From Boundary Layer Climates, T.R. OKE

1. Pabitra Gurung
CHAPTER 3
CLIMATES OF SIMPLE
NON-VEGETATED
SURFACES

2. CONTENTS
1. Sandy desert
(a) Energy and water balances
(b) Climate
2. Snow and ice
(a) Radiation budget
(b) Energy and water balance
(c) Climate
3. Water
(a) Radiation budget
(b) Energy and water balance
(c) Climate

3. Energy balance components and wind speed at a dry
lake (desert) surface on 10-11 Jun 1950, at El Mirage,
California (35°N) (Tropical desert)
1. ENERGY AND WATER BALANCES, AND CLIMATE
Temperature in the air, at the surface and at two
depths in a sand dune of the Central Sahara desert
in mid-August
Sandy Desert
 Water vapour content is low and cloud is generally absent
 ≈ 80% of the extra-terrestrial SW (K) radiation reaches at desert surface
 High albedo (Large reflection) (0.20 – 0.45)
(38°C)
(27°C)
(64°C)
(Dry soil and sand: Low diffusivities)
-ve energy flux
+ve energy flux
Zero energy flux

4. Typical profiles of solar radiation within snow and ice
illustrating the exponential attenuation with depth
2. RADIATION BUDGET
Snow and ice Water
Transmission of SW radiation Yes Yes Ψ + 𝛼 + ζ = 1
𝑎 – extinction coeff. (m-1) Snow > Ice Impurities Depends on the nature of the transmitting
medium and the wavelength of the radiation
Albedo High (snow: 0.40-0.95,
ice: 0.20-0.45)
Low
(0.03-0.10)
Depends on the solar altitude
𝐵𝑒𝑒𝑟′
𝑠 𝐿𝑎𝑤: 𝐾 ↓ 𝑧= 𝐾 ↓0 𝑒−𝑎𝑧
,z
Relation between solar altitude and the albedo of lake
water for clear and cloudy days over lake Ontario

5. Variation of the radiation budget components over snow at
Mizuho Station, Antarctica (70°S), on 13 Nov 1979
2. RADIATION BUDGET
Snow and ice Water
Transmission of SW radiation Yes Yes Ψ + 𝛼 + ζ = 1
𝑎 – extinction coeff. (m-1) Snow > Ice Impurities Depends on the nature of the transmitting
medium and the wavelength of the radiation
Albedo High (snow: 0.40-0.95,
ice: 0.20-0.45)
Low
(0.03-0.10)
Depends on the solar altitude
,z
Variation of the radiation budget components for Lake
Ontario (43°N), on 28 Aug 1969, with cloudless skies
𝜶 = 𝟎. 𝟎𝟕
High 𝑲∗
Low 𝑳∗
𝑺 = 𝑲 ↓ −𝑫

6. Schematic depiction of the fluxes involved in the (a, b)
energy and (c) water balances of a snowpack volume
3. ENERGY AND WATER BALANCES
Snow and ice Water
Vertical heat flux 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝑀 + 𝑄G 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝐴
𝑄R − Heat supply by rain , ∆𝑄S - Sensible storage, ∆𝑄 𝑀 - Latent heat storage (L 𝑓∆r), ∆𝑄A - Net horizontal heat
transfer,Q 𝐸 = L 𝑠 𝐸
,z
Schematic depiction of the fluxes involved in the energy balance
of a water volume
Cold or frozen
pack
Wet or melting
pack

7. Diurnal variation of the Energy balance components for a melting
snow cover at Bad Lake, Saskatchewan (51°N) on 10 Apr 1974
3. ENERGY AND WATER BALANCES,z
Diurnal variation of the Energy balance components for the surface of a
melting glacier at Peyto Glacier, Alberta (51°N) on 29 Aug 1971
Snow and ice Water
Vertical heat flux 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝑀 + 𝑄G 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝐴
𝑄R − Heat supply by rain , ∆𝑄S - Sensible storage, ∆𝑄 𝑀 - Latent heat storage (L 𝑓∆r), ∆𝑄A - Net horizontal heat
transfer,Q 𝐸 = L 𝑠 𝐸

8. Diurnal variation of the Energy balance components in and above a
shallow water layer on a clear September day in Japan
3. ENERGY AND WATER BALANCES,z
Diurnal variation of the Energy balance components in and
above the tropical Atlantic Ocean (20 Jun – 02 July, 1969)
Snow and ice Water
Vertical heat flux 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝑀 + 𝑄G 𝑄∗
+ 𝑄 𝑅 = 𝑄 𝐻 + 𝑄 𝐸 + ∆𝑄 𝑆 + ∆𝑄 𝐴
𝑄R − Heat supply by rain , ∆𝑄S - Sensible storage, ∆𝑄 𝑀 - Latent heat storage (L 𝑓∆r), ∆𝑄A - Net horizontal heat
transfer,Q 𝐸 = L 𝑠 𝐸

9. Diurnal sequence of snow temperature profiles from Devon
Island
4. CLIMATE,z
Sequence of nocturnal temperatures in a fresh snow cover and the
underlying soil at Hamilton
(a) Snow and ice
 Occurrence of a maximum temperature just beneath the surface
 Day radiative heat transfer dominates over heat conduction in the upper 0.5 m of snow, and the upper 5 m of ice.

10. Diurnal sequence of snow temperature profiles from Devon
Island
4. CLIMATE,z
Vertical variation of radiative loss and gain, and the resulting profile
of net all-wave radiation (𝑄 𝑧
∗
), in the upper layer of a snowpack
(a) Snow and ice
 Occurrence of a maximum temperature just beneath the surface
 Day radiative heat transfer dominates over heat conduction in the upper 0.5 m of snow, and the upper 5 m of ice.

11. Diurnal sequence of ocean temperature profiles for the tropical
Atlantic Ocean from measurements (20 Jun-02Jul, 1969)
4. CLIMATE,z
Profile of mean wind speed ( 𝑢), potential temperature ( 𝜃),
& specific humidity ( 𝑞) over the tropical Atlantic Ocean
(b) Water
 Deep SW penetration
 Mixing by fluid motions
0.275°C
thermocline
Most active in diurnal
heat exchange
Stable
EPILIMNION
HYPOLIMNION
 Unlimited water availability, an efficient latent heat sink and evaporative
cooling, and destabilize the surface layer
 Large thermal capacity

12. THANK YOU