[Response] We thank the reviewer for their positive assessment and are grateful for their encouraging comments on the quality, clarity, and relevance of our study. Please find our point-by-point responses to the reviewer’s comments below

Q1：I feel that the manuscript would benefit from a clearer and more explicit illustration of the relationships between soil moisture, soil texture, and albedo, which are mentioned in the abstract, objectives, and discussion (see also L391, L429, L455 and following).

[Response] Following the reviewer’s suggestion, we have revised Introduction and section 4.2 to clarify the relationship between soil moisture, soil texture, and albedo.

Lines 44-49: “Bare soil albedo is controlled by a combination of intrinsic soil properties and varying environmental conditions (He et al., 2019). Soil properties, including texture, mineral composition, roughness, organic matter content, and bulk density determine the optical characteristics of soil surface (Matthias et al., 2000, Cierniewski et al., 2018) and  soil hydrological properties  (Han et al., 2023). As a result, they  affect soil albedo directly and indirectly (via modulating  the relationship between albedo and water availability). Soil moisture and solar radiation geometry further modulate the short-term temporal variability of soil albedo by altering the amount and direction of the observed reflected solar radiation (Hapke, 1981; Gascoin et al., 2009, Badía et al., 2016).”

Lines 380-384: “The decomposition of bare soil albedo into spatial and temporal components provides a framework for interpreting its physical controls. Intrinsic soil properties affect bare soil albedo by establishing the optical characteristics of the soil surface and regulating soil-water interaction, while soil moisture dynamics and radiative geometry control the temporal fluctuations of the observed bare soil albedo.”

Lines 399-401: “The magnitude and duration of these responses depend on the soil water retention capacity  (Post et al., 2000), resulting in different αbs responses to the same soil moisture change for different soil textures”.

Lines 408-413: “Soil properties explain much of the stable spatial structure onto which moisture and geometry act (Rizzo et al., 2023). For example, soil texture influences bare soil albedo through both direct and indirect pathways. Particle size, mineral composition directly influence soil optical properties (e.g., surface color and scattering characteristics), thereby establishing the inherent bare soil albedo. In addition, these properties related with texture regulate the soil hydraulic behaviour (Sadeghi et al 2018)” 

Lines 430-432: “Overall, these controls are interacting components governing bare soil albedo rather than independent drivers. Among the intrinsic soil properties, soil texture plays an important role because it establishes the background optical characteristics of the soil surface and regulates soil-water interactions, while soil moisture and solar geometry determine the short-term variability of the observed αbs.”

Q2: As a 1st step I suggest moving Supplementary Figure 7 (linear relationship between site-level bare soil albedo and soil moisture) into the main text, as it directly supports some of the  key arguments of the study.

Along the same lines, it would be useful to provide some basic contextual information for the validation sites, such as pedoclimatic conditions, crop rotations, and fallow periods. This would help the reader better understand the representativeness and variability of the dataset.

[Response] Following the reviewer’s suggestion, we moved Fig S7 into section 3.3. We also added a summary table (Table S1) describing the validation sites, including their climatic conditions, dominant crop rotations, and typical length of fallow periods. Regarding fallow periods, we note that quantifying a fixed period for each site is difficult, as it varies among years depending on crop rotation and management practices (e.g., cover crops and tillage operations). Therefore, we provide the average fallow period duration in 2018-2020 estimated from the crop calendars reported for each site. Table S1 please see the Supplement.

Specific comments

Q3. L238 and following:

Could you add a notion of a gradient in your evaluation dataset? The dataset includes only eight sites, and it would strengthen the manuscript to better demonstrate that these sites cover a meaningful pedoclimatic gradient. I recommend to better  describ how the selected sites represent variability in:

soil types (e.g. texture, possibly linked to soil color), climatic conditions (e.g. radiation, cloud cover), management practices (e.g. crop rotations, fallow periods), seasonal dynamics (as proxies for variations in radiation intensity, cloud cover, and soil moisture throughout the year; see also L271).

[Response] Following the reviewer’s suggestion, we summarized the climatic, soil, and management characteristics of each validation site in Table S1 (see above) and described the broad pedoclimatic gradient represented by these sites in Section 2.3:

Lines 256-264: “The selected eight sites encompass a broad pedoclimatic and management gradient across European croplands (Table S1). They represent contrasting soil conditions, including Luvisol, Fluvisol, Cambisol, and Chernozem/Phaeozem, with the ranges of silt, clay and sand contents from 26.6 to 78.1 %, from 14.7 to 53.0 %, and from 7.2 to 38.0 %, respectively. These sites also cover diverse climatic conditions in air temperature, incoming shortwave solar radiation, precipitation and cloud cover at annual scale. Seasonal variability in solar radiation and soil moisture (characterized by the seasonal minimum and maximum values in Table S1) captures the range of environmental conditions experienced across seasons. In addition, these sites implement different agricultural management practices, including crop rotations of 2-8 years and bare soil periods occurring mainly in spring, autumn and winter (approximately 30-180 days, Fig. S2). ”

