True-colour approach 5 — a daily MODIS time-lapse of the middle-Danube corridor¶

Sentinel-2/Landsat resolve a single reach; to watch a whole corridor dry out day by day you need a daily sensor. MODIS (MOD09GA, ~500 m, daily) is too coarse for channel width but perfect for a smooth basin-scale true-colour movie — the land browning and the big rivers/reservoirs standing out across the drought. We animate the middle-Danube corridor through summer 2026.

Needs GEE_SERVICE_ACCOUNT / GEE_SERVICE_KEY and pyramids-gis[viz].

Setup¶

pyramids reads and plots the GeoTIFFs (Dataset / DatasetCollection); earthlens provides the EarthLens entry point. Earth Engine credentials come from a repo-root .env.

In [ ]:

import os
import warnings
from pathlib import Path

import matplotlib.pyplot as plt
from IPython.display import Image, display
from loguru import logger
from pyramids.dataset import DatasetCollection

from earthlens.core import EarthLens

warnings.filterwarnings("ignore")
logger.remove()
plt.rcParams["figure.dpi"] = 80

from dotenv import find_dotenv, load_dotenv

load_dotenv(find_dotenv(usecwd=True))
SERVICE_ACCOUNT = os.environ["GEE_SERVICE_ACCOUNT"]
SERVICE_KEY = os.environ["GEE_SERVICE_KEY"]

import os import warnings from pathlib import Path import matplotlib.pyplot as plt from IPython.display import Image, display from loguru import logger from pyramids.dataset import DatasetCollection from earthlens.core import EarthLens warnings.filterwarnings("ignore") logger.remove() plt.rcParams["figure.dpi"] = 80 from dotenv import find_dotenv, load_dotenv load_dotenv(find_dotenv(usecwd=True)) SERVICE_ACCOUNT = os.environ["GEE_SERVICE_ACCOUNT"] SERVICE_KEY = os.environ["GEE_SERVICE_KEY"]

The corridor and the window¶

A wide box over the middle Danube (Hungary–Serbia) and a daily MODIS true-colour frame across the drought. MODIS bands sur_refl_b01/b04/b03 are red/green/blue.

In [ ]:

CORRIDOR = {"lat_lim": [44.0, 48.5], "lon_lim": [16.0, 22.0]}
MODIS = "MODIS/061/MOD09GA"
OUT = Path("out") / "tc5_modis_corridor"
raw = OUT / "daily"
raw.mkdir(parents=True, exist_ok=True)

CORRIDOR = {"lat_lim": [44.0, 48.5], "lon_lim": [16.0, 22.0]} MODIS = "MODIS/061/MOD09GA" OUT = Path("out") / "tc5_modis_corridor" raw = OUT / "daily" raw.mkdir(parents=True, exist_ok=True)

Pull one daily true-colour frame per day (cached)¶

One daily MODIS true-colour GeoTIFF per day over the corridor, mid-June to mid-July 2026 (the peak of the drought). Cached, so re-runs skip the pulls.

In [ ]:

cached = sorted(raw.glob("*.tif"))
if cached:
    frames = cached
else:
    job = EarthLens(
        data_source="gee",
        dataset=MODIS,
        variables=["sur_refl_b01", "sur_refl_b04", "sur_refl_b03"],
        start="2026-06-15",
        end="2026-07-15",
        temporal_resolution="daily",
        scale=2000.0,
        path=raw,
        export_via="url",
        **CORRIDOR,
    )
    job.authenticate(service_account=SERVICE_ACCOUNT, service_key=SERVICE_KEY)
    frames = job.download(progress_bar=False)
len(frames)

cached = sorted(raw.glob("*.tif")) if cached: frames = cached else: job = EarthLens( data_source="gee", dataset=MODIS, variables=["sur_refl_b01", "sur_refl_b04", "sur_refl_b03"], start="2026-06-15", end="2026-07-15", temporal_resolution="daily", scale=2000.0, path=raw, export_via="url", **CORRIDOR, ) job.authenticate(service_account=SERVICE_ACCOUNT, service_key=SERVICE_KEY) frames = job.download(progress_bar=False) len(frames)

Animate the corridor day by day¶

Read the daily frames into one collection and animate the true colour. MODIS surface reflectance needs a brightness stretch, which pyramids applies via surface_reflectance.

In [ ]:

dc = DatasetCollection.read_multiple_files(str(raw), date=False)
gif = OUT / "modis_corridor.gif"
dc.plot(
    rgb_options={"rgb": [0, 1, 2], "surface_reflectance": 3200},
    figsize=(6, 5),
    title="Middle Danube corridor - MODIS true colour, Jun-Jul 2026",
).save_animation(str(gif), fps=3)
plt.close("all")
display(Image(filename=str(gif)))

dc = DatasetCollection.read_multiple_files(str(raw), date=False) gif = OUT / "modis_corridor.gif" dc.plot( rgb_options={"rgb": [0, 1, 2], "surface_reflectance": 3200}, figsize=(6, 5), title="Middle Danube corridor - MODIS true colour, Jun-Jul 2026", ).save_animation(str(gif), fps=3) plt.close("all") display(Image(filename=str(gif)))

Notes¶

• MODIS is basin-scale, not channel-scale: watch the land brown and the reservoirs/large reaches, not individual sandbars. Cloudy days are part of a daily time-lapse (the weather moving through).
• Swap MOD09GA (Terra, morning) for MYD09GA (Aqua, afternoon), or widen the box to the whole basin.