The SSC is now being run in near-real time for all stations for which NCEI has the requisite data (which is nearly all).
The missing 2011-2013 data for many Canadian stations have been added.
Many new SSCs are available for North America and Europe and the Mediterranean; there are now more than 800 stations.
Synoptic weather-typing and the SSC
Synoptic weather-typing - the classification of ambient weather conditions into
categories - is a useful tool for numerous climate impact applications. On this website,
the classifications produced by one such scheme, the Spatial Synoptic Classification
(SSC), are presented.
The SSC is a hybrid classification scheme, based on both manual and automated
processes. Initially, weather type (see right) identification was made manually for
each of the weather types, based on climatological knowledge. As the character
associated with these weather types changes from season to season, typical days in each
type- "seed days"- were picked for each station for different times of the year.
Algorithms then develop hypothetical seed days for each of the 365 days of the year.
Once this process is complete, actual conditions on each day were compared to the
seed days, and the day ends up being classified as the one it most closely resembles.
Hence, when the process is complete, a weather type 'calendar' is available, whereby
each day in a station's period of record is classified into one of the weather types.
In order to increase spatial cohesion, seed days were transferred to geographically
neighboring stations, thus creating a true spatial grid of weather types.
DP (dry polar) is synonymous with the traditional cP air mass classification. This air mass is
generally advected from polar regions around a cold-core anticyclone, and is usually associated with the lowest
temperatures observed in a region for a particular time of year, as well as clear, dry conditions.
DM (dry moderate) air is mild and dry. It has no traditional analog, but is often found
with zonal flow in the middle latitudes, especially in the lee of mountain ranges. It also arises when a traditional
air mass such as cP or mT has been advected far from its source region and has thus modified considerably.
The DT (dry tropical) weather type is similar to the cT air mass; it represents the hottest
and driest conditions found at any location. There are two primary sources of DT: either it is advected from the
desert regions, such as the Sonoran or Sahara Desert, or it is produced by rapidly descending air, whether via
orography (such as the chinook) or strong subsidence.
MP (moist polar) air is a large subset of the mP air mass; weather conditions are
typically cloudy, humid, and cool. MP air appears either by inland transport from a cool ocean, or as a result of
frontal overrunning well to the south of the region. In can also arise in situ as a modified cP air mass, especially
downwind of the Great Lakes.
MM (moist moderate) is considerably warmer and more humid than MP. The MM air mass typically
appears in a zone south of MP air, still in an area of overrunning but with the responsible front much nearer. It
can also arise within an mT air mass on days when high cloud cover suppresses the temperature.
MT (moist tropical), analogous to the traditional mT air mass, is warm and very humid.
It is typically found in warm sectors of mid-latitude cyclones or in a return flow on the western side of an anticyclone;
as one approaches the tropics this weather type dominates. MT+ (moist tropical plus) is a subset of MT that
was derived after the initial classification, to account for the lack of utility of a weather-type scheme in the warm
subtropics when one weather type dominates most of the year. It is defined as an MT day where both morning and afternoon apparent
temperatures are above seed day means, and thus captures the most "oppressive" subset of MT days.
MT++ (moist tropical double plus) is an occasionally used subset of
MT+, in which morning and afternoon apparent temperatures average out to being
at least one standard deviation above seed day means.
TR (transitional) days are defined as days in which one weather type yields to another, based
on large shifts in pressure, dew point, and wind over the course of the day.
Development of the SSC
Larry Kalkstein and Scott Greene are two principal developers of the original SSC, created in the mid-1990s for all
stations east of the Rockies within the US. Calendars were originally available for
only winter and summer. Kalkstein et al. (1996) contains a detailed discussion of
this original system.
The SSC was then later redeveloped to be able to classify days year-round; an
expansion was also done geographically to include more than 300 stations across the
US and Canada. The "SSC2" - which is what is featured on this site - is written
up in significant detail in Sheridan (2002). As this version is now the only available
version of the SSC, it is usually just written as "SSC" and not "SSC2".
Later expansions of the SSC have taken the SSC global.
Donna Bower, as part of her dissertation, worked with Glenn McGregor and Scott Sheridan to
expand the SSC to Western Europe. Whereas the US and Canada classifications all began
from one origin, the European classifications began from multiple origins in station
'clusters'. More detail on this methodology can be found in Bower al. (2007).
