for(i in 1:277) for(j in 1:363) {ifelse(is.na(LST_summer_day_NA_index[i,j])==FALSE,
                                        (df <- data.frame(x=summer_day_mod1[i,j,],y=summer_night_mod1[i,j,]))&
                                          (mod <- lm(data = df))&
                                          (MAE_model2_day <- mean(abs(mod[[2]]))) &
                                          (for(k in 1:228) {ifelse(is.na(complete_summer_day[i,j,k])==TRUE,
                                                                  summer_day_mod2[i,j,k] <- (mod[[1]][1])+(summer_night_mod1*mod[[1]][2]),"")}),"")}