Sentinel-1 Reference Guide

This reference guide provides detailed information about Sentinel-1 SAR data parameters and options available through the Copernicus Data Space Ecosystem.

Note

New in version 0.1.20: Sentinel-1 SLC Burst Mode is now available! Search for individual bursts from SLC products with enhanced filtering capabilities. See the Sentinel-1 SLC Burst Mode guide for complete documentation.

Overview

Sentinel-1 is a constellation of two polar-orbiting satellites (Sentinel-1A and Sentinel-1B) carrying a C-band Synthetic Aperture Radar (SAR) instrument. The mission provides continuous all-weather, day-and-night imagery for land and ocean services.

Key Features: - C-band SAR instrument operating at 5.405 GHz - Four exclusive acquisition modes - Dual polarization capability (HH+HV, VV+VH) - 12-day repeat cycle (6 days with both satellites) - Global coverage - Individual burst access for SLC products (available from August 2, 2024)

Search Parameters

Parameter Types

When searching for Sentinel-1 data, parameters are passed in two ways:

  1. Direct Parameters: Passed directly to the search() method - collection_name - Mission/collection identifier - product_type - Product type (GRD, SLC, OCN, etc.) - orbit_direction - Orbit direction (ASCENDING/DESCENDING) - aoi_wkt - Area of interest in WKT format - start_date / end_date - Temporal range - top - Maximum number of results

  2. Attributes: Passed in the attributes dictionary - sensorMode - Acquisition mode (IW, EW, SM, WV) - platform - Satellite platform (S1A, S1B) - polarisation - Polarization combination - processingLevel - Processing level - relativeOrbitNumber - Relative orbit number - orbitNumber - Absolute orbit number - instrument - Instrument type - status - Product availability status - timeliness - Data delivery timeliness - processingBaseline - Processing baseline version - swathIdentifier - Specific swath identifier

Basic Parameters

Collection Name

Use 'SENTINEL-1' as the collection name.

results = searcher.search(collection_name='SENTINEL-1')

Geographic Parameters

Geometry

Region of Interest defined in Well Known Text (WKT) format with coordinates in decimal degrees (EPSG:4326).

# Polygon example
aoi_wkt = 'POLYGON((12.4 41.9, 12.5 41.9, 12.5 42.0, 12.4 42.0, 12.4 41.9))'
results = searcher.search(
    collection_name='SENTINEL-1',
    aoi_wkt=aoi_wkt
)

Product Parameters

Product Types

Sentinel-1 offers various product types for different applications:

# Search for GRD products
results = searcher.search(
    collection_name='SENTINEL-1',
    product_type='GRD'
)

Processing Level

Available processing levels:

  • LEVEL0 - Raw data

  • LEVEL1 - Single Look Complex (SLC) and Ground Range Detected (GRD)

  • LEVEL2 - Ocean (OCN) and other derived products

# Search for LEVEL1 products
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'processingLevel': 'LEVEL1'}
)

Platform

Sentinel-1 constellation satellites:

  • S1A - Sentinel-1A

  • S1B - Sentinel-1B

# Search for Sentinel-1A data only
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'platform': 'S1A'}
)

Swath Identifier

Filter by specific swath. This is an attribute-based search.

  • Stripmap (SM): S1 to S6

  • Interferometric Wide (IW): IW1, IW2, IW3

  • Extra Wide (EW): EW1 to EW5

  • Wave (WV): WV1, WV2

# Search for data from Stripmap swath S1
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'swathIdentifier': 'S1'}
)

Instrument

  • SAR - Synthetic Aperture Radar

# Search for SAR instrument data
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'instrument': 'SAR'}
)

Sensor Mode

Sentinel-1 acquisition modes:

  • SM - Stripmap mode (S1-S6)

  • IW - Interferometric Wide swath mode (default)

  • EW - Extra-Wide swath mode

  • WV - Wave mode

# Search for Interferometric Wide swath data
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'sensorMode': 'IW'}
)

Mode Characteristics:

  • Stripmap (SM): 80 km swath, 5 m resolution, 6 beams (S1-S6)

  • Interferometric Wide swath (IW): 250 km swath, 5×20 m resolution, 3 sub-swaths

  • Extra Wide swath (EW): 400 km swath, 20×40 m resolution, 5 sub-swaths

  • Wave (WV): 20×20 km vignettes, 5 m resolution, for ocean applications

Orbit Parameters

Orbit Direction

  • ASCENDING - Satellite moving from south to north

  • DESCENDING - Satellite moving from north to south

results = searcher.search(
    collection_name='SENTINEL-1',
    orbit_direction='DESCENDING'
)

Orbit Number

Absolute orbit number (integer value or range).

# Single orbit
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'orbitNumber': 12345}
)

Relative Orbit Number

Relative orbit number (1-175 for Sentinel-1), representing the orbit within a repeat cycle.