Other extensions of the SSC include stations in South Korea, Brazil, and Russia.
What the SSC is
The SSC is based solely on surface based observations at an individual
station. Four-times daily observations of temperature, dew point, wind, pressure, and
cloud cover are incorporated into the model. It does not take upper-level conditions
into account, and does not concern itself with the origin of the air above a
station, though there are obvious correlations. Hence, the SSC is most properly
called a weather type classification and not an air mass classification
Within the SSC scheme, weather-type characteristics change from station to station
and day to day. Thus, a Moist Tropical weather type is hotter and more humid in the
southeastern US, nearer its source region, than in the northeastern US, after it has
modified somewhat. Similarly, MT is warmer at all locations in July than in January.
You can look up an air mass climatology for a particular station on the left.
Available data sets
On this website, SSC "calendars" are available for nearly 400 stations across the US,
Canada, and parts of Europe. The European calendars are limited to 1974-2000, but the
US and Canadian calendars generally cover a station's total period of record. A total of over
8,000,000 days have been classified across all of these stations. The SSC is also
being continually updated - you can see yesterday's (preliminary) classifications and
today's and tomorrow's forecast classifications as well. The "official" SSC calendar
for a year will be added to this site within a couple of months of the calendar year's
These data are free to be used in research, as long as proper citation is given.
The SSC is not free to use for any commercial purpose, and the classification program
is not publicly available.
If you have any questions, comments, or notice any errors, please e-mail me. Thanks!
Below is a list of known articles that have incorporated the SSC into their research design.
An overview of the use of the SSC in climate-health relationships is nicely detailed in Hondula et al. 2013 and Dixon et al. 2016. If any SSC-related publications are missing, please let me know!
- Ashley, W. S., Bentley, M. L., and Stallins, J. A., 2012: Urban-induced thunderstorm modification in the Southeast United States. Climatic change, 113(2), 481-498.
- Ballinger, T.J. and Sheridan, S.C., 2016. Sea ice impacts on polar surface weather types in the North American Arctic. Climate Research, 67(2), pp.117-134.
- Bentley, M. L., Ashley, W. S., and Stallins, J. A., 2010: Climatological radar delineation of urban convection for Atlanta, Georgia. International Journal of Climatology, 30(11), 1589-1594.
- Bentley, M. L., Stallins, J. A., and Ashley, W. S., 2012: Synoptic environments favourable for urban convection in Atlanta, Georgia. International Journal of Climatology, 32(8), 1287-1294.
- Blandford, T, et al., 2008. Seasonal and synoptic variations in near-surface air temperature lapse rates in a mountainous basin. Journal of Applied Meteorology and Climatology, 47, 249-261.
- Bower, D., G. R. McGregor, D. Hannah, S.C. Sheridan, 2007: Development of a Spatial Synoptic Classification Scheme for Western Europe. International Journal of Climatology, 27, 2017-2040.
- Brazel, A., et al., 2007: Determinants of changes in the regional urban heat island in metropolitan Phoenix (Arizona, USA) between 1990 and 2004. Climate Research, 22, 171-182.
- Budikova, D., Ford, T.W., and Ballinger, T.J., 2017: Connections between north-central United States summer hydroclimatology and Arctic sea ice variability. International Journal of Climatology.
- Cakmak, S., and C. Hebbern. "Pollution levels and the effect of air pollution on asthma hospitalisations modified by synoptic weather type and aeroallergens." Air Pollution XXII 183 (2014): 191.
- Cakmak, S., Hebbern, C., Pinault, L., Lavigne, E., Vanos, J., Crouse, D. L., & Tjempka, M. (2018).Associations between long-term PM2.5 and ozone exposure and mortality in the Canadian Census Health and Environment Cohort (CANCHEC), by spatial synoptic classification zone. Environment International, 111, 200-211.
- Cakmak, S., Hebbern, C., Vanos, J., Crouse, D. L., & Burnett, R. (2016). Ozone exposure and cardiovascular-related mortality in the Canadian Census Health and Environment Cohort (CANCHEC) by spatial synoptic classification zone. Environmental Pollution, 214, 589-599.
- Chow, W.T.L. and B. M. Svoma, 2011: Analyses of noctural temperature cooling rate response to historical local-scale urban land-use/land-cover change. Journal of Applied Meteorology and Climatology, 50, 1872-1884.
