Climatic conditions over the territory of Russia.

By and large, the year 2010 was warm in Russia. The anomaly of mean annual air temperatures averaged over the Russian territory was 0.7⁰C ( Fig.1).

Anomalies of air temperatures averaged over the Russian territory were positive for all seasons, except for winter (Fig.2), with the summer air temperature anomaly being the highest.

Figure 1. Anomalies of mean annual air temperatures averaged over the Russian territory, 1939-2010 (against 1961-1990 normals)

Figure 2. Anomalies (deviations from 1961-1990 averages) of mean seasonal air temperatures averaged over the Russian territory in 2010

The last winter in Russia as a whole was included in the list of ten coldest winters.

Figure 3 shows anomalies of mean winter air temperatures (December – February) averaged over quasi-homogeneous climatic regions (I – northern European Russia and northern Western Siberia, II – northern Eastern Siberia and northern Yakutia, III – Chukotka and Kamchatka, IV – central and southern European Russia, V – central and southern Western Siberia, VI – central and southern Eastern Siberia, and VII – Far East). In Western Siberia (region V), this anomaly was -5.6 ⁰С (the second in size negative value for the period in question). In this region, the mean monthly temperature was substantially below normal for all winter months.

Figure 3. Anomalies (deviations from 1961-1990 averages) of mean winter air temperatures (December – February) averaged over quasi-homogeneous climatic regions, 1939-2010

Figure 5. Anomalies of mean spring air temperatures averaged over quasi-homogeneous climatic regions, 1939-2010

Following very cold winter, March proved to be warm over most of Western Siberia, particularly in the east of the Yamalo-Nenets District, where mean monthly air temperature anomalies exceeded 3^оС. In March, most of the Far East region experienced cold weather, particularly in Kamchatka and the southern Far East, where mean monthly air temperature proved to be 2-3^оС below normal. In the eastern Sakha-Yakutia Republic and continental regions of the Chukotka Autonomous Area, mean monthly air temperatures were above normal, although in early March, air temperature in Chukotka dropped to -51^оС and in places new record-breaking daily air temperature minima were registered. In the third ten-day period, spring floods were recorded in the rivers in southern European Russia. Due to significant snow accumulation during the winter, despite preventive measures taken, a very complex hydrological situation existed on the rivers of the Voronezh, Volgograd and Rostov Regions (Don, Medveditsa, Khoper, Ilovlya, Chir, etc.). In places, water level rose to 600-700 cm, which resulted in impoundment of many houses and evacuation of people.

Over most of Russia, April was warm, especially in northeastern European Russia, where mean monthly air temperatures were 4-5^оС above normal. In early April, record-breaking maximum air temperatures were registered in the Northwestern Federal Area (St-Petersburg, Pskov, Arkhangelsk, Kotlas, Syktyvkar), Volga Federal Area (Kirov, Izhevsk, Orenburg, Perm), and Ural Federal Area (Ufa, Magnitogorsk). In the third ten-day period of April, record-breaking warm weather settled in southern Western Siberia. Although rivers were still icebound and snow was retained here and there, air temperature rose as high as +25º. This has not been recorded since 1972. Record-breaking maximum air temperatures were observed in the Tyumen, Tomsk, Kurgan and Kemerovo Regions, the Altai Territory and the Altai Republic. Most of the region received below normal or normal precipitation. In Kamchatka and the Magadan Region it was cold. Mean monthly air temperature anomalies at the centre of this cold island attained -3…-4^оС. Record-breaking cold weather was observed during the first week of the month in Kolyma and eastern Yakutia. In Magadan, such cold weather at this time of the year has not been recorded for more than 50 years and in Oimyakon, which is known as “cold pole”, a new daily temperature minimum was set.

