Trends in Landfalling Tropical Cyclone–Induced ...

Trends in Landfalling Tropical Cyclone–Induced Precipitation over China

LU LIU

State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, China

YUQING WANG

International Pacific Research Center and Department of Atmospheric Sciences, School of Ocean and Earth Science and

Technology, University of Hawai‘i at M�anoa, Honolulu, Hawaii, and State Key Laboratory of Severe Weather, Chinese

Academy of Meteorological Sciences, Beijing, China

(Manuscript received 17 September 2019, in final form 6 January 2020)

ABSTRACT

In this study, trends in landfalling tropical cyclone (TC)-induced precipitation over China during 1980–2017

and the involved possible mechanisms are analyzed. Consistent with previous studies, it is found that the total

annual TC precipitation shows a distinct spatial distribution with a significant increasing trend in southeastern

China but a decreasing trend in southern China. This characteristic is found to be related to the increase in

both the annual TC precipitation frequency and the precipitation intensity per TC over southeastern China

but to the decrease in the annual TC precipitation frequency over southern China. A noticeable northward

shift of total landfalling TC-induced annual precipitation has been identified. It is shown that the precipitation

induced by strong TCs (STCs) significantly increased in southern China, whereas that induced by weak TCs

(WTCs) increased in southeastern China, with the latter dominating the northward shift of total landfalling

TC-induced precipitation over mainland China. The increasing trend of STC-induced precipitation in

southern China is found to be closely related to sufficient water vapor supply and the increase in average

duration and intensity of STCs after landfall. The increasing trend of WTC-induced precipitation in south-

eastern China is related to the northward shift of the average landfalling position ofWTCs and changes in the

environmental conditions that are more favorable for TC maintenance and precipitation.

1. Introduction

In response to global warming, precipitation has

shown significant regional dependent trends in the

globe. For more than half of the global land, an in-

creasing probability of intense precipitation events has

been documented by Groisman et al. (2005). A number

of weather systems can produce intensive precipitation

over land. The tropical cyclone (TC) is one of them. A

strong TC can produce torrential rainfall, leading to

floods and landslides after their landfall, which could

cause loss of life and severe damage of properties (Karl

and Easterling 1999; Zhang et al. 2009). Many studies

have shown an increasing trend in the destructiveness of

TCs due to the increasing trend in TC intensity and

lifetime from observations and climate model simula-

tions (Knutson and Tuleya 2004; Emanuel 2005;

Webster et al. 2005; Klotzbach 2006; Knutson et al. 2007;

Knutson et al. 2010; Park et al. 2014; Zhang et al. 2016;

Liu et al. 2020). Some studies have also shown that a

positive relationship exists between TC-induced rainfall

rate and TC intensity (Rodgers et al. 2001; Lonfat et al.

2004; Jiang 2012; Yu et al. 2017; M. Liu et al. 2019).

Other studies have reported significant contributions by

landfalling TCs to both the annual total precipitation

and extreme precipitation events in the United States

(Knight and Davis 2009; Shepherd et al. 2007; Kunkel

et al. 2010).

East Asia is one of the regions that suffer the most

severe damages from landfalling TCs. Several studies

have investigated the changes in spatial distribution and

variability of heavy rainfall induced by landfalling TCs

(Ren et al. 2006, 2007; Kim et al. 2006; Wu et al. 2007;

Ying 2011a,b; Zhang et al. 2013). Kim et al. (2006) found

an abrupt increase in heavy rainfall ($100mmday21)

related to TCs over the Korean peninsula during

August–September after the late 1970s. Ren et al. (2006,

2007) investigated TC precipitation over China andCorresponding author: Prof. Yuqing Wang, [email protected]

