Adjust Station Segments
Description
In order to correct daily historical temperature data for poor thermometer exposure signals, daily fixed hourly or minimum and maximum temperature data need to be adjusted relative to the modern diurnal temperature cycle (e.g., Chenoweth 1998; Bergström and Moberg 2002). This tool transforms the historical and modern temperature data into anomalies relative to their individual time periods. Differences between the fixed hourly or minimum and maximum observations and the same observations in the modern period are then calculated on a monthly basis. These differences yield monthly correction values that are then applied to the input historical data.
Notice of Temperature Assessment
HOB Tools will assess each fixed hourly or minimum and maximum temperature before a final temperature value is calculated and output. A warning message will be generated if any temperature value is ≥ 60°C or ≤ -40°C (e.g., Fig. 1). This allows for detection of temperature data that were incorrectly recorded (e.g., a value of 533 was entered instead of 53).
![]() |
Figure 1. HOB Tools validates that all fixed hourly or minimum and maximum temperatures fall between -40°C and 60°C (inclusive), and generates a warning message if this condition is not met. The message details the temperature value that triggered the warning (purple box) and the exact date where it occurs (red box). It is then up to the user to decide if this potentially unrealistic temperature is acceptable. Select “No” to cancel the station adjustment process. |
Output Data
The output file specified by the user (see "Output" section below) contains the adjusted fixed hourly or minimum and maximum temperature data. An additional file is also output with the word "Adjustments" appended to the end of the name. This file contains the adjustments performed on each fixed hourly or minimum and maximum temperature observation, which can yield potential clues about the thermometer exposure (cf., Chenoweth 1998; Burnette 2009).
Temperature Format
Select the format the daily temperature data. Two different formats are supported--three times daily and two times daily.
Historical Input
Historical Temperature File
Select the historical temperature data to analyze by clicking on "Browse" and navigating to the proper file.
Historical Input Data Format
Year / Month / Day / Data
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".
Temperature Units
Select the proper temperature units for the historical data.
Historical Start Row
This input is the row number where the main data to be processed begin in the historical temperature file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Data Columns
Enter the two or three columns of hourly temperature data in the historical dataset that will be compared to the modern data. An example of how column numbers are entered is shown in Figure 2 located in the Running HOB Tools topic. If "Three Observations Daily" is selected under "Temperature Format" above, then all three input fields will be enabled. If "Two Observations Daily" is selected, then the last field will be disabled (i.e., only two input columns will be required). These data columns must "match" with the selected hours in the “Modern Input” section as shown in Figure 2 (see also "Times to Compare" below).
![]() |
Figure 2. Example of the Adjust Station Segments tool. In this example, column number 4 in the historical dataset must correspond to 7 a.m. temperatures (red), column number 5 must correspond to 2 p.m. temperatures (purple), and column number 6 must correspond to 9 p.m. temperatures (green). The temperature format selected is "Three Observations Daily”, so the “Second Daily Observation” under “Modern Input” is disabled. Neither sunrise nor sunset is a selected time, so the “Sunrise/Sunset File” and “Sunrise/Sunset Start Row” areas are disabled. |
Modern Input
Modern Temperature File
Select the modern temperature data to analyze by clicking on "Browse" and navigating to the proper file.
Modern Input Data Format
Year / Month / Day / 1 a.m. / 2 a.m. / … / 11 p.m. / 12 a.m. / Maximum / Minimum
Each "/" is a tab (i.e., data should be tab-delimited). The “…” denoted above represents 3 a.m. through 10 p.m. Missing data should be denoted as “-99”.
Temperature Units
Select the proper temperature units for the modern data.
Modern Start Row
This input is the row number where the main data to be processed begin in the modern temperature file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Top of the Hour Correction (minutes)
Enter the number of minutes prior to the top of the hour when observations were recorded in the modern temperature record. The default entry is 20 minutes, which was typical of many U.S. stations prior to the establishment of the Automated Surface Observing System (ASOS).
Solar Time Correction (minutes)
Enter the solar time correction in minutes. This allows HOB Tools to extrapolate standard time zones to solar time, so modern observations can be more directly compared to the historical observations recorded prior to the development of standard time zones. If no solar time correction is required, a value of zero can be entered and no correction will be performed.
Second Daily Observation
If "Two Observations Daily" is selected under "Temperature Format" above, then this field will be enabled. Select either an afternoon or an evening time that corresponds to the second fixed hourly observation. “Afternoon” is selected by default, but if “Evening” is selected, then the middle “Times to Compare” drop-down list box will be disabled (Fig. 2, circled in purple) and the list box on the right will be enabled (Fig. 2, circled in green).
Times to Compare
Select the times in the modern dataset that will be compared to the historical data. These selected hours must "match" with the column numbers entered in the “Historical Input” section as shown in Figure 2 (see also "Columns to Compare to Modern Data" above).
Sunrise/Sunset File
If sunrise and/or sunset is selected as one of the "Times to Compare" above, then the modern hourly temperature data will need to be extrapolated to sunrise and/or sunset. HOB Tools will then enable this input area, so the sunrise/sunset data file can be selected. Sunrise and sunset observations are available from the United States Naval Observatory website.
Sunrise/Sunset Input Data Format
If only sunrise is selected:
If only sunset is selected:
If both sunrise and sunset are selected:
Each "/" is a tab (i.e., data should be tab-delimited). Missing data should be denoted as “-99”. These data must start and end on the same day as the modern hourly temperature data input above.
Sunrise/Sunset Start Row
This input is the row number where the main data to be processed begin in the sunrise/sunset data file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic. This field will only be enabled if sunrise or sunset is selected as one of the "Times to Compare" above.
Output
Output File
Select the file where the numerical results will be stored.
Output File Header
Information entered here will be output in the first line of the output file.