Journal of Natural Disaster Science, Volume 31, Number 1, 2009, pp23-33

Recent Tendency of Mongolian Wildland Fire Incidence:
Analysis Using MODIS Hotspot and Weather Data
Murad Ahmed FARUKH*
Hiroshi HAYASAKA**
Odbayar MISHIGDORJ****Graduate School of Engineering, Hokkaido University, Kita-ku, N13 W8, Sapporo, Hokkaido 060-8628, Japan
Corresponding author: E-mail: maf_bau@yahoo.com; Facsimile: +81-11-706-6784**Graduate School of Engineering, Hokkaido University, Kita-ku, N13 W8, Sapporo, Hokkaido 060-8628, Japan***National Remote Sensing Center, Ministry for Nature and the Environment, Mongolia(Received for 25 Jun., 2008 and in revised from 17 Oct., 2008)
ABSTRACT
Mongolian wildland fires are a human-made disaster like some floods as shown by
these fire disasters becoming prominent around the 1990s due to opening up of the country.
The worst fire losses were in 1996, costing 192% of the GDP. This study reports recent
wildland fire incidence and climate relationships analyzed using NASA-MODIS hotspots(fires) and NOAA weather data. Fires are categorized into spring fires from April to Junein pasture areas, summer fires in July and August in forested areas, and autumn fires in
September and October in forested areas. Fires frequently occur after 10 rainless days,
while several millimeters of daily precipitation reduces the extent of fire. A weeklong
effective humidity of below 35% coincided with large fires. In the seven most recent years,
average temperatures increased by 3.4ºC in July and summer precipitation decreased byabout 50%, while the fire disaster intensity increased. The fires were mainly human caused,began at relatively low altitudes after the snow melt in April, and moved to higher-altitude
areas in May. From 2001 to 2007, around 30% of forest areas were affected; the Selenge,
Khentii, and Dornod provinces were the most fire prone. The severest spring and autumn
fires occurred on May 5, 2007 and September 22, 2002.
Keyword: Wildland fire, Global warming, Boreal forest, MODIS, Effective humidity
Short running title: Mongolian Wildland Fires
78,308 km2 of burnt pastures in a total of 417 fires.
During the 1996 to 1998 period, 29 people died, 82
were injured, 11,700 head of livestock perished, and1,066 communication facilities and 263,000 km2 ofpasture and forest areas were burned. The country
suffered large-scale fires in 1968-1969, 1977-1978,
1985-1987, 1991-1992, 1996-1998, and 2000-2002(Enkthur et al., 2005). Mongolia is vulnerable to climatic extremes and variability with severe droughts
frequently occurring in the summer months. In Mon-

1. INTRODUCTION
Wildland fires play a major role in determining
the spatial and temporal dynamics of forest ecosystems as they degrade forests. In Mongolia, about 95%
of steppe and forest fires are human caused (IFFN26, 2002) or anthropogenic. Fire-susceptible larchand pine forests growing on permafrost are vulnerable
to fires. In 1996, the worst forest and steppe fires occurred, with a burnt forest area of 23,636 km2 and23

MURAD AHMED FARUKH, H. HAYASAKA, ODBAYAR MISHIGDORJ

golia, extremely hot weather with record temperaturesof up to 60ºC at ground level badly affect hay andcrop production and have caused serious forest fires(Nandintsetseg et al., 2007). To implement measures
to protect forests from wildland fires, the characteristics of fires and their relation to weather parametersneed to be intensively investigated. There are several
papers describing various aspects of forest fires in different areas of the world. Hayasaka et al. (2005) described Alaskan large-scale forest fires in 2004 basedon weather components. Under climate conditions
with higher air temperatures and lower precipitation,
large forest fires occurred near Yakustk, Sakha in2002 (Hayasaka, 2003). However, it is very difficult
to find scientific research papers related to forest fires
in Mongolia. There are a few reports focusing on
weather condition and fire statistics reports (Enkthur
et al., 2005). Jacoby et al. (2003) described the temperature and precipitation conditions of Mongolia, andextreme climatic events in Mongolia are explained by
Batima et al. (2005). They clarify which weather components are responsible for recent Mongolian climate
warming but do not refer to wildland fires.
In this paper, we discuss the recent wildland fireconditions in Mongolia from various scientific pointsof view. Mongolian wildland fire history, recent wildland fire detection, causes, tendency, and distribution
are thoroughly discussed in this paper considering
climatic conditions.