Q4: L238 please cite Figure 3

[Response] Following the reviewer’s suggestion, we cited Fig 3 in section 2.3:

Line 245-248: “Five types of αbs datasets were utilized to evaluate the performance of the final spatiotemporal albedo predictions (αbs, RF) at seven ICOS European cropland sites (BE-Lon, FR-Lam, FR-Aur, FR-EM2, DE-RuS, DE-Geb, DE-Kli), one European Fluxes Database Cluster (EFDC) European cropland site (CZ-KrP), and one Swedish cropland site in Uppsala, and the overall European cropland regions during bare soil periods (Fig. 3, Table 3).”

Q5: Figure 5 as non of the values is over 0.4 may be adjust the Figure to y axis 0-0.3. Figure 6 as non of the values is over 0.4 may be adjust the Figure to y axis 0-0.3

[Response] Following the reviewer’s suggestion, we adjusted the range of y-axis to 0-0.3 in Figures 5-6. The modified Figures 5-6 please see Supplement. 

We thank the reviewer for their thorough and accurate summary of our methodology and findings. We also appreciate the reviewer highlighting the role of soil surface roughness and its modification by heavy rainfall as a contributor to short-term albedo variability, and the consistency of our derived European-scale average (0.15 ± 0.01) with previously published values. Regarding the influence of soil taxonomic class on prediction accuracy (better performance for bright Alfisols versus dark Mollisols/Inceptisols), we agree this is an important point and have ensured it is appropriately emphasized as a consideration for similar future studies (see response 1).

MAJOR COMMENT

Q1. In my opinion, the daily abs prediction for bare soils would be more accurate if the authors of this manuscript also included the roughness of the bare soils among their analyzed soil properties, resulting from the use of specific agricultural tools, modification of this roughness after heavy rainfall, and the formation of a thin crust, primarily on heavy soils. The omission of soil roughness in this study seems strange to me, especially since the authors mentioned this property as significantly affecting the albedo of bare soils in the "Introduction" (line 43). 

[Response] We agree that soil roughness, influenced by agriculture practices, rainfall events and crust formation, is an important determinant of bare soil albedo (Matthias et al., 2000; Cierniewski et al., 2023), however there is a lack of gridded soil roughness reconstructions required for the upscaling. We discussed the implication of the omission changes in soil roughness but admit it was rather limited  (See section 4.3). Following the reviewer's suggestion, we now extended the discussions. In addition, we note that some selected predictors included in our RF framework, such as soil texture (sand and clay content) and bulk density, could partly capture the variability of soil roughness (Herodowicz-Mleczak et al., 2022; Rizzo et al., 2023), but the quick change of roughness induced by agriculture practices, rainfall events and crust formation cannot be resolved. We have clarified the missed soil roughness in section 4.3.

“One important example is varying soil surface roughness which varies according to agriculture practices, rainfall events and crust formation. Its impact on αbs was not explicitly represented as the required spatiotemporal datasets of soil roughness are currently unavailable at the European scale. In addition, assessing the impact of temporal variation of soil roughness on predicted αbs at the site scale remains challenging, as no soil roughness measurements are available at the evaluation sites. Our RF framework relies on intrinsic soil properties that may partially capture roughness-related variability (Herodowicz-Mleczak et al., 2022; Rizzo et al., 2023) but cannot explicitly resolve the effects of agricultural practices, rainfall-induced smoothing, or soil crust formation.”

MINOR COMMENTS

Q2: I have found a certain disagreement between references in the list of “References” and references inside of the manuscript text. The following items in the “References” list, Carrer et al. 2010, Jr et al. 2007, and Liu et al. 2002, are not referenced in the text. Also, several items mentioned in the text, Carrier et al. 2018, Charles et al. 2007, Liu et al. 2023, and Liu et al. 2002, are not referenced in the “References” list.

[Response] We apologise for the misleading information in the citations and reference list. We have carefully checked all references and made the following corrections:

- The unreferenced entries ‘Carrer et al. 2010, Jr et al. 2007, and Liu et al. 2002’ have been removed from the reference list.

- ‘Carrier et al. 2018’ has been added to the reference list.

- The citation ‘Charles et al. 2007’ in the manuscript was a typographical error and has been corrected to Garten et al., 2007, which has also been included in the reference list.

- The citation "Liu et al. (2023)" referred to Lin et al. (2022) in Section 2.1.1. This has been corrected accordingly.