spikes. In “E 3”, the left vertical axis ranges from “negative 0.02” to “0.03” in increments of 0.01. The blue dashed line starts at (2022-10-01, 0.00), rises to (2023-04-01, 0.01), decreases to (2023-10-01, “negative 0.01”), then increases to (2024-04-01, 0.02), drops again to (2024-10-01, “negative 0.01”), and ends with a sharp rise at (2024-10-01, 0.03). The red temperature line fluctuates between (2022-10-01, 22), (2023-04-01, 18), (2023-10-01, 30), (2024-04-01, 15), and continues toward (2024-10-01, 20), with visible vertical red spikes. In the right panel of “(b)”, “E 2” and “E 4” are stacked vertically. In “E 2”, the left vertical axis ranges from “negative 0.02” to “0.02” in increments of 0.02. The blue dashed line starts near (2022-10-01, 0.00), drops to (2023-04-01, “negative 0.01”), fluctuates slightly through (2023-10-01, “negative 0.01”), then decreases to (2024-04-01, “negative 0.02”), and ends near (2024-10-01, “negative 0.02”). The red temperature line fluctuates between (2022-10-01, 21), (2023-04-01, 17), (2023-10-01, 30), (2024-04-01, 15), and continues toward (2024-10-01, 20), with visible vertical red spikes. In “E 4”, the left vertical axis ranges from “0.00” to “0.08” in increments of 0.02. The blue dashed line starts at (2022-10-01, 0.00), rises to (2023-04-01, 0.02), remains near (2023-10-01, 0.02), increases to (2024-04-01, 0.04), then slightly decreases to (2024-10-01, 0.03), and finally rises sharply to (2024-10-01, 0.08). The red temperature line fluctuates between (2022-10-01, 22), (2023-04-01, 18), (2023-10-01, 30), (2024-04-01, 15), and continues toward (2024-10-01, 20), with visible vertical red spikes. Note: All numerical data values are approximated.Monitored time-series data for (a) FBG_1 system and (b) FBG_2 system