Geoskill: MODIS Lst Download

Search and download Terra and Aqua MODIS Land Surface Temperature products (daily and 8-day, 1km) from NASA LAADS DAAC with GeoTIFF output and Earthdata auth.

MODIS Land Surface Temperature Download

Search and download MODIS LST products from NASA LAADS DAAC with Earthdata authentication.

Overview

MODIS Land Surface Temperature (LST) products provide per-pixel land surface temperature with 1km spatial resolution. This skill supports both Terra (MOD) and Aqua (MYD) satellite products at daily and 8-day composite intervals.

Products

Product	Satellite	Temporal	Resolution
MOD11A1	Terra	Daily	1km
MOD11A2	Terra	8-day	1km
MYD11A1	Aqua	Daily	1km
MYD11A2	Aqua	8-day	1km

Features

• Day and night LST: separate daytime and nighttime temperature layers
• Quality control: includes QC bands for quality filtering
• Search by date range and bbox: find available granules
• GeoTIFF output: standard georeferenced raster format
• Earthdata authentication: secure access to NASA data
• Fallback URL listing: shows download URLs even without credentials

Authentication

NASA Earthdata requires a free account. To configure:

1. Register at https://urs.earthdata.nasa.gov/
2. Set environment variables:

   bash

   export EARTHDATA_USERNAME="your_username"
   export EARTHDATA_PASSWORD="your_password"
   

3. Or use the configure command:

   bash

   python scripts\modis_lst_download.py configure --username your_username
   

Usage

bash

# Search for available LST data
python scripts\modis_lst_download.py search \
  --product MOD11A1 \
  --start 2023-06-01 --end 2023-06-30 \
  --bbox 116.0 39.5 116.8 40.2

# Download daily LST (requires Earthdata auth)
python scripts\modis_lst_download.py download \
  --product MOD11A1 \
  --start 2023-07-01 --end 2023-07-01 \
  --bbox 116.0 39.5 116.8 40.2 \
  --output ./lst_data/ --layers LST_Day_1km,QC_Day

# Download 8-day composite
python scripts\modis_lst_download.py download \
  --product MOD11A2 \
  --start 2023-07-01 --end 2023-07-08 \
  --bbox 73 18 135 54 \
  --output ./china_lst/

# List download URLs without downloading
python scripts\modis_lst_download.py download \
  --product MYD11A1 \
  --start 2023-08-01 --end 2023-08-01 \
  --bbox 116.0 39.5 116.8 40.2 \
  --list-only

Parameters

• --product: MOD11A1, MOD11A2, MYD11A1, or MYD11A2
• --start/--end: Date range (YYYY-MM-DD)
• --bbox: Bounding box as west south east north
• --output: Output directory
• --layers: Comma-separated layer names (LST_Day_1km, LST_Night_1km, QC_Day, QC_Night)
• --list-only: Only list download URLs, do not download
• --username: Earthdata username (or set EARTHDATA_USERNAME env var)

Installation

bash

# Install dependencies
pip install requests>=2.28.0 tqdm

# Or install from requirements.txt
pip install -r scripts/requirements.txt

Data Source

• API: NASA LAADS DAAC (https://ladsweb.modaps.eosdis.nasa.gov/)
• Search API: CMR (Common Metadata Repository) via CMR-STAC
• License: Public Domain (NASA open data)
• Rate Limit: No strict limit; recommended max 10 requests/minute
• CRS: Sinusoidal (MODIS native projection)
• Temporal coverage: Terra from 2000-02-24; Aqua from 2002-07-04
• Data latency: ~2 weeks for standard products

Product Citations

• MOD11A1: Wan, Z., S. Hook, and G. Hulley, 2015. MOD11A1 MODIS/Terra Land Surface Temperature/Emissivity Daily L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC.
• MOD11A2: Wan, Z., S. Hook, and G. Hulley, 2015. MOD11A2 MODIS/Terra Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC.
• MYD11A1: Wan, Z., S. Hook, and G. Hulley, 2015. MYD11A1 MODIS/Aqua Land Surface Temperature/Emissivity Daily L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC.
• MYD11A2: Wan, Z., S. Hook, and G. Hulley, 2015. MYD11A2 MODIS/Aqua Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC.

Citation Format

bibtex

@misc{wan2015mod11a2,
  title={MOD11A2 MODIS/Terra Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006},
  author={Wan, Z. and Hook, S. and Hulley, G.},
  journal={NASA EOSDIS Land Processes DAAC},
  year={2015},
  doi={10.5067/MODIS/MOD11A2.006}
}

LST Scale Factor

• Raw values: Integer DN (Digital Number)
• Conversion: Multiply by 0.02 to get temperature in Kelvin
• To Celsius: T(°C) = DN × 0.02 - 273.15
• Example: DN 15000 → 300.00 K → 26.85°C

QC Band Interpretation

Bits	Field	Values
0-1	Quality flag	0=good quality, 1=other quality, 2=cloud contaminated, 3=not produced
2-3	Emissivity error flag	0=≤0.01, 1=≤0.02, 2=≤0.04, 3=>0.04
4-5	LST error flag	0=≤1K, 1=≤2K, 2=≤3K, 3=>3K

Cloud filtering: Keep only pixels where bits 0-1 = 0 (good quality).

8-Day Compositing Algorithm

MOD11A2 composites daily LST values over 8 days using:

• Cloud-free preference: Pixels with no cloud contamination are prioritized.
• Maximum temperature: For overlapping observations, the highest quality LST value is retained.
• QC-driven: Only pixels passing QC checks are included in the composite.

