Description:

The NASA-ISRO Synthetic Aperture Radar (NISAR) Ancilliary and Auxiallry collection contains products that are supplementary information for the NISAR mission and are created a limited number of times. The collection contains Time Series Ratio (TSR_STATIC), Physical Model Inversion (PMI_STATIC), Corner Reflector locations (CORNER_REFL), Combined ADT Flight Table (INT_CAL), LSAR Calibration File (EXT_CAL), Flight Table Waveform (FT_WAVEFORM), Flight Table Parameters (FT_PARAM), Antenna Pattern (ANTPAT), Block Floating Point Quantization Look-up Table (BFPQ), Track Frame Database (TFDB), L-SAR Channel Data (L_CHAN_DATA), Soil Moisture Static File (SM_STATIC), and Disaggregation File (DSG_STATIC).

Links:

• Data link
• undefined
• Metadata link
• Metadata link

Temporal Extent:

Start: 2022-01-01T00:00:00.000Z

Spatial Extent:

Minimum Bounding Rectangle: -90 -180 90 180

ASF Short Name: NISAR_ANC_AUX Version ID: 1 Unique ID: C3622222871-ASF

Search this collection...

Description:

The NASA-ISRO Synthetic Aperture Radar (NISAR) Geocoded Polarimetric Covariance (GCOV) product is a Level 2 product derived from the Level 1 Range Doppler Single Look Complex (RSLC). The GCOV product provides terrain-corrected polarimetric covariance projected onto a predefined Universal Transverse Mercator (UTM) or polar stereographic projection system grid. RSLC radar samples, organized as a polarimetric scattering vector, are cross-correlated with the scattering vector’s conjugate transpose, originating the polarimetric covariance matrix expressed in the same grid as the RSLC range-Doppler grid. The magnitude of the resulting polarimetric covariance terms is strongly affected by the topography, with areas facing the sensor becoming brighter and areas away from the sensor turning darker in the images, biasing covariance measurements. To reduce the effect of the topography, an area-based radiometric terrain correction (RTC) is applied over the covariance terms, normalizing the backscatter coefficient from beta-naught to gamma-naught. The normalized covariance terms are then geocoded onto the output grid using an area-based adaptive multilooking. Since the polarimetric covariance matrix is Hermitian, only the upper triangular covariance terms are provided. The diagonal terms of the polarimetric covariance matrix are real-valued, representing the radar backscatter associated with each polarimetric channel. The off-diagonal terms of the polarimetric covariance matrix are complex-valued and may or may not be present depending on the GCOV processing mode. The products in this collection are considered Beta products and are intended to enable users to gain familiarity with the parameters and the data formats. Beta products are not intended for use in scientific research.

Links:

• Data link
• Data link
• undefined
• Metadata link

Temporal Extent:

Start: 2025-10-01T00:00:00.000Z

Spatial Extent:

Minimum Bounding Rectangle: -90 -180 90 180

ASF Short Name: NISAR_L2_GCOV_BETA_V1 Version ID: 1 Unique ID: C3622214170-ASF

Search this collection...

Description:

The NASA-ISRO Synthetic Aperture Radar (NISAR) Geocode Unwrapped Interferogram (GUNW) product is a Level 2 product derived from the Range Doppler Wrapped Interferogram (RIFG) and Range Doppler Unwrapped Interferogram (RUNW) products by geocoding the unwrapped phase and associated data layers (i.e., coherence magnitude, ionospheric phase screen) on a geographical grid at 80 m posting. Geocoding is performed using the orbit of the reference Range Doppler Single Look Complex (RSLC) product and a Digital Elevation Model (DEM) to project the data onto a predefined Universal Transverse Mercator (UTM) or Polar stereographic projection system map grid. The geocoding algorithm uses a bilinear interpolation for interpolating data layers with floating-point data types, Sinc for the complex wrapped interferogram, and nearest-neighbor interpolation for unsigned integer datasets (e.g., connected components mask). The GUNW products also include the wrapped complex interferogram (multilooked at 30 m in range-Doppler coordinates and geocoded at 20 m posting), the unwrapped interferometric phase in radians (80 m posting), the normalized interferometric coherence magnitude (20 m and 80 m posting), connected components mask, and sub-pixel offset layers obtained from incoherent cross-correlation. If a Range Doppler Pixel Offsets (ROFF) product is available for the processed frame, the sub-pixel offset layers included in GUNW are obtained by optimally blending the multi resolution offset layers included in ROFF. The GUNW product includes an ionospheric phase screen layer from the RUNW product and a layer quantifying its uncertainty. In the case of mode transitions where the continuity of spectral bands is impacted, a split spectrum ionospheric phase estimate is derived from the main imaging band frequency A. The estimated ionospheric phase screen is included in the product but not applied to the data layers within GUNW by default. The GUNW product also includes geocoded lookup tables for external phase corrections (e.g., solid Earth tides, hydrostatic and wet tropospheric phases). These phase corrections, when available, are not removed from the interferometric data. The products in this collection are considered Beta products and are intended to enable users to gain familiarity with the parameters and the data formats. Beta products are not intended for use in scientific research.

