The phrase "average surface air" is correct and usable in written English.
It can be used in contexts related to meteorology, climate studies, or environmental science when discussing typical air conditions at the Earth's surface.
Example: "The average surface air temperature has been rising steadily over the past few decades, indicating significant climate change."
Alternatives: "mean surface air" or "typical surface air".
Current global average surface air temperature is warmer than that for all but a small fraction of the past 11,300 years.
Figure 2 Monthly average surface air temperatures of Northern Hemisphere at surface level 700 hPa and its decomposition results by EMD and SEMD.
We also consider monthly average surface air temperatures of Northern Hemisphere at surface level 700 hPa for the period January 1961 August 200303 in Figure2.
The future climate series are obtained by using 20 Global Climate Models (GCMs) outputs from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) to reflect a 1 °C increase in the global average surface air temperature.
Although a few Arctic areas have cooled over recent decades, overall average surface air temperatures have risen almost twice as much as global averages.
The time series of hourly total rainfall, hourly averaged surface air temperature, and global solar radiation during the period from 23 November to 17 December 2015 are shown in Fig. 2.
Fig. 2 Time series of a hourly total rainfall, b hourly averaged surface air temperature, and c hourly averaged global solar radiation observed at Bengkulu Meteorological Observatory (3°51′30″ S 102°20′11″ E) on Sumatra Island from 23 November to 17 December 2015.
The globally averaged surface air temperature increase, averaged over a 20-year period, centered at the time of CO2 doubling (i.e., at year 70 in a 1% per year compound CO2 increase experiment with a global coupled climate model).
Difference in responses of the globally and annually averaged surface air temperatures between coupled and uncoupled simulation also increases early in the simulations, then attains a maximum (which occurs later than t m ) and diminishes afterwards tending to zero (not shown).
In [ 5], the following expression for climate-carbon cycle feedback gain g = (f - 1)/ f is derived (2) g = - α (γ l + γ oc )/(c 0 + β l + β oc ) = - αG with transient temperature sensitivity α = d T g c p l / d q CO 2 c p l, T g c p l is globally and annually averaged surface air temperature in the coupled simulation, and c0 = 2.1 PgC/ppmv.
Linearising carbon fluxes [ 5] and neglecting difference between the changes of globally averaged annual mean surface air and sea surface temperatures one obtains (5) F X c p l = β X d q CO 2 c p l / d t + γ X d T g c p l / d t, F X u c p l = β X d q CO 2 u c p l / d t, where X = l, oc, T g stands for globally averaged annual mean temperature, and γ X and β X were defined in Introduction.
