Decadal differences of the diurnal temperature range in the Aral Sea region at the turn of the century

Figures & data

Fig. 1. Map of the area studied presenting the different locations of the Aral Sea shoreline during its recession. The two main tributaries of the lake and other relevant geographical features of the region are also shown. The locations of the meteorological stations used in this study are indicated by their reference number (see Table 1).

Table 1. Locations of the meteorological stations used in this study.

Reference	RIHMI-WDC code	Name	Lat (°N)	Lon (°E)	High (m asl)
1	35532	MUGODZARSKAJA	48.633	58.500	398
2	35605	MAHAMBET	47.667	51.583	–18
3	35700	ATYRAU	47.117	51.917	–22
4	35739	AQKKUM	46.667	59.000	111
5	35746	ARALSKOE MORE	46.783	61.650	62
6	35849	KAZALINSK	45.767	62.117	68
7	35925	SAM	45.400	56.117	88
8	38023	KARAKALPAKIJA	44.850	56.333	126
9	38044	UQLY	44.583	60.933	55
10	38049	IRIK-RABAT	44.067	62.900	88
11	38062	KYZYLORDA	44.850	65.500	130
12	38111	SHEVEHENKO	43.600	51.183	–28
13	38141	JASLYK	43.883	57.517	128
14	38149	KUNGRAD	43.083	58.933	64
15	38178	AK-BAJTAL	43.150	64.333	234
16	38232	AKKUDUK	42.967	54.117	78
17	38262	CHIMBAJ	42.950	59.817	66
18	38264	NUKUS	42.450	59.617	77
19	38267	KENEURGENCH	42.300	59.133	71
20	38383	SHASENEM	41.583	58.717	62
21	38388	EKEZHE	41.033	57.767	62
22	38392	DASHKHOVUZ	41.750	59.817	82
23	38396	URGENCH	41.567	60.567	101
24	38403	BUZAUBAJ	41.750	62.467	98
25	38413	TAMDY	41.733	64.617	237
26	38427	MASHIKUDUK	41.050	65.283	200
27	38507	TURKMENBASHI	40.033	52.983	90
28	38511	CHAGYL	40.783	55.333	115
29	38529	DEVERZE	40.183	58.483	84
30	38545	DARGANATA	40.467	62.283	142
31	38551	DZANGELDY	40.850	63.333	208
32	38553	AYAKAGITMA	40.683	64.483	219
33	38565	NURATA	40.550	65.683	485

Fig. 2. Monthly mean of the DTR from 1991 to 2010 at several representative stations. On the plots, large white circles indicate the months in which there were no data and the small different coloured circles indicate the number of missing days in each month: white circles more than 85%, grey circles between 80 and 50%, magenta circles between 50 and 15% and black below 15%.

Fig. 3. Averaged seasonal differences of the monthly mean DTR between two consecutive decades starting from 1991. The averaged periods are indicated above each panel.

Fig. 4. Differences of the annual mean of the DTR between the two consecutive decades: 1991–2010 and 2001–2010.

Fig. 5. (a) Decadal differences of the mean temperature (VAR-TEMPmean) and of the minimum and maximum daily temperature (VAR-TEMPdmax, VAR-TEMPdmin). The averaged periods are: November–January (NDJ), February–April (FMA), May–July (MJJ), and August–October (ASO). Numbers are the references of the station represented for each point. At the stations highlighted in yellow, the decadal differences of the mean DTR are negative. (b) Spatial representation of the decadal differences of VAR-TEMPmean for the seasonal periods indicated in each plot.

Fig. 6. Mean curves for all the stations from 1991 to 2010 of the monthly averaged DTR and of the monthly mean temperature. The coloured rectangles indicate the natural period for averaging three consecutive months which appears when the DTR and mean temperature curves are considered.

Fig. 7. Decadal differences of the mean annual temperature (VAR TEMPmean) at each station considering two different averaging segmentations based either on the annual cycle of the DTR (NDJ, FMA, MJJ, ASO) or on the annual cycle of the mean temperature (DJF, MAM, JJA, SON).

Table 2. Main conclusions about the decadal variation (between 1990 and 2010) of the monthly mean of DTR in the studied region (considering the stations available) on annual and seasonal time-scales.

Decadal variation of the DTR (VAR_DTR) on the annual time-scale
VAR_DTR is maximum at the stations closest to 1960s Aral Sea shoreline (up to about 0.6º/dec^–1 on the south and 0.4º/dec^–1 on the north-west).
VAR_DTR is significantly positive at the Kyzyl Kum and Kara Kum deserts, in the Eastern part of the Ustyurt Plateau and in the North Western region of the Aral Sea.
VAT_DTR is larger in the southern part of the Kyzyl Kum Desert than in the northern part.
VAR_DTR at the stations along the Amu Darya river is smaller than at the neighbouring stations.
At Station 5 (close to the Small Aral Sea) VAR_DTR is approximately zero.
VAR_DTR at the stations along the Syr Darya river is close to zero.
At the stations close to the Caspian Sea, VAR_DTR is either only slightly positive or negative.
At Station 21, close to the artificial lake Sarygamysh, which expanded during the studied period, VAR_DTR is negative although at the other stations around it is positive.
Decadal variation of the DTR (VAR_DTR) on the seasonal time-scale
At Station 5 (in the north-east, next to the Small Aral Sea) from February to April VAR_DTR is –0.37 º / dec^–1 and during the rest of the year it is positive and about 0.2 º / dec^–1. From February to April, the temperature in this region increased by more than 2ºC /dec^–1.
From November to April at the stations along the Syr Darya riverbed, VAR_DTR is negative and during the rest of the year it is positive.
From February to April VAR_DTR in the entire Kyzyl Kum Desert is positive. From November to January VAR_DTR in the southern part of the desert it is also positive but in the northern part it is negative.
From November to January VAR_DTR, is positive only to the west of the Aral Sea (and far from the Caspian) and in the south of the Kyzyl Kum Desert.
From February to April, VAR_DTR at the stations along the Caspian Sea are negative extending into the Ustyurt Plateau
At the stations in the Amu Darya delta, VAR_DTR is positive for all the seasons and around 1º/dec^–1 from May to October.
From May to October, VAR_DTR is positive almost everywhere and it is larger at the stations closer to the Aral Sea’s 1960s shoreline