the help of Google Earth software.
2.2 Weather data
This paper analyzes daily weather data fromJanuary 2001 to November 2007 obtained from the
NCDC Climate Services Branch of the World Meteorological Organization (WMO, 2007). The reliabilityof historic weather data in recorded and published information of the climate of Mongolia is unfortunatelypoor, and some abnormal summertime temperature
data in the database were disregarded. The weather
components considered are temperature in degrees
centigrade, precipitation in millimeters, air pressure in hectopascals, relative humidity a percentage,wind speed in meters per second, and wind direction.
Weather maps by NACSIS (2007), the Electronic Library Service of the Meteorological Society of Japan,
were used and analyzed to elucidate the connection
between weather and fire. The wind direction andwind speed data on the Weather Underground website(http://www.wunderground.com/history/) is found to
be relatively reliable and thus used for comparison
with the NCDC weather data.
3. GENERAL INFORMATION ON MONGOLIA
3.1 Weather
Historical weather records of Mongolia for the
Ulaanbaatar weather station are obtained from a dataencyclopedia named Rika-nen-pyo (Chronological
Scientific Tables). Figure 1 shows air temperaturesand precipitation in Ulaanbaatar. The figure showsthat temperatures are increasing considerably in winter. The mean temperature was -3.2ºC from 1891 to1902, and from 1971 to 1999, this value was -1.3ºC.
The annual mean air temperature for Ulaanbaatar has
increased significantly, by about 1.9ºC. In Ulaanbaatar, the mean air temperature at present in spring(April-June) is 7.7ºC, in summer (July-August), it
is 15.2ºC, and in autumn (September-October), it is
4.2ºC. The maximum air temperature has increased
by about 1.8ºC in the last three and half decades.
The situation clearly indicates the influence of global
warming as the temperature changes in Mongolia
are in agreement with worldwide twentieth-century
warming (Jacoby et al., 2003). In northern Mongolia,
mean temperatures have increased by 1.8ºC in the last
four decades (Nandintsetseg and Goulden, 2003).

2. METHODOLOGY
2.1 Fire (MODIS hotspot) data
MODIS hotspot data are obtained using softwaredeveloped by NASA based on the NASA ATBDMOD14 algorithm (Giglio and Descloitres, 2003)
where, MODIS geolocation data are used as input.
The active fire products of MODIS obtained fromWeb Fire Mapper (Justice et al., 2002) clearly show
and describe hotspot occurrence. Daily hotspot datafrom January 2001 to October 2007 were visualized
and analyzed to determine fire occurrence tendencies.
Hotspot data and images acquired by Terra and Aqua
(NASA: MODIS Rapid Response System) were analyzed comprehensively to clarify fire trends. ArcView
3.3 software was used to position the hotspots overa digital map of Mongolia. Plotting of hotspots overaccurate coordinates of Mongolia was performed with
24

RECENT TENDENCY OF MONGOLIAN WILDLAND FIRE INCIDENCE

P:1891-1902

90

Total Precip. (1891-1902): 209 mm
Total precip. (1971-2000): 282 mm
Mean temp. (1891-1902): -3.2˚C
Mean temp. (1971-1999): -1.3˚C

Ulaanbaatar

P:1971-2000

80

T:1971-1999

15
10
5

T:1891-1902

0

60

Dec

Nov

Jul

Oct

-30
Sep

-25

0
Aug

-20

10

Jun

-15

20

May

30

Apr

-10

Mar

-5

40

Feb

50

Jan

Precipitation (mm)7020Temperature (ºC)

100

Month

Fig. 1. Air temperature and precipitation in Ulaanbaatar, Mongolia.

Fig. 2. Vegetation zones in Mongolia.

[Weather data source: Rika-nen-pyo (Chronological Scientific Tables), Maruzen]

area and the eastern steppe zone are fire-affected areasthat comprise about one fifth (20%) of the total landarea. In this area, the high fire incidence is largely due
to the dominant light-needled conifers adjacent to the
steppe areas. There is boreal forest vegetation in thenorth in the Selenge, Khentii, and Bulgan provinces(locally called AIMAG), and the areas south of the
Dornod and Sukhbaatar provinces are characterized
by steppe vegetation.

Figure 1 also depicts precipitation data of thepast and present in Mongolia. In recent years, theaverage value of winter (November-February) and autumn precipitation has increased. Summer precipitation has also increased, but the precipitation peak has
shifted from July to August.
3.2 Landscape
Forest and grassland (steppe or pasture and prairie) areas of Mongolia comprise 8.1% and 70% of thetotal land area of 1,565,000 km2 (IFFN-26, 2002). It is
assumed that most of today’s steppe vegetation is on
former forest areas that have been degraded by fire.
Between 1974 and 2000, about 9.1% (16,000 km2) of
the forest cover was lost. The southern edge of boreal
forest and permafrost overlap in the northern partof the country. The northern forested high mountain
ranges feature alternating dry areas and lake-coveredbasins. The pastureland in the transitional zone between the boreal forest and steppe is the so-called
forest-steppe zone.

