## 5 Conclusions  
We investigated seasonal and annual patterns for the components of energy and CO2 balances during a wet (2009) and a dry (2014) year in a site (Cabrobo) known as a desertification hotspot in Northeast Brazil using biophysical soil-vegetation-atmosphere transfer and compared the observed trends with those recorded in a site (Ibimirim) in the same area but outside the hotspot. We found an increasing air temperature trend in the Cabrobo site, mainly during the night, which was not observed as remarkably in the Ibimirim site. Overall, there was an increasing air temperature trend in the Cabrobo site, mainly during the night, which was not observed as remarkably in the Ibimirim site. Regarding relative humidity, no trends were observed in the first semester. However, a few increasing trends were observed in the Cabrobo site (particularly in November), while decreasing trends were observed in Ibimirim (mainly in August). Wind speed series presented an increasing trend in the Cabrobo site from June to August, while the opposite was observed in Ibimirim from September to May.  
Sensible heat fluxes, latent heat fluxes, GPP, and NEE were satisfactorily simulated by the SITE model. GPP values were higher in the first half of the year in Ibimirim and Cabrobo, indicating that the CO2 balance dynamics in Caatinga are closely linked to rainfall seasonality. NEE values were mostly negative throughout the year, indicating a higher CO2 uptake even though minimum values were registered during dry months due to the lack of soil water. The results of this study show that the SITE model can be used to simulate adequate responses of energy and CO\({}_{2}\) fluxes for the Caatinga region, considering the remarkable phenological seasonality of this biome.  
Conceptualization, A.C.S., C.M.S.e.S. and K.R.M.; methodology, A.C.S., C.M.S.e.S. and K.R.M.; validation, A.C.S., C.M.S.e.S., K.R.M., D.T.R. and P.R.M.; analyses formal A.C.S., C.M.S.e.S., K.R.M., D.T.R., P.R.M., R.R.F. and B.G.B.; investigation A.C.S., C.M.S.e.S. and K.R.M.; writing--original draft preparation, A.C.S., C.M.S.e.S. and K.R.M.; writing--review and editing, A.C.S., C.M.S.e.S., K.R.M., D.T.R., G.B.C., D.T.C.d.S., P.R.M., R.R.F. and B.G.B. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Council for Scientific and Technological Development (CNPq), Process N\({}^{\circ}\)310781/2020-5 and National Observatory of Water and Carbon Dynamics in the Caatinga Biome (INCT-MCTI/CNPq/CAPES/FAPs 16/2014, grant: 465764/2014-2 and MCTI/CNPq N\({}^{\circ}\) 28/2018, grant 420854/2018-5).  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.  
The authors are thankful to the Brazilian National Institute of Semi-Arid (INSA) for funding the project and providing the EC data used in this study. The authors are also thankful to the Coordination for the Improvement of Higher Education Personnel (CAPES) for the postdoctoral funding granted to the second author. This work was partially supported by the high-performance computing facilities of NPAD/UFRN. Finally, we are thankful to the National Council for Scientific and Technological Development (CNPq) for the research productivity grant of the C.M.S.e. author (Process N\({}^{\circ}\) 310781/2020-5) and the financial support in the NOWCDCB project: National Observatory of Water and Carbon Dynamics in the Caatinga Biome (INCT-MCTI/CNPq/CAPES/FAPs 16/2014, Grant: 465764/2014-2 and MCTI/CNPq N\({}^{\circ}\) 28/2018, Grant 420854/2018-5).  
The authors declare no conflict of interest.