| Level 1B Issues |
22 November 2009: The SeaWinds antenna spin rate began degrading substantially and officially entered into a "non-spinning" mode after orbital rev 54296. Even during this "non-spinning" mode, the antenna RPM was above 0, yet too low to fully retrieve enough observations to resolve a wind vector retrieval.
23 November 2009 (orbital rev number 54315): At 7:07 UTC, the antenna stalled to 0 RPM, and has remained stalled in a fixed-azimuth position since that time. Science data processing has been caught up through rev 54315. The latest delivery batch covering 18-22 November (revs 54240-54296) is less affected by the spin degradation, and is generally considered usable although we do advise caution. Please be advised that due to uncertain data quality, the delivery of science data products from revs 54297 up to the stall time on rev 54315 may either be delayed or unavailable for public distribution. The antenna remains powered, however the usability and quality of any retrievable data beyond the stall time on rev 54315 is highly uncertain.
29 January 2013 to 5 February 2013: Starting with orbital rev number 7909 and continuing to 71011 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. After this time, the antenna stalled to 0 RPM.
14 March 2013: Starting with orbital rev number 71536 and continuing to 71549 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. After this time, the antenna stalled to 0 RPM.
18 March 2013 to 21 March 2013: Starting with orbital rev number 71590 and continuing to 71634 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. After this time, the antenna stalled to 0 RPM.
28 March 2013 to 31 March 2013: Starting with orbital rev number 71735 and continuing to 71769 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. After this time, the antenna stalled to 0 RPM.
User Advisory: Sigma-0 data in the level 1B files is only calibrated correctly in the "spinning" configuration. Data for which "non-spinning" sigma-0 values have been correctly calibrated will be released in 2016 in a simplified data format. The "non-spinning" calibration needs to adjusted to account for 1) planned changes in pointing during non spinning mode and 2) increase in effective antenna gain because there are no scan-losses in the "non spinning" configuration.
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| Level 2A Issues |
12 June 2000: Near 66.6° South Latitude and 359.0° East Longitude approximately 12-15 pixels are being reported as land instead of ice. The ice mask will be fixed in upcoming data.
22 November 2009: The SeaWinds antenna spin rate began degrading substantially and officially entered into a "non-spinning" mode after orbital rev 54296. Even during this "non-spinning" mode, the antenna RPM was above 0, yet too low to fully retrieve enough observations to resolve a wind vector retrieval. This date marks the official end of the prime operational mission for wind vector retrieval and the cease of production of L2A data through 29 January 2013.
29 January 2013 to 5 February 2013: Starting with orbital rev number 7909 and continuing to 71011 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2A data production resumed. After this time, the antenna stalled to 0 RPM, and L2A data production ceased.
14 March 2013: Starting with orbital rev number 71536 and continuing to 71549 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2A data production resumed. After this time, the antenna stalled to 0 RPM, and L2A data production ceased.
18 March 2013 to 21 March 2013: Starting with orbital rev number 71590 and continuing to 71634 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2A data production resumed. After this time, the antenna stalled to 0 RPM, and L2A data production ceased.
28 March 2013 to 31 March 2013: Starting with orbital rev number 71735 and continuing to 71769 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2A data production resumed. After this time, the antenna stalled to 0 RPM, and L2A data production ceased.
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| Level 2B Issues |
General Usage Notes (23 July 1999 - 31 March 2013; orbital revs 430-71769):
- The Level 2B wind vectors have been processed with the new QSCAT-1 model function, developed by M. Freilich and B. VanHoff. The mean model coefficients [A(0)] have been tuned specifically to induce a mean speed bias relative to numerical weather prediction winds of about +0.3 m/s, addressing the observed wind speed under-prediction problem inherent in the NWP products. The reference height for the QuikSCAT wind vectors remains at 10 meters. Furthermore, the azimuthal modulation of the QSCAT-1 model has been tuned to remove, as far as possible, systematic instrument-induced direction errors ("beam spikes" and "square circulations").
- The Level 2B product includes two additional scientific data set (SDS) elements, the "mp_rain_probability" and the "nof_rain_index", to indicate the detection of rain contamination in the QuikSCAT data.
- For all wind vector cells, the mp_rain_probability element contains a value between 0 and 1 based on an extended version of the Multi-Parameter rain algorithm developed by J. Huddleston and B. Stiles at JPL. Cells for which the algorithm could not compute a valid value contain the value -3. Additionally, bit 12 of the "wvc_quality_flag" indicates whether the MP algorithm computation was valid (0) or invalid (1), and bit 13 indicates whether rain was detected (1) or not detected (0) by the algorithm. Bit 14 of the wvc_quality_flag indicates whether the rain detection is based on data from both beams (0) or from outer-beam measurements only (1).
- The nof_rain_index is a value ranging from 0-249, with 250 as the "invalid" value, based on the Expected Normalized Objective Function (NOF) algorithm developed by C. Mears, D. Smith, and F. Wentz at Remote Sensing Systems.
- The Level 2B product includes two additional scientific data set (SDS) elements, the "wind_speed_selection" and the "wind_dir_selection". These elements contain the final output of the wind retrieval/ambiguity removal processing using the Direction Interval Retrieval with Threshold Nudging (DIRTH) algorithm.
22 November 2009: The SeaWinds antenna spin rate began degrading substantially and officially entered into a "non-spinning" mode after orbital rev 54296. Even during this "non-spinning" mode, the antenna RPM was above 0, yet too low to fully retrieve enough observations to resolve a wind vector retrieval. This date marks the official end of the prime operational mission for wind vector retrieval and the cease of production of L2B data through 29 January 2013.
29 January 2013 to 5 February 2013: Starting with orbital rev number 7909 and continuing to 71011 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2B Version 2 data production resumed. After this time, the antenna stalled to 0 RPM, and L2B Version 2 data production ceased.
14 March 2013: Starting with orbital rev number 71536 and continuing to 71549 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2B Version 2 data production resumed. After this time, the antenna stalled to 0 RPM, and L2B Version 2 data production ceased.
18 March 2013 to 21 March 2013: Starting with orbital rev number 71590 and continuing to 71634 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2B Version 2 data production resumed. After this time, the antenna stalled to 0 RPM, and L2B Version 2 data production ceased.
28 March 2013 to 31 March 2013: Starting with orbital rev number 71735 and continuing to 71769 the antenna resumed rotating within the nominal RPM range resulting in a transition from "non-spinning" to "spinning" mode, thus enabling a brief period of wind vector retrieval. During this time, L2B Version 2 data production resumed. After this time, the antenna stalled to 0 RPM, and L2B data production ceased.
1 April 2013: The QuikSCAT Level 2B 12.5 km dataset was reprocessed and released as Version 3. The data time series extends from 27 October 1999 to 22 November 2009. The time series has not yet been extended into the brief "spinning" modes that occurred in 2013. The Version 2 L2B 25 km and 12.5 km datasets are still available. To access the Version 3 data, please visit: https://podaac.jpl.nasa.gov/dataset/QSCAT_LEVEL_2B_OWV_COMP_12
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