Knowledge Base

All Products
FAQ
Options Available for Bulk Downloading Data from HTTPS with Earthdata Login

There are a few options depending on the tools that you have available ... Read more

What is the Map Transformations Library (Mapx)?

Mapx is a coordinate transformation library developed at NSIDC. The C ... Read more

How does the Reverb tool select which granules contain data in a specific geographic region?

The Backtrack Orbit Search Algorithm (BOSA) is used so that Reverb can ... Read more

Where can I find the Reverb Tutorial?

Reverb Tutorial can be found on the Reverb Web site: ... Read more

Can I view virtual globe animations offline?

Google earth tries to connect to the internet when viewing KMZ's. The ... Read more

How To
How to access data using an FTP client

To access data using an FTP client (e.g. FileZilla, Cyberduck, FireFTP ... Read more

How to see a list of data sets

The NSIDC Data ... Read more

FORTRAN I/O Samples
Unsigned byte data in a two dimensional array
 ... Read more
FORTRAN Binary I/O

Kenneth W. Knowles, National Snow & Ice Data Center

There ... Read more

A Mapping and Gridding Primer: Points, Pixels, Grids, and Cells
Introduction:

Satellite remote sensing has made possible the ... Read more

How to use the new data services in the Reverb search and order tool?

In July 2013, NSIDC and NASA's Reverb|ECHO introduced new functionality ... Read more

How do I programmatically request data services (e.g. subsetting, reformatting, reprojection) using an API?

The subsetting, reformatting, and reprojection services provided by ... Read more

AMSR
FAQ
Why are AMSR/ADEOS-II data only available for nine months?

On 25 October 2003, at 8:49 a.m. (JST), JAXA discovered that ADEOS-II ... Read more

Are any higher-level AMSR/ADEOS-II products available?

No, the AMSR/ADEOS-II L2A ... Read more

How do AMSR and AMSR-E improve upon previous passive microwave radiometers?

First, the spatial resolution of AMSR/ADEOS-II and AMSR-E/Aqua data ... Read more

AMSRE
FAQ
Where can I find AMSR2 data?

The Japan Aerospace Exploration Agency (JAXA) distributes ... Read more

What is AMSR-E Slow Rotation Data?

... Read more

What is the difference between smoothed and unsmoothed data in the AE_L2A data set, and how should I use them together?

Each frequency is looking at a different size footprint. Each frequency ... Read more

How do I extract latitude and longitude information from AMSR-E sea ice data?

AMSR-E sea ice data sets are provided in the Polar Stereographic ... Read more

Why does the number of pixels per scan vary among different Level-2 AMSR-E data sets?

A typical AMSR-E swath width consists of approximately 2000 scans, with ... Read more

Is there a Level-1B AMSR-E data set available?

Yes. An AMSR-E Level-1B data set exists, but it is not available from ... Read more

How do the calibration coefficients differ between the Level-1A and Level-2A AMSR-E data sets?

The calibration coefficients and offsets for the  ... Read more

What is NOSE and how does it work with AMSR-E data?

AMSR-E Level-2A data ... Read more

Do you have code for reading AMSR-E data into MATLAB, IDL, Python, or NCL?

The ... Read more

Do you provide the algorithm source code for AMSR-E data?

Yes. This code is provided in files called Delivered Algorithm Packages ... Read more

Why are there holes at the poles, and why do they vary in size?

See the ... Read more

What do the various levels of AMSR-E data represent?

The following table describes the different levels of AMSR-E data. ... Read more

Do you have antenna patterns for AMSR-E?

Yes. We archive antenna patterns for both AMSR-E/Aqua and AMSR/ADEOS-II ... Read more

How do AMSR and AMSR-E improve upon previous passive microwave radiometers?

First, the spatial resolution of AMSR/ADEOS-II and AMSR-E/Aqua data ... Read more

Do you have a listing of maneuvers for the Aqua satellite?

Yes. A listing of maneuvers that have occurred for the Aqua satellite, ... Read more

Why are there holes at the North and South Poles, and why are there different sizes in the ascending and descending grids?

