Proposal of a new climate classification based on Köppen and Trewartha

A new and detailed climate classification based on Köppen-Geiger and Trewartha schemes is proposed, which uses four components (thermal zone, continentality, humidity, and seasonal distribution of precipitation) to determine a location’s climate type. It specifies thermal zones into nine types by subdividing tropical, subtropical, temperate, and polar zones, which are based on original Trewartha classification. Continentality classification (continental, oceanic, and transitional) is based on modified Ivanov’s equation considering diurnal and annual temperature range. Humidity zone is based on the smoothed formula of Köppen’s approach, and th...  more

A new and detailed climate classification based on Köppen-Geiger and Trewartha schemes is proposed, which uses four components (thermal zone, continentality, humidity, and seasonal distribution of precipitation) to determine a location’s climate type. It specifies thermal zones into nine types by subdividing tropical, subtropical, temperate, and polar zones, which are based on original Trewartha classification. Continentality classification (continental, oceanic, and transitional) is based on modified Ivanov’s equation considering diurnal and annual temperature range. Humidity zone is based on the smoothed formula of Köppen’s approach, and this classification adds a ‘semi-humid’ zone to distinguish dry and wet forest climate zones. Monsoonal and Mediterranean climate are specified by seasonal distribution of precipitation.
This study explores climate types in major global cities, and found that there are 82 different climate types among them. Cities tend to be in areas with mild to warm thermal conditions, oceanic climate (low annual and diurnal temperature ranges), high precipitation, and uniform seasonal distribution of precipitation, with the climate type C1oaf (warm-temperate oceanic humid climate with uniform precipitation) most common among global cities. Cities in subpolar and polar climate zones are extremely rare.
An important improvement of this classification compared to Köppen and Trewartha climate schemes is its inclusion of arid and semi-arid climate zone into thermal zones and seasonal distribution of precipitation types. Compared to Thornthwaite and Holdridge climate classifications, the classification only uses temperature and precipitation instead of other meteorological elements, making data more accessible for mapping and research.