264 lines
3.6 KiB
Markdown
264 lines
3.6 KiB
Markdown
# NavSea Weather Server
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Task: WeatherServer_GFS_Subset_Downloader
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Architecture: V11
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Codex: codex6
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Status: TODO
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---
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# 任务目标
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升级现有 gfs_downloader.py
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当前问题：
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直接下载完整 GFS 文件：
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gfs.t00z.pgrb2.0p25.f000
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文件大小：
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≈ 500MB
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下载 72 小时预测需要：
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≈ 12GB
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这是不可接受的。
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解决方案：
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使用 NOAA 提供的 GRIB Subset API：
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filter_gfs_0p25.pl
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只下载：
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1 指定区域
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2 指定变量
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3 指定高度层
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目标：
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将单个 GRIB 文件缩小到：
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2MB – 10MB
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---
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# 下载区域
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NavSea 天气服务器只需要日本附近区域：
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leftlon = 120
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rightlon = 150
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toplat = 50
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bottomlat = 20
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覆盖：
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日本海
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东海
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太平洋日本海域
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---
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# 下载变量
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Weather System V1 需要以下变量：
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UGRD
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VGRD
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APCP
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PRMSL
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TMP
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HTSGW
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DIRPW
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PERPW
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说明：
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UGRD VGRD → 风
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APCP → 降水
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PRMSL → 气压
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TMP → 温度
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HTSGW → 浪高
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DIRPW → 浪方向
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PERPW → 浪周期
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变量参数来自 NOAA GFS 参数列表。 :contentReference[oaicite:0]{index=0}
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---
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# 下载高度层
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需要以下层：
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10 m above ground
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surface
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mean sea level
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参数：
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lev_10_m_above_ground
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lev_surface
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lev_mean_sea_level
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---
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# URL 构造规则
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基础地址：
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https://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_0p25.pl
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示例：
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https://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_0p25.pl?
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file=gfs.t00z.pgrb2.0p25.f003
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&lev_10_m_above_ground=on
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&lev_surface=on
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&lev_mean_sea_level=on
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&var_UGRD=on
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&var_VGRD=on
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&var_APCP=on
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&var_PRMSL=on
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&var_TMP=on
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&var_HTSGW=on
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&var_DIRPW=on
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&var_PERPW=on
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&leftlon=120
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&rightlon=150
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&toplat=50
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&bottomlat=20
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&dir=%2Fgfs.20260312%2F00%2Fatmos
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---
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# 修改文件
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weather_server/downloader/gfs_downloader.py
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---
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# 新代码
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```python
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import os
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import requests
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from datetime import datetime
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BASE_URL = "https://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_0p25.pl"
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OUTPUT_DIR = "data/grib"
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FORECAST_HOURS = [
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0,3,6,9,12,15,18,21,24,
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27,30,33,36,39,42,45,
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48,51,54,57,60,63,66,
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69,72
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]
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REGION = {
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"leftlon":120,
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"rightlon":150,
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"toplat":50,
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"bottomlat":20
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}
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VARIABLES = [
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"UGRD",
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"VGRD",
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"APCP",
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"PRMSL",
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"TMP",
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"HTSGW",
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"DIRPW",
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"PERPW"
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]
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LEVELS = [
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"lev_10_m_above_ground",
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"lev_surface",
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"lev_mean_sea_level"
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]
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os.makedirs(OUTPUT_DIR, exist_ok=True)
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def get_cycle():
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now = datetime.utcnow()
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hour = (now.hour // 6) * 6
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cycle = f"{hour:02d}"
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date = now.strftime("%Y%m%d")
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return date, cycle
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def build_url(date, cycle, fh):
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filename = f"gfs.t{cycle}z.pgrb2.0p25.f{fh}"
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params = {
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"file": filename,
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"leftlon": REGION["leftlon"],
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"rightlon": REGION["rightlon"],
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"toplat": REGION["toplat"],
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"bottomlat": REGION["bottomlat"],
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"dir": f"/gfs.{date}/{cycle}/atmos"
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}
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for v in VARIABLES:
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params[f"var_{v}"] = "on"
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for l in LEVELS:
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params[l] = "on"
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return BASE_URL, params
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def download_file(url, params, path):
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if os.path.exists(path):
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print("skip", path)
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return
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print("downloading", path)
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r = requests.get(url, params=params, stream=True)
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if r.status_code != 200:
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print("failed", r.status_code)
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return
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with open(path, "wb") as f:
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for chunk in r.iter_content(1024*1024):
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f.write(chunk)
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def main():
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date, cycle = get_cycle()
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print("cycle:", date, cycle)
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for fh in FORECAST_HOURS:
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fh_str = f"{fh:03d}"
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url, params = build_url(date, cycle, fh_str)
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output = os.path.join(
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OUTPUT_DIR,
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f"{date}_{cycle}_f{fh_str}.grib2"
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)
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download_file(url, params, output)
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if __name__ == "__main__":
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main() |