15 MARCH 2020 L IU AND WANG 2223

DOI: 10.1175/JCLI-D-19-0693.1

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found a significant downward trend in annual TC precip-

itation volume. Wu et al. (2007) studied the effect of TCs

on the total and extremeTCprecipitation inHainan Island

and found that both the number of TCs affecting Hainan

Island and the TC-induced precipitation and its contribu-

tion to the total precipitation decreased. However, both

the total amount of precipitation from the extreme rainfall

events and the number of extreme heavy precipitation

days affected by TCs increased significantly. On average,

both the number of extreme rainfall days and the precip-

itation amount induced by each TC also increased signifi-

cantly over Hainan Island. Based on a quantile regression

analysis of station data, Ying et al. (2011a) estimated the

TC-induced precipitation trends over mainland China and

found that although the landfalling TC frequency de-

creased over China, especially over South China, both

precipitation per TC and maximum hourly precipitation

induced by a TC increased significantly at stations in the

southeast coastal region. They also found that the location

of significant precipitation trends was related tomountains

and coastline in southeastern China. However, in another

study, Ying et al. (2011b) found that there were insignifi-

cant trends in extreme TC rainfall, such as the maximum

TC precipitation and the maximum hourly precipitation

over China during 1955–2006.

Zhang et al. (2013) further investigated the landfalling

TC precipitation features over mainland China and the

contribution of TC rainfall to changes in the precipita-

tion climate and the average rainfall per TC in the peak

TC season (July–September) during 1965–2009. They

found that the TC rainfall accounted for more than 10%

of the summer rainfall in South and Southeast China,

even more than 40% along the southeast coastline, and

the average rainfall per TC significantly increased in

Southeast China south of the Yangtze River and east of

1108E, which was consistent with the results of Ying

et al. (2011a). Zhang et al. (2013) also found that the

increasing trends in the average rainfall per TC were not

accompanied by enhanced TC intensity, nor did they

result from the slowdown of TC movement. Instead,

they argued that the increasing trends in the average

rainfall per TC in China might be associated with

changes in the East Asian summer monsoon activity

through modulating the moisture transport and other

synoptic forcing conditions.

Although previous studies have revealed many char-

acteristics of TC-induced precipitation over mainland

China, including the long-term increasing trend in the

average rainfall per TC, the detailed spatial patterns and

the contributions by different category TCs have not

been examined, and the involved factors responsible for

the observed trends have not been well understood. In

this study, we explore the spatial distribution of trend

in landfalling TC-induced precipitation over mainland

China and the involved possiblemechanisms. The rest of

the paper is organized as follows. Section 2 describes the

data and analysis methods. The temporal and spatial

characteristics of trends in the observed landfalling TC

precipitation over mainland China are presented in

section 3. Section 4 examines the trend characteristics of

TC precipitation in different categories and the involved

possible mechanisms. The primary findings are sum-

marized in the last section.

2. Data and analysis methods

The best-track TC dataset used in this study is ac-

quired from the Shanghai Typhoon Institute of China

Meteorological Administration (STI/CMA), which in-

cludes latitude and longitude of the TC center, TC in-

tensity in terms of the maximum sustained 10-m wind

speed, and central sea level pressure at 6-h intervals. TCs,

including tropical depressions (TD), that made landfall

over mainland China, including Hainan Island, during

1980–2017 are included in our analyses. In this study, the

STI/CMA best-track dataset is used as the primary TC

data because relatively more observational data were

available over mainland China when the postseason TC

analysis was conducted to generate the best-track TC

data. Actually, the annual postseason analysis of TC data

is performed by STI/CMA to reduce uncertainties and

improve the accuracy using all available data, including

station observations, ship weather reports, automatic

surface observations, synoptic charts, radiosonde data,

aircraft reconnaissance, satellite, coastal radar observa-

tions, and the real-time TC warming advice from various

agencies (Ying et al. 2014). Note that TCs whose centers

remained offshore and did not make landfall over main-

land China were not considered in our analyses.

