In 2015 as part of the Canadian Artic Weather Science (CAWS) project, Environment and Climate Change Canada (ECCC) established an enhanced monitoring reference site at Iqaluit, Nunavut (CYFB, 63°45N, 68°33W) in the eastern Canadian Arctic. The site was strategically selected at the loci of synoptic storm tracks and primary transportation corridors. CYFB is also a major aviation hub for the North. It is an operational upper air site with an existing office building and instrument test facility infrastructure with a co-located Double Fence International Reference for solid precipitation measurements. The site was to provide automated and continuous observations of altitude-resolved winds, clouds and aerosols, visibility, radiation fluxes, turbulence, and precipitation. The benefit of integrated measurement systems at the Iqaluit supersite are being investigated to: 1) Recommend the optimal cost-effective observing system for the Canadian Arctic that can complement existing radiosonde observations 2) Provide enhanced meteorological observations during the World Meteorological Organization’s Year of Polar Prediction (WMO YOPP). Instrumentation at Iqaluit includes a Ka-band radar, water vapour lidars (both in-house and commercial versions), multiple Doppler lidars, ceilometers, radiation flux and precipitation sensors, and others. Data collection for a subset of the instruments at Iqaluit began in March 2016.

The Whitehorse enhanced meteorological site is located at Erik Nielsen Whitehorse International Airport (CYXY, 60°43N, 135°04W). This scientific observation site aims to provide a better understanding of the region’s weather conditions to help improve local weather forecasts across the Canadian Arctic and sub-Arctic. For instance, new radar technology is being tested at this site to assess its suitability for detecting and analyzing this region’s weather systems. A companion site in Iqaluit NU (CYFB, 63°45N, 68°33W), in the eastern Canadian Arctic, has also been established. It is important to note that Iqaluit is located above the tree line, while Whitehorse is below, resulting in a significantly more humid atmosphere at Whitehorse suggesting different weather monitoring requirements. The Whitehorse site includes an X-band radar, a Doppler lidar, ceilometers, radiation flux and precipitation sensors, and others. Data collection for a subset of instruments at Whitehorse began in January 2018.

The Regional Air Quality Deterministic Prediction System FireWork (RAQDPS-FW) carries out physics and chemistry calculations, including emissions from active wildfires, to arrive at deterministic predictions of chemical species concentration of interest to air quality, such as fine particulate matter PM2.5 (2.5 micrometers in diameter or less). Geographical coverage is Canada and the United States. Data is available at a horizontal resolution of 10 km. While the system encompasses more than 80 vertical levels, data is available only for the surface level. The products are presented as historical, annual or monthly, averages which highlight long-term trends in cumulative effects on the environment.

The Precipitation Occurrence Sensor System (POSS) is a small X-band 10.525 GHz continuous-wave bi-static vertically pointing Doppler radar. The system reports precipitation occurrence, type and intensity of precipitation at 1-min temporal resolution. Raw measurements are 960 samples per minute. Doppler velocity and return power of hydrometeors intersect the sensing volume near and up to about 3 m above the sensor head. Post-processing of the spectral data produces a results file containing derived precipitation rate and radar reflectivity, for both liquid and solid precipitation assumptions, at 1-minute temporal resolution. The minutely POSS precipitation rates are estimated using two different methods. The “mass flux (MF) method” is for liquid precipitation. The “regression method” or “Z-R method” is used by large-scale precipitation radars where there is a relationship (regression) between radar reflectivity (Z) and precipitation rate (R). POSS units have been deployed at a number of sites worldwide. Datasets are listed as follows, 1) YEU, 2007-07-28 to 2020-03-01 - Eureka, Nunavut, Canada. 2) GNL, 2010-09-15 to 2020-05-01 - Summit Station, Greenland Ice Sheet. 3) CAR, 2011-01-01 to 2019-08-23 - Egbert, Ontario, Canada. 4) YYZ, 2013-06-11 to 2019-05-23 - Toronto Pearson Int. Airport, Ontario, Canada. 5) JAR, 2010-09-17 to 2011-04-20 - Jarvenpaa (40 km N of Helsinki), Finland. 6) EMA, 2010-09-18 to 2010-10-22 - Emasalo (50 km E of Helsinki), Finland.

