• Skip to primary navigation
  • Skip to content
  • Skip to primary sidebar
  • Skip to footer
Jennifer Marohasy

Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

  • Home
  • About
  • Publications
  • Speaker
  • Blog
  • Temperatures
  • Coral Reefs
  • Contact
  • Subscribe

Infilling missing data

Ideally weather records would be complete for every station – no missing values for any day, month or year. Unfortunately, in reality many values are missing. An example of a temperature record, with several monthly values missing, is shown below. The Rochester record spans a total of 416 months, of which 118 are missing.

Possible reasons that data values are missing from weather records are given below.

  • Historically – and still in several weather stations today – weather measurements are taken by human observers. If the human observer is absent, there are no observations for that day (or period of absence).
  • Equipment may fail, and until replacements arrive there are no observations.
  • Stations may be closed down and opened again later, or moved to a new location.
  • Extreme weather events, such as floods, may damage or destroy weather stations, taking them offline for a period of time.
  • Some observations may fail quality control checks and may be removed from the record.

If too many daily values are missing, an accurate monthly average value cannot be calculated and is better left out. Missing daily values become missing monthly values, which likewise become missing annual values.

What can be done to improve this situation? The missing values can be estimated to infill the incomplete record. There are generally two approaches to perform infilling:

  1. Data from the same record can be used to estimate the missing values. For example, to estimate a missing January value from a monthly record (such as the Rochester one shown above), the average of all available January values can be used as substitute.
  2. Data from neighbouring stations can be used to estimate missing values.

The drawback of approach 1 above is its inability to infer extraordinary events. Suppose the missing January mentioned above were exceptionally cold. It would not be possible to tell this by looking at other measurements from the same site. A better approach in this case would be to investigate neighbouring weather stations – those that do have a value recorded for the date that is missing.

The missing value can then be recovered by combining data from neighbouring stations, and exploiting the known historical differences between the station under question and its neighbours.

More technical details are available in this report.

Go back to temperature information table

Primary Sidebar

Latest

Why Craig Kelly Resigned on Tuesday

February 26, 2021

Priorities, Life is a Journey – And Happy Birthday to My Daughter

February 19, 2021

Fly-Past Coral Surveys, And

February 11, 2021

Naming a First Old Porites, Craig

February 5, 2021

Don’t Cancel Craig Kelly MP, Debate Him

February 3, 2021

Recent Comments

  • Gary Parker on Why Craig Kelly Resigned on Tuesday
  • Richard Bennett on Why Craig Kelly Resigned on Tuesday
  • steve craig on Why Craig Kelly Resigned on Tuesday
  • Allan Cox on Why Craig Kelly Resigned on Tuesday
  • Damien Rogers on Why Craig Kelly Resigned on Tuesday

Subscribe For News Updates

  • This field is for validation purposes and should be left unchanged.
February 2021
M T W T F S S
« Jan    
1234567
891011121314
15161718192021
22232425262728

Archives

Footer

About Me

Jennifer Marohasy Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation. Read more

Subscribe For News Updates

Subscribe Me

Contact Me

To get in touch with Jennifer call 0418873222 or international call +61418873222.

Email: jennifermarohasy at gmail.com

Connect With Me

  • Facebook
  • Google+
  • LinkedIn
  • RSS
  • Twitter
  • YouTube

Copyright © 2014 - 2018 Jennifer Marohasy. All rights reserved. | Legal

Website by 46digital