diff --git a/GEE_Scripts/S1andS2_download.js b/GEE_Scripts/S1andS2_download.js
index 5efc89c..6764a74 100644
--- a/GEE_Scripts/S1andS2_download.js
+++ b/GEE_Scripts/S1andS2_download.js
@@ -2,7 +2,7 @@
  * Sentinel-1 & Sentinel-2 哨兵一号与二号长时序数据下载 —— 适用于小范围区域年度数据获取
  *
  * @author CVEO Team
- * @date 2026-01-05
+ * @date 2026-01-06
  *
  * 1. 加载 Sentinel-1, Sentinel-2 数据与 Cloud Score+ 云掩膜, 以及 HLS 数据
  * 2. 合成年度Sentinel-1, Sentinel-2, HLS无云影像
@@ -10,7 +10,7 @@
  * 4. 合并Sentinel-1和Sentinel-2影像
  * 5. 导出COG云优化并填补缺失值的GeoTIFF影像 (小区域不分块)
  *
- * 注: 截止至 2026-01-05, GEE 仍未集成 2015-2017 年的 L2A 数据.
+ * 注: 截止至 2026-01-05, GEE 仍未集成 2015-2017 年的 L2A 数据, 且 2018 年的 L2A 数据仍不完整.
  */
 
 // 加载研究区域和影像
@@ -20,7 +20,7 @@ var name_list = [
   "高雄左营区左营军港",
   "高雄旗山区陆军第八军团指挥部",
 ];
-var target_index = 2; // 从 0 开始计数, 0-3
+var target_index = 0; // 从 0 开始计数, 0-3
 var region_name = name_list[target_index];
 var region = ee.FeatureCollection(
   demoPoints
@@ -121,6 +121,30 @@ function sortedByPriority(collection, region, cloud_field) {
   return ee.ImageCollection(sorted);
 }
 
+// 加载HLS L30和L30数据
+var HLSL30 = ee
+  .ImageCollection("NASA/HLS/HLSL30/v002")
+  .filter(common_filter)
+  .filter(ee.Filter.lt("CLOUD_COVERAGE", cloud_threshold))
+  .map(maskHLSclouds)
+  .select(L30Bands, commonBands);
+var HLSS30 = ee
+  .ImageCollection("NASA/HLS/HLSS30/v002")
+  .filter(common_filter)
+  .filter(ee.Filter.lt("CLOUD_COVERAGE", cloud_threshold))
+  .map(maskHLSclouds)
+  .select(s2Bands, commonBands);
+var HLSdataset = ee.ImageCollection(HLSL30.merge(HLSS30));
+print(start_date + " - " + end_date + " HLSdataset", HLSdataset);
+var targetHLSCol = sortedByPriority(HLSdataset, region, "CLOUD_COVERAGE");
+// Mosaic 处理后会丢失投影信息, 需重新设置投影
+var proj = targetHLSCol.first().select(1).projection();
+var hls_img = ee.Image(targetHLSCol.mosaic()).setDefaultProjection(proj);
+var hls_10m_img = hls_img.resample("bicubic").reproject({
+  crs: proj,
+  scale: 10,
+});
+
 // 加载Sentinel-1 GRD数据
 var S1dataset = ee
   .ImageCollection("COPERNICUS/S1_GRD")
@@ -150,28 +174,21 @@ var S2dataset = ee
   .linkCollection(S2csPlus, [QA_BAND])
   .map(maskS2cloudsByCS)
   .select(s2Bands, commonBands);
-var targetS2 = sortedByPriority(S2dataset, region);
-var s2_img = ee.Image(targetS2.mosaic());
+var targetS2Col = sortedByPriority(S2dataset, region);
+var s2_img = ee.Image(targetS2Col.mosaic());
 print(start_date + " - " + end_date + " S2dataset", S2dataset);
+
+// 2015-2018 年间若 Sentinel-2 数据为空, 则使用重采样到 10m 的 HLS 数据
+if (
+  S2dataset.size().getInfo() === 0 ||
+  (start_year === 2018 && (target_index === 0 || target_index === 3))
+) {
+  s2_img = hls_10m_img;
+}
+
 var s2_img_rgb = s2_img.select(["Red", "Green", "Blue"]);
 var s2_img_frgb = s2_img.select(["NIR", "Red", "Green"]);
 
-var HLSL30 = ee
-  .ImageCollection("NASA/HLS/HLSL30/v002")
-  .filter(common_filter)
-  .filter(ee.Filter.lt("CLOUD_COVERAGE", cloud_threshold))
-  .map(maskHLSclouds)
-  .select(L30Bands, commonBands);
-var HLSS30 = ee
-  .ImageCollection("NASA/HLS/HLSS30/v002")
-  .filter(common_filter)
-  .filter(ee.Filter.lt("CLOUD_COVERAGE", cloud_threshold))
-  .map(maskHLSclouds)
-  .select(s2Bands, commonBands);
-var HLS = ee.ImageCollection(HLSL30.merge(HLSS30));
-var targetHLS = sortedByPriority(HLS, region, "CLOUD_COVERAGE");
-var hls_img = ee.Image(targetHLS.mosaic());
-
 var s1_vis = {
   min: -25,
   max: 5,
@@ -185,8 +202,8 @@ var s2_vis = {
 
 var true_rgb_vis = {
   bands: ["Red", "Green", "Blue"],
-  min: 0.01,
-  max: 0.15,
+  min: 0.0,
+  max: 0.2,
 };
 
 var false_rgb_vis = {
@@ -202,10 +219,10 @@ var styling = {
 };
 
 Map.centerObject(region, 14);
-Map.addLayer(s1_vv_img, s1_vis, start_year + " Sentinel-1 GRD VV");
-Map.addLayer(s1_vh_img, s1_vis, start_year + " Sentinel-1 GRD VH");
-Map.addLayer(hls_img, false_rgb_vis, start_year + " HLS False RGB", false);
+Map.addLayer(s1_vv_img, s1_vis, start_year + " Sentinel-1 GRD VV", false);
+Map.addLayer(s1_vh_img, s1_vis, start_year + " Sentinel-1 GRD VH", false);
 Map.addLayer(hls_img, true_rgb_vis, start_year + " HLS True RGB");
+Map.addLayer(hls_10m_img, true_rgb_vis, start_year + " HLS True RGB 10m");
 Map.addLayer(
   s2_img_frgb,
   false_rgb_vis,
@@ -234,6 +251,7 @@ Export.image.toDrive({
   folder: "Sentinel",
   region: region, // 添加后会自动裁剪
   scale: 10,
+  crs: "EPSG:4326",
   maxPixels: 1e13, // GEE 最多支持 1e8 像素, 当超过时会自动分块
   fileFormat: "GeoTIFF",
   // 导出COG云优化的GeoTIFF影像, 并明确设置缺失值为-9999.0