3.4 Fire history
The history of fires in Mongolia from 1963 to2000 is shown in Figure 3 where, the dark bars, andthe diagonal line bars show the burnt areas of forestand pasture, respectively, and the line graph shows
the number of fires. Annual data from 1963 to 1999
were obtained from the International Forest Fire
News (IFFN-26, 2002) country archive of Mongolia.
In the 1960s, the mean annual burnt forest and pastureareas were 1,169 km2 and 3,532 km2, respectively,
with 64 fires recorded. Burnt pasture areas increased
considerably in the 1970s and 1980s, and the high-100,000

450
Data Source: International
Forest Fire NewsCountry archive
IFFN-26

Burnt area (km2)

80,000

400
350
300

No. of f ires
60,000Burnt pasture

250
200

Burnt
f orest40,000

Number of f ires

3.3 Vegetation
Figure 2 shows the vegetation zones of Mongolia as well as spring fires in the steppe area and summer and autumn fires in the forest area. The major
tree species in the forest is larch (Enkhsaikhan, 1998).
The predominating forest species are larch (Larixsibirica), pine (Pinus sylvestris), birch (Betula platyphylla), cedar (Pinus sibirica), spruce (Picea spp.),and saxaul (Haloxylon ammodendron).
The forest-steppe in Mongolia extends over
375,000 km2 (Wallis de Vries et al., 1996). The northern larch and pine forests in the easternmost forest

150
100

20,000

50
0

1999

1996

1993

1990

1987

1984

1981

1978

1975

1972

1969

1966

1963

0

Year

Fig. 3. Details of the fire history of Mongolia(1963 - 2000).
[Data Source: International Forest Fire News, Country archive of Mongolia, IFFN-26, 2002]

25

MURAD AHMED FARUKH, H. HAYASAKA, ODBAYAR MISHIGDORJ

sents monthly average precipitation and temperature
values from 1971 to 2000; values other than hotspots
in Table 1 show departures from average values forthe precipitation (∆P) and temperature (∆T).
There are numerous large precipitation ∆P values in Table 1. The low precipitation in the summer
months of July and August is especially remarkable,
and this situation is most directly related to the forest
fire incidence in Mongolia. The highest ∆P value was
60 mm for July and August of 2002, which is equivalent to precipitation reductions of -86% and -75%, respectively. The total precipitation in July and Augustof 2002 was 30 mm (20% of the average), and thisaffected the fire situation directly. Table 1 shows theaverage ∆P for July and August to be 30 mm (-43%)
and 44 mm (-56%), respectively, suggesting about a
50% reduction in precipitation in the summer months.
The maximum ∆P of 63 mm (-78%) was in August
2004, followed by 42 mm (-60%) in July. Similarvalues are also shown for July and August of 2001,
2003, 2005, and 2007. The spring fire peak occurs in
May (29% of all spring fires, see Table 2) though thepositive ∆P is somewhat high in May 2001 and May
2003. In both cases, there were significant amounts
of precipitation (total precipitation of 36 mm in May
2001 and 52 mm in May 2003) after the appearanceof the fire peaks. In June 2004, total precipitation
was 3 mm and 82 mm before and after fire peaks.
Therefore, Table 1 suggests that recent summertime(July and August) precipitation is greatly decreasing
in Mongolia and that these two months of relative

est number of fires here was 289 in 1977 with 26,727
km2 of burnt pasture area. In the 1990s, the fire hazard reached the highest level so far. The largest fire
episodes in 1996 affected 101,944 km2 and in 1997,
there was 100,010 km2 of burnt area, a five-fold increase compared with the burnt areas of the previous
decade (see Fig. 3).
The northern forest areas of Khovsgol, Bulgan,
Selenge, Khentii, and Dornod and the pasture areasof Dornod and Sukhbaatar were largely burnt in thesefire episodes. Combining the burnt areas of forest andpasture, the third and fourth-largest fires occurred in1991 and 1998, respectively. The mean annual number of fires was 130 up to 1999, with the incidenceof fires increasing decade by decade probably due toongoing changes in climatic patterns; steppe and forest fires are directly or indirectly related to the recent
warming climate (Nandintsetseg et al., 2007) andthere has been a major influence on pasture conditions. Recent large-scale fires have changed the forestfrom a sink to a source of carbon in both tropical andboreal forests due to increases in the incidence of fires
and worsening global warming conditions (Hayasaka,2006).
4. RESULTS AND DISCUSSION
4.1 Recent trends in weather conditions
Precipitation, air temperatures, and fires(hotspots: March to October) from 2001 to 2007 areshown in Table 1. The bottom line in Table 1 repre-

