ACRIMII_TSI_UARS_NAT Version 2.0 1.0 Introduction This readme file provides information on the ACRIM II Total Solar Irradiance Version 2.0 data from the UARS spacecraft. Information for the ACRIM II project can be found at the following URL: http://www.acrim.com/ This document includes the following sections: Section 2.0 - Data Set Description Section 3.0 - Format and Packaging Section 4.0 - Science Parameters Information Section 5.0 - Description of Sample Read Software Section 6.0 - Implementing Sample Read Software Section 7.0 - Sample Output Section 8.0 - Additional Data Information If you have questions, please contact the Atmospheric Science Data Center User and Data Services Office at: Atmospheric Science Data Center User and Data Services Office Mail Stop 157D NASA Langley Research Center Hampton, Virginia 23681-2199 U.S.A. E-mail: support-asdc@earthdata.nasa.gov Phone: (757) 864-8656 FAX: (757) 864-8807 URL: http://eosweb.larc.nasa.gov 2.0 Data Set Description (provides information on the data set) Data Set Name: Upper Atmosphere Research Satellite (UARS) ACRIM II Total Solar Irradiance in Native Format (ACRIMII_TSI_UARS_NAT) 2.1 Instrumentation Description Geophysical parameters: Total Solar Irradiance at 1 A.U. (Watts/meters-squared), Daily Means Instrument: Active Cavity Radiometer Irradiance Monitor II Sensor: Active Cavity Radiometer Type V (Pyrheliometer) Platform: Upper Atmosphere Research Satellite (UARS) Processing Level: 1B, 2 (0=Raw radiance data, 1A=Data unprocessed to sensor units, 1B=Data processed to sensor units, 2=Derived geophysical parameters, 3=Geolocated geophysical parameters, 4=Data from multiple measurements) Spatial Resolution: 2.5 deg. circle centered on sun. Temporal Coverage: Start Date (mm/dd/yy): 10/04/1991 Stop Date (mm/dd/yy): 11/01/2001 (and ongoing) Temporal Resolution: What is the smallest unit of data collected (e.g., 1 second, daily, monthly, etc.)? 1.024 sec. 2.2 Data Quality A note from the PI on this version of the data: ******************** ACRIM2 results were reprocessed by ACRIM3 Science Team in 2001. In the process of developing the ACRIMSAT/ACRIM3 algorithm the original UARS/ACRIM2 algorithm was found to be skipping good data. ACRIM2 level0 data flag errors were discovered that caused rejection of significant data. Use of a variant of our new ACRIMSAT/ACRIM3 algorithm yielded increased numbers of observations per day, fewer days without observations and many more multi-sensor degradation calibrations. The re-processed ACRIM2 results (version 2) are more precise and accurate, incorporating a much superior calibration for sensor degradation. ******************** 2.3 Other pertinent information This is an ongoing data set. To obtain more data like this data set, please refer to the ACRIM III project. 2.4 Science and Production Contact: Name: Dr. Richard C. Willson (PI) Address: ACRIM Science Computing Facility Columbia University 1001 B. Ave. Suite 200 Coronado, CA 92118 Telephone: (619) 522-2945 Fax: (619) 522-2967 E-mail: acrim@acrim.com URL: http://www.acrim.com 3.0 Format and Packaging Each file is written in ASCII format. This is an ongoing data set. Therefore, new data will be added to the existing data file. Please continue checking back at the ASDC to obtain further updates/additions to this data set. 4.0 Science Parameters Information Data are contained in a 5 column table: Column 1: Decimal time of observations (decimal year) Column 2: Total Solar Irradiance at 1 A.U. in Watts/meters-squared Column 3: Uncertainty of Total Solar Irradiance (Watts/meters-squared) Column 4: Epoch 1980 day count Column 5: Date of observation in yymmdd format A note from the PI on this version of the data: ******************** ACRIM2 results were reprocessed by ACRIM3 Science Team in 2001. In the process of developing the ACRIMSAT/ACRIM3 algorithm the original UARS/ACRIM2 algorithm was found to be skipping good data. ACRIM2 level0 data flag errors were discovered that caused rejection of significant data. Use of a variant of our new ACRIMSAT/ACRIM3 algorithm yielded increased numbers of observations per day, fewer days without observations and many more multi-sensor degradation calibrations. The re-processed ACRIM2 results (version 2) are more precise and accurate, incorporating a much superior calibration for sensor degradation. ******************** 5.0 Description of Sample Read Software No read software is available for this data set. 6.0 Implementing Sample Read Software N/A 7.0 Sample Output This section contains a snapshot of a portion of the Version 2 data file. ******************** 1991.76057400 1363.489 0.015 4295 911004 1991.76300400 1364.022 0.015 4296 911005 1991.76572900 1364.659 0.015 4297 911006 1991.76819200 1365.151 0.014 4298 911007 1991.77105300 1365.241 0.015 4299 911008 1991.77393300 1365.571 0.014 4300 911009 1991.77630400 1365.547 0.015 4301 911010 1991.77943800 1365.581 0.015 4302 911011 1991.78198200 1365.284 0.014 4303 911012 1991.78493400 1365.185 0.014 4304 911013 1991.78770000 1365.096 0.015 4305 911014 1991.79027200 1365.053 0.015 4306 911015 ... ... ... ******************** 8.0 Additional Data Information References: Willson, R.C., Gulkis, S., Janssen, M., Hudson, H.S., Chapman, G.A., (1981), Observations of solar irradiance variability, Science, v.211, p. 700. Willson, R.C., (1982) J. Geoph. Res., v. 86, P. 4319. Willson, R.C., (1984) Measurements of solar total irradiance and its variability, Space Science Reviews, v. 38, pp 203-242. Willson, R.C., Hudson, H.S., Frohlich, C., Brusa, R.W.; (1986) Science, v. 234, p 1114. Willson, R.C., Hudson, H.S., (1988) Nature, v. 332, No. 6167, 810. Willson, R.C., Hudson, H.S., (1991) Nature, v. 351, pp. 42-44. Updated: November 23, 2001 April 10, 2012 (User Services email changed)