A morte do satélite QuikSCAT

Vince

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23 Jan 2007
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Já se esperava há algum tempo e muitos alertas foram sendo feitos nos últimos anos para rapidamente se arranjar um substituto. Agora parece que foi de vez, o sensor de vento do satélite avariou restando o europeu ASCAT que já era bastante limitado que este.

Nos próximos anos será mais difícil detectar a fase inicial da formação dos ciclones tropicais, o quikscat costuma ser precioso para detectar e localizar o LLC.

Está previsto um novo que estava apenas agendado para 2015. Há também em projecto há muitos anos uma tecnologia mais avançada denominada Extended Ocean Vector Winds Mission (XOVWM) mas neste caso nem existe um plano de construção.

QuikSCAT, 1999 - 2009: R.I.P.

Several hours ago, shortly past 7:00Z today (23Nov), telemetry received from QuikSCAT indicates that the antenna rotation rate has dropped to zero and remains at zero. The motor remains powered. The system can be operated safely in this state for an indefinite period. The QuikSCAT operations team will be meeting later this morning, but in all likelihood this is the end of the nominal mission".

Launched in 1999, the QuikSCAT satellite became one of the most useful and controversial meteorological satellites ever to orbit the Earth. Forecasters world-wide came to rely on QuikSCAT wind data to issue timely warnings and make accurate forecasts of tropical and extratropical storms, wave heights, sea ice, aviation weather, iceberg movement, coral bleaching events, and El Niño. Originally expected to last just 2-3 years, QuikSCAT made it past ten, a testament to the skill of the engineers that designed the satellite. To show you what a dweeb I am, I'll admit to tearing up a bit when heard yesterday that the venerable old bird had finally bitten the dust. It was like losing a valued friend.

Alternatives to QuikSCAT
Two valuable alternatives to QuikSCAT are available, but neither can come close to making up for the loss of QuikSCAT. The Windsat instrument aboard the Coriolis satellite (launched in 2003) measures wind speed and wind direction using a different technique. Evaluation of these data at NHC and NOAA's Ocean Prediction Center (OPC) shown the winds to be unreliable in and around the storm environment. There's also the European ASCAT satellite, launched in 2007. Like QuikSCAT, ASCAT can measure global wind speed and direction twice per day. However, the data is available at 25 km resolution (two times coarser than the 12.5 km QuikSCAT), and ASCAT covers only 60% of the area covered by QuikSCAT in the same time period. QuikSCAT sees a swath of ocean 1800 km wide, while ASCAT sees two parallel swaths 550 km wide, separated by a 720 km gap. I find it frustrating to use ASCAT to monitor tropical storms, since the passes miss the center of circulation of a storm of interest more than half the time. On the plus side, ASCAT has the advantage that the data is not adversely affected by rain, unlike QuikSCAT.

The need for a new QuikSCAT
NOAA has been pushing for a QuikSCAT replacement for years. Former National Hurricane Center director Bill Proenza laudably made a big push in 2007 for a new QuikSCAT satellite. Unfortunately, he made claims about the usefulness of QuikSCAT for improving hurricane track forecasts that were not supported by scientific research, an error that may have ultimately led to his downfall. While there is evidence that QuikSCAT data may improve hurricane track forecasts of some computer models, NHC uses many models to make hurricane track forecasts, and some of these models are not helped by QuikSCAT data. For example, a 2009 model study by Dr. Jim Goerss of the Naval Research Lab found that QuikSCAT winds made no improvement to hurricane track forecasts of the NOGAPS model, one of the key models used by NHC to predict hurricane tracks. QuikSCAT is extremely valuable for many other aspects of hurricane forecasting, though. It provides early detection of surface circulations in developing tropical depressions, and for defining gale (34 kts) and storm-force (50 kts) wind radii. The information on wind radii from QuikSCAT is especially important for tropical storms and hurricanes outside the range of aircraft reconnaissance flights conducted in the Atlantic and Eastern Pacific basins, and for the regions where there are no reconnaissance flights (Central Pacific, Western Pacific, and Indian Ocean). Accurate wind radii are critical to the National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), and Guam Weather Forecast Office (WFO) watch and warning process, since they affect the size of tropical storm and hurricane watch and warning areas. Between 2003 and 2006, QuikSCAT data were used at NHC 17% of the time to determine the wind radii, 21% of the time for center fixing, and 62% of the time for storm intensity estimates.

A QuikSCAT replacement
A replacement dual-frequency QuikSCAT satellite that has superior capabilities to old one is being explored by NOAA and NASA, in partnership with the Japanese Space Agency (JAXA). The new QuikSCAT instrument would fly on the Japanese GCOM-Water Cycle satellite, scheduled to launch in January 2016. However, funding must begin in 2010 in order to meet this launch deadline, and no funding for a new QuikSCAT has been put into the Administration's FY 2011 budget. The proposed QuikSCAT replacement would be able to measure winds as high as 100 mph (Category 2 hurricane strength), and have improved ability to measure winds in heavy rain. The new satellite would have a 20% improvement in spatial resolution. The cost would be less than usual, since the rocket and and satellite are already paid for. However, there are additional costs involved in adapting QuikSCAT to the Japanese engineering requirements. The final costs of such a replacement QuikSCAT have not been determined yet, but would probably be several hundred million dollars. According to the Palm Beach Post, in September, U.S. Representative Ron Kline, D-FL, introduced a bill in Congress to fund a new QuikSCAT satellite. Klein introduced a similar bill in 2007, which failed. "Today's news of its failure simply strengthens our commitment to ensure that a next-generation satellite is constructed and launched as quickly as possible", Klein said in a statement made yesterday.

Thanks to all of you who've written your Senators and Representatives. Let's hope that the final failure of QuikSCAT yesterday will finally motivate Congress to fund a replacement satellite.

Rest in Peace, QuikSCAT.
 

stormy

Super Célula
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7 Ago 2008
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Lisboa
um momento sem duvida nefasto para as entidades competentes pela previsao de sistemas tropicais:(
acho, tambem, estranho...senao algo negligente nao haver outros satelites com as mesmas apetencias que o substituam:unsure:
 

Agreste

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29 Out 2007
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Aljezur (48m) - Faro (11m)
Isto é aquilo que se chama negligência... Programas para novas missões lunares, missões marcianas e aqui a instrumentação básica vai caindo de podre... em que país é que eu já vi isto :mad: