Geographic Tools and Data – APHUG Quick Notes

Geography is both a field of study and an approach to understanding the Earth's complexities; it combines spatial patterns with human and physical processes.
The field spans multiple branches and overlaps with biology, geology, cartography, GIS, and visual arts.

Observation starts with WHAT phenomenon is happening and WHERE it is happening.
Numerous questions address WHY a phenomenon occurs in a location; core questions begin geographic inquiry (why here, why there, why now).
In global and local contexts, spatial patterns prompt investigation into the causes and conditions that enable or constrain phenomena.

Geographers use a broad toolbox, integrating methods from biology, economics, mathematics, etc., to study spatial patterns.
They seek the WHY of WHERE by examining data and patterns, often collaborating with experts in other fields.

Geography is a visual discipline; primary tools include maps, photographs, and satellite imagery.
Models are simplified visual diagrams to understand patterns and processes; several models will be learned during the course.

Reference maps provide general geographic information (roads, borders, physical features).
Thematic maps display one pattern or theme at a time (e.g., election results, language, income) and reveal patterns not obvious from the landscape alone.

Choropleth maps: data shown by color/shading within geographic units (e.g., counties or states).
Isoline maps: lines connect points of equal value (e.g., temperature, precipitation).
Graduated symbol maps: symbol size varies by data magnitude within areas.
Dot density maps: each dot represents a set number of occurrences (as defined in the legend).
Heat maps: shading represents intensity; each occurrence is plotted, blending dot density and choropleth ideas.

Projections are mathematical transformations of the globe to a 2D map (Mercator, Conic, Planar/Azimuthal, or a compromise).
All maps distort some property (size, shape, distance, or direction) due to 3D to 2D conversion.
For assessment, recognize projection types by appearance and know where distortions occur.

Map scale expresses the relationship between map distance and real-world distance.
Representative Fraction (RF) scales: $1:20000$ means 1 unit on the map equals 20000 units on the ground.
Small-scale maps cover large areas with less detail; large-scale maps cover smaller areas with more detail.
Verbal scales (e.g., "one inch equals ten miles") and visual scales (bar scales) provide alternative representations.

The most common grid system is latitude and longitude.
Latitudes (parallels) measure angular distance north/south from the Equator ( $0^\circ$ ).
Well-known parallels: Equator $0^\circ$ , Tropic of Cancer $23.5^\circ N$ , Tropic of Capricorn $23.5^\circ S$ , Arctic Circle $66.5^\circ N$ , Antarctic Circle $66.5^\circ S$ , North Pole $90^\circ N$ , South Pole $90^\circ S$ .
Longitudes (meridians) measure angular distance east/west from the Prime Meridian (0°) at Greenwich.
Earth rotates about $15^\circ$ per hour, completing 360° in 24 hours.
The International Date Line is near $180^\circ$ longitude.

GIS (Geographic Information Systems): software that layers multiple data sets to create integrated maps for analysis.
GPS: satellite-based positioning that computes absolute locations using signals from at least four satellites for accuracy.
Remote sensing: acquisition of data about objects/areas without direct contact (via satellites, aircraft, or sonar).
Satellite imagery: Earth observation data used for climate, environment, and various analyses; often public through sources like NASA Earth Observatory.

Georeferencing ties data to real-world locations (latitude/longitude, addresses, etc.).
Qualitative data: descriptive, subjective information.
Quantitative data: numerical measurements and counts.
Geospatial data: data with a geographic component tied to a location.

Demographic data capture socio-economic characteristics (population, income, education, employment, race).
The U.S. census is conducted every 10 years to collect data that inform policy, funding, and representation, typically rolled up to census tracts, counties, or states.
Census data can be combined with other variables (crime, access to services, housing) for deeper analysis.

Governments: planning, boundaries, resource management, disaster preparedness.
Disaster management: GIS supports prevention, mitigation, preparation, response, and recovery.
Businesses: asset tracking, route optimization, real-time decision making; GIS + GPS enable efficiency and safety.
Personal decision making: informed housing, travel, safety, and risk assessment using geospatial information.

Government planning: school zoning, infrastructure, service provision.
Disaster response: oil spill tracking (NASA data) and other emergency management tasks.
Industry examples: Amazon logistics, trucking routes, precision agriculture, and supply chain optimization.
Everyday use: route planning, crime statistics, and neighborhood safety assessments.

Geography: study of spatial patterns and the WHY of WHERE phenomena occur.
Observations: WHAT happens, WHERE it occurs; WHY requires additional sources.
Tools: maps, GIS, GPS, remote sensing, satellite imagery.
Data types: quantitative, qualitative, and geospatial data.
Scale concepts: map scale (RF), scale of analysis, and projection distortions.
Projections: Mercator, conical, planar/azimuthal, and compromise.
Thematic maps: choropleth, isoline, graduated symbol, dot density, heat maps.
Coordinates: latitude/longitude, Prime Meridian, International Date Line, and major lat/long values.