May 2010 ranked second among the warmest Mays in the Northwestern Federal Area. As early as the beginning of the month, record-breaking temperatures were registered in northern European Russia, Upper and Mid-Volga, Ural, and central Russia. In the first ten-day period of May, abnormally hot weather settled in the Central Chernozem Region: maximum diurnal air temperature attained 28-31^оС. As a result, the areas in question experienced hot winds and extreme fire hazards. Forest fires were registered in the Lipetsk and Tambov Regions. Abnormally hot weather during the first ten-day period of May was also recorded in the Ulyanovsk, Penza, Saratov and Orenburg Regions, where mean daily air temperatures were 7-11^оС above normal. Combined with precipitation deficit, this gave rise to soil drought in separate areas of the Penza and Ulyanovsk Regions. Unusually warm weather propagated from central European Russia outside the Polar circle. By the end of the first ten-day period, mean daily air temperature anomalies were larger than 10^оС. On 11 May, record-breaking maximum temperatures were registered in many northern cities (Naryan-Mar, Pechora, Syktyvkar). Weather in the north of European Russia proved to be warmer than that in the south of it. On 18 May, air temperature in Murmansk rose as high as 26.4^оС, which was nearly 5^оС higher than the previous record of 1984. Due to large accumulation of snow, torrential spring floods were recorded in May in Western Siberia. Particularly complex hydrological situation existed on the rivers Ob, Chaya, Chulym, Peschanaya, and Tom. Break-up of the river Tom in the vicinity of Tomsk was accompanied by ice clogging with the abrupt water level rise.

By and large, summer in Russia was warmest for the period in question, with the temperature anomaly being 1.8 ^оС (Fig.2). Abnormally hot summer was recorded in quasi-homogeneous regions II, III, IV and VII. It was particularly warm in central and southern European Russia, where seasonal temperature anomaly was 4.1 ^оС (Fig.6).

Figure 6. Anomalies of mean summer air temperatures averaged over quasi-homogeneous climatic regions, 1939-2010

In June, positive temperature anomalies were prevailing over the Russian territory. In European Russia, a heat island formed over the Volga Region and southern Ural, where mean monthly air temperature anomalies were higher than 5^оС (Fig.7а). Particularly hot was the third ten-day period in most of the central and eastern regions. From 22 through 24 June, abnormally hot weather settled in Upper Volga, Mid-Volga, Lower Volga and Central Chernozem Region. Mean daily air temperatures were 7-11^оС above normal; maximum diurnal air temperatures attained 33-38^оС and 40-41^оС in the Astrakhan Region. On 25 June, a temperature record was also established in Moscow, 32.8^оС (Fig.7c). Southern and Northern Caucasian Federal Areas experienced the hottest June that has ever been recorded for 120 years of regular meteorological observations. Central and southern European Russia experienced substantial rainfall deficit in June (Fig.8). A particularly tight situation existed in the last ten-day period of June, when Central and Volga Federal Areas, as well as Lower Volga received no or a few millimeters of rainfall. Hot weather, combined with significant rainfall deficit, contributed to strong hot winds, soil and air droughts. Emergency regime was introduced in some of the regions. Abnormally hot and dry weather gave rise to extreme fire hazards in central European Russia. Forest fires occurred in the Tambov, Lipetsk and Volgograd Regions. In the late ten-day period it was very hot in the Altai Territory, where air temperatures in places attained 36^оС. Hot winds and soil drought were observed in the northern Altai Territory and steppe areas of the Kemerovo Region. In Transbaikalia, strong heat with maximum air temperatures 33-43^оС persisted throughout the third ten-day period of the month. In Chita and most of the other cities of the region, absolute daily maxima of air temperature were exceeded. Air temperatures in Buryatia and Transbaikalia on these days proved to be highest for the Russian territory. Clear sky and the warm air arriving from the southern latitudes provoked extremely hot weather with mean daily air temperatures 8-12^оС above normal. Hot and dry weather caused forest fires. June temperature records were also broken in many southern regions of the Far East. In the first ten-day period, a steady anticyclone blocked the way to the Maritime Territory for the Chinese and Mongolian cyclones, which allowed the air temperature to rise, in places, to 33-35^оС. In the afternoon on 9 June, the air temperature in Vladivostok attained 29.9^оС, which is more than 3^оС above the previous record in 1969. Such weather is not at all typical for the early summer in the Maritime Territory. In the Territory, particularly in its coastal regions, the weather is usually dull, moist and cool, which is accounted for by monsoon effects.