Table 1. Recent changes in precipitation and air temperature in Mongolia.
Year

No. ofHotspots(Mar.-Oct.) Mar∆P (Precipitation) mm∆T (Temperature) ºC

Apr May

Jun

Jul

Aug

Sep

Oct

Mar

Apr May

Jun

Jul

Aug

Sep

Oct

26

2001

1179

1

16

*(4+36)

-10

-58

-30

-15

-7

1

1

0

3

2

2

2

1

2002

7295

3

3

37

5

-60

-60

-18

2

3

0

1

4

5

4

1

-3

2003

2429

-2

-8

*(0+52)

38

-28

-2

-58

8

-7

0

2

0

2

2

-1

1

0

2004

3554

3

4

6

*(3+82)

35

-42

-63

1

-7

-2

4

1

4

3

2

2

0

2005

2886

1

0

-1

-25

-26

-37

-9

-9

-1

1

0

3

5

3

1

2

2006

4409

0

-4

57

-22

15

-54

-17

0

2

-2

-1

2

2

3

2

1

2007

7598

8

-5

5

-26

-36

-9

-33

-8

-2

2

3

5

5

4

4

-1

2.0
3.3

0.9 24.0 -10.1 -29.9 -44.4 -11.9 -5.1
10.0 14.0 49.5 69.5 79.9 33.5 9.9

0.1
-9.0

1.1
0.9

0.6
9.4

3.3 3.4 2.4
14.4 16.9 15.1

1.9
8.3

0.0
-0.3

Average departure
Average (1971-2000)∆P and ∆T show departures from average precipitation and average temperatures, respectively. Values in bold font and solid
rectangles represent very large departure values and months with the highest fire incidences, respectively.
* Precipitation before and after fires in May 2001, May 2003, and June 2004.
[Calculations were performed based on NCDC weather data from Ulaanbaatar weather station, Mongolia.]

26

RECENT TENDENCY OF MONGOLIAN WILDLAND FIRE INCIDENCE

Table 2. Monthly hotspot incidence in Mongolia (2001 - 2007).
Year
Monthly total
Month
(%)
2001
2002
2003
2004
2005
2006
2007
Mar.
3
3
10
4
14
28
17
79(1%)
Apr.
241
146
356
199
234
1790
322
3288(11%)
May
598
103
1314
203
618
1740
4035
8611(29%)
Jun.
117
62
231
2249
391
287
1424
4761(16%)
Jul.
8
290
123
333
106
35
942
1837(6%)
Aug.
42
1509
22
54
10
22
97
1756(6%)
Sep.
169
4983
18
197
140
179
468
6154(21%)
Oct.
1
199
355
315
1373
328
293
2864(10%)
Total
1179
7295
2429
3554
2886
4409
7598
29350
[The hotspot data source is the University of Maryland, NASA/GSFC, FIRMS, Maryland, USA.]drought affect the forest fire occurrences in autumn.
Temperature increases in June and July are noticeable and have a strong influence on fire incidence.
In recent years, there have been abnormal temperature
departure (∆T) values in June and July (see Table
1). A ∆T of 5ºC occurred in July of 2002, 2005, and2007; in June, the ∆T reached 4-5ºC. The average ∆T
for June and July was 3.3ºC and 3.4ºC. For 2007, therecords show the largest ∆T of 5ºC for June and July.
This situation suggests that the air temperature in
Mongolia has increased in the summer months, June
and July, at a rate of about 3ºC. Average ∆T values(Table 1) suggest a situation of climatic change inMongolia, with the highest hotspot peak in September
2002 following 4 to 5ºC temperature rises in the previous three months. This situation undoubtedly affects
the fire incidence in Mongolia, which has reported
rapid warming during the past several decades (IPCC,
1992; 1996). Very low precipitation or drought conditions in association with considerable temperaturerises resulted in the largest autumn fires in September
2002 and largest spring fires in May 2007.
Precipitation is an important factor in controlling fires because rain is the only natural extinguisherof fires, and precipitation also strongly influencessoil moisture as well as the availability of fuel for
fires. Miyanishi and Johnson (2002) reported thatsoil moisture in the organic matter containing layersof soil plays a critical role in smoldering combustionof deeper organic horizons. Figure 4 shows the relationship between precipitation and hotspot numbers
from 2002 to 2007, where the horizontal axis represents precipitation in millimeters and the vertical axis
represents the number of hotspots. Each data pointin the graph represents the value of hotspot numbers% ofhotspots
Spring57%
Summer12%
Autumn31%
100%

and the corresponding amount of precipitation in a
one-day period. A period of 20 days was taken into
consideration for precipitation and hotspot occurrence
and is designated as DN (Day Number) in the figure.
Figure 4 clearly illustrates that the maximum number

400
300

Northern forested area

200

Northern
forested
area
Precipitationand hotspot
from DNand
263-282,
2002
Precipitation
hotspot
from DN 263-282, 2002

100
0
300
200

North-eastern steppe area

North-eastern
steppePrecipitation
and area
hotspot
from DN
133-152,
2003
Precipitation
andhotspot
from DN 133-152, 2003

100
0Easternmost steppe area

Number of hotspots

300
200

Easternmost
steppearea
Precipitationand hotspot
Precipitation
andhotspot
from DN
162-181,
2004
from DN 162-181, 2004

100
0Easternmost forested area

300
200

Easternmost
forested
area
Precipiotationand hotspot
from DN
302-321,2005
Precipitation
andhotspot
from DN 302-321, 2005

100
0Eastern steppe area

Eastern
steppe area
Precipitationand hotpsot
fromand
DN 111-130,
2006
Precipitation
hotspot
from DN 111-130, 2006

300
200
100
0
300

North-eastern steppe area

200

Precipitation
and area
hotspot
North-eastern
steppefrom DN
122-141,2007
Precipitation
andhotspot
from DN 122-141, 2007

100
0

0 1 2 3 4 5 6 7 8 9 10 11 12 13

Precipitation (mm)Fig. 4. Precipitation versus hotspot numbers
2002 - 2007.

27

MURAD AHMED FARUKH, H. HAYASAKA, ODBAYAR MISHIGDORJ

from 1995 to 1999 (IFFN-26, 2002). But to investigate the fire situation precisely for a country like
Mongolia, it is useful to rely on satellite data otherthan those of official data records.
Figure 6 illustrates forest fires captured by the
Terra satellite in Zavkhan province on September 22,
2002. The location of the fire area is the south of thesubdivisions (locally termed SUM) Tosontsengel and
Ikh-Uul. This fire area is about 138 km northeast of
the provincial capital Ulaistai. The area is characterized by dense forest on the northern slopes of highmountains with elevations of about 2500 m.
An approximate estimate of burnt areas from thenumber of hotspots has been calculated for the above
fire area. Based on the calculations of hotspot occurrences in 2002, the estimated total burnt area is twice
the burnt area of the fire reports, suggesting large
disparities between fire reports and satellite data for2002 and 2003. This implies that the fire data from
the Mongolian Remote Sensing Center may containhuman error or that fire detection by satellite was not
ideal for 2002 and 2003.
From 2001 to 2007, the monthly hotspots detected by MODIS are presented in Table 2. The percentage of monthly and fire season hotspot incidence isalso shown in Table 2. Based on seasonal hotspot occurrence, spring, summer, and autumn fires compriseabout 57%, 12%, and 31% of the total number offires. The largest number of hotspots was 8,611 (29%)
in May, the second-highest number of hotspots was
6,154 (21%) in September, and the third highest was
4,761 (16%) in June. The number of summer firesof hotspots was found under zero-precipitation conditions, and this situation is common in the case of
2004, 2005, 2006, and 2007. Moreover, an increase in
the amount of precipitation decreases the number of
hotspots greatly. We may say that several millimetersof precipitation is effective in suppressing hotspots or
fires (see Fig. 4).
4.2 Recent fires
4.2.1 Recent fire detection
Figure 5 shows areas burnt by fires obtained
from satellite data and official data records for 2001 to
2007. Burnt areas at hotspots were estimated assuming that one hotspot is equal to 1 km2 and that there
is no overlap among hotspots. Annual burnt area datafrom official records for 2001 to 2007 were collectedfrom the National Remote Sensing Center (NRSC),
Mongolia, and data on burnt forest and pastures
showed the highest values in 2007 with values of 9,081
km2 and 21,400 km2. The fire history for 1963~2000
differs from the recent 2001~2007 data and shows adifferent pattern. Recent Mongolian satellite official
data records are inadequate and unreliable, and basedon MODIS Aqua and Terra images, satellite data aresometimes unable to detect pasture fires well underthick cloud layers and dense smoke as occurred in
2003. There is also the possibility of data overlap,
which could have occurred in 2002. Additionally, satellite remote sensing is not used systematically to assess the extent and impact of fires (FAO, 2006). From1996 to 1998, about 788 fires were detected primarily
by satellite, helping to limit destruction considerably.
The accuracy of detected fire hotspots (detection rate)is estimated to be 76.9% of the total number of fires

