methods used by kenya meteorological …
TRANSCRIPT
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KENYA’s CLIMATE
BY
Mary Kilavi
Kenya
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Position
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Kenya lies astride the equator, bounded by
longitudes 34oE to 42oE and latitudes
5.5oN to 5oS and hence enjoys a tropical
climate. It is hot and humid at the coast,
temperate inland and very dry in the north
and northeast parts of the country
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Topography
1650 1350 1050 750 675 600 525 450 375 300 225 150 135 120 105 90 75 60 45 30 15 0
-2
2
34 38 42
Longitude (°E)
-4
36 40
Elevatio
n (m
etres)
4
0
Lati
tud
e (°
N)
It has complex
topography eg.
large lakes, Great
Rift Valley and
snow-capped
mountains which
influence circulation
and modify climate
of various parts of
the country.
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INTRODUCTION
Kenya experiences two rainy seasons (bimodal), namely the long-rains (March to May) and the short-rains (October to December) seasons as the Inter-Tropical Convergence Zone (ITCZ) migrates through the equator from south to north, and vice versa lagging the overhead sun by about 3 to 4 weeks. However, some stations in the western and central parts of the Rift Valley experience tri-modal rainfall pattern
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Mean seasonal rainfall distribution during MAM over Kenya
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Mean seasonal rainfall distribution during OND over Kenya
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INTROD CONTI..
The western parts of the country do realise significant rainfall during the period June-August associated with influences from the tropical south Atlantic and incursions of moist Congo air mass when the meridional branch of ITCZ has maximum eastward displacement over the region.
Coastal is also wet during this period.
The January to February period is generally dry over most parts of the country.
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Mean seasonal rainfall distribution during JJA over Kenya
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65
194
104
514
565
12
143
85
0
26
18
22
621
702
24
5 649
319
486
328
47
157
78
8
353
4
264
48
70
286
457
67
17
165
359
220
99
128 714
74
42
206
28
10 BARA
COLCH
DAGO
ELDORET
ELGON
ELWAK
EMBU
GALO
GARB
GARI
ILERET
ISIOL
KAIS
KAKA
KATUMANI
KATZE KISI
I
KISUM
KITALE
LAMU
LODW
LOKICH
LOKOM
MAKI
MALI
MAND
MARL
MARS
MERU
MOMB
MONI
MOYA
MUTO
NAIV
NAKURU
NANY
NARO
NYER OLEN
G THIKA
TODEN
VANGA
VOI
WAJIR
34E 35E 36E 37E 38E 39E 40E 41E 42E
5S
4S
3S
2S
1S
0
1N
2N
3N
4N
5N
0MM
50MM
100MM
150MM
200MM
250MM
300MM
350MM
400MM
450MM
500MM
550MM
600MM
650MM
700MM
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Mean annual total rainfall distribution over Kenya
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Annual Rainfall variability in Kenya
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Temperatures
Generally:
• Highest temperatures: January to Feb
• Lowest temperatures: June to August
The Lake Victoria Basin, Highlands west of the Rift Valley, Central and South Rift :
Max 22°C ( July) - 31°C (Feb)
Min 9°C (Sep) - 14 °C (April)
Narok and Nyandarwa counties experience the experience the lowest average minimum temperature in the country of about 6°C which on a number of occasions has dropped to close to freezing point
•
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Temperatures
The Northwestern counties: • Max > 35°C throughout much of the year except in June and July when
the maximum temperatures drop slightly to less than 34°C. The average High average minimum temperatures: 22°C - 25°C
Central highlands including, Nairobi area:
• Max 21°C (July) - to 24°C (Jan)
• Min 10°C (Jan)- 16°C ( April).
Northeastern counties:
• Maximum temperatures are very high all year round (> 34 °C)
June to August falls slightly to between 31°C to 33°C.
• The minimum temperatures average between 24°C during the hot months and 21°C during the cooler months except for points at high elevation like Marsabit
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Temperatures
Southeastern lowlands counties:
• These counties are characterized by hot temperatures and extreme
evaporation. Maximum temperatures range from 26°C in July to 31°C in March. Minimum temperatures range from 14°C in July to 18°C in March
The Coastal counties : • Generally hot with temperatures exceeding 22°C throughout the year.
• Max 27°C (July)- 33°C (March)
• Min 22°C( July) –25°C (April)
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The interannual variability of rainfall in Kenya results from complex interactions of forced and free atmospheric variations which include-
SST forcing,
Land-surface forcing,
Monsoon and trade winds,
Persistent mesoscale circulations,
Tropical cyclones,
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Subtropical anticyclones,
Easterly/westerly wave perturbations,
Extra-tropical weather systems,
Jet streams,
El Niño / Southern Oscillation (ENSO), QBO etc.
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First example of a teleconnection between SSTs and
rainfall in East Africa:
El Niño Southern Oscillation (ENSO)
El Niño: Warm Episode Relationships (December - February)
60
40
20
0
-20
-40
-60
0 60 120 180 240 300
Longitude (°E)
La
titu
de
(°
N)
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60
40
20
0
-20
-40
-60
0 60 120 180 240 300
Longitude (°E)
La
titu
de
(°
N)
First example of a teleconnection between SSTs and
rainfall in East Africa:
El Niño Southern Oscillation (ENSO)
La Niña: Cold Episode Relationships (December - February)
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Second example of a teleconnection between SSTs and
rainfall in East Africa:
The Indian Ocean Dipole (IOD)
Positive Dipole Mode: (May - October)
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Second example of a teleconnection between SSTs and
rainfall in East Africa:
The Indian Ocean Dipole (IOD)
Negative Dipole Mode: (May - October)
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Trends
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Minimum Temperature trend for Kisumu
Trend line equation:y = 0.0189x + 16.534
15.5
16.0
16.5
17.0
17.5
18.0
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
Time in years
Tem
pera
ture
(°C
)Increasing significant
temperature over most
locations
Rainfall decreasing during
MAM and increasing during
DJF over some locations
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THANK YOU
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