- Davis, R.E., C.P. Normile, L. Sitka, D.M. Hondula, D.B. Knight, S.P. Gawtry, and P.J. Stenger, 2010: A comparison of trajectory and air mass approaches to examine ozone variability. Atmospheric Environment, 44, 64-74.
- Davis, R.E., C.E. Rossier, and K.B. Enfield, 2012: The impact of weather on influenza and pneumonia mortality in New York City, 1975-2002: a retrospective study. PlosOne
- Delavau, C., et al. "North American precipitation isotope (δ18O) zones revealed in time series modeling across Canada and northern United States." Water Resources Research 51.2 (2015): 1284-1299.
- Dixon, P.G., and T.L. Mote, 2003: Patterns and causes of Atlanta's Urban Heat-Island Precipitation. Journal of Applied Meteorology, 42, 1273-1284.
- Dixon, P. G., Allen, M., Gosling, S. N., Hondula, D. M., Ingole, V., Lucas, R., & Vanos, J. (2016). Perspectives on the Synoptic Climate Classification and its Role in Interdisciplinary Research. Geography Compass, 10(4), 147-164.
- Dolney, T.J., and S.C. Sheridan, 2006: The relationship between extreme heat and ambulance calls for the city of Toronto, Ontario, Canada. Environmental Research, 101, 94-103.
- Dyer, J.L. and T.R. Mote, 2007: Trends in snow ablation over North America. International Journal of Climatology 27, 739-748.
- Fuhrmann, C. M., Konrad, C. E., Kovach, M. M., and Perkins, D. J., 2011: The August 2007 Heat Wave in North Carolina: Meteorological Factors and Local Variability. Physical Geography, 32(3), 217-240.
- Girardin, M.P., Berglund, E., Tardif, J., and Monson, K. 2005 Radial growth of tamarack (Larix laricina) in the Churchill area (Manitoba) in relation to climate and larch sawfly (Pristiphora erichsonii) herbivory. Arctic, Antarctic, and Alpine Research 37: 206-217.
- Greene, S., Kalkstein, L. S., Mills, D. M., and Samenow, J., 2011: An Examination of Climate Change on Extreme Heat Events and Climate-Mortality Relationships in Large US Cities. Weather, Climate, and Society, 3(4), 281-292.
- Grundstein, A., 2003: A synoptic-scale climate analysis of anomalous snow water equivalent over the Northern Great Plains of the USA. International Journal of Climatology, 23, 871-886.
- Haberlie, A. M., Ashley, W. S., & Pingel, T. J. (2015). The effect of urbanisation on the climatology of thunderstorm initiation. Quarterly Journal of the Royal Meteorological Society, 141(688), 663-675.
- Hanna, A. F., Yeatts, K. B., Xiu, A., Zhu, Z., Smith, R. L., Davis, N. N., ... and Pinto, J. P., 2011: Associations between ozone and morbidity using the Spatial Synoptic Classification system. Environmental Health, 10(49), 15.
- Hardin, A.W. and J.K. Vanos, 2017: The influence of surface type on the absorbed radiation by a human under hot, dry conditions.
International Journal of Biometeorology.
- Hardin, A.W., Y. Liu, G. Cao, and J.K. Vanos, 2017: Urban heat island intensity and spatial variability by synoptic weather type in the northeast US. Urban Climate.
- Hayhoe, K., S. C. Sheridan, L.S. Kalkstein, and J.S. Greene, 2010: Climate change, heat waves, and mortality projections for Chicago. Journal of Great Lakes Research, 36, 65-73.
- Hebbern, C., & Cakmak, S. (2015). Synoptic weather types and aeroallergens modify the effect of air pollution on hospitalisations for asthma hospitalisations in Canadian cities. Environmental Pollution, 204, 9-16.
- Hildebrandt, M. L. (2015). An Analysis of Air Masses Associated with Federal Ozone Exceedances Across St. Louis, Missouri: 2001–2010. Papers in Applied Geography, 1(1), 73-78.
- Hondula, D.M. and R.E. Davis, 2010: Climatology of winter transition days for the contiguous US, 1951-2007. Theoretical and Applied Climatology.
- Hondula, D. M., Sitka, L., Davis, R. E., Knight, D. B., Gawtry, S. D., Deaton, M. L., ... and Stenger, P. J., 2010: A back.trajectory and air mass climatology for the Northern Shenandoah Valley, USA. International Journal of Climatology, 30(4), 569-581.