Burnt area f rom f ire report (km2)
Estimated burnt area f rom hotspots

25,00020,000

Data Source:
Satellite data (line) - NASA MODIS
Oﬃcial data (bar) - NRSC, Mongolia
Burnt pasture

15,00010,000Burnt forest
Satellite data
5,000

0
2001

2002

2003

2004
Year

2005

2006

2007

Fig. 5. Satellite data and fire report data on burnt areas
2001 - 2007.
Fig. 6. Forest fires in Zavkhan province recorded
by Terra on September 22, 2002.

[Data source: Satellite data – NASA MODIS and official record
for burnt area – National Remote Sensing Center, Mongolia]

28

RECENT TENDENCY OF MONGOLIAN WILDLAND FIRE INCIDENCE

fire was on May 5, 2007 with 630 hotspots. Most of
the fire peaks appear within two to five days of thestart of the fire, suggesting that fires in Mongolia
have a strong relationship with climatic conditions.
In recent years, pasture fires occurred every spring
except in 2002. Summer fires in July and August andautumn fires in September and October occurred inboth forest and pasture areas in 2002, 2003, 2005,

is small because summer has the highest seasonal
precipitation. Therefore, May and September can be
regarded as the most fire-prone months in spring andautumn respectively in Mongolia.
4.2.2 Large fires
Figure 7 illustrates the distribution of hotspots(fires) in the latest seven years (2001-2007) acrossMongolia. The recent fire distribution in Figure 7
clearly shows that the majority of fires occurred in thenorthern and eastern forest and steppe regions. The
northern forested high mountains (average altitude ofabout 1500 m) and the eastern steppe (average altitude of about 800 m) areas are affected by fires almost
every year. Fires in Selenge, Khentii, and Dornod occurred every year. There were fires in Bulgan in 2002,
2003, 2005, and 2007, and in Sukhbaatar in 2004,
2005, and 2006. From the distribution of hotspots andmeasurements utilizing Google Earth software, it canbe estimated that about 30% (52,500 km2 of 175,000
km2) of the total forest area was affected by fires. The
pastureland of the forest-steppe zone is severely prone
to fires. The western mixed forest area and southernsemi-deserts and deserts can be regarded as fire-freeareas.
Figure 8 shows the fire incidence using daily
hotspot data from March 2001 to October 2007.
Figure 8 also has daily data on precipitation and airpressure. The day number in Figure 8 is by the Julian
Day calendar (day number counted from January 1st).
Mongolian fires were classified into three categories:
spring fires from April to June, summer fires in Julyand August, and autumn fires in September and October. Analysis of the hotspot data yields a distinct autumn fire peak in forested areas with 665 hotspots on
September 22, 2002 (see Fig. 8). The severest spring

Fig. 8. Fire occurrence tendency using hotspots.
(Precipitation, bars from top of figures; hotspots, bars frombottom of figures; air pressure shown by line graphs)

Fig. 7. Hotpot (fire) distribution in forest and steppeareas of Mongolia (2001 - 2007).

[Weather data source: NCDC, Ulaanbaatar weather station,
Mongolia]

29

MURAD AHMED FARUKH, H. HAYASAKA, ODBAYAR MISHIGDORJ

Fig. 9. Location of the most recent four largest fires in Mongolia.
[HS: Number of hotspots in a fire. The numbers in parentheses are the ratios of all hotspots in this month.]and 2007 (Fig. 8). Figure 9 illustrates the locations
and percentage of hotspots for the four largest fires in
Mongolia. The recent two largest autumn fires werein September 2002 and October 2005. About 23% offires (1147 hotspots) were in the forest areas of Zavkhan province in September 2002, while 49% fires(674 hotspots) were detected in the easternmost forest areas of Dornod province in October 2005. There
were spring fires in Khentii and south Dornod provinces in May 2007 and June 2004, respectively.
About 37% of fires (1501 hotspots) in Khentii
and 45% fires (1016 hotspots) in Dornod were in
steppe vegetation. From the location of the hotspots,
the forest and steppe areas of Selenge, Khentii, andDornod provinces are the most fire prone in Mongolia. A notable feature of Mongolian fires is that the appearance of the largest fires occurs following several
rainless days. Fires frequently occur when precipitation is zero or very low. All the fire peaks in recent
years appear after droughts or 10 to 13 rainless days,
and Figure 10 shows the top four fires among thosethat followed rainless days. The flat, unchanging, accumulated precipitation indicates drought because
the increments in accumulated precipitation is nearzero. However, summer and autumn fires are greatly
influenced by rainless days or drought conditions aswell as by the increased temperature. In recent years,
the largest autumn fire (September 22, 2002) and thelargest spring fire (May 5, 2007) incidence occurredunder high-temperature and severe drought conditions. Overall, about two weeks of drought or days
without rain could trigger devastating fires in Mongolia. Subsequently, reductions in effective humidity as
well as a low moisture content of the vegetable matteras fuel and an ambient micro-environment enhance
any fires occurring at this time. Frequent spring fires