July in 2010 became the hottest in Russia for the whole period of record, despite the fact that over much of the country (Ural and Western Siberia) it was substantially colder than is generally recorded. During a long time, most of the regions in European Russia experienced strong heat due to a steady anticyclone that brought hot air from Central Asia. Nearly each day brought new temperature records. In Moscow alone, ten temperature records were established in July (Fig.7c). Again, over most of European Russia, daily air temperatures above 30^оС lasted for very long, more than a month, and in all Federal Areas of European Russia, mean monthly air temperature attained its absolute maximum. A combination of abnormally hot weather and substantial rainfall deficit (4-40% of monthly normal) observed in many regions caused damage and destroyed crops over vast areas (Fig. 8). Forest fires is another disaster produced by abnormally hot and dry weather. Particularly serious situation existed in the Nizhniy Novgorod, Ryazan and Moscow Regions, where forest fires were aggravated with burning peat bogs. Fires in the Nizhniy Novgorod, Vladimir and Ryazan Regions completely destroyed several villages leaving thousands of people homeless. Abnormally hot weather settled in northern and eastern Yakutia on the first five days, with mean daily air temperatures being 8-12^оС above normal.

Figure 7. Temperature conditions in the summer 2010 in European Russia
а) Mean monthly air temperature anomalies (against 1961-1990 normals)
b) Mean monthly air temperatures in the summer months in Moscow for the period of record
c) Mean daily and maximum air temperature in the summer 2010, daily temperature
normals and absolute daily temperature maxima in the summer months in Moscow

Figure 8. Anomalies of monthly precipitation totals in the summer months over European Russia

This heat was caused by a high warm anticyclone that formed in the very warm Transbaikalian air accumulated above these regions. On 4 July, a new absolute air temperature maximum for this day was established in Oimyakon known as “cold pole”. In the afternoon the air temperature rose as high as 30.6°С, which is 0.8^оС above the previous record value of 1998. After that, warm air masses moved further eastward. The absolute temperature maximum, 32^оС, was registered on 19 July in the north of Kamchatka; it was the first time ever recorded that the air temperature rose above 30^оС in Korfa. Western Siberia proved to be the only Russian region, where mean monthly air temperature in July was below normal. In Surgut, a new record value of cold was established on 20 July: minimum air temperature in predawn hours dropped to 3.5^оС.

In the first half of August, most of European Russia experienced abnormally hot weather However, the heat island formed above central European Russia in July moved slightly southward. In Moscow and some other cities of European Russia, the August of 2010, like July, proved to be the hottest for the whole period of meteorological observations (Fig.7b). Up to 19 August, maximum temperature records were registered nearly every day over the large area from the Pechora River to Kuban and from the western borders of Russia to the Cis-Ural region. In the third ten-day period of August, high air temperatures declined in central and eastern European Russia and the first frosts were recorded in the Ural, Upper Volga and Northwestern regions. Precipitation deficit was registered over the area from the Upper Volga region to the southern regions. In August, air drought spread farther southwards: Rostov Region, Krasnodar and Stavropol Territories, and republics of Northern Caucasia. Extreme fire hazards persisted and forests and peat bogs were still on fire. The tightest situation was retained in the forests of the Nizhniy Novgorod and Ryazan Regions. On the first days of August, dense smog wrapped Moscow, Ryazan and other cities. The fire that wrapped the roads and zero visibility brought traffic along highway Moscow-Chelyabinsk to a standstill and disturbed railroad movement. In the Central, Volga, Southern and North-Caucasian Federal Areas, like in the country as a whole, the 2010 summer was the hottest for the past 120 years.

Autumn air temperatures were above normal in all the regions (Fig.9). The largest anomaly was derived in quasi-homogeneous climatic region III (Chukotka and Kamchatka), 2.9 ^оС. This is the record value in the region for the period in question.

Figure 9. Anomalies of mean autumn air temperatures averaged over quasi-homogeneous climatic regions, 1939-2010

In September, maximum mean monthly air temperature anomalies were recorded in the Chukotka Autonomous District (4-5^оС). Mean monthly air temperature over European Russia was above long-term averages. In the third ten-day period, the Ural region turned out to be in the warm rear part of the anticyclone that moved to Kasakstan. Therefore, sunny and dry weather settled. Diurnal air temperatures attained 25-28^оС, which was 7-10^оС above normal. This resulted in new temperature records. On 21 September, a new temperature maximum for the day was established in Yekaterinburg (25.8^оС) and Kurgan (27.5^оС). Drought persisted in eastern and southern European Russia. By the end of the month, due to air temperature fall and effective precipitation that fell in some areas of the region, air drought ceased. Again, precipitation deficit against increased air temperatures promoted fire hazards in southern and eastern European Russia. New fire sources arose in the Ulyanovsk, Volgograd and Sverdlovsk Regions. Dense smog produced by forest fires wrapped Yekaterinburg. Hot and dry weather caused naturally occurring fires in the western Altai Territory.