Visualization

• Temperature maps: Load GeoTIFF in QGIS with single-band pseudocolor, apply color ramp (blue→red).
• Time series: Stack multiple dates and plot with matplotlib.
• QC overlay: Use QC band to mask unreliable pixels before visualization.

Troubleshooting

Error	Cause	Solution
ConnectionError	Network issue or API down	Check internet connection, retry in 1 minute
HTTP 429	Rate limit exceeded	Wait 60 seconds before retrying
HTTP 404	Invalid parameters or date range	Check parameter names and date format
ValueError: bbox	Invalid bounding box	Ensure format is west,south,east,north
Empty output	No data for query region/time	Try different date range or check coordinates
ModuleNotFoundError	Missing dependency	Run pip install requests tqdm
401 Unauthorized	Earthdata auth failed	Check EARTHDATA_USERNAME/PASSWORD or run configure

---

Advanced Usage

Batch Time Series Download

bash

# Download every month for a year
for month in $(seq -w 1 12); do
  python scripts\modis_lst_download.py download     --product MOD11A1 --bbox 116 39.5 117 40.2     --start 2023-${month}-01 --end 2023-${month}-28     --output lst_2023_${month}.tif
  sleep 2
done

CI/CD Integration (GitHub Actions)

yaml

# .github/workflows/update-modis-lst.yml
name: Update MODIS LST
on:
  schedule:
    - cron: '0 12 * * *'  # Daily
jobs:
  download:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: '3.11'
      - run: pip install requests
      - env:
          EARTHDATA_USERNAME: ${{ secrets.EARTHDATA_USER }}
          EARTHDATA_PASSWORD: ${{ secrets.EARTHDATA_PASS }}
        run: |
          python scripts\modis_lst_download.py download \
            --product MOD11A1 --bbox 116 39.5 117 40.2 \
            --start $(date -d '3 days ago' +%Y-%m-%d) \
            --end $(date +%Y-%m-%d) \
            --output data/lst_latest.tif

LST Conversion & QC

python

import rasterio
import numpy as np
with rasterio.open('lst.tif') as src:
    raw = src.read(1)
    # Convert DN to Celsius: scale factor 0.02, offset 273.15
    lst_celsius = raw * 0.02 - 273.15
    # QC: use QC band bits 0-1, keep only value 0 (good quality)

PostgreSQL/PostGIS Raster Import

bash

raster2pgsql -s 4326 -I -C lst.tif public.lst_raster | psql -d gis_db

Performance Tips

• Use --list-only first to preview URLs, then download in parallel
• Add sleep 2 between requests to avoid NASA rate limits
• For time series analysis, prefer MOD11A2 (8-day composite) over MOD11A1 to reduce cloud contamination

---

中文说明

从 NASA LAADS DAAC 搜索和下载 MODIS 地表温度（LST）产品。支持 Terra 和 Aqua 卫星的逐日和 8 天合成产品。

产品列表

产品	卫星	时间分辨率	空间分辨率
MOD11A1	Terra	逐日	1km
MOD11A2	Terra	8天合成	1km
MYD11A1	Aqua	逐日	1km
MYD11A2	Aqua	8天合成	1km

核心功能

• 昼夜地表温度：分别获取白天和夜间温度图层
• 质量控制：包含 QC 波段用于质量过滤
• 按日期范围和区域搜索：查找可用数据
• GeoTIFF 输出：标准地理参考栅格格式
• Earthdata 认证：安全访问 NASA 数据
• URL 列表回退：无认证时仍可列出下载链接

认证说明

NASA Earthdata 需要免费账号。配置方法：

1. 在 https://urs.earthdata.nasa.gov/ 注册
2. 设置环境变量：

   bash

   set EARTHDATA_USERNAME=your_username
   set EARTHDATA_PASSWORD=your_password
   

3. 或使用 configure 命令：

   bash

   python scripts\modis_lst_download.py configure --username your_username
   

使用示例

bash

# 搜索可用 LST 数据
python scripts\modis_lst_download.py search \
  --product MOD11A1 \
  --start 2023-06-01 --end 2023-06-30 \
  --bbox 116.0 39.5 116.8 40.2

# 下载逐日 LST（需要 Earthdata 认证）
python scripts\modis_lst_download.py download \
  --product MOD11A1 \
  --start 2023-07-01 --end 2023-07-01 \
  --bbox 116.0 39.5 116.8 40.2 \
  --output ./lst_data/ --layers LST_Day_1km,QC_Day

# 下载 8 天合成产品
python scripts\modis_lst_download.py download \
  --product MOD11A2 \
  --start 2023-07-01 --end 2023-07-08 \
  --bbox 73 18 135 54 \
  --output ./china_lst/

# 仅列出下载 URL 不下载
python scripts\modis_lst_download.py download \
  --product MYD11A1 \
  --start 2023-08-01 --end 2023-08-01 \
  --bbox 116.0 39.5 116.8 40.2 \
  --list-only

数据来源

• API: NASA LAADS DAAC (https://ladsweb.modaps.eosdis.nasa.gov/)
• 搜索 API: CMR (Common Metadata Repository) via CMR-STAC
• 许可证: 公共领域（NASA 开放数据）
• 引用: Wan, Z., S. Hook, and G. Hulley, 2015. MOD11A2 MODIS/Terra Land Surface Temperature/Emissivity 8-Day L3 Global 1km SIN Grid V006. NASA EOSDIS Land Processes DAAC.