See the ... Read more

What do the various levels of data represent?

The following table describes the levels associated with AMSR-E ... Read more

What is the spatial resolution of AMSR-E products?

The spatial resolution of AMSR-E products varies from 6.25 to 57 km. ... Read more

What format are the data in?

The Level-1A products are in Hierarchical Data Format (HDF). The AMSR-E ... Read more

What data subsetting, reformatting, and reprojection services are available for AMSR-E data?

The following table describes the data subsetting, reformatting, and ... Read more

How To
How do I retrieve a time array from AE_L2A data?

Each AE_L2A data file has a time stamp for each scan. The time array is ... Read more

How do I import AMSR-E Daily Soil Moisture data into ArcGIS?

The following are instructions on how to import and display AMSR-E ... Read more

How can I read AMSR-E Level-2 Soil Moisture Data?

HDF-EOS defines three different data models – point, swath, and grid – ... Read more

How can I view AMSR-E data?

Note: These instructions do not apply to the Level-2B ... Read more

DEMS
FAQ
Is the Greenland Surface DEM provided in an alternative format?

Yes. Attached to this article are the following Greenland Surface DEM ... Read more

How To
How do I read the Greenland DEM in Fortran?

Directions for reading the Bamber Greenland DEM, Ice Thickness, and ... Read more

How to import the Greenland DEM into ArcGIS

Directions for Importing Bamber Greenland DEM, Ice Thickness, and ... Read more

How to import the Digital SAR Mosaic of Greenland into ArcGIS

These are directions for importing the grnlnd_dem_wgs84.dat (a

... Read more
EASE
FAQ
Why use equal-area maps?

Given the choices of either shape distortion or areal distortion or ... Read more

What do I use to convert Northern EASE-Grid to Global EASE-Grid?

Assuming that the data that was produced conforms to the ML (25km) EASE ... Read more

How To
How do I import EASE-Grid 2.0 snow cover and sea ice data into ArcGIS?

This document describes how to import  EASE-Grid 2.0 data files into ... Read more

How to import Global Monthly EASE-Grid SWE data products into ArcGIS

The global, monthly SWE EASE-GRID products can be found at the ... Read more

IceBridge
FAQ
Why are the 2009 images 1-band, while the other images are 3-band?

During the first campaign for this data set (2009 Antarctica), the ... Read more

When are the IceBridge data collected? What is an IceBridge data campaign?

The IceBridge project was initiated in order to fill a gap in the ... Read more

How To
How can I search for IceBridge data?

1. To see a listing of all the IceBridge data sets, ... Read more

How do I use the IceBridge Data Portal?

The IceBridge Data Portal allows for map-based visualization of flight ... Read more

ICESat
FAQ
Will the location (Lat, Lon) of each GLAS footprint change after converting to WGS84?

The Lat Lon stay the same because the difference was/is not significant ... Read more

What data subsetting and reformatting services are available for ICESat/GLAS data?

The following table describes the data subsetting and reformatting ... Read more

Why is spatial searching not enabled for GLA01 (GLAH01) to GLA04 (GLAH04)?

The orbit for GLA01 (GLAH01) and GLA02 (GLAH02) is a ... Read more

Why are laser footprint shape parameters not available for low energy campaigns?

Several parameters help quantify the shape of the GLAS laser footprint ... Read more

What is the basic difference between a standard and alternate fit and when would you normally choose one over the other?

The standard fit is optimized for "ice sheet-like" returns. The ... Read more

What is meant by the first and last shot in the record?

There are 40 laser shots in one second which are associated with the ... Read more

What is GRACE and how does it contribute to GLAS?

The Gravity Recovery and Climate Experiment (GRACE) satellite was ... Read more

Since two different algorithms are used in GLA08 (GLAH08) and GLA09 (GLAH09), are the aerosol layers different between the two products?

GLA09 (GLAH09) should not contain elevated aerosol layers, ... Read more

In the GLAS altimetry products is there an indicator to the presence of clouds?