October in the Ural region, northern and northeastern European Russia, Western Siberia, Chukotka and Kamchatka was very warm. In the Altai Territory, air temperatures attained 13-15^оС. Southern European Russia received very much precipitation, especially the Astrakhan Region and the Republic of Kalmykia, where monthly normal precipitation was exceeded, in places, by three to five times. Heavy rains (47-93mm) that occurred on 15-16 October in the Apsheron and Tuapse Regions of the Krasnodar Territory caused an abrupt water level rise on local rivers (340-916cm). High-strength rain floods destroyed settlements. October was colder than that in the long-term average over most of European Russia. In early October, an extensive cold anticyclone caused new daily air temperature minima in Tver, Tula, Saratov and other settlements. In most of the Upper Volga regions, snow cover formed ten and more days earlier than the long-tern averages show. One more flow of cold moving to the Mid-Volga region was recorded at the beginning of the third ten-day period.

November was abnormally warm over most of the Russian area (Fig.10). The first half of the month was particularly warm over most of European Russia and southern Western Siberia. Southerlies and south-westers brought moist and very warm air from North Africa and the West Atlantic to European Russia. In many cities (Smolensk, Tver, Vladimir, Kostroma, Nizhni Novgorod, Izhevsk, Cheboksary, Bryansk, Kursk, Lipetsk), air temperature records were exceeded. Warm and moist Atlantic air masses moving to Siberia over European Russia brought warm “London-like” rainy weather to the south of Western Siberia. For most of the month, both mean daily air temperatures and minimum air temperatures were above mean daily air temperature normals at Altai station Turochak (see inset in Fig. 10). On 15-16 November, the absolute temperature maximum was exceeded. Similar temperature conditions were also recorded at many stations in Yakutia, specifically, in Verhoyansk that is known as the second cold pole. Several temperature records were also broken in southern Western Siberia: on 15 November, diurnal air temperature in Novosibirsk attained 6.4^оС. For the third consecutive month, positive temperature anomalies were observed in Chukotka and Kamchatka. On the last days of the month, cold Arctic air masses over European Russia transported warm air southward and the genuine winter came to the central regions. In late November, winter weather also settled in the north of Western Siberia. At polar long nights, additional air cooling in steady anticyclones decreased air temperature to -47^оС in the Yamalo-Nenets Autonomous District. The Taimyr Peninsula and Evenkia experienced hard frosts in the third ten-day period of the month (-40…-47^оС).

Figure 10. Air temperature anomalies in November 2010. Insets show mean monthly and mean daily air temperature series in November 2010 at meteorological stations Turochak and Verhoyansk

A large cold island formed over the Russian territory in December. The island had two centres, one of which was located above northwestern European Russia and the other, above central Eastern Siberia. Here, mean monthly air temperature anomalies -6…-7^оС и -8…-10^оС, respectively. It was warm in December in southern European Russia, with mean monthly air temperature anomalies being larger than 7-8^оС in individual regions. In Elista, the December of 2010 was the warmest for the whole period of instrumental observations at the station (see the inset in Fig.11а). On the Black Sea coast, diurnal air temperature rose as high as 25^оС. In Vladikavkaz, air temperatures attained 27^оС. In the North Ossetia valleys, tree buttons swelled and roses bloomed and in some villages, strawberries bloomed. On 26 December, the previous temperature record of 1954 was exceeded by 6 оС in Stavropol, with air warming up to 17.1^оС. Even a more extensive warm island formed over the northeastern Far East– in the Magadan Region, Chukotka Autonomous Area and Kamchatka Territory. In the individual regions of these Russian Federation constituent entities, mean monthly air temperature anomalies were higher than 10^оС. At meteorological station Omolon (Fig. 11а), mean monthly air temperature was -23.1 оС at the normal value -35.8 оС. In the period 6-25 December, mean daily and minimum air temperatures were above mean daily air temperature normals. Warm weather was accompanied by a large amount of precipitation; monthly normals were exceeded by four to five times at many points. Petropavlovsk-Kamchatsky was inundated with heavy rains throughout the first half of the month (high temperatures turned snow into rain). On 9 and 11 December, daily precipitation maxima were exceeded and the monthly precipitation total, 446.3mm, became the absolute December precipitation record at the station (see the inset in Fig.11b). Heavy snowfalls that attacked the southern Far East have been record-breaking for the past 60 years. At many stations in the Khabarovsk and Maritime Territories and Sakhalin, monthly precipitation normals were exceeded by four to five times. For example, the town of Poronask received 215mm of precipitation, which is equal to more than five monthly normals (see the inset in Fig.11b).

Figure 11. Weather conditions in December 2010
а) Air temperature anomalies. Insets show mean monthly and mean daily air temperature series in December 2010 at meteorological stations Elista and Omolon;
b) Monthly precipitation totals against normal. Insets show monthly and daily precipitation total series in December 2010 at meteorological stations Poronaisk and Petropavlovsk-Kamchatsky.

The number of days with snow covering more than 50% of the area around a meteorological station was used from daily observations to estimate the snow cover duration.

Figure 12. Linear trend coefficients (days/decade; 1- to 5-percent significance level) in the series of the number of days with snow covering more than 50% of the area around a meteorological station. 1976-2010.

A tendency for the decrease in snow duration in the period 1976-2010 was revealed in European Russia, Western Siberia, the Taimyr Peninsula and eastern Yakutia. Snow duration increase was recorded in the Ural region, southern Eastern Siberia, the Maritime Territory and on the coast of the Sea of Okhotsk.

In the winter of 2009-2010, the snow duration was significantly lower than that recorded in the long-term average for the most of European Russia, except extreme northeastern areas, Leningrad and Pskov Regions, northwestern Murmansk Region, southern Central Chernozem Region and southern Lower Volga (Fig.13). Even in the mountain regions of Northern Caucasia, snow cover persisted not as long as it usually did. First snow in northeastern and central European Russia and in Northern Caucasia appeared later than that recorded in the long-term average due to very warm weather in October and November 2009 (Fig.14). In northwestern European Russia and Upper Volga, snow fell earlier than is generally recorded. In the Republic of Tatarstan, snow cover formed as early as 1 November, which is ten to twenty five days earlier than that recorded in the long-term averages. Snow in the Ural and Cis-Kama regions persisted somewhat longer than it generally did, which is related to a large amount of precipitation in February.

Figure 13. Anomalies of the number of days with snow covering more than 50% of the area around a meteorological station in the winter of 2009-2010 (as against mean long-term values for the period 1961-1990). Insets show mean daily air temperatures, amount of snow covering the area around a meteorological station, snow heights, and daily precipitation totals at meteorological stations Kaliningrad, Vorkuta, Volochanka and Vladivostok.

Negative snow duration anomalies are recorded in the north of the Asian territory. On the Taimyr Peninsula and in Evenkia, snow cover formed later than that recorded in the long-term average, due to very warm weather that persisted here in September-October 2009. For example, at station Volochanka (see the inset in Fig. 13), owing to positive air temperatures, snow cover formed as late as the end of the second ten-day period of October. Again, a small amount of precipitation in winter and high air temperature in spring contributed to earlier snow melt. Shorter duration of snow cover in Chukotka was caused by very warm autumn, particularly September. Snow generally forms here in the second half of September. In the south of the Asian territory and on Kamchatka, snow persisted longer than it generally did. In Transbaikalia, first snow fell much earlier than it usually did (Fig.14), and a large amount of precipitation in February and March and cold weather in the first spring months contributed to longer snow duration. In the southern Far East, a large amount of precipitation increased snow cover throughout the winter and the spring was long and cool, which contributed to longer snow duration. For example, snow cover in Vladivostok, which melted in early April, formed again and persisted as long as the end of the second ten-day period (see the inset in Fig. 13). In the south of the Asian territory of Russia, the isolines of the earliest dates of snow formation are of a very complex form due to a strong influence of the Altai and Sayan mountain orography.

