The following examples illustrate the use of long-term climate data for
siting, design, and operational planning in Newfoundland and Labrador.
Normally, the lack of moisture is not a major concern for agricultural crops
grown in Newfoundland, so that the need for irrigation water is low or nil. A more
important issue is that of the heat required by the crop to reach maturity with
good yield and quality.
To determine the amount of heat needed to grow a crop, farmers may use
an index called growing degree-days (GDD), which is defined as a day on which the
mean daily temperature is one degree above a "base" or "threshold" temperature.
The "base" temperature, in turn, is defined as the minimum temperature required
for the growth of a particular crop. The base temperature for sweet corn, for
example, is 10 °C while the base temperature for peas is 5°C.
||Potato Gardens, circa 1915.
Potato plants cover the gardens around the homes in Haystack, Placentia Bay.
Courtesy of the Maritime History Archive (Haystack Collection
PF-285-011), Memorial University of Newfoundland, St. John's, Newfoundland.
with more information (47 kb).
The GDD sum is most often set at or near 5°C for most mid-latitude
agricultural crops. The running total or sum is only begun when the average daily
temperature is consistently above the base value in spring (marking the start of
the growing season), and ends when the average daily temperature falls below the
base for several consecutive days in the fall.
Although moisture and other conditions are not taken into account, growing
degree-days serve as a useful guide in forecasting approximate dates of crop
To see how GDD data can be used, let us use potatoes as an example. On a summer
day in Newfoundland, the mean temperature might be 20°C. On this day potatoes
would accumulate (20 C - 5 C) or 15 growing degree days for that day.
Theoretically, potatoes need, as a minimum, 1000 to 1100 growing degree
days to be ready for harvest. If 15 growing degree-days were obtained for each day
of the entire summer, potatoes planted in mid-May would be ready toward the end of
July. Unfortunately, this does not often happen in Newfoundland. Most places barely
achieve between 1100 and 1200 growing degree-days for the entire season. As a
result, potatoes planted in mid-May are usually not harvested until early
The GDD accumulations for selected Newfoundland locations and the probabilities
of these requirements being reached by given dates during the fall, are listed in
the following hyperlinked GDD Table. The larger
version of the map below provides information on growing degree days for the
Annual Number of Growing Degree-Days.
From Joyce and Alan Macpherson, The Natural Environment of Newfoundland and
Labrador, Past and Present (St. John's, Newfoundland: Department of Geography,
Memorial University of Newfoundland and Labrador, © 1981) 106. Adapted by
Duleepa Wijayawardhana with permission of MUNCL, 1998.
with more information (18 kb).
The map shows that the greatest accumulations of growing degree-days
(in celsius), above a base of 5°C, between May and October (averaging 1250-
1350) are for the sheltered lowland areas of the lower Humber Valley, lower
Exploits Valley and the inner parts of Bonavista and Conception bays. However,
from an agricultural viewpoint it should be remembered that the central interior
valleys are prone to a greater frost risk near the start and end of the growth
season. In Labrador the higher degree-day accumulations around Goose Bay, for
the same period, reflect the contributions of (1) heat released from storage in
Lake Melville in early fall, delaying the autumnal cooling and (2) the local
chinook-type heating effects that accompany warm southwesterly winds descending
from the interior plateau.
(2) Water resources planning:
Climatic considerations are clearly essential in planning the optimal location and
design of reservoirs, recognising that other socio-economic considerations apply.
Annual precipitation inputs (P) and runoffs (R), the seasonal timing of the
maximum and minimum amounts, long term variability, and the probability of extreme high
and low P and R, are important factors.
surveys of snow depth and its water equivalent have been conducted over many years for the
Grand Lake and Red Indian Lake basins (west-central Newfoundland) and the Churchill River
basin, Labrador, in order to estimate the volume of spring runoff into major reservoirs.
The accuracy and reliability of these statistics increases with the lengthening of the
available data series.
with more information (16 kb).
with more information (19 kb).
| Alpine Level Snow Survey, Gros Morne National
As part of a research study into the climate and weather of Gros Morne National
Park, a survey of snow cover conditions on the alpine summit area of Big Level
plateau, at elevations near 750 metres, is undertaken at the time of maximum
snow depth in late winter-early spring.
Both images reproduced by permission of Colin Banfield. © 1999.
(3) Urban planning, design and infrastructure:
The fields of urban and building climatology are well established and provide a wide
range of concepts and procedures for incorporating climatic considerations into the planning of
new urban areas, improvements to existing ones and the seasonal maintenance
operations. Examples include:
1. Engineering design and construction of roads and walkways, water supply and storm
drainage systems: required climatic information includes annual temperature regime (especially
the severity of winter frost and its ground penetration, frequency of freeze-thaw cycles);
precipitation amount, types and frequencies through the year, as well as amounts and duration
of snow and ice cover.
2. Urban climatic landscaping: incorporation of local climate characteristics and microclimatic
principles in the design of residential sub-divisions, open spaces and parks, major public
streetscapes (e.g. to reduce effects of high winds and snow drifting, exploit exposure to
||Heavy Snow Accumulation in Urban Area.
A street in St. John's after a heavy snowfall in early 1987.
Reproduced by permission of Colin Banfield. ©1987.
with more information (20 kb).
(4) Transportation and power transmission:
Given the vulnerability of highways and transmission lines to certain forms of
harsh weather, the planning of new or improved sections should
recognise danger areas that are particularly exposed to known weather hazards, and their
avoidance or reduction where possible. This may require temporary installation of weather
monitoring instrumentation to document locally severe conditions, as is the case with the
on-going recording of wind, temperature, precipitation and ice accretion by Newfoundland
Hydro at the Hawke Hills test site on the Avalon peninsula.
|Icing Test and Measurement Site.
Newfoundland Hydro Icing Test and Measurement Site at Hawke Hills near
Reproduced by permission of Colin Banfield. ©1999.
with more information (25 kb).
©2000, Newfoundland and Labrador Heritage Web Site Project