Precipitation variability in Portugal from 1960 to 2011

doi:10.1007/s11442-015-1202-y

Abstract

Abstract:

This study analyses spatial variability and trends in annual and monthly precipitation (amount and concentration) based on data from 42 stations in mainland Portugal during the period 1960-2011. Relationships between certain geographic variables (elevation, latitude and longitude) and precipitation variability were also determined in order to check for specific dependencies and spatial patterns in precipitation distribution, concentration and changing trends. Trends and relationships have been analysed using both parametric and non-parametric tests. The results showed that annual precipitation had decreased in all stations and that this trend is statistically significant for most of the time series (70% of the stations showed negative trends with at least a 0.1 significance level). The Annual Precipitation Concentration Index revealed an opposite behaviour pattern, suggesting that even though the annual trend for precipitation amount was negative overall, more than half of the udometric stations registered a more marked seasonality for precipitation during the period 1960-2011. However, only one station showed statistical significant time trend. Regarding the influence of geographical features, latitude is the most important variable, governing spatial distribution and variations in annual precipitation as well as its intra-annual changeability. These important changes in precipitation, involving both amount and concentration, may have severe consequences for ecosystems and societies.

Key words: precipitation trend, precipitation concentration index, spatial patterns, geographical variables, Portugal

N. NUNES A., LOURENÇO L.. Precipitation variability in Portugal from 1960 to 2011[J].Journal of Geographical Sciences, 2015, 25(7): 784-800.

Figures/Tables 10

Figure 1

Table 1

Characteristics of gauging stations used in this study (Length of record =52 yr)"

Rain gauges*	Altitude (asl m)	Latitude North	Longitude W Greenwich	Mean rainfall (mm)	St. deviation (mm)
(1) Portelinha	1018	42º05'	8º17'	1975	525
(2) Deilão	892	41º85'	6º59'	784	211
(3)Travancas	884	41º83'	7º31'	941	263
(4) Ponte da Barca	39	41º80'	8º42'	1599	406
(5) Ponte de Lima	18	41º77'	8º60'	1566	403
(6) Argozelo	685	41º64'	6º60'	756	197
(7) Rio Torto	322	41º54'	7º28'	537	149
(8) Barcelos	36	41º53'	8º62'	1511	390
(9) S.M.Montanha	866	41º50'	7º75'	1709	448
(10) Folgares	739	41º30'	7º28'	623	165
(11) Amarante	146	41º26'	8º07'	1215	330
(12) Escalhão	615	40º95'	6º92'	546	127
(13) Castro Daire	697	40º92'	7º94'	1577	456
(14) B.Burgães	306	40º85'	8º38'	1733	452
(15) Pinhel	606	40º77'	7º06'	597	165
(16) Pega	770	40º43'	7º14'	773	231
(17) Almaça	116	40º34'	8º23'	1056	308
(18) Covilhã	719	40º28'	7º51'	1615	506
(19) Soure	18	40º05'	8º63'	851	238
(20) Ladoeiro	215	39º83'	7º27'	577	168
(21) R. Murta	241	39º77'	8º36'	987	297
(22) V.V.Ródão	84	39º65'	7º67'	739	217
(23) Cela	2	39º57'	9º07'	769	197
(24) Abrantes	105	39º45'	8º10'	679	199
(25) Castelo Vide	552	39º41'	7º45'	823	236
(26) Chouto	126	39º27'	8º35'	725	210
(27) Pragança	183	39º20'	9º06'	912	260
(28) B. Caia	217	39º00'	7º14'	489	155
(29) B. Magos	43	38º99'	8º69'	640	187
(30) Pavia	189	38º90'	8º01'	590	170
(31) S.J. Tojal	6	38º84'	9º12'	736	217
(32) Vila Viçosa	417	38º78'	7º42'	709	212
(33) Moinhola	41	38º58'	8º62'	681	175
(34) Reguengos	218	38º42'	7º53'	527	165
(35) V. Alentejo	314	38º33'	8º01'	676	187
(36) Grândola	95	38º17'	8º55'	651	180
(37) Serpa	209	37º94'	7º60'	509	174
(38) Relíquias	232	37º70'	8º48'	640	207
(39) Castro Verde	217	37º70'	8º09'	524	157
(40) Martim Longo	294	37º44'	7º77'	515	190
(41) B. Bravura	64	37º20'	8º70'	693	229
(42) S.B. Alportel	334	37º16'	7º90'	865	291
Mean				896	254