Figure 14. а) Earliest dates of snow formation over the Russian territory in the winter 2009-2010; b) Anomalies in the earliest dates of snow formation over the Russian territory in the winter 2009-2010 (against 1971-2000 normals)

The isolines in the North-Caucasian region are even more complex, also due to orographic effects (Fig.14а). It should be noted that first snow fell much later than it usually did in the southern Central Chernozem Region and Upper Volga (Fig.14b). On the eastern coast of the Asian territory, snow cover formed later than in the continental regions, due to the softening effects of the ocean. The latest dates of the snow formation (second ten-day period of January) were registered on the Black Sea and Caspian Sea coasts of North Caucasia.

In the last decades, maximum seasonal snow heights increased in northern Western Siberia, most of Eastern Siberia, Kamchatka, Chukotka, on the coast of the Sea of Okhotsk, southern Far East, Ural region, and individual regions of European Russia. In western European Russia and Yakutia, a maximum seasonal snow height is decreasing (Fig.15).

Figure 15. Linear trend coefficients (cm/ decade; 1- to 5-percent significance level) in the series of maximum seasonal snow heights. 1976-2010

In the winter 2009-2010, positive anomalies of maximum snow heights were recorded in most of European Russia, except the Volga-Vyatka region, individual areas of the Arkhangelsk Region, and the Black Sea and Caspian Sea coasts of Northern Caucasia (Fig.16). This is accounted for by both a rather large amount of precipitation and an absolute absence of thaws in central European Russia, which had not been recorded for several decades.

A vast zone of negative anomalies in central Eastern Siberia is caused by the strengthening of the Siberian anticyclone in December through February and, therefore, by a decrease in scarce precipitation (see data from station Zhigansk, inset in Fig.16). First snow in these regions formed considerably later than is generally recorded due to the warm autumn, the season when the major snow increase occurs. Chukotka received below normal precipitation throughout the winter season. Therefore, even heavy snowfalls in March were of no effect: maximum snow height anomalies proved to be negative. In the southern Far East, positive snow height anomalies were related to substantial precipitation in the period December-February. Particularly heavy snowfalls were recorded in the Maritime Territory and Sakhalin in December 2009, when monthly precipitation normal was exceeded by four to six times at individual stations. At station Poronaisk, heavy snowfalls in April also contributed to the snow cover elevation (seethe inset in Fig. 16).

Figure 16. Maximum snow height anomalies in the winter 2009-2010 (as against mean long-term values for the period 1961-1990). The insets show daily means of air temperature, snow extent around a meteorological station and snow height, and daily precipitation totals at meteorological stations Velikie Luki, Zhigansk and Poronaisk.

In Kamchatka, a long growth in snow cover occurred throughout the winter season and the largest contribution to the snow height increase was made by substantial precipitation in March.

Snow water supply is another important characteristic. Observations of this characteristic are made under the programme of route snow surveys. Figure 17 shows snow water supply characteristics obtained from route snow surveys in the field (left) and in the forest (right). Regular route snow survey observations have been available since 1966. Therefore, long-term means of snow water supply for the period 1971-2000 are used as normals.

Figure 17. Snow water supplies from route snow surveys in the field (left) and in the forest (right)
а) Linear trend coefficients (mm/ decade; 1- to 5-percent significance level) in the snow water supply series for the winter 1966-2009;
b) Snow water supply anomalies (mm) in the winter 2008-2009 гг. (as against mean long-term values for the period 1971-2000).

According to route snow surveys in the field, tendencies for the changes in maximum winter snow water supplies in the past decades (1976-2010) coincide in many respects with tendencies for the changes in maximum winter snow heights. The increase is recorded in Western Siberia, Sakhalin and eastern European Russia (Fig.17а). Snow water supply decreases in western and southeastern European Russia and in the south of Western Siberia. According to route snow surveys in the forest, maximum winter snow water supplies decrease over most of European Russia and Western Siberia. Areas of positive linear trend coefficients are located in Eastern Siberia, northeastern Yakutia, Maritime Territory and Sakhalin.

Space distribution of snow water supply anomalies in the winter 2009-2010 coincides with the distribution of maximum winter snow height anomalies (Fig.17b). Positive snow water supply anomalies are recorded over much of European Russia, in southern Siberia and the southern Far East. In northwestern European Russia, the higher snow water supply values as against long-term means are due to substantial precipitation throughout the winter season. A vast zone of negative anomalies formed in northern and central Siberia. Snow water supply below long-term mean was also recorded in eastern European Russia.