Fig. 10. Accumulated precipitation plotted withhotspot numbers(March - October 2002, 2004, 2005, and 2007).
[Weather data source: NCDC, Ulaanbaatar weather station,
Mongolia]

every year (except 2002) occur after very low precipitation from November to March. Summer fires in Julyand August would not occur because the relatively
large monthly precipitation of more than 75 mm prior
30

RECENT TENDENCY OF MONGOLIAN WILDLAND FIRE INCIDENCE

to July would suppress them.
Severe summer and autumn fires would occur
under drought conditions as happened in 2002, 2004,
and 2007. In 2002, fires started in mid July and lasted
until the end of September, with a total number of
hotspots of 7,295. The highest number of hotspots(7,598) was in 2007 with prolonged fires from late
April to early August. The highest number of hotspots
in autumn was 665 occurring on September 22, 2002
after a cold front had passed on September 16 and 17
after 40 days of drought (August to September) conditions.
4.2.3 Fire propagation
There is a rapid air temperature rise of about
10ºC per month in spring (Fig. 1) especially fromMarch (-9˚C) to May (9.4˚C), and the average airtemperature rises above freezing in April resulting insnow melting. The occurrence of spring fires in April
and May could be closely related to snow melting because vegetation in pasture areas is exposed to air justafter the snow melting and thus becomes good fuel for
fires. Flammable long grass fuels dry more easily andearlier than those of forest stands. Northerly winds(3~5 m/s) accelerate fire phenomena in April, while
fuel in mixed forest and pasture areas take more time
to dry and become flammable. Fires ignited at low
altitudes start to spread to higher altitudes and subsequently, the forest areas are ignited slightly later thanthe pasture areas. Figure 11 shows the propagation offires from relatively low- to relatively high-altitude
areas in spring; fires start comparatively late in forest
areas, namely in May. Each data point represents an

independent fire that was found to ignite in the steppearea in early spring and with the advancement of time,fires gradually occurred in the forest area. To obtainvegetation area information, Google Earth software isused. Each fire point was checked for steppe, foreststeppe, and forest through Google Earth images. The
vegetation zones are also clearly shown in Figure
2. However, fires tend to start after snow melting in
April (0.9ºC) and end around the start of snowfall in
October (-3ºC); overall, the dried fuels of pasture areas ignite earlier than those of mountainous forest andpasture zones and consequently, fires spread towards
higher altitudes.
Steppe (pasture) fires occur regularly in the relatively lower eastern part of Mongolia. Fires in loweraltitude (800 m) pasture areas tend to start from April
when the temperature rises above 0ºC, while fires inhigher-altitude (about 1500 m) forests and pastureareas start from May (Fig. 11) when the average temperature rises above 9ºC. In winter, vegetable matterat low altitudes subject to an absence of precipitation promotes the starting of fires in April. The highaltitude mountainous regions are cooler than the lowaltitude pasture regions and the average altitude in the
mid-sized mountains reaches 1500-1600 m while themean altitude of pastures or valleys is 800-900 m. In
spring, low-altitude pasture areas of about 700 meters
are affected by fires; in April, fires occur here especially on southern and western slopes.
4.2.4 Effective humidity
Effective humidity can be used as an indicatorof fire-promoting conditions in Mongolia; many fire
phenomena have been explained using effective humidity. Humidity close to mountain barriers and awayfrom the ocean is typically low, and the effective humidity for peak fire weeks was calculated to evaluate
the moisture content that was directly related to fire
phenomena. The results are presented in Table 3. The
effective humidity for a peak fire week and the corresponding month was calculated using Equation (1),He = (1-r) (H0 + rH1 + r2H2 +…) ............... (1)where He = effective humidity; r = a constant(here, 0.7 is used); H0 = humidity of the current day;
H1 = humidity of the previous day; H2 = humidity twodays before; and so on.
Table 3 describes the effective humidity andFig. 11. Occurrence of spring fires, April to May, by
longitude versus latitude and altitude.
31

MURAD AHMED FARUKH, H. HAYASAKA, ODBAYAR MISHIGDORJ

Table 3. Effective humidity and precipitation in peak fire weeks.

