Lambert Azimuthal Equal Area (Modified)
Sep 24,2026

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Introduction

Lambert Azimuthal Equal Area (Modified) is an equal-area azimuthal projection proposed by the German mathematician Johann Heinrich Lambert in 1772. Its core characteristic is maintaining a strictly proportional relationship between the area of any region on the map and the actual area on the Earth's surface. At the same time, shapes and angles are significantly distorted, with the effect becoming more pronounced in regions farther from the projection center. The term "Modified" does not refer to a separate projection type, but rather to parameter adjustments made to the standard spherical model in practical applications. For example, using the WGS84 ellipsoid instead of a sphere, setting the projection center to a specific region such as China or Europe, or using auxiliary sphere parameters to optimize regional area fidelity. This makes it suitable for national surveying, environmental statistics, and polar science mapping. At the projection center, there is no distortion and directions are accurate, with a circular boundary at the periphery. It is mainly used to display global or hemispheric-scale distribution data, such as species distribution, climate patterns, and geological structure analysis.

Projection Basic

The Lambert Azimuthal Equal Area (Modified) is not a cylindrical projection, but an azimuthal projection that projects the Earth's surface radially onto a projection plane with the projection center as the origin. The name "cylindrical" is a misnomer; it is actually classified as a planar projection. This projection uses mathematical transformation to make the area of any region proportional to its actual area. Distortion is minimal at the projection center and gradually increases outward. Away from the projection center, shapes and angles are significantly distorted. The term "Modified" refers to the use of the WGS84 ellipsoid, a custom projection center (e.g., 105°E, 35°N), or auxiliary sphere parameters during implementation to suit the surveying needs of China and surrounding regions. This optimizes area accuracy in regional maps.

Pros

Complete area fidelity: Maintains a strictly proportional relationship between the area of any region on the map and the actual area on the Earth's surface, making it suitable for thematic maps requiring accurate quantitative comparison, such as resource distribution, population statistics, and ecosystem patterns.
Accurate directions from the center: All directions viewed from the projection center match actual geographic directions, making it useful for navigation, remote sensing positioning, and spatial analysis.
Minimal distortion in the central region: At the projection center, there is no distortion in distance, angle, or shape, making it an ideal reference point for regional maps (such as all of China). In particular, when 105°E, 35°N is used as the projection center, area accuracy in the East Asian region is greatly improved.
Clear, circular boundary: The projection extent is limited to a circle, giving it strong visual focus and making it suitable for displaying global or hemispheric-scale data centered on a single point, such as polar ice sheet changes or species distribution.

Cons

Severe shape distortion: In regions far from the projection center, geographic outlines are greatly stretched or compressed, and continental shapes are noticeably deformed, making it unsuitable for scenarios requiring accurate representation of feature outlines.
Complete angular distortion: Angles between any two points on the map do not match actual azimuths, so it cannot be used for tasks requiring preservation of directional relationships, such as route planning or topographic surveying.
Cannot fully represent the globe: In this projection, the antipode is mapped to the entire circular periphery, so antipodal regions (e.g., the central Pacific) are extremely compressed into what appears to be a single line, making it impossible to intuitively represent global continuity.
Distortion increases sharply at the periphery: Toward the edge of the map, even though area ratios remain "accurate," shape distortion expands non-linearly. This makes interpreting geographic information in peripheral regions difficult and limits practical utility in cross-regional comparisons.

Application Scenario

The core value of the Lambert Azimuthal Equal Area (Modified) lies in its ability to accurately preserve area ratios between regions. It is therefore widely used in scientific cartography that requires quantification of spatial distribution. The United States Geological Survey (USGS) adopts this projection as one of its standard projections for visualizing hemispheric- and continental-scale ecological and geological data. The European Space Agency (ESA) uses its area-unbiased property to analyze global carbon cycles and ice sheet changes. The National Oceanic and Atmospheric Administration (NOAA) uses it for accurate representation of aurora forecasts and polar meteorological grid data, enabling accurate comparison of polar observations. In ecological research, this projection is incorporated into specialized toolkits such as CCAMLRGIS for modeling biological resource distribution in the Southern Ocean. Additionally, the spatial epidemiology software FGBASE adopts its grid structure for area calculations of disease risk. In China, the "Modified" version centered at 105°E, 35°N has become an industry standard for national resource surveys, ecological assessments, and geological mapping, greatly improving area accuracy in the East Asian region. Due to its circular boundary and distortion-free center, it is a suitable choice for displaying thematic maps focused on a single center, such as global carbon storage, species distribution, population density, and ice sheet melting trends.