- Hondula, D. M., Davis, R. E., Knight, D. B., Sitka, L. J., Enfield, K., Gawtry, S. B., ... and Lee, T. R., 2013: A respiratory alert model for the Shenandoah Valley, Virginia, USA. International journal of biometeorology, 57(1), 91-105.
- Hondula, D. M., J. K. Vanos, and S. N. Gosling. "The SSC: a decade of climate–health research and future directions." International journal of biometeorology 58.2 (2014): 109-120.
- Huang, J., Tardif, J. C., Bergeron, Y., Denneler, B., Berninger, F., and Girardin, M. P., 2010: Radial growth response of four dominant boreal tree species to climate along a latitudinal gradient in the eastern Canadian boreal forest. Global Change Biology, 16(2), 711-731.
- Jing, P., Lu, Z., & Steiner, A. L. (2017). The ozone-climate penalty in the Midwestern US. Atmospheric Environment.
- Kalkstein, A.J. and R.C. Balling Jr., 2004: Impact of unusually clear weather on United States daily temperature range following 9/11/2001. Climate Research, 26, 1-4.
- Kalkstein, A. J., Kuby, M., Gerrity, D., and Clancy, J. J., 2009: An analysis of air mass effects on rail ridership in three US cities. Journal of Transport Geography, 17(3), 198-207.
- Kalkstein, L.S., J.S. Greene, D.M. Mills, A.D. Perrin, J.P. Samenow, and J.-C. Cohen, 2007: The development of analog European heat waves for U.S. cities to analyze the impacts on heat-related mortality. Bulletin of the American Meteorological Society, 88.
- Kalkstein, L.S., C.D. Barthel, M.C. Nichols, and J.S. Greene, 1996: A New Spatial Synoptic Classification: Application to Air Mass Analysis, International Journal of Climatology, 16:983-1004.
- Kim, H. C., Choi, H., Ngan, F., & Lee, P. (2014). Surface Ozone Variability in Synoptic Pattern Perspectives. In Air Pollution Modeling and its Application XXIII (pp. 551-556). Springer International Publishing.
- Kim, Y. M., Kim, J., Jung, K., Eo, S., Ahn, K. (2018). The effects of particulate matter on atopic dermatitis symptoms are influenced by weather type: Application of spatial synoptic classification (SSC). International Journal of Hygiene and Environmental Health.
- Knight, D.B., R.E. Davis, S.C. Sheridan, D.M. Hondula, L.J. Sitka, M. Deaton, T.R. Lee, S.D. Gawtry, P.J. Stenger, F. Mazzei, and B.P. Kenny, 2008: Increasing frequencies of warm and humid air masses over the conterminous United States from 1948 to 2005. Geophysical Research Letters, 35, L10702.
- Kysely, J. and Huth, R., 2010: Relationships between summer air masses and mortality in Seoul: comparison of weather-type classifications. Physics and Chemistry of the Earth, Parts A/B/C, 35(9), 536-543.
- Labosier, C.F., O.W. Frauenfeld, S.M. Quiring,, and C.W. Lafton, 2014: Weather type classification of wildfire ignitions in the central Gulf Coast, United States. International Journal of Climatology, in press.
- Lacke, M. C., Mote, T. L., and Shepherd, J. M., 2009: Aerosols and associated precipitation patterns in Atlanta. Atmospheric Environment, 43(28), 4359-4373.
- Leathers, D.J., D.Y. Graybeal, T. Mote, 2004: The role of air mass types and surface energy fluxes in snow cover ablation in the central Appalachians. Journal of Applied Meteorology, 43, 1887-1898.
- Leathers, D.J., T.L. Mote, A.J. Grundstein, D.A. Robinson, K. Felter, K. Conrad, L. Sedywitz, 2002: Associations between continental-scale snow cover anomalies and air mass frequencies across eastern North America. International Journal of Climatology, 22. 1473-1494.
- Lee, C. C., Ballinger, T. J., and Domino, N. A., 2012: Utilizing map pattern classification and surface weather typing to relate climate to the Air Quality Index in Cleveland, Ohio. Atmospheric Environment.
- Lee, C.C., S.C. Sheridan, and S. Lin, 2013: Relating weather types to asthma-related hospital admissions in New York State. EcoHealth, 9, 424-439.
