Passive Microwave Data @

Report to the Polar DAAC Advisory Group

PoDAG XXII, June 2-4, 2004 Boulder, CO

Overview

• Material originally compiled in response to a request from Waleed to host a workshop.

• This presentation is intended to provide a summary of activities and share information that may be used for future planning and decision making.

Activities

• Undertook two primary activities to gather information for the workshop: Development of a bibliography Statistics to determine how many users and

what products were accessed

Bibliography

• Conducted a limited search and compiled results from 2 different databases (Engineering Village 2 and Web of Science)

• 545 citations were returned • All names contained in a reference were compared to user list.

If at least one name appeared on our list, the reference was categorized as a 'yes' for NSIDC User.

• The user list used for comparison totaled 1488 individuals • 434 citations or 80% were identified as NSIDC Users

Summary: Bibliography

• The bibliography can be a useful indication of usage of data sets and be a useful product for the user community

• The bibliography in this presentation is only partial based on two reference search services

• It is time consuming and resource intensive to compile and maintain

Products

NSIDC NASATeam (NNT) & NSIDC Bootstrap (NBT)DMSP Daily and Monthly Sea Ice Concentrations

http://nsidc.org/data/nsidc-0002.html

GSFC NASATeam (GNT)Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave

http://nsidc.org/data/nsidc-0051.html

GSFC Bootstrap (GBT)Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I

http://nsidc.org/data/nsidc-0079.html

Products and Distribution Methods

• NNT & NBT Sea Ice Pre-packaged CD-ROMs

o Can determine how many users and who they areo Can't determine which algorithm used

Switched to FTPo Can determine which algorithms, # hosts, # of files and

volume distributedo Can't determine how many users or who they are

Products and Distribution Methods

• GBT Sea Ice Distributed via FTP only

o Can determine algorithm, # hosts, # of files and volume distributed

o Can't determine how many users or who they are

• GNT Sea Ice Distributed on CD-ROM only

o Can determine algorithm usedo Can determine how many users and who they are

User Statistics: Data Request Tracking System

• Based on data request tracking system(does not incorporate ftp logs): 1376 individual users 1605 requests (including subscriptions) Tb data requests

o 490 users, 575 requests Sea Ice data requests

o 965 users, 1323 requestso Not possible to identify algorithm used

User Statistics: FTP

• The following chart illustrates the total number of files and volume of all of the passive microwave products by fiscal year

• Number of files and volume affected by how the data are organized and whether or not compressed. Different data sets organized differently over time

• Shows a steady increase due to updates, transition in distribution methods (CD to FTP) and new products released

Passive Microwave: Number of Files and Megabytes Transferred via FTPFY 1996 - FY 2003

0

20000

40000

60000

80000

100000

120000

140000

FY 1996 FY 1997 FY 1998 FY 1999 FY 2000 FY 2001 FY 2002 FY 2003

# of Files

Mybtes

Total Files 391,163 Total Mbytes 180,889

Statistics: FTP

• The following chart illustrates a comparison of FTP statistics for the NSIDC-produced sea ice products with the GBT sea ice data for the period April 2001 - February 2004

• GNT data were distributed on CD-ROM during this time period and had 77 requests for the data set, 210 in total since the product was released

• The larger number of files distributed associated with the NNT algorithm is attributed to differences in the way the data are organized.

There were 77 requests for the GNT CD-ROMs during this time period.

GSFC BT

NSIDC-BT

NSIDC-NT

0

5000

10000

15000

20000

25000

FTP Distribution by ProductApril 2001 - February 2004

Hosts

Mbytes

Summary: Digital Data

• Our conclusion is that there is fairly evenly distributed use of the four products by the user community based on the information that we have available

Summary: Digital Data

• It is difficult to determine access to the data based on algorithm because of differing or changing distribution methods

• It is difficult to distinguish between products, though we have recently implemented a system that should make it easier to report in the future