Sea Level Lecture 1- Introduction to sea level, what is it and why should we care?

Question 1

How many people are estimated to live in coastal floodplains?

Answer 1

200 million

Question 2

If Antarctic and Greenland Ice sheets were to melt how much would global sea levels rise by?

Answer 2

70m

Question 3

How many damage is Hurricande Katrina estimated to have made?

Answer 3

$96 billion

Question 4

How many died in 2004 Indian ocean tsunami?

Answer 4

Quater of a million

Question 5

What did the 1953 North Sea storm lead to?

Answer 5

Thames barrage

Question 6

What time scale do waves happen across?

Answer 6

Seconds

Question 7

What time scale do tides happen across?

Answer 7

hours, days, weeks, months, years

Question 8

What time scale does weather happen across?

Answer 8

hours, days, weeks, months and years

Question 9

What time scale does glacio-eustacy happen across?

Answer 9

Years to millennia

Question 10

Name 4 causes of sea-level changes?

Answer 10

Waves, tides, weather and glacio-eustacy

Question 11

What is MSL?

Answer 11

Mean sea level

Question 12

What is mean sea level?

Answer 12

Arithmetic mean of hourly tides

Question 13

What is mean tide level?

Answer 13

The sea level halfway between the mean levels of high and low water

Question 14

What are tides?

Answer 14

Astronomical-gravitational influence of the moon and sun

Question 15

What cycles do tides happen on?

Answer 15

Dirunal and semi-siurnal cycles

Question 16

What are spring tides?

Answer 16

Moon and sun aligned
Higher highs and lower lows

Question 17

What are neap tides?

Answer 17

Sun and moon out of phase
Lower highs and higher lows

Question 18

How many low tides and high tides do most coastal areas experience every 24 h?

Answer 18

2 high and 2 low

Question 19

What do tidal bulges represent?

Answer 19

High tides

Question 20

What causes tidal bulges?

Answer 20

Greater or less gravity than the centre of the earth

Question 21

What is microtidal spring tide range?

Answer 21

<2m

Question 22

What is mesotidal spring tide range?

Answer 22

2-4m

Question 23

What is macrotidal spring tide range?

Answer 23

> 4m

Question 24

Where do some of the largest tides occur?

Answer 24

Bay of Fundy

Question 25

How can we measure tides?

Answer 25

Tide gauges and satellite records

Question 26

What does GRACE stand for?

Answer 26

Gravity recovery and climate experiment

Question 27

What is diurnal tide pattern?

Answer 27

One high tide and one high tide per day - least common

Question 28

What is semi diurnal tide pattern?

Answer 28

2 high and 2 low per day - most common

Question 29

What is mixed tide pattern?

Answer 29

2 high and 2 low per day but at different magnitudes throughout the day

Question 30

What can cause large tidal ranges?

Answer 30

Geomorphology

Question 31

where are tide gauges mounted?

Answer 31

Harbours

Question 32

Can anthropogenic influences be seen within tidal gauges?

Answer 32

Yes

Question 33

What is the bias related to tidal gauges?

Answer 33

More in NH than SH despite more ocean in SH. Led to overestimation in sea level change.

Question 34

Do satellite records look at whole ocean?

Answer 34

yes

Question 35

What is satellite altimeter?

Answer 35

Speed to beam to reach bottom of ocean Very accurate

Question 36

How does GRACE work?

Answer 36

Gravity Used more for ice sheet change Two satellites measuring distance Connected by radiation

Question 37

Is sea level change linear?

Answer 37

No - it fluctuates

Question 38

What is RSL?

Answer 38

Relative sea level

Question 39

What could RSL rise be due to?

Answer 39

Land sinking Ocean level rising Some combination

Question 40

What could RSL fall be due to?

Answer 40

Land rising Ocean level falling Some combination

Question 41

What is RSL a combination of?

Answer 41

What oceans and land are doing

Question 42

What are complex causes of RSL?

Answer 42

Ocean density changes Ocean-atmospheric interaction terrestrial water storage Ice melting Ocean circulation Vertical land motion

Question 43

Have all sites along any coastline experienced the same sea level history?

Answer 43

No due to variations in how wayer added to the oceans is distributed across the planet and differing land movements and so term RSL is used.