AHN en technologische ontwikkelingen

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AHN en technologische ontwikkelingen Ramon Hanssen Mathematische Geodesie en Puntsbepaling, TU Delft


AHN1, AHN2, en dan verder? •  Wat gebeurt er om ons heen? •  Wat is de volgende stap? Welke “Δ” is nu nodig? •  Meer punten/ hogere ruimtelijke resolutie? •  Betere hoogteprecisie? •  Korter herhalingsinterval? •  Andere parameters? •  ?? •  Conclusies


Behoefte aan hoogtemodellen!


Topografie van de aarde: goed bekend?


Topografie van Mars (MOLA, 1997)


Topografie Aarde versus Mars

• Ocean floor Mid-Atlantic ridge • Ship soundings and radar altimeter

• Mars Valles Marineris

• Horiz res 15 km

• Horiz res 1 km

• Vert prec 250 m

• Vert prec 1 m

• MOLA laser altimeter

We kennen de topografie van Mars, Venus en de Maan beter dan die van de Aarde!

Source: Oceanography, vol 17, 1, 2004


Digitale hoogtemodellen DEM •  Corona: 144 satellieten (1959 and 1972) •  Vrijgegeven in 1995 •  Resolution tot 1.8 m •  14x188 km2 : 18 USD


Digitale hoogtemodellen (DEM) •  GTOPO30 •  30 arcsec = 1 km ruimtelijk •  Bron: verschillende topografische bestanden •  Nauwkeurigheid: •  Afhankelijk van bronbestand •  Sigma ~18-300 m •  vrij beschikbaar


SRTM, C-band SRTM C-band 3 arcsec = 90 m ruimtelijk Bron: Shuttle Radar Bedekking: ~80% van landmassa Nauwkeurigheid: •  Sigma ~7-8 m •  vrij beschikbaar •  •  •  •  • 


ASTER GDEM ASTER 15 m ruimtelijk Bron: Stereo optisch Bedekking: ~99% van landmassa Nauwkeurigheid: •  Sigma ~10 m, maar variabel •  vrij beschikbaar •  •  •  •  • 


SRTM-X SRTM X-band 25 m ruimtelijk Bron: Shuttle Radar Bedekking: inhomogeen Nauwkeurigheid: •  Sigma ~6 m •  vrij beschikbaar •  •  •  •  • 



TanDEM-X TanDEM-X 12 m ruimtelijk Bron: Satelliet radar Bedekking: ~99% van landmassa Nauwkeurigheid: •  Sigma ~1 m •  vrij beschikbaar •  •  •  •  • 


Meetconcept: Helix baan


TanDEM-X voorbeeld 12 meter posting, 2 meter relatieve hoogteprecisie (90%)


TanDEM-X DEM products

Ruimtelijke resolutie

1m 3m 10 m

Laser altimetrie (Airborne)

0.05-0.5 m

Radar SAR (Airborne)

0.5-1 m

TanDEM-X (1)

1 -5 m

Fotogrammetrie (Airborne) HR satelliet

INSAR-ERS

30 m

SPOT-5 5-10 m

SRTM-C (USA)

100 m

TanDEM-X (2)

ASTER

SRTM-X SRTM-C

300 m

0 0

50

Bedekking in miljoen km2

GTOPO30

10-20 m >20 m


AHN1, AHN2, en dan verder? •  Wat gebeurt er om ons heen? •  Wat is de volgende stap? Welke “Δ” is nu nodig? •  Temporele update? •  Meer punten/ hogere ruimtelijke resolutie? •  Betere hoogteprecisie? •  Andere parameters? •  ??


De nieuwe “Delta”: Temporele update? •  Nut en noodzaak hangt af van: •  Fysisch proces (verandert de hoogte? Hoe snel in de tijd?) •  Is dit relevant (toepassingsvraag) •  Meetprecisie (kunnen we meten wat we willen?) •  Keuze techniek


De nieuwe “Delta”: Puntdichtheid? •  0.5 m voldoende? •  Nut en noodzaak hangt af van: •  Fysisch proces (“hoogtegladheid”?) •  Is dit relevant? (toepassingsvraag) •  Meetprecisie (kunnen we meten wat we willen?) •  Keuze techniek


De nieuwe “Delta”: Hogere precisie? •  Nut en noodzaak hangt af van: •  Fysisch proces (welk proces heeft signaal <sigma?) •  Is dit relevant? (toepassingsvraag) •  Keuze techniek


De nieuwe “Delta”: Andere parameters? •  Hoogte? of mutaties? •  Hoogte of hoogte? •  Orthometrisch of geometrisch •  Absoluut of relatief? •  NAP of locaal stelsel? •  Hoogteveranderingen (temporeel)