- Leung, A. and W. Gough, 2015: Air mass distribution and the heterogeneity of the climate change signal in the Hudson Bay/Foxe Basin region, Canada. Theoretical and Applied Climatology, 12 pp.
- Liu, Y. C.J. Paciorek, and P. Koutrakis, 2009: Estimating regional spatial and temporal variability of PM2. 5 concentrations using satellite data, meteorology, and land use information. Environmental Health Perspectives, 117, 886-892.
- Liu, Z., Bowen, G. J., and Welker, J. M., 2010: Atmospheric circulation is reflected in precipitation isotope gradients over the conterminous United States. Journal of Geophysical Research: Atmospheres (1984.2012), 115(D22).
- Liu, Z., Bowen, G. J., Welker, J. M., and Yoshimura, K., 2012: Winter precipitation isotope slopes of the contiguous USA and their relationship to the Pacific/North American (PNA) pattern. Climate Dynamics, 41, 1-18.
- Makra, L., Puskás, J., Matyasovszky, I., Csépe, Z., Lelovics, E., Bálint, B., & Tusnády, G. (2014). Weather elements, chemical air pollutants and airborne pollen influencing asthma emergency room visits in Szeged, Hungary: performance of two objective weather classifications. International journal of biometeorology, 1-21.
- Merrill, R.M., E.C. Shields, G.L. White Jr., D. Druce, 2005: Climate conditions and Physical Activity in the United States. American Journal of Health Behavior, 29, 371-381.
- Metzger, K. B., Ito, K., and Matte, T. D., 2010: Summer heat and mortality in New York City: how hot is too hot?. Environmental health perspectives, 118(1), 80.
- Mote, T.L., M.C. Lacke, J.M. Shepherd, 2007: Radar signatures of the urban effect on precipitation distribution:
A case study for Atlanta, Georgia. Geophysical Research Letters, 34, doi:10.1029/2007GL031903
- Oswald, E. M., Rood, R. B., Zhang, K., Gronlund, C. J., O'Neill, M. S., White-Newsome, J. L., ... and Brown, D. G., 2012: An Investigation into the Spatial Variability of Near-Surface Air Temperatures in the Detroit, Michigan, Metropolitan Region*. Journal of Applied Meteorology and Climatology, 51(7), 1290-1304.
- Power, H.C., S.C. Sheridan, and J.C. Senkbeil, 2006: Synoptic climatological influences on the spatial and temporal variability of aerosols over North America. International Journal of Climatology, 26, 723-741.
- Quiring, S; Goodrich, G., 2008. Nature and causes of the 2002 to 2004 drought in the southwestern United States compared with the historic 1953 to 1957 drought. Climate Research, 36, 41-52.
- Rainham, D.G.C., K.E. Smoyer-Tomic, S.C. Sheridan, and R.T. Burnett, 2005: Synoptic weather patterns and modification of the association between air pollution and human mortality. International Journal of Environmental Health Research, 15, 347-360.
- Robinson, P.J., 2006: Implications of long-term precipitation amount changes for water sustainability in North Carolina. Physical Geography, 27, 286-296.
- Scheitlin, K.N. and P.G. Dixon, 2010: Diurnal temperature range variability due to land cover and airmass types in the southeast. Journal of Applied Meteorology and Climatology, 49, 879-888.
- Scheitlin, K.N., 2013: The Maritime Influence on Diurnal Temperature Range in the Chesapeake Bay Area. Earth Interact., 17, 1–14.
- Seidel, T; Grant, A; Pszenny, A; Allman, D., 2007: Dewpoint and humidity measurements and trends at the summit of Mount Washington, New Hampshire, 1935-2004. Journal of Climate, 202, 5629-5641.
- Senkbeil, J.C., J.C. Rodgers, and S.C. Sheridan, 2007: The sensitivity of tree growth to air mass variability and the Pacific Decadal Oscillation in coastal Alabama. International Journal of Biometeorology, 51, 483-492.
- Shem, W. and M. Shepherd, 2009: On the impact of urbanization on summertime thunderstorms in Atlanta: two numerical model case studies. Atmospheric Research, 92, 172-189.
- Sheridan, S.C., 2003: North American weather-type frequency and teleconnection indices. International Journal of Climatology, 23, 21-45.
