Speedwell Recalibrated Datasets re-base historical temperature data for important
reference sites by adjusting for known or observed discontinuities that have accumulated
over the lifetime of the observations. Discontinuities may arise from instrumentation
changes or changes in the location of the measuring instruments.
"Recalibrated data is the best possible baseline for risk analysis"
Why Recalibrated data is crucial:
- Houston (KIAH): discontinuity in previous decade equivalent to > 200 HDD on a
seasonal basis
- Kansas (KMCI): repeated discontinuities in current decade equivalent to circa 100
HDD on a seasonal basis
- Philadelphia (KPHL): discontinuity corresponding to > 200 HDD on a seasonal basis
in previous decade
- Dallas (KDFW): large warming and cooling discontinuities due to recent station changes
Impact of station moves on the KIAH historical record (minimum temperature)
What is a Discontinuity?
A discontinuity is a sudden, distinct, and continuous change in the long term observations
for a site. A discontinuity represents an end of one continuous regime and the beginning
of another. A discontinuity is not a trend. Temperature discontinuities can take
the form of warmer or cooler temperatures and / or changes in the variance of the
observations. Corrections for all aspects of the discontinuity are important.
Discontinuity: a sudden, distinct, and lasting change
Recalibration Theory
Let's suppose that for every location (airport) you have an ideal station (no moves, changes) and a real-world station.
By comparing the difference between the two time series you can detect discontinuities created by the real-world changes to the station.
Unfortunately, ideal stations do not really exist.
The solution is to create your own ideal station. This is accomplished by modelling an ideal station using data from surrounding stations.
The modelled ideal station is known as the reference time series.
We are then able to statistically analyse the difference time series (DTS) for discontinuities.
These results coupled with an understanding of the stations history (metadata) allows
one to accurately detect and quantify discontinuities.
Who should use Speedwell Recalibrated Datasets?
Weather Derivatives Traders - critical for pricing of weather risk contracts
where such adjustments are financially material in the modelling of current behaviour
of a weather reference site.
Energy Demand Modellers- important for demand modelling and those seeking
a precise understanding of current "climatology" at a given site.
Meteorologists / Climatologists - recalibrated data serves as an accurate baseline for comparison
when forecasting or making comparisons against "normal".
Speedwell Recalibrated Datasets (What is included?)
The Speedwell Recalibrated Datasets bring an unprecedented level of sophistication
to the process of recalibration combined with transparency of method and a unique real time
web-based service for monitoring the ongoing behaviour of the reference site.
Speedwell Recalibrated Datasets are provided on a subscription basis and are available
for individual sites or packs. Subscribers receive access to the Recalibrated Dataset
pack, the Monthly Report, Airport Maps, and the Real-Time Web Monitor.
Recalibrated Datasets Pack
Delivered on initial subscription and then updated on a six month cycle the pack comprises:
- Raw meteorological observation dataset as provided by the relevant National Met
Service.
- Cleaned dataset (erroneous observations replaced and missing values filled).
- Speedwell Recalibrated Dataset (cleaned data that has been adjusted to remove discontinuities).
- Recalibrated data supporting documentation:
- Station overview with commentary.
- Information regarding the proxy stations used and the creation of the synthetic
time series.
- Graphical representation of the statistical analysis.
- Station metadata - the most comprehensive archive available (includes an airport
change analysis diagram).
- Discontinuity table with comments.
- Valuation impact on monthly HDD and CDD values of the Speedwell Recalibrated Dataset
compared with the cleaned dataset.
Monthly Report
Monthly report detailing changes in recent station behaviour with meteorological
commentary, metadata updates, and the notification of future station changes.
Airport Maps
For US CME sites, the Speedwell Recalibrated Datasets subscription provides access to an on-line archive of annotated airport maps in one year time steps.
This helps the user to understand how recent site developments may impact on behaviour.
Real-Time Web Monitor
Subscribers to the Speedwell Recalibrated Dataset are provided with access to web-delivered
software that allows the user to see the latest performance of the primary site
against a synthetic basket of nearby sites. The user is able to plot moving averages
and difference series for different periods to view recent trends. Key statistics
are summarised in an easy-to-read sortable table for all subscribed sites. This
is updated daily showing any significant recent moves.
