CMOS Bulletin SCMO
Vol. 45, No.2
13
50th Anniversary: Interviews
in these cases for a better assessment of the trends. Therefore, it is with more confidence that we were able to
present our trends results in our papers, and in particular greatest warming during winter and spring (Zhang,
Vincent, Hogg and Niitsoo, 2000), and fewer cold nights, cold day, frost days and more warm nights, warm days
and summer days across Canada (Vincent and Mekis 2006).
Q: What do you perceive was the main impact of this research?
It became quickly obvious that detecting inhomogeneities and adjusting climate datasets requires detailed
information regarding the instruments in use, observing procedures, and also a lot of time. For this reason, in the
early 1990’s, we have created the Adjusted and Homogenized Canadian Climate Data (AHCCD) for use in
climate research. The data have been used by hundreds of people including scientists from meteorological
offices and other federal/provincial agencies, university and high school professors and students, and by the
public in general. The data are available at the Government of Canada Open Data portal
(
http://open.canada.ca/
en/open-data
) and at the Environment Canada website (
http://www.ec.gc.ca/dccha-ahccd/
). Today, scientists
recognize that it is preferable to use homogenized/adjusted data for climate change studies and, in particular, for
climate trends analysis.
Q: How did this research inform your
own goals?
Both studies provide further evidence that,
based on long and high quality
observational records, the climate is
changing in Canada. The changes include
a more pronounced warming in winter and
spring, increase in precipitation in the
north, and decrease in the fraction of
precipitation falling as snow in the south.
The warming is also associated with fewer
cold events and more warm events, more
days with precipitation and a reduction in
the maximum number of consecutive dry
days. No consistent changes were found
in extreme precipitation events. Since
climate
extremes
have
far-reaching
consequences on our society, economy
and environment, it is important to
continue to develop methodologies to
assess changes in extremes events. Since
the publication of both studies, my main research goal has been to continue the development of procedures to
homogenize/adjust temperature and precipitation datasets, but for daily and sub-daily observations, which are
needed for an appropriate assessment of changes in climate extremes.
Q: What are your hopes for climatological research in general in the future?
The climate observing network has changed considerably in Canada since the 1990s due to the downsizing of
the traditional network and increasing use of automated systems. The preferred practice when the observing
system is replaced is to have parallel observations from the collocated instruments for a period of two to five
years in order to develop mathematical relations between the old and new systems, and to derive and apply
adjustments if necessary. The collection of parallel observations has been gradually becoming a practice in
recent years in Canada. However, this practice should be well recognized and applied each time that a new
instrument is used or a new observing procedure is taken place. This should be done especially in the northern
and isolated regions of the country where climate observations are of a great value for climate monitoring and
studying climate change. My colleagues, Ewa Milewska and Éva Mekis, and I are currently developing
methodologies to integrate long-term homogenized temperatures and adjusted precipitations with new
measurements taken at automated systems in order to preserve the continuity of the climate records for use in
climate change analyses.
Trends in annual mean temperature for 1948-2012 (°C for 65 years). Grid
squares with trends statistically significant at the 5% level are marked with
a dot.
CMOS Bulletin SCMO
Vol. 45, No.2
14
50th Anniversary: Interviews
About Lucie
Lucie A. Vincent received her Bachelor’s degree in Mathematics from
l’Université de Sherbrooke in 1984, and her Master’s degree in Statistics from
York University in 1990. She has been working as a scientist for Environment
Canada since 1984. She has published numerous articles in peer reviewed
literature on climate data homogenization/adjustments and climate trends in
Canada. She was an associate editor for the AMS (American Meteorological
Society) State of the Climate reports for 2008 to 2011. She currently co-leads
the CCl (Commission of Climatology) Expert Team on National Climate
Monitoring Products (ET NCMPs) supported by WMO (World Meteorological
Organization) who develops products and software specifications and
requirements for climate monitoring. Lucie is pictured here, in centre, with
colleagues Éva Mekis (on left) and Ewa Milewska (on right).
Paper Summary
Changes in Daily and Extreme Temperature and Precipitation Indices for Canada over the Twentieth Century
:
L.A. Vincent and É. Mekis, 2006
Lucie Vincent and Éva Mekis analyse the trends and variations in several indices of daily and extreme
temperature and precipitation in Canada. The indices are based on homogenized daily temperature and
adjusted daily precipitation. Previous studies on climate change in Canada have shown changes in long-term
annual and seasonal means and it became pertinent to investigate if the warming in Canada was accompanied
by detectable changes in temperature and precipitation extremes. Extreme climate events have the greatest and
most direct impact on our everyday lives, community and environment. The results indicate fewer cold nights,
cold days and frost days and, conversely, more warm night, warm days and summer days across the country for
1950-2003. The results also reveal more days with precipitation, a decrease in the precipitation intensity and a
decrease in the maximum number of consecutive dry days. No consistent changes are found in most of the
indices of extreme precipitation. This study also provides further evidence that the warming in Canada has
changed some of the precipitation from solid to liquid which in turn can have a serious impact on some of the
economics activities in Canada such as agriculture.
Interview with Xuebin Zhang
Xuebin Zhang is the lead author of the paper
Temperature and Precipitation Trends in Canada during the 20
th
Century
(Zhang, Vincent, Hogg and Niitsoo, 2000). This important paper shows clearly the long-term changes in
Canada’s climate.
Q: How did you get interested in this area of research?
I obtained a PhD in Portugal at the University of Lisbon, with a specialization in climatology. I was interested in
climate studies. Prior to 1995, my work was about the impact of climate change on water resources as well as
construction of climate change scenarios. After moving to Canada at the end of 1995 I was looking for a job, and
I was very lucky to be offered a Visiting Fellowship by the Climate Research Branch at the time. The first project
I did in Canada led to this paper.
Q: What was the main impact of this research, and how was it used by other researchers in Canada, or
around the world?
This was the first paper that comprehensively documented long-term trend in Canadian temperature and
precipitation. The paper was very simple, with two main components. One, was methodological development.
There we showed a simple method to reliably and robustly estimate trends in climate series. Because of this (I
*think*), the paper has generated quite a few citations. Most of the citations are in the field of climate research,
where the method we developed is used. The other component is that it was the first paper to systematically
document long-term changes in Canadian temperature and precipitation. This has played an important role to
inform the climate research community, and to some extent policy makers and the general public about
long-term changes in Canadian climate that have been happening.