Table 1

Figure 2

Figure 3

Table 2

Monthly precipitation trends (1960-2011)"

Rain gauges	Months
Rain gauges	J	F	M	A	M	J	J	A	S	O	N	D
(1) Portelinha	-0.284^**	-0.314^**	-0.255^*	-0.052	-0.089	-0.116	0.134	0.079	-0.190	0.110	-0.105	-0.061
(2) Deilão	-0.204	-0.300^**	-0.197	-0.016	-0.074	-0.270^*	-0.207	0.047	-0.154	-0.001	-0.113	0.035
(3) Travancas	-0.302^**	-0.305^**	-0.211	-0.089	-0.153	-0.240^*	-0.113	0.010	-0.246^*	0.050	-0.180	-0.018
(4) P. Barca	-0.232^*	-0.385^***	-0.236^*	-0.026	-0.085	-0.100	0.184	0.112	-0.241^*	0.042	-0.049	-0.031
(5) P.Lima	-0.258^*	-0.357^***	-0.239^*	-0.099	-0.184	-0.050	0.169	0.138	-0.296^**	-0.043	-0.053	-0.092
(6) Argozelo	-0.223	-0.285^*	-0.094	0.124	-0.094	-0.053	0.054	0.105	-0.036	0.090	-0.027	0.067
(7) Rio Torto	-0.136	-0.378^**	-0.191	-0.096	0.097	-0.240	-0.122	0.204	-0.116	0.088	-0.155	-0.021
(8) Barcelos	-0.259^*	-0.341^**	-0.230	-0.043	-0.140	-0.120	0.309^**	-0.025	-0.303^**	0.126	-0.054	-0.132
(9) S.M.Montanha	-0.044	-0.265^*	-0.228	0.053	-0.004	-0.164	0.167	0.124	-0.172	0.026	-0.086	0.032
(10) Folgares	-0.187	-0.310^**	-0.228	-0.067	-0.107	-0.311^**	-0.054	0.217	-0.134	0.138	-0.115	0.069
(11) Amarante	-0.153	-0.345^**	-0.296^**	-0.029	-0.066	-0.215	-0.042	0.115	-0.181	-0.010	-0.079	0.022
(12) Escalhão	-0.115	-0.233^*	-0.200	0.008	-0.017	-0.200	-0.060	0.190	-0.075	0.173	-0.114	0.081
(13) Castro Daire	-0.245^*	-0.343^**	-0.300^*	-0.040	-0.186	-0.308^**	0.130	0.170	-0.132	0.138	-0.120	-0.006
(14) B.Burgães	-0.274^*	-0.393^***	-0.326^**	-0.107	-0.189	-0.145	0.266^*	0.134	-0.220	0.056	-0.008	-0.023
(15) Pinhel	-0.177	-0.257^*	-0.293^**	-0.028	-0.007	-0.262^*	-0.020	0.158	-0.110	0.099	-0.183	0.012
(16) Pega	-0.169	-0.275^*	-0.197	-0.197	0.010	-0.286^**	-0.054	0.231	0.006	0.128	-0.202	-0.030
(17) Almaça	-0.208	-0.258^*	-0.325^**	-0.092	-0.214	-0.260^*	0.102	0.155	-0.066	0.102	-0.146	-0.020
(18) Covilhã	-0.242^*	-0.345^**	-0.146	0.061	-0.131	-0.288^**	-0.086	0.210	-0.018	0.136	-0.092	0.020
(19) Soure	-0.325^**	-0.302^**	-0.253^*	-0.053	-0.137	-0.280^**	0.073	0.164	-0.196	0.043	-0.157	-0.152
(20) Ladoeiro	-0.192	-0.250^*	-0.293^**	-0.027	-0.095	-0.437^***	-0.027	0.037	0.008	0.177	-0.081	-0.033
(21) R. Murta	-0.321^**	-0.343^**	-0.355^***	-0.082	-0.244	-0.338^**	0.037	0.234^*	-0.204	0.095	-0.242^*	-0.097