Links:

• Data link
• Data link
• undefined
• Metadata link

Temporal Extent:

Start: 2025-10-01T00:00:00.000Z

Spatial Extent:

Minimum Bounding Rectangle: -90 -180 90 180

ASF Short Name: NISAR_L2_GUNW_BETA_V1 Version ID: 1 Unique ID: C2850261892-ASF

Search this collection...

Description:

The NASA-ISRO Synthetic Aperture Radar (NISAR) Range Doppler Single Look Complex (RSLC) product is in the zero-Doppler radar geometry convention. The output image is on a grid characterized by constant azimuth time interval and one-way slant range spacing. The output grid is also characterized by a fixed starting slant range, azimuth time interval, and slant range spacing values for easy interpolation. All the primary image layers for a multi-polarization or multi-frequency product are generated on a common azimuth time-slant range grid. The RSLC product, which is used to derive other L1 and L2 products, contains individual binary raster layers representing complex signal return for each polarization layer. The RSLC data corresponding to the auxiliary sub-band is stored in a similar format but in a separate data group within the HDF5 product granule. The RSLC product is also packed with input, instrument and processing facility information; processing, calibration and noise parameters; geolocation grid; and data quality flags. The RSLC product complex backscatter is in digital numbers (DNs) with secondary layer look-up tables (LUTs) provided to convert to beta-naught, sigma-naught, and gamma-naught. These radiometric correction LUTs are defined for the ellipsoid (e.g., not for the local terrain). All standard (i.e., non-urgent response) products are processed using the Medium-fidelity Orbit Ephemeris (MOE) product for forward processing and the Precise Orbit Ephemeris (POE) product for reprocessing campaigns. The products in this collection are considered Beta products and are intended to enable users to gain familiarity with the parameters and the data formats. Beta products are not intended for use in scientific research.

Links:

• Data link
• Data link
• undefined
• Metadata link

Temporal Extent:

Start: 2025-10-01T00:00:00.000Z

Spatial Extent:

Minimum Bounding Rectangle: -90 -180 90 180

ASF Short Name: NISAR_L1_RSLC_BETA_V1 Version ID: 1 Unique ID: C2850225585-ASF

Search this collection...

Description:

The NASA-ISRO Synthetic Aperture Radar (NISAR) Range Doppler Wrapped Interferogram (RIFG) product represents the ellipsoid and topography flattened wrapped interferogram generated from two Level 1 Range-Doppler Single Look Complex (RSLC) products in the range-Doppler geometry of the earlier reference acquisition. The WGS84 ellipsoid is used as the reference surface for flat earth correction. The RIFG product contains a binary raster layer of complex numbers, i.e., the wrapped interferogram; its phase represents the wrapped interferometric phase in radians. The product also contains a binary raster layer of floating-point numbers representing the normalized interferometric correlation, i.e., the interferometric coherence magnitude. The wrapped interferogram and the interferometric coherence magnitude are multi-looked to a nominal posting of 30 m on the ground. No ionospheric phase screen correction layers are available with this product. The interferometric workflow producing RIFG products coregisters a pair of RSLC products using a Digital Elevation Model and the best available orbit ephemeris. This coregistration is refined using incoherent cross-correlation on the pair of coarsely coregistered RSLCs. The RIFG product includes the slant range and along-track sub-pixel offsets obtained from incoherent cross-correlation and used to generate the complex wrapped interferogram. If a Range Doppler Pixel Offsets (ROFF) product is available for the processed frame, the sub-pixel offset layers included in RIFG are obtained by optimally blending the multi-resolution offset layers included in ROFF. The products in this collection are considered Beta products and are intended to enable users to gain familiarity with the parameters and the data formats. Beta products are not intended for use in scientific research.

Links:

• Data link
• Data link
• undefined
• Metadata link

Temporal Extent:

Start: 2025-10-01T00:00:00.000Z

Spatial Extent:

Minimum Bounding Rectangle: -90 -180 90 180

ASF Short Name: NISAR_L1_RIFG_BETA_V1 Version ID: 1 Unique ID: C2850234202-ASF

Search this collection...