Yes, it is an element of: GLA06 (GLAH06), GLA12 (GLAH12) ... Read more

In preliminary data from laser #1, why does the "i_surfType" record indicate surface classifications that are simultaneously land, sea ice, ocean, and ice sheet?

This is not an error. The masks for these surfaces purposely overlap in ... Read more

In GLA09 (GLAH09), is there a cloud bottom for every cloud top? How do you match them?

For every top of layer given, there is definitely a bottom of layer ... Read more

In GLA01 and GLAH01 waveform plots, what does the "relative time" axis mean?

The relative time axis represents two-way travel time. Two adjacent ... Read more

How is the surface elevation at each laser footprint determined?

In short, the elevation of the surface at each laser footprint is the ... Read more

How do GLAS data improve upon past ice sheet altimetry data?

Seasat data collected in 1978 provided scientists with 20 km elevation ... Read more

Do you have code for reading GLAS data into MATLAB, IDL, Python, or NCL?

... Read more

How does surface roughness affect the accuracy of the elevation measurement?

Over most of the ice sheets, the accuracy of each elevation measurement ... Read more

Are the altimetry data already adjusted to the Geoid, or only to the Ellipsoid?

The elevation data is relative to the ellipsoid.
The data also ... Read more

How often were data collected for a given geographic area?

The first several months of ICESat operations were in an orbit that ... Read more

How does GLAS geolocate data and provide off-nadir pointing?

Analysis of altimetric data acquired by the GLAS instrument requires ... Read more

GLA08 and GLA09 were originally designed to use only the 532 nm profiles from GLA07; however, these two products use the 1064 nm channel data in addition to 532 nm. Where do the 1064 nm layers come from, and do the 532 nm and 1064 nm algorithms differ?

The GLAS science team added the 1064 nm-based layer detection just a ... Read more

How different are the cloud layer heights in GLA09 identified by the 532 nm and 1064 nm channels?

Users may note duplication of cloud layers in GLA09, meaning that a ... Read more

In GLA09 (GALH09), is there a cloud bottom for every cloud top? How do you match them?

For every top of layer given, there is definitely a bottom of layer ... Read more

Does GLA14 (GLAH14) cover the ice sheets, and if so, does it use a different algorithm over ice sheets?

Yes, the land mask (and thus, GLA14) includes ice sheets, although it ... Read more

In GLA13 (GLAH13), values of "surfType" all indicate combinations of surface types, with no values for pure sea ice or pure land. Is this correct?

Yes, surface type flags are never purely sea ice; ocean is always ... Read more

What data subsetting and reformatting services are available for ICESat/GLAS data?

The following table describes the data subsetting and reformatting ... Read more

How To
Stepping through the HDFView User Guide with GLAS HDF5 Data
HDFView

... Read more

How to order a subset of GLAS HDF5 data

The NASA Reverb search and ... Read more

How to run NGAT

To use the NGAT tool, first download and extract the files into one ... Read more

How to run an IDL reader for glas products (read_glas_file.pro)

Here is the link to the IDL readers: ... Read more

How to extract elevation from GLAS HDF5 data

ou can extract elevation from GLAS HDF5 data in tabular format using ... Read more

How do I import GLAS/ICESat 500 m Laser Altimetry Digital Elevation Model of Antarctica into ArcMap?

The following steps outline the process for visualizing the GLAS/ICESat ... Read more

How do you compute sea ice freeboard using GLA13 (GLAH13) data?

"Freeboard" is a measure of the height of sea ice above the ocean ... Read more

MODIS
FAQ
How do I use the MODIS Reprojection Tool (MRT) with MODIS Level-3 Snow Cover Products?

There are several things to consider when using MRT with MODIS Level-3 ... Read more

What data subsetting, reformatting, and reprojection services are available for MODIS data?
Is it possible to create a "Vertical Perspective" projection map using ll2cr/fornav?

No. The "vertical perspective" projection, is not supported by the mapx ... Read more

What is MS2GT and what can it do?

The MODIS Swath-to-Grid Toolbox (MS2GT) is a set of software tools that ... Read more

Do you have code for reading MODIS data into MATLAB, IDL, Python, or NCL?