(22) V.V.Ródão	-0.100	-0.211	-0.189	0.161	0.070	-0.345^**	0.097	0.293^**	0.019	0.203	-0.067	0.016
(23) Cela	-0.322^**	-0.262^*	-0.271^*	0.026	-0.133	-0.248^*	0.280^**	0.230	-0.096	0.050	-0.177	-0.110
(24) Abrantes	-0.268^*	-0.252^*	-0.306^**	-0.035	-0.103	-0.314^**	0.231^*	0.166	-0.126	0.099	-0.160	0.030
(25) Castelo Vide	-0.129	-0.216	-0.248^*	0.025	-0.085	-0.349^**	0.066	0.197	-0.184	0.191	-0.113	0.038
(26) Chouto	-0.311^**	-0.324^**	-0.227	-0.084	-0.060	-0.326^**	-0.078	0.021	-0.068	0.043	-0.141	-0.159
(27) Pragança	-0.321^**	-0.383^***	-0.259^*	0.041	-0.064	-0.123	0.384^***	0.450^***	0.113	0.127	-0.070	-0.075
(28) B. Caia	0.022	-0.158	-0.100	-0.235	-0.263	-0.225	-0.118	-0.048	-0.411^***	0.200	0.335^**	-0.031
(29) B.Magos	-0.250^*	-0.339^**	-0.271^*	0.022	-0.188	-0.280^**	0.168	0.113	0.025	0.099	-0.216	-0.120
(30) Pavia	0.133	-0.146	-0.063	-0.172	-0.325^**	-0.336^**	-0.078	-0.155	-0.456^***	-0.006	0.260^*	-0.127
(31) S.J. Tojal	-0.090	-0.194	-0.203	0.051	0.022	-0.050	0.335^**	0.194	0.141	0.186	-0.081	-0.005
(32) Vila Viçosa	-0.228	-0.302^**	-0.372^**	0.021	0.055	-0.287^**	0.198	0.292^**	0.024	0.050	-0.116	-0.159
(33) Moinhola	-0.200	-0.252^*	-0.206	-0.022	0.026	-0.136	0.299^**	0.226	0.002	0.170	-0.058	-0.077
(34) Reguengos	-0.299^**	-0.281^**	-0.285^**	0.103	-0.050	-0.312^**	0.387^***	0.299^**	-0.046	0.056	-0.214	-0.085
(35) V. Alentejo	-0.129	-0.175	-0.171	0.146	0.094	-0.203	0.228	0.188	0.014	0.164	-0.105	-0.083
(36) Grândola	-0.122	-0.238^*	-0.196	0.117	0.071	-0.167	0.416^***	0.236^*	0.292^**	0.137	-0.098	0.063
(37) Serpa	-0.169	-0.223	-0.131	0.114	0.018	-0.457^***	0.287^**	0.238^*	0.208	0.135	-0.075	-0.008
(38) Relíquias	-0.299^**	-0.281^**	-0.285^**	0.103	-0.050	-0.312^**	0.387^***	0.299^**	0.010	-0.119	-0.175	-0.059
(39) Castro Verde	-0.192	-0.258^*	-0.228	0.063	-0.066	-0.524^***	0.248^*	0.366^***	0.168	0.084	-0.062	0.040
(40) M. Longo	0.205	0.047	-0.479^***	0.368^**	0.186	0.214	0.082	-0.007	0.152	-0.193	-0.210	-0.149
(41) B. Bravura	-0.239^*	-0.195	-0.223	0.084	-0.056	-0.040	0.539^***	0.241^*	0.190	0.079	0.019	0.150
(42) S.B. Alportel	-0.281^**	-0.331^**	-0.232^*	0.053	0.032	-0.305^**	0.428^***	0.161	0.217	0.094	-0.085	0.090

