A quick revision: what exactly is microclimate (and meso, macro, local climate)?

It’s typically useful to talk about three spatial-temporal scales of climate for a given area or region: (1) Macro-climate, (2) Meso-climate, and (3) Micro-climate.

Macroclimate refers to the average atmospheric conditions of the ambient air across a large geographic region, characterized by: (1) averaging over large space (100-1000 kms), (2)Conditions above the atmospheric boundary layer (which is typically >1 kms in height near the tropics), (3) Long-term averages. Macroclimate is primarily determined by factors such as distance from the sea, seasons, and the latitude/altitude of the area. Phenomena like El Niño and La Niña are examples of macroclimate events. The current global warming and climate change resulting from anthropogenic increases in greenhouse gases are contemporary macroclimate phenomena.

Mesoclimate, often referred to as topoclimate, is influenced by the topography of the land, such as proximity to large water bodies or mountains. It typically: (1) covers an area of 1-100 km, (2) extends vertically up to the atmospheric boundary layer (ABL); it varies in scale depending on the consistency of the topography.

Microclimate represents the climatic/atmospheric conditions directly interacting with the biotic and abiotic components of the Earth's surface [1], [2]. It is characterized by occupying the lowest 10% of the atmospheric boundary layer and typically scaling 1-100 m in extent. The Earth-Atmosphere interface can thus be viewed as a patchwork of different microclimates, each interacting uniquely with its immediate surroundings. Meso and micro-scales of climate together are referred to as the local climate [3]. It is the state of the climate that is directly influenced by the land surface. In the language of geo/climate-physics, it is the climatic conditions caused at the surface of the ground, as a result of matter/energy exchanges and radiation processes occurring close to the ground surface. It is basically an energy balance between (mainly) the following processes: solar radiation, soil moisture, soil temperature, air temperature, air humidity, and wind velocity. The detailed geophysics of these components could be referred to in chapter 2 of [3].

Microclimate illustration: This is a a thermal image from a midsummer day in Chile indicating more than 5 degrees Celsius variability due to different on-farm practices in an irrigated vineyard. This example is illustrated in [4], originally sourced by Irriwatch.

Schematic of three climate scales nested into each other. This figure is adapted from [2], page 12, fig 6.

[1] Microclimate in Forest Ecosystem and Landscape Ecology | BioScience | Oxford Academic. Link here.

[2] Ten practical guidelines for microclimate research in terrestrial ecosystems - De Frenne - Methods in Ecology and Evolution - Wiley Online Library. Link here.

[3] Woesik, F. van et al. Managing the Local Climate. 1–154. Link here.

[4] Steenbergen, Femke van Woesik, Frank van. “Managing Microclimates — a ‘Third Way’ to Combat Climate Change.” Down To Earth, March 2, 2023. Link here.