The main radar covering the Toronto Area is the King City Doppler Dual-Polarization C-Band radar (43.96388, -79.57416). Other nearby radars include the Exeter Doppler C-Band radar (43.37027,-81.38416) and the Buffalo Doppler Dual-Polarization S-Band radar (42.94889,-78.73667) from the United States. Though the primary radar for the project is the King City radar, the raw data from all three radars are included in their native format (IRIS or Nexrad Level 2) and are intended for radar specialists. The data is available from May 1 2015 to Sept 30 2015. The scan strategy for each radar is different, with at least 10 minute scan cycles or better. The user should consult with a radar specialist for more details. Reflectivity and radial velocity images (presented as a pair) for the lowest elevation angle (0.5o) centred on a 128 km x 128 km box around from the King City radar are provided for general use. Besides their normal use as precipitation observations, they are particularly useful to identify Lake Breezes as weak linear reflectivity and as radial velocity discontinuity features for the entire period. The target providing the radar returns are insects. Analysis indicates the presence of Lake Breezes on 118 days, only 35 days did not have any kind of lake breeze-like features. Daily movies have been created. The format of the single images is PNG and the movies is an animated GIF. The data is organized by radar and by day in the following structure. The raw data is organized in the following directory structure: RADAR - greater than lesser than WKR|WSO|BUF greater than - greater than YYYY - greater than YYYYMM - greater than YYYYMMDD; where YYYY is the appropriate year (always 2015), MM is the month, DD is the day. The images are organized as: RADAR - greater than QUICKLOOK - greater than YYYY - greater than YYYYMM - greater than YYYYMMDD; where YYYY is the year, MM is the month, DD is the day. The movies are located in the YYYYMMDD folders and are named as YYYYMMDD_movie.gif

Short-duration rainfall intensity-duration-frequency (IDF) statistics in the form of tables and graphs with accompanying documentation for 549 locations across Canada. These files can be downloaded for each province, territory or for all of Canada.

Climate observations are derived from two sources of data. The first are Daily Climate Stations producing one or two observations per day of temperature, precipitation. The second are hourly stations that typically produce more weather elements e.g. wind or snow on ground.

The Canadian Meteorological Centre (CMC) produces Numerical Weather Prediction (NWP) as one of the key inputs to the Meteorological Service of Canada's overall public weather and environmental prediction and warning process. The raw data from NWP is made available to outside users who may use it for their own purposes. As NWP data is an early input into the overall MSC public forecast process, it may differ from the official forecast.

The Regional Deterministic Precipitation Analysis (RDPA) produces a best estimate of precipitation amounts that occurred over a period of 24 hours. The estimate integrates data from in situ precipitation gauge measurements, weather radar, satellite imagery and numerical weather prediction models. Geographic coverage is North America (Canada, United States and Mexico). Data is available at a horizontal resolution of 10 km. The 24 hour analysis is produced twice a day and is valid at 06 and 12 UTC. A preliminary analysis is available approximately 1 hour after the end of the accumulation period and a final one is generated 7 hours later in order to assimilate more gauge data.

Mesoscale boundaries have an important influence on mesoscale weather. They can trigger, enhance or inhibit convections and severe weather. They are also indicators of shifts in wind speed and direction, temperature and relative humidity, and can affect air quality and heat indices. Around the Great Lakes, it has been observed that mesoscale boundaries are prevalent and can have complex interactions between each other. A mesoscale boundary is the interface between two air masses for weather phenomenon on a scale of 5km to 100km. Mesoscale boundaries are generally associated with wind and differences in temperature, pressure and relative humidity. During the 2015 Pan Am and Parapan Am Games periods, boundary information were collected from July 10 to August 15, 2015. These included lake and land breeze fronts, outflow boundaries, as well as merged and other boundaries. Each mesoscale boundary is represented as a curve on the surface of the Earth with a list of coordinates. The data are stored in GeoJSON format and Shapefiles. A CSV file summarizes all the properties of the boundaries, but does not include any geometric information.