HadCM3 is a coupled atmosphere-ocean general circulation model developed at the Hadley Centre in the UK. It does not require flux adjustment and is composed of the atmospheric model HadAM3 and ocean model HadOM3. HadCM3 deals with land and sea surface temperatures, precipitation, ocean circulation, and vegetation distribution. It has been widely used for climate change studies over the last 15 years but is being replaced by more recent models.

2. HadCM3
Hadley Centre Coupled Model ,version

3. HadCM3
• Abbreviation for Hadley Centre Coupled Model, version 3
• coupled atmosphere-ocean general circulation model (AOGCM)
developed at the Hadley Centre in the United Kingdom
• the major models used in the IPCC Third Assessment Report in 2001
• HadCM3 does not need flux adjustment (additional "artificial" heat and
freshwater fluxes at the ocean surface) to produce a good simulation
• HadCM3 is composed of two components: the atmospheric model
HadAM3 and the ocean model (which includes a sea ice model).

4. HadCM3
• HadCM3 atmospheric model (HadAM3) is a grid point model and has
a horizontal resolution of 3.75×2.5 degrees in longitude × latitude
• This gives 96×73 grid points on the scalar (pressure, temperature and
moisture) grid; the vector (wind velocity) grid is offset by 1/2 a grid
box.
• ocean model (HadOM3) has a resolution of 1.25×1.25 degrees,
• HadCM3 deals with the land and sea surface temperatures,
precipitation, ocean circulation and vegetation

5. HadCM3
• HadCM3 has been heavily used during the last 15 years for a range of
future (and past) climate change studies but is now largely being
replaced by more recent models

6. HadCM3
Atmosphere
Temperature
• more than 10 thousand stations for temperature
• More than 25 thousand stations for precipitation
• .The differences between the 1960–1990 climate means compared to
the 1860–1890 climate means
• mean warming between the two periods being 0.6 C◦

7. HadCM3
Atmosphere

9. HadCM3
Precipitation
• Deals with frontal, convective and mesoscale.
• Convective precipitation is generally more intense, and of shorter
duration, than stratiform precipitation. Orographic precipitation occurs
when moist air is forced upwards over rising terrain, such as a
mountain. Precipitation can also fall in either liquid or solid phases, or
transition between them.
• Stratiform precipitation, in general, is relatively continuous and uniform in
intensity (i.e., steady rain versus rain showers).
• Mesoscale an intermediate scale between those of weather systems and
of microclimates, on which storms and other phenomena occur

10. HadCM3
Precipitation
• Monsoonal regions of south-east Asia,Austral-Asia,southern South
America, Westland central Africa, over estimate precipitation by 0.5
mm day−1 to 2 mm day−1
• Precipitation in the Indian and northern arm of the South American
10 region by 1mm day−1 to 4 mm day−1∼
• It is also noted that an increase in resolution does not produce a
noticeable improvement on spatial annual precipitation bias in
certain monsoon regions

11. HadCM3
Ocean
(Sea Surface Temperature)

12. HadCM3
Sea Surface Salinity
• in the global average, the models show a fresh bias of about 0.5
gkg−1
• exhibiting higher salinities (up to 10 gkg−1) in the Kara Sea and
generally north of Russia. Generally lower salinities (of up to 5 gkg−1)
are found in the10 Chukchi and Beaufort seas.
• The largest differences are found in enclosed or semi-enclosed
basins,

13. HadCM3
Land
(Vegetation Distribution)
• These models have a simple representation of terrestrial vegetation,
with five plant functional types that each covers a large climatic
range.
• The broadleaf trees in the models have a known problem of
extending too far, especially in the Southern Hemisphere, and this
can be seen in Fig. The southern mid-latitudes are difficult to capture
accurately, for a variety of reasons, including the challenge of
precipitation patterns in this region.

14. HadCM3
Land
(Vegetation Distribution)