Cycle 247

General information

Cycle 247 started on 99/05/29 at 09:35:16 and ended on 99/06/08 at 07:33:46. 254 passes are present. TOPEX altimeter was on for passes 1 to 254. POSEIDON altimeter was off throughout the cycle.

Cycle 247 is distributed with cycles 247,248,249 onto AVISO CD ROM labelled AV_MGC083_2. CD ROM is sent to users on week 41. Cycle 247 and up are computed with an orbit that includes ITRF97.

Ground Tracks for cycle 247

Day Nbr Calendar date Julian date Passes 1 05/29/99 15123 1-16 2 05/30/99 15124 17-41 3 05/31/99 15125 42-67 4 06/01/99 15126 68-93 5 06/02/99 15127 94-118 6 06/03/99 15128 119-144 7 06/04/99 15129 145-170 8 06/05/99 15130 171-195 9 06/06/99 15131 196-221 10 06/07/99 15132 222-246 11 06/08/99 15133 247-254

DORIS orbit quality assessment report for cycle 247

Validating the data

The CLS Space Oceanography Division routinely validates the data distributed. Systematic extended quality control and global statistical analysis on TOPEX and POSEIDON data are performed. Altimetric measurements and corrections are first validated using thresholds and flags present in the GDR-Ms. The proportion of non-valid data is then checked. Validation results shown here covers the following analysis:
• Crossover Analysis
• Repeat-Track Analysis
• Comparison between geophysical corrections:
  
  • TMR versus ECMWF Wet Tropospheric Corrections
  • TOPEX versus DORIS Ionospheric Corrections
• dynamic topography mapping,
• significant wave height mapping,
• wind speed modulus mapping,
• sea level anomaly mapping.

Crossover Analysis

The rms crossover difference, integrated all over the oceans, is 6.49 cm. This value compares well with previous results (see the synthesis validation report).

Repeat-Track Analysis

The rms of sea level variability (relative to a 3-year mean) is 11.38 cm. This value compares well with previous results (see the synthesis validation report).

TMR Versus ECMWF Wet Tropospheric Corrections

cycle 247

The scatter diagram for the TMR and ECMWF wet tropospheric corrections shows the good compatibility between the two corrections. Analyzing the difference (ECMWF - TMR) for cycle 247 gives a 1.9 cm rms standard deviation and a bias of 0.8 cm.

TOPEX Versus DORIS Ionospheric Corrections

cycle 247 - ascending passes cycle 247 - descending passes

The scatter diagram for the TOPEX ionospheric correction and the DORIS ionospheric correction shows the good compatibility between the two corrections. Analyzing the difference (TOPEX - DORIS) for cycle 247 gives : Ascending passes: standard deviation = 2.4 cm rms bias = 1.6 cm. Descending passes: standard deviation = 1.5 cm rms bias = 1.2 cm.

Dynamic Topography

cycle 247

Units are centimeters. The geoid is OSU91A and JGM3. Blue represents the lows, green the moderate features, and red the highs. The relief ranges over about 2 meters from low to high. The monitoring of the dynamic topography is shown in the synthesis validation report. To view another cycle or animate the maps all together

Significant Wave Height

cycle 247

Units are centimeters. Blue represents the weak or moderate features, green the highs, and red over 5 meters wave heights. Effects due to the Roaring Forties (in the Antarctic Ocean) are easily singled out. The monitoring of the significant wave height is shown in the synthesis validation report. To view another cycle or animate the maps all together

Wind Speed Modulus

cycle 247

Units are meters per second. Blue represents the weak or moderate feaures, green the highs, and red over 15 meters per second wind speed. To forecast ocean waves, we will need to simultaneously observe wave height and wind speed, which are closely correlated. To view another cycle or animate the maps all together

Sea Level Anomaly

cycle 247

Units are centimeters. The mean is a 3-year mean (cycles 4 to 113). Blue represents the lows, green the moderate features, and red the highs. The relief ranges over about 2 meters from low to high. The topographic relief ranges over about 20 centimeters from low to high. To view another cycle or animate the maps all together

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