This study reports on four consecutive winter campaigns (2016 – 2020) at the “Davos-Laret Remote Sensing Field Laboratory” in the Swiss Alps to gain insight into the L-band microwave emission of ground covered with seasonal snow. Close-range L-band Brightness temperatures T^p,ϕ_B(θ) were measured over the site scanning different observation nadir angles θ and azimuth angles ϕ at Horizontal and Vertical polarizations p = {H,V}. State parameters of the snowpack (e.g., height, density, SWE) and the subnivean soil (permittivity, temperature) were measured quasi-simultaneously using in-situ sensors and sampling, as well as meteorological data. In each campaign T^p,ϕ_B(θ) were measured over a “natural area” and a “reflector area” with a metal mesh reflector laid on the ground before snow accumulation. The radiometer measurements over “reflector area” allowed to retrieve the time-series of Snow liquid Water-Content W_S and Snow liquid Water-Column WC_S which are employed as “derived measurements” to support interpretation of T^p,ϕ_B(θ) measured over “natural areas” during different Winter phases. The detailed approach for the estimation of W_S and WC_S using L-band radiometer data is presented. The data and analyses in this paper address the following major points: i) Determination of the characteristic features of measured T^p,ϕ_B(θ) during different periods in each of the four winter campaigns; ii) effects of dry- and wet snow precipitation on L-band radiometer data compared to corresponding simulations; iii) effect of removal and compression of the snowpack on T^p,ϕ_B(θ); and iv) effects of spatial heterogeneity on brightness temperatures. Finally, the study is concluded with recommendations relevant for future close-range remote sensing campaigns.