The ... Read more

What are the limitations of MODIS data?

MODIS is an optical sensor, which has inherent limitations in observing ... Read more

What are the MODIS sensor's strongest attributes, and how do they compare to other sensors?

MODIS provides global coverage every one to two days in 36 spectral ... Read more

What is the lag time between observations and the availability of products?

The lag time between observations and availability of products is only ... Read more

Since Aqua and Terra have the same data products, which one should I use?

See the ... Read more

How can I compare the latest version of data to an earlier version of data I used for a research project?

Due to differences in science quality of the products, users are ... Read more

How To
How to order specific MODIS tiles from Reverb

Using Reverb's 2D coordinate data search. ... Read more

NOAA
FAQ
What if I need SNODAS data in real or neal-real time?

NSIDC has scripts that run several times a day. If new SNODAS files are ... Read more

How can I find information about the model input for the SNODAS data set?

NOHRSC provides/creates the data, we just archive it. If you have ... Read more

When visualizing SNODAS data, why is the image skewed?

This is most likely due to a problem with Windows Winzip which corrupts ... Read more

Why can't I convert IMS ascii data into a raster in ArcMap?

The problem is that some IMS ascii files were created without spaces in ... Read more

How To
How do I import SNODAS data into ArcGIS?

Follow the steps below (which are also ... Read more

How can I interpolate large segments of missing data?

Unfortunately, there's not much to be done. Sea ice varies so ... Read more

How can I plot IMS-24km ASCII data using General Mapping Tools (GMT)?

There are two "tricks" to using this dataset with GMT: reading the data ... Read more

Polar Stereo
FAQ
Do you have code for reading NISE data into MATLAB, IDL, Python, or NCL?

The ... Read more

How To
How to import the sea ice trends data into ArcGIS

The following are instructions describing how to import "Sea Ice Trends ... Read more

How to import the near-real-time sea ice data into ArcGIS

The following are instructions describing how to import "Near-Real-Time ... Read more

How to display and analyze the Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data

The Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS ... Read more

How to import the NSIDC-0051 sea ice concentration data into ArcGIS

The following are instructions describing how to import "Sea Ice ... Read more

SMAP
FAQ
Why do the soil moisture values in the SMAP Level-4 data vary from what I expect in a particular region?

There are a few reasons that the soil moisture data values in SMAP ... Read more

Do you have code for reading SMAP data into MATLAB, Python, IDL, or NCL?

The ... Read more

What are the latencies for SMAP radiometer data sets?

The following table describes both the required ... Read more

Why does the root zone soil moisture in the SMAP Level-4 soil moisture products vary in such close unison with the surface soil moisture?

The surface and root zone soil moisture estimates in the SMAP Level-4 ... Read more

When will SMAP data be available?

The following table describes the release schedule for SMAP data. ... Read more

Why don't the SMAP enhanced soil moisture products include landcover class?

While the standard SMAP Level-2 and -3 radiometer soil moisture ... Read more

What data subsetting, reformatting, and reprojection services are available for SMAP data?

The following table describes the data subsetting, reformatting, and ... Read more

How are the enhanced SMAP radiometer products generated and what are the benefits of using these products?

There is considerable overlap of the SMAP radiometer footprints, or ... Read more

How To
How do I search, order, and customize SMAP data using Earthdata Search?

The attached video tutorial (.mp4) and document (.pdf) provide step-by- ... Read more

How do I visualize SMAP data in Worldview?

The attached video tutorial provides step-by-step instructions on how ... Read more

How to read SMAP data into MATLAB, Python, IDL, or NCL

The ... Read more

How to import and geolocate SMAP Level-3 and Level-4 data in ENVI

The following are instructions on how to import and geolocate SMAP ... Read more

How to import and geolocate SMAP Level-1C and Level-2 data in ENVI

The following are instructions on how to import and geolocate SMAP ... Read more

How do I identify files adversely affected by the SMAP Level-1B atmospheric correction error?

Due to a problem involving the atmospheric correction algorithm used to ... Read more