Hoogte of mutaties? •  Mutaties: Alternatieven door radarsatellieten (herhalingsfrequentie van dagen-weken, resolutie in orde van meters, gratis)


151

380

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029

151 380

423

151 380

344

380

108 215


92/4-93/11 95/4-97/1 97/4-99/7 99/10-02/4

Regio Almere vanuit satelliet radar perspectief 1992-2002 April ’92November ’93 April ’95January ’97 April ’97July ’99 October ’99April ’02

1992

1994

1996

1998

2000

2002


92/4-93/11 95/4-97/1 97/4-99/7 99/10-02/4

Regio Almere vanuit satelliet radar perspectief 1992-2002 April ’92November ’93 April ’95January ’97 April ’97July ’99 October ’99April ’02

1992

1994

1996

1998

2000

2002


De nieuwe “Delta”: Andere parameters? •  Hoogte? of mutaties? •  Hoogte of hoogte? •  Orthometrisch of geometrisch •  Absoluut of relatief? •  NAP of locaal stelsel? •  Hoogteveranderingen (temporeel)


Orthometrische of geometrische hoogte? “h = H + N” GPS, laser, radar

Zwaartekracht waterpassing

P

Loodlijn

h Ellipsoide

Q Gemiddeld zeeniveau

N

H Geoide

PO

Zee

NAP

h (Ellipsoidische hoogte) = Afstand ┴ op ellipsoide (Q-P) N (Geoide hoogte) = Afstand ┴ op ellipsoide (Q-PO) H (Orthometrische hoogte) = Afstand langs loodlijn (PO - P)


NLGEO2004 [m] t.o.v. GRS80 (ETRS89/WGS84)

•  •  • 

Precisie (sigma) op cm niveau ~10 jaar houdbaar Applicatie-afhankelijk

Update van AHN ivm ‘absolute hoogte’ vergt update van geoide!


De nieuwe “Delta”: Andere parameters? •  Absolute hoogte of relatieve hoogte?


IPCC AR4, hoofdstuk 12, pagina 147

12.2.3 Current adaptation and adaptive capacity It is apparent that climate variability and change already affects features and functions of Europe’s production systems (e.g., agriculture, forestry and fisheries), key economic sectors (e.g., tourism, energy) and its natural environment. Some of these effects are beneficial, but most are estimated to be negative (EEA, 2004b). European institutions have recognised the need to prepare for an intensification of these impacts even if greenhouse gas emissions are substantially reduced (e.g., EU Environmental Council meeting, December 2004). The sensitivity of Europe to climate change has a distinct north-south gradient, with many studies indicating that southern Europe will be more severely affected than northern Europe (EEA, 2004b). The already hot and semi-arid climate of southern Europe is expected to become warmer and drier, and this will threaten its waterways, agricultural production and timber harvests (e.g., EEA, 2004b). Nevertheless, northern countries are also sensitive to climate change. The Netherlands is an example of a country highly susceptible to both sea-level rise and river flooding because 55% of its territory is below sea level where 60% of its population lives and 65% of its Gross National Product (GNP) is produced. As in other regions, natural ecosystems in Europe are more vulnerable to climate change than managed systems such as agriculture and fisheries (Hitz and Smith, 2004). Natural ecosystems usually take decades or longer to become established and therefore adapt more slowly to climatic changes than managed systems. The expected rate of climate change in Europe is likely to exceed the current adaptive capacity of various non-cultivated plant species (Hitz and Smith, 2004). Sensitivity to climate variability and change also varies across different ecosystems. The most sensitive natural ecosystems in Europe are located in the Arctic, in mountain regions, in coastal zones (especially the Baltic wetlands) and in various parts of the Mediterranean (WBGU, 2003). Ecosystems in these regions are already affected by an increasing trend in temperature and decreasing precipitation in some areas and may be unable to cope with expected climate change. The possible consequences of climate change in Europe have stimulated efforts by the EU, national governments, businesses, and Non-Governmental Organisations (NGOs) to develop adaptation strategies. The EU is supporting adaptation research at the pan-European level while Denmark, Finland, Hungary, Portugal, Slovakia, Spain and the UK are setting up national programmes for adapting to climate change. Plans for adaptation to climate change have been included in flood protection plans of the Czech Republic and coastal protection plans of the Netherlands and Norway.

The Netherlands is an example of a country highly susceptible to both sea-level rise and river flooding because 55% of its territory is below sea level where 60% of its population lives and 65% of its Gross National Product (GNP) is produced.

AHN en technologische ontwikkelingen

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