# Search for relative orbit 87
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'relativeOrbitNumber': 87}
)

Polarization

Sentinel-1 supports various polarization combinations:

  • HH - Horizontal transmit, Horizontal receive

  • VV - Vertical transmit, Vertical receive

  • HH&VH - Horizontal transmit, Horizontal and Vertical receive

  • VV&VH - Vertical transmit, Vertical and Horizontal receive

  • VH&VV - Vertical transmit, Horizontal and Vertical receive

  • VH&HH - Vertical transmit, Horizontal and Vertical receive

  • HH&HV - Horizontal transmit, Horizontal and Vertical receive

  • VV&HV - Vertical transmit, Vertical and Horizontal receive

  • HV&HH - Horizontal transmit, Vertical and Horizontal receive

  • HV&VV - Horizontal transmit, Vertical and Vertical receive

# Search for dual polarization VV+VH
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'polarisation': 'VV&VH'}
)

Polarization by Mode: - IW and EW modes: VV+VH or HH+HV - SM mode: Single (HH, VV, HV, VH) or dual polarization - WV mode: Single polarization (HH or VV)

Quality and Timeliness

Timeliness

Data delivery timeliness categories:

  • NRT-10m - Near Real-Time within 10 minutes

  • NRT-3h - Near Real-Time within 3 hours

  • Fast-24h - Fast delivery within 24 hours

  • Off-line - Standard offline processing

  • Reprocessing - Reprocessed data

# Search for near real-time data
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'timeliness': 'NRT-3h'}
)

Processing Baseline

Processing baseline version (affects product quality and algorithms used).

# Search for specific processing baseline
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'processingBaseline': '003.40'}
)

Status

Product availability status:

  • ONLINE - Immediately available for download

  • OFFLINE - Requires retrieval from long-term storage

  • ALL - Both online and offline products

# Search for immediately available products
results = searcher.search(
    collection_name='SENTINEL-1',
    attributes={'status': 'ONLINE'}
)
results = searcher.search(
    collection_name='SENTINEL-1',
    status='ONLINE'
)

Practical Examples

Example 3: Ocean Applications

from phidown import CopernicusDataSearcher

searcher = CopernicusDataSearcher()

# Search for ocean products and wave mode data
ocean_results = searcher.search(
    collection_name='SENTINEL-1',
    product_type='OCN',
    aoi_wkt='POLYGON((0 35, 10 35, 10 45, 0 45, 0 35))',  # Mediterranean
    start_date='2023-06-01',
    end_date='2023-06-30'
)

wave_results = searcher.search(
    collection_name='SENTINEL-1',
    product_type='GRD',
    aoi_wkt='POLYGON((0 35, 10 35, 10 45, 0 45, 0 35))',
    start_date='2023-06-01',
    end_date='2023-06-30',
    attributes={'sensorMode': 'WV'}
)

print(f"Found {len(ocean_results)} ocean products and {len(wave_results)} wave mode products")

Example 4: Time Series Analysis

from phidown import CopernicusDataSearcher
import pandas as pd

searcher = CopernicusDataSearcher()

# Search for consistent time series data
results = searcher.search(
    collection_name='SENTINEL-1',
    product_type='GRD',
    aoi_wkt='POLYGON((12.4 41.9, 12.5 41.9, 12.5 42.0, 12.4 42.0, 12.4 41.9))',
    start_date='2023-01-01',
    end_date='2023-12-31',
    orbit_direction='DESCENDING',
    attributes={
        'sensorMode': 'IW',
        'relativeOrbitNumber': 87,
        'polarisation': 'VV%26VH'
    }
)

# Group by date to analyze temporal coverage
results['Date'] = pd.to_datetime(results['ContentDate']).dt.date
temporal_coverage = results.groupby('Date').size()

print(f"Found {len(results)} products over {len(temporal_coverage)} unique dates")

Search Optimization Tips

  1. Use Relative Orbit Numbers: For time series analysis, filter by relative orbit number to ensure consistent geometry.

  2. Specify Orbit Direction: Choose ascending or descending based on your application needs.

  3. Filter by Polarization: Select appropriate polarization for your analysis (VV+VH for most land applications).

  4. Consider Processing Baseline: Newer baselines generally provide better quality but may not be available for historical data.

  5. Use Sensor Mode Appropriately: - IW for most land applications (use attributes={'sensorMode': 'IW'}) - EW for wide-area monitoring (use attributes={'sensorMode': 'EW'}) - WV for ocean wave analysis (use attributes={'sensorMode': 'WV'})

  6. Check Product Status: Use attributes={'status': 'ONLINE'} for immediate download needs.

Common Use Cases

Land Applications: - Deforestation monitoring: IW GRD, VV+VH polarization - Urban change detection: IW GRD, VV polarization - Agricultural monitoring: IW GRD, VV+VH polarization

Ocean Applications: - Ship detection: IW GRD, VV polarization - Oil spill monitoring: IW GRD, VV polarization - Wave analysis: WV mode products

Interferometry: - Ground deformation: IW SLC, same relative orbit - Topographic mapping: IW SLC, interferometric pairs

Emergency Response: - Flood mapping: IW GRD, VV polarization - Disaster assessment: IW GRD, available polarization

Technical Specifications

Frequency: 5.405 GHz (C-band) Repeat Cycle: 12 days (constellation), 6 days (with both satellites) Orbital Altitude: 693 km Incidence Angle Range: 20-47 degrees Swath Width: - SM: 80 km - IW: 250 km - EW: 400 km - WV: 20 km

Spatial Resolution: - SM: 5 m (single-look) - IW: 5x20 m (single-look) - EW: 20x40 m (single-look) - WV: 5 m (single-look)

For more detailed information about Sentinel-1 specifications and applications, refer to the official ESA Sentinel-1 documentation.