Table 2

Table 3

Monthly and annual PCI trends (1960-2011)"

Rain gauges	Months
Rain gauges	J	F	M	A	M	J	J	A	S	O	N	D	Year
(1) Portelinha	-0.133	-0.197	-0.130	0.087	0.099	0.002	0.236^*	0.163	-0.061	0.245^*	0.048	0.103	-0.068
(2) Deilão	-0.068	-0.195	-0.083	0.108	0.057	-0.173	-0.044	0.097	-0.103	0.128	0.014	0.188	0.142
(3) Travancas	-0.094	-0.206	-0.045	0.064	-0.010	-0.126	-0.046	0.131	-0.133	0.185	-0.023	0.179	0.146
(4) P. Barca	-0.044	-0.339^**	-0.080	0.112	0.044	0.025	0.258^*	0.195	-0.193	0.129	0.072	0.131	0.056
(5) P.Lima	-0.028	-0.256^*	-0.092	0.075	-0.072	0.099	0.279^**	0.216	-0.150	0.072	0.091	0.137	-0.049
(6) Argozelo	-0.175	-0.246^*	-0.043	0.173	0.001	-0.006	0.089	0.119	0.011	0.161	0.076	0.151	-0.130
(7) Rio Torto	0.002	-0.310^**	-0.075	0.028	0.199	-0.115	-0.040	0.302^**	-0.010	0.248^*	-0.036	0.123	-0.065
(8) Barcelos	-0.001	-0.238^*	-0.057	0.133	-0.002	0.012	0.351^**	0.054	-0.219	0.192	0.080	0.065	0.095
(9)S.M.Montanha	0.054	-0.209	-0.106	0.157	0.103	-0.085	0.197	0.172	-0.131	0.030	0.001	0.141	-0.023
(10) Folgares	-0.046	-0.273^*	-0.151	0.041	0.029	-0.222	0.050	0.264^*	-0.047	0.236^*	-0.017	0.169	0.074
(11) Amarante	-0.046	-0.310^**	-0.195	0.142	0.089	-0.093	0.021	0.241^*	-0.107	0.098	0.038	0.192	0.069
(12) Escalhão	-0.040	-0.203	-0.077	0.038	0.053	-0.170	-0.030	0.221	-0.028	0.252^*	-0.022	0.137	0.096
(13) Castro Daire	-0.048	-0.258^*	-0.209	0.069	-0.039	-0.177	0.186	0.273^**	-0.013	0.248^*	0.024	0.189	-0.025
(14) B.Burgães	-0.163	-0.317^**	-0.202	0.079	-0.037	-0.047	0.348^**	0.229	-0.068	0.212	0.142	0.195	-0.116
(15) Pinhel	-0.023	-0.186	-0.190	0.087	0.166	-0.151	0.040	0.183	-0.019	0.207	-0.129	0.127	0.105
(16) Pega	-0.072	-0.192	-0.065	-0.020	0.091	-0.160	-0.005	0.267^**	0.154	0.313^**	-0.122	0.089	-0.056
(17) Almaça	-0.129	-0.175	-0.171	0.146	0.094	-0.203	0.228	0.219	0.042	0.248^*	0.011	0.060	0.010
(18) Covilhã	-0.215	-0.307^**	-0.031	0.211	-0.021	-0.275^**	-0.059	0.242^*	0.082	0.231^*	-0.030	0.147	-0.008
(19) Soure	-0.129	-0.177	-0.152	0.111	0.048	-0.216	0.139	0.222	-0.028	0.207	0.003	0.015	0.022
(20) Ladoeiro	-0.131	-0.114	-0.211	0.067	-0.029	-0.397^***	-0.020	0.077	0.125	0.281^**	0.028	0.072	0.249^*
(21) R. Murta	-0.154	-0.186	-0.207	0.134	-0.089	-0.231^*	0.103	0.308^**	-0.016	0.258^*	-0.051	0.203	0.140
(22) V.V.Ródão	-0.100	-0.211	-0.189	0.161	0.070	-0.345^**	0.097	0.293^**	0.019	0.273^*	0.015	0.088	0.105
(23) Cela	-0.210	-0.131	-0.183	0.186	-0.048	-0.168	0.321^**	0.288^**	0.010	0.175	0.021	0.013	-0.044
(24) Abrantes	-0.147	-0.095	-0.221	0.083	0.058	-0.226	0.238^*	0.210	-0.025	0.188	-0.016	0.191	-0.065
(25) Castelo Vide	-0.014	-0.137	-0.176	0.091	-0.019	-0.325^**	0.091	0.244*	-0.137	0.245^*	-0.002	0.155	0.110
(26) Chouto	-0.155	-0.134	-0.074	0.078	0.106	-0.220	-0.026	0.109	0.077	0.185	0.008	-0.040	0.110
(27) Pragança	-0.278^**	-0.293^**	-0.152	0.158	0.035	-0.084	0.410^***	0.475^***	0.220	0.220	0.039	0.081	-0.174
(28) B. Caia	0.199	-0.001	0.030	-0.048	-0.142	-0.098	0.041	0.061	-0.329^**	0.232^*	0.360^***	0.044	0.048
(29) B.Magos	-0.159	-0.180	-0.110	0.209	-0.082	-0.224	0.204	0.179	0.151	0.249^*	-0.104	0.024	0.099
(30) Pavia	0.256^*	0.029	0.065	0.021	-0.167	-0.201	0.047	-0.068	-0.372^***	0.013	0.307^**	-0.004	0.216
(31) S.J. Tojal	-0.130	-0.148	-0.128	0.168	0.057	-0.427^***	0.291^**	0.237^**	0.251^*	0.194	-0.060	0.032	-0.021
(32) Vila Viçosa	-0.131	-0.201	-0.243^*	0.180	0.125	-0.233^*	0.216	0.324^**	0.120	0.185	-0.016	-0.043	0.083
(33) Moinhola	-0.126	-0.124	-0.123	0.041	0.095	-0.109	0.310^*	0.256^*	0.075	0.228	-0.011	-0.005	-0.059
(34) Reguengos	-0.065	-0.171	-0.242^*	0.226	0.184	-0.277^**	0.053	0.162	0.036	0.150	-0.102	0.065	0.107
(35) V. Alentejo	-0.129	-0.175	-0.171	0.146	0.094	-0.203	0.228	0.219	0.042	0.248^*	0.011	0.060	0.010
(36) Grândola	-0.096	-0.187	-0.181	0.167	0.110	-0.170	0.427^**	0.255^*	0.296^*	0.180	-0.081	0.110	-0.154
(37) Serpa	-0.100	-0.162	-0.161	0.108	0.071	-0.035	0.333^*	0.203	0.168	0.259^*	-0.071	0.067	-0.183
(38) Relíquias	-0.161	-0.179	-0.129	0.254^*	0.097	-0.268^*	0.419^**	0.337^**	0.106	0.009	-0.049	0.093	0.020
(39) Castro Verde	-0.164	-0.184	-0.177	0.127	0.014	-0.518^***	0.251	0.377^***	0.195	0.134	-0.002	0.151	-0.018
(40) M. Longo	0.200	0.069	-0.508^***	0.352^**	0.182	0.188	0.117	-0.025	0.158	-0.230	-0.283^**	-0.148	-0.034
(41) B. Bravura	-0.248^*	-0.209	-0.158	0.083	0.010	-0.003	0.555^***	0.249*	0.216	0.097	0.054	0.207	-0.159
(42) S.B. Alportel	-0.263^*	-0.233^*	-0.148	0.101	0.103	-0.288^**	0.452^***	0.180	0.258*	0.158	-0.019	0.151	-0.135

