Meteorological Analysis and Comparisons

This document presents all of the timeseries for the meteorological data collected from Wheatfen. Firstly hourly, daily, monthly and annual means are created followed by some main observations.

This workbook then goes through and looks for extremes / anomalies where the monthly averages are compared followed by a comparison between the Wheatfen monthly averages and Coltishall monthly averages (the closest long term weather station from the site).

Creating Timeseries

Figures 1: Mean Annual Temperature

Figure 2: Min, Mean and Max temperatures

The two temperature plots shows definitive annual cycles. The maximum range of temperatures recorded by the station was -8.7 to +36.7 °C on the 21st of January 2018 and 18th of July 2022, respectively.

Figure 3: Total Precipitation

The precipitation bar chart only reports the monthly totals as the scale is significantly different when plotting daily compared to annual totals, simply because we are not using means like the other plots. Below we plot the annual means to look at the summary across each year.

Total precipitation is more variable than other meteorological variables in terms of their annual cycle, however, there is in general a greater amount of precipitation collected in the autumn and winter months. 2018 collected the most precipitation with a annual total of 585.6 mm. Whilst 2017 and 2024 look significantly lower, these are incomplete years. 2022 therefore recorded the lowest amount of precipitation with only 457.0 mm.

Figure 4: Wind Speed

Whilst wind speed is still variable, there is an apparent annual cycle with higher wind speeds in the winter and spring months.

The data collected for wind speed is rather low to what is expected for this part of the UK. Typically we would be looking for approximately 9 ms-1. It is likely that the woodland to the west of the station is blocking the full force of the wind, especially as the wind gage is below the average height for other meteorological stations. A further calibration of the gage should help correct for these low values.

Figure 5: Wind Direction

The dominant wind direction for the site is west / southwest. This reinforces that the wind speeds plotted above are low as the westerly winds are blocked by the woodland and then reaches the gage after being blocked. There is some occurrances of the wind coming from the east and north east.

Figure 6: Relative Humidity

In general the lowest humidy is recorded in the late spring, early summer, and the highest in the winter months.

Figure 7: Solar Insolation

Insolation is very cyclic with clear trends. The differences between the years are very minimal and overall remains stable.

Figure 8: Atmospheric Pressure

There seems to be no clear trend or cycle recorded with the atmospheric pressure. The extremes are recorded during the winter months with both the highest high pressure systems and lowest low pressure systems. There is very marginal differences between the hourly and daily data which is as expected as pressure systems are typically stable for a period of days for high pressure systems, and stable for 24 hours for low pressure systems.

Data Analysis

This next section is for data analysis. Firstly we compare with long term (1991-2020) meteorological data from the MetOffice from Coltishall which is the closest long term meteorological station available, and then the long term data for England. This is important to identify whether there is any unusual anomalies either uncertainties with the meteorological station, or more importantly actual anomalies in the weather patterns which can be used to address possible changes in the monitoring data. We will focus primarily on temperature, total precipitation and wind speed as our main meteorological parameters for this Data Analysis section.

The first plots use just the Wheatfen meteorological data to look at the monthly means across the whole period.

Temperature

The black point with the error bars marks the average temperature across the full monitoring period with minimum and maximum values. If all the months were to follow a really stable trend then we would expect to see all of the years fitting within the errors. However, weather is not that predictable and therefore we can see many years where the different months are not confined to those ranges. Below we will just highlight some interesting take away points from the plot.

Annual trend

Lowest temperatures are recorded in January and from then temperatures increase until they reach their maximum in August where they then continue to decrease. Interestingly, in the mid-latitudes for the Northern Hemisphere, it is expected that maximum temperatures are always reached in July, whereas here maximum temperatures are reached in August.

Anomalies

Interestingly there seems to be more of a larger spread in data during the winter and early spring months with summer and early autumn having most years very close to the mean.

February has the largest spread of data with very low mean temperatures in 2018 (2.4 °C), and high mean temperatures in 2024 (8.17 °C).

Total Precipitation

Precipitation is much more variable than precipitation. February remains the most variable month similar to temperature with a range between 4.6 mm to 84 mm in 2023 and 2024, respectively.

Wind Speed

The annual trend is much clearer when looking at this graph for wind speed. There is clearly maximum winds in Feb and gradually decreases until July and then increases thereafter. The spread of data is more constrained with only February showing a large range.

June and August shows the smallest spreads of data suggesting that during these months, the wind speeds are rather stable and as expected.

2020 wind speed in February is the highest mean for the month at 2.3 ms-1.

Comparison with Coltishall

Now we are going to compare the Wheatfen temperatures and total rainfall with the long term average from Coltishall, the closest meteorological station which has been collecting data for more than 30 years. These averages have use the 1991-2020 mean and are plotted as the black points. The coloured points are then the monthly mean for each month from each year as similar to the plot above.

Coltishall Temperature

In black we have the monthly means from all the years from Wheatfen, in blue we have the Cortishall means, and then finally all the colours representing the individual years.

Comparing the blue and black dots (Cortishall and Wheatfen averages, respectively) we can see that for most of the months there is good agreement between the two sites (e.g. Jan, Mar, May, Aug, Sep, Oct and Nov). The divergence between the two sites are because there is a large spread of data from Wheatfen, through this is expected.

For the most part Cortishall is slightly cooler (though only marginally with less than a degree difference).

Coltishall Precipitation

Concentrating just on the blue and black dots which, as per the previous plot, blue is the Cortishall data and black is the Wheatfen data. There is much more deviance between these two sites which is expected as rainfall is a very local signal. However, in the winter and Spring months there is some consistency and it is the summer and early Autumn which sees the largest changes.