Year
2001
2002
2003
2004
2005
2006
2007

Peak
hotspot
number160 (DN 132)665 (DN 265)
220 (DN 125)423 (DN 163)455 (DN 298)
336 (DN 113)630 (DN 125)

Effective Humidity(He7), %(Peak fire week)
26 (DN 126-132)
32 (DN 259-265)
22 (DN 119-125)
22 (DN 157-163)
43 (DN 292-298)
33 (DN 107-113)
21 (DN 119-125)

Effective Humidity(Hem), %(2001~2007)
37 (May)
58 (Sep.)
42 (May)
65 (Jun.)54 (Oct.)
36 (Apr.)
28 (May)

Precipitationmm(Peak fire week)
1.0 (DN 126-132)
0.0 (DN 259-265)
0.0 (DN 119-125)
0.0 (DN 157-163)
0.0 (DN 292-298)
1.0 (DN 107-113)
0.0 (DN 119-125)

Monthly avg.
precipitation(1971~2000)
14.0 mm33.5 mm14.0 mm49.5 mm
9.9 mm
10.0 mm14.0 mm

DN: day number by the Julian Day calendar
He7: effective humidity of peak fire weeks
Hem: effective humidity of peak fire months[Effective humidity was calculated based on weather information from Ulaanbaatar weather station, Mongolia.]

precipitation of peak fire weeks as well as the corresponding months. Table 3 shows that an effective
humidity below 35% for one week was a good indicator of big fires in Mongolia except in 2005. The effective humidity and precipitation was very low at thetime of a fire peak, and precipitation was 0 for all thefire peak weeks except in 2001 (1 mm) and 2006 (1mm). The prevailing condition of more than 10 rainless days affected effective humidity reduction in thepeak fire weeks and was one of the major factors that
resulted in large fires.

3. Autumn fires occurred mainly in forest areas underdrought conditions with more than 10 rainless daysin 2002, 2003, 2005, and 2007 when the effective
humidity decreased to below 35%. The largest autumn fires happened in September 2002 with 665
hotspots.
4. Wildland fires in Mongolia tend to start soon aftersnow melting and end around the time that snowfall
starts. Fires tend to start from low-altitude (about
800 m) pasture areas in April and gradually moveto relatively high-altitude (about 1500 m) forestand pasture areas in May.
5. In the last seven years, around 30% of Mongolian
forest areas have been affected by fires. The forestand steppe areas of Selenge, Khentii, and Dornod
provinces were the most fire prone. In recent years,
May and September were the months with the highest fire incidence.
6. Under global warming conditions, the years 2001
to 2007 have seen temperature increases of 3.4ºC
in July and summer with precipitation decreases ofabout 50% when compared to the last three decades(1971-2000).

5. CONCLUSIONS
Mongolian wildland fires and their relation toweather parameters were analyzed using MODIS
hotspot and weather data. The conclusions from thediscussion may be summarized as follows:
1. Wildland fire disasters in Mongolia were categorized into three kinds: spring fires in pasture areas,
summer fires, and autumn fires both in forest areas.
Low winter precipitation (monthly average <20mm) and an air temperature rise of about 10ºC fromMarch to May could trigger spring fires after snow
melting in April. Fires in pasture areas occurred every spring except 2002. Recently, the largest spring
fire happened in May 2007 with 630 hotspots.
2. Summer fires occurred in forest areas in Julyand August of 2002, 2004, and 2007 under longdrought conditions. But fires did not occur when
there was average, normal monthly precipitation(60-90 mm). Reductions in the extent of fires wereobserved with daily precipitation of at least 10 mm.

ACKNOWLEDGEMENTS
This research is supported by 1) a Grant-in-Aid for
Scientific Research, Japan Society for the Promotionof Science (JSPS) and 2) IARC/JAXA Arctic Research, Japan Aerospace Exploration Agency (JAXA).
The authors wish to thank Minnie Wong, Universityof Maryland, NASA/GSFC, Fire Information for Resource Management System, Maryland, USA for her
32

RECENT TENDENCY OF MONGOLIAN WILDLAND FIRE INCIDENCE

immense help and support in providing the fire data
sets and the many other people who have cooperated
and assisted in the study of forest fires.

(GFMC), pp.75-83.
IPCC, 1992. Climate change 1992. In The Supplementary
Report to the IPCC Scientific Assessment, Houghton
J. T., Callander B. A.,Varney S. K. (eds). Cambridge
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