Table 3

Table 4

Figure 4

Figure 5

Table 5

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Precipitation (1960-2011)
Negative trend					Positive trend
	ns	0.1	0.05	0.01	ns	0. 1	0.05	0.01
J	47.6	21.4	23.8		7.2
F	19.0	28.6	40.5	9.5	2.4
M	50.0	23.8	21.4	4.8
A	52.4				45.2		2.4
M	71.4		2.4		26.2
J	40.5	11.9	38.1	7.1	2.4
J	31.0				35.7	7.0	11.9	14.4
A	9.5				66.7	9.5	9.5	4.8
S	47.6	4.8	4.8	4.8	35.7		2.4
O	14.3				85.7
N	90.4	2.4			2.4		4.8
D	64.3				35.7
Precipitation (1960-2011)
Negative trend					Positive trend
	ns	0.1	0.05	0.01	ns	0. 1	0.05	0.01
J	81.0	4.8	2.4		9.4	2.4
F	66.6	14.2	14.4		4.8
M	88.0	4.8		2.4	4.8
A	4.8				90.5	2.4	2.4
M	31.0				69.0
J	62.0	7.1	11.9	7.1	11.9
J	19.0				45.2	11.9	16.7	7.1
A	4.8				52.4	16.7	21.4	4.8
S	42.9		2.4	2.4	45.2	7.1
O	2.4				59.5	33.3	4.8
N	47.6			2.4	45.2		2.4	2.4
D	11.9				88.1

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