- Sheridan, S.C., 2004: The development of heat-warning systems for cities worldwide. In WorldMinds: Geographical Perspectives on 100 Problems, Association of American Geographers, D.G. Janelle, B. Warf, K. Hansen, eds., 487-492.
- Sheridan, S.C. and T.J. Dolney, 2003: Heat, mortality, and level of urbanization: Measuring vulnerability across Ohio, USA. Climate Research, 24, 255-265.
- Sheridan, S.C., and A.J. Kalkstein, 2010: Seasonal variability in heat-related mortality across the United States. Natural Hazards, 55, 291-305.
- Sheridan, S.C. A.J. Kalkstein, and L.S. Kalkstein, 2009: Trends in heat-related mortality in the United States, 1975-2004. Natural Hazards, 50, 145-160.
- Sheridan, S.C. and L.S. Kalkstein, 2004: Progress in Heat Watch-Warning System Technology. Bulletin of the American Meteorological Society, 85, 1931-1941.
- Sheridan, S.C. and L.S. Kalkstein, 2004: A synoptic Climatological approach to separate weather- and pollution-induced impacts on human mortality. Epidemiology, 15, S40.
- Sheridan, S.C., C.C. Lee, M.J. Allen, and L.S. Kalkstein, 2012: Future heat vulnerability in California Part I: Projecting future weather types and heat events. Climatic Change, 115, 291-309.
- Sheridan, Scott C., and Shao Lin. "Assessing variability in the impacts of heat on health outcomes in New York City over time, season, and heat-wave duration." Ecohealth 11.4 (2014): 512-525.
- Sheridan, S.C, H.C. Power, and J.C. Senkbeil, 2007: A further analysis of the spatio-temporal variability in aerosols across North America: incorporation of lower-tropospheric flow. International Journal of Climatology, in press.
- Stallins, J. A., Carpenter, J., Bentley, M. L., Ashley, W. S., & Mulholland, J. A. (2013). Weekend.weekday aerosols and geographic variability in cloud-to-ground lightning for the urban region of Atlanta, Georgia, USA. Regional Environmental Change, 13(1), 137-151.
- Sullivan, R. C., R. C. Levy, and S. C. Pryor. "Spatiotemporal coherence of mean and extreme aerosol particle events over eastern North America as observed from satellite." Atmospheric Environment 112 (2015): 126-135.
- Vanos, J. K., & Cakmak, S. (2014). Changing air mass frequencies in Canada: potential links and implications for human health. International journal of biometeorology, 58(2), 121-135.
- Vanos, J.K., S. Cakmak, C. Bristow, V. Brion, N. Tremblay, S.L. Martin, and S.C. Sheridan, 2013: Synoptic weather typing applied to air pollution mortality among the elderly in 10 Canadian cities. Environmental Research, 10 pp., in press.
- Vanos, J. K., L. S. Kalkstein, and T. J. Sanford. "Detecting synoptic warming trends across the US Midwest and implications to human health and heat‐related mortality." International Journal of Climatology 35.1 (2015): 85-96.
- Vanos, J.K., Cakmak, S., Kalkstein, L.S., and Yagouti, A. (2014). Association of weather and air pollution interactions on daily mortality in 12 Canadian cities . Air Quality, Atmosphere, and Health. Online. May 21st. DOI: AIRQ-D-13-00026R1.
- Vanos, J.K., Cakmak, S. Bristow, C., and Hebbern, C. (2014). Risk assessment for cardiovascular and respiratory mortality due to air pollution and synoptic meteorology in 10 Canadian cities. Environmental Pollution. 185, 322-332.
- Zander, R., A. Messina, and M. Godek, 2013: An Air Mass based approach to the establishment of spring season synoptic characteristics in the northeast United States. Atmospheric and Climate Sciences, 3, 408-419.
- Zhang, K., Rood, R. B., Michailidis, G., Oswald, E. M., Schwartz, J. D., Zanobetti, A., ... and O'Neill, M. S., 2012: Comparing exposure metrics for classifying .dangerous heat.in heat wave and health warning systems. Environment international, 46, 23-29.
- Zhao, N., Cao, G., Vanos, J. K., & Vecellio, D. J. (2017). The effects of synoptic weather on influenza infection incidences: a retrospective study utilizing digital disease surveillance. International Journal of Biometeorology, in press.