THE GLOBAL NETWORK OF ISOTOPES IN PRECIPITATION

GNIP

Pradeep Aggarwal

Luis Araguás

International Atomic Energy Agency

Water Resources Programme

Isotope Hydrology Section

Main objective of the Water Resources Programme of the IAEA

To improve the management of water resources by Member States with the use of isotope technologies

• Improve understanding of the water cycle• Sustainable exploitation of water resources• Improved hydrogeological and hydrogeo- chemical data. • Capacity for monitoring the quantity and quality of water resources

• Isotope fractionation of 18O and 2H occurs during evaporation, condensation, and vapor transport

• Stable isotopes are fingerprints of water excellent tracers of the origin of water, and of changes in the hydrological cycle

Isotopes in the Global Water Cycle:Isotopes in the Global Water Cycle:scientific background of isotope hydrologyscientific background of isotope hydrology

VapourVapor

Fraction of remaining vapour

18 O

Cloud Temperature (°C)

13 ‰

9 ‰

Rain Rain

-15 ‰

-15 ‰

-7 ‰

-5 ‰

-3 ‰

0 ‰

-13 ‰

-16 ‰-25‰

-10 ‰

-7 ‰-10 ‰

-17 ‰

0-2T U

0-20T U

0-5 T U

-13 ‰

0-10T U

PRECIPITATION EVAPORATION TRANSPIRATION

VAPOURTRANSPORT

GROUNDWATER FLOW

RETURNFLOW

RIVER

LAKE

EVAPORATION

PRECIPITATION

SURFACERUNOFF

PERCOLATION

Oxygen and hydrogen isotopes as tracers in the Water cycle and climate

Joint activity IAEA/WMO since 1961

GNIP programme in hydrology, climatology and related fields

GNIP

Systematic collection of basic data on isotopic content in precipitation (monthly basis) on a global scale to determine temporal and spatial variations of environmental isotopes in precipitation

Main objective of GNIP

1990s

New monitoring needs, besides “classical input function for hydrology”

Global climate modelling requires broader spatial coverage AGCM

Interest in:

High latitudes and altitude areas

Climate-sensitive areas

Tropical zones

GNIP STATIONS

1953-2006, about 830 stations

GNIP STATIONS / Record > 2 years

ACTIVE GNIP STATIONS

18O and 2H RECORDS (in years)

0 - 10 11 - 20 21 - 30 31 - 40 41 - 50

0 - 10

11 - 20

21 - 30

31 - 40

41 - 50

Contents of the GNIP database

Monthly values:

•Total amount of precipitation (mm)

•Type of precipitation (rain, snow, both)

•Mean air temperature (ºC)

•Mean water vapour pressure (hPa)

•Stable Isotope contents (O-18, H-2) (‰)

•Tritium content and uncertainty (TU)

Status of the network

 

About 210 active stations in 53 countries

The IAEA´s Isotope Hydrology Laboratory is currently performing isotope analyses of about 40 % of the collected precipitation samples

30 other laboratories are analysing GNIP samples

Structure of the GNIP network 

The network is composed of:

- IAEA/WMO stations situated in climatically relevant locations

- National Networks composed of stations and labs operated by national authorities

- affiliated stations which are stations resulting from hydrological studies, often of short-term in nature

Operation of GNIP

• International Atomic Energy Agency• Isotope Hydrology Section• Isotope Hydrology Laboratory

• World Meteorological Organization•Link to the stations•Meteorological information

• Cooperating institutes and laboratories (voluntary basis)

• Scientific Steering Committee

Operational Problems

• Collaboration with Member States is on voluntary basis

• Sampling/storage protocols not always properly followed

• Access to meteorological information• Insufficient communication with stations• Partial or incomplete isotope records• Uneven spatial coverage of stations• Need for data in remote areas • Automatic weather stations

• Difficulties to create new stations in remote and climate-sensitive areas

• Identify “national co-ordinators”• Statistics: Incomplete records• Quality control of isotope analysis

inter-laboratory exercises

Operational problems (cont.)

Latest developments

• GNIP data distributed into 3 categories• GNIP- monthly ~100.000 records ~780 st• GNIP- event ~25.000 records ~100 st• GNIP- vapour ~700 records ~6 st

• Completion of ISOHIS-Map• Easier visualization to GNIP, GNIR, IGLASS• Statistical treatment of data

• Yearly, monthly, long-term weighted means

Creation of National focal points

• Link with national institutes coordinating activities related to isotope monitoring

• Data compilation and quality control at national level submission to the GNIP database

Contact

Luis Araguas (IAEA): L.Araguas@iaea.org

Initiatives to correct negative trend

- Involvement of other groups/organizations- Collection Met. Services (WMO)- Analysis IH labs

- Creation/continuity of National Networks

- Long/term operation - GNS stations (?)

- Remote or climate-sensitive areas

- Links with other projects/programmes (AMMA, TRACE, etc)

GCOS - CLIMAT reports by ca. 1000 monitoring reference stations

GNIP link to GCOS - GSN

• Advice on operational aspects

• IAEA request to stations to participate in the GNIP programme endorsed by WMO (GCOS)

• Reactivation/establishment of long-term GNIP stations

• Ensure availability of meteorological information

Isotopes help to define groundwater origin, dynamics and flow patterns

Oxygen-18

Santiago de Chile: Isotopes help to define sources of recharge, groundwater origin, flow

patterns and pollutant transport

Modelling isotope contents over the Andes

Links of GNIP with intern. programs

• GTN-H Global Terrestrial Networks – Hydrology

• GCOS Global Climate Observing System

• UNESCO-IHP

• UNEP-GEMS Global Env Monitoring System

• IGBP-PAGES Past Global Changes

• World Data Centre-A for paleoclimatology

• WMO - WCRP (GEWEX, CLIVAR)

GNIP/WMO stations

National networks

 

Argentina, Australia, Austria, Canada, China, Chile, Croatia, France, Germany, Morocco, Netherlands, Portugal, South Africa, Spain, Switzerland, Turkey, USA

One station maintained in:

Algeria, Egypt, Indonesia, Israel, Jordan, New-Zealand, Poland, Slovenia, U.K.