The daily precipitation dataset used in this study is

obtained from STI/CMA as well. Previous studies sim-

ply defined the TC precipitation as precipitation within a

radius of 550 km from the center of a TC (Englehart and

Douglas 2001) or 500km from the center of a TC (Dare

et al. 2012; Zhang et al. 2019). In this study, the objective

synoptic analysis technique (OSAT) developed by Ren

et al. (2006, 2007) is adopted to isolate the TC-induced

rainfall from the total daily precipitation; a similar

technique was also used in Zhang et al. (2013). TC

precipitation can result from the TC eyewall and spiral

rainbands, or from the interactions between the TC

circulation and other local weather systems. TC rain-

bands are generally asymmetric about the TC center.

Therefore, the simple circle method is not good enough.

The OSAT method imitates the process by which a

weather forecaster manually analyzes a synoptic map.

2224 JOURNAL OF CL IMATE VOLUME 33


There are two primary steps: first, separating the daily

precipitation into several independent rainbands, and

second, according to the distance function between the

TC center and the distribution of the rainbands, dis-

tinguishing which rainbands are related to the TC. The

details of the method can be found in Ren et al. (2006,

2007). Note that because having too few stations with

precipitation is not representative, the only cases that

are considered in our analyses are those for which there

were more than 30 stations at which daily precipitation

was observed in a TC day. The TC precipitation is de-

termined when the TC’s rainbands are over mainland

China, including Hainan Island, even if the center of the

TC was still over the ocean but made landfall later.

The European Centre for Medium-Range Weather

Forecasts (ECMWF) interim reanalysis (ERA-Interim)

data at the horizontal resolution of 0.758 3 0.758 (Dee

et al. 2011) are used to examine changes in large-scale

environmental conditions responsible for the observed

changes in the precipitation characteristics of landfalling

TCs over mainland China. The sea surface temperature

(SST) data are obtained from NOAA’s Optimum

Interpolation Sea Surface temperature (OISST), which

provide a series of global analysis products including the

daily SST at the resolution of 0.258 3 0.258. The soil

moisture is obtained from the NOAA Gridded Climate

Dataset, which has a horizontal resolution of 0.58 3 0.58.

3. Characteristics of landfalling TC precipitation

Figure 1a shows the spatial distribution of the average

annual precipitation induced by landfalling TCs over

mainland China during 1980–2017. Consistent with pre-

vious studies (Ren et al. 2006; Zhang et al. 2013), large

TC precipitation is mainly located in the southern and

southeastern China, including Guangxi, Guangdong, and

Fujian provinces, and Hainan Island. The time series of

total annual TC precipitation over mainland China as a

whole presents a slightly decreasing linear trend (Fig. 1b),

which is consistent with the results of Ren et al. (2006),

who found that the total volume of landfalling TC pre-

cipitation over China was slightly decreasing. However,

the trend of the annual landfalling TC precipitation over

mainland China shows a distinct spatial distribution

(Fig. 1c). The annual TC precipitation increased signifi-

cantly over southeastern China and decreased notably

over southern China, including Hainan Island (Fig. 1c).

Comparing Figs. 1a and 1c, we can see that the maximum

increasing trend in the annual TC precipitation occurs in

the northern area and the maximum decreasing trend

occurs in the southern area of the large precipitation re-

gion, indicating a northward shift in landfalling TC-

induced precipitation over mainland China during the

study period. The frequency of landfalling TCs shows a

significant decreasing trend (Fig. 1d); that is, the number

of TCsmaking landfall overmainlandChina decreased in

recent decades. Further, we calculated the frequency

of landfalling TCs in the southern area and southeast-

ern area (with 248N as the dividing line; Figs. 1e and 1f).

The results show that the landfalling TC frequency in

the southeastern area was stable, while the frequency in

the southern area experienced a significant decreasing

trend during recent decades. Therefore, the decrease in

total landfalling TC frequency over mainland China was

contributed primarily by the decrease in frequency in the

southern area. This suggests that the total annual pre-

cipitation decrease could be primarily due to the signifi-

cant decrease in landfalling TCs over mainland China,

especially in southern China.

Figure 2 shows the time series and trend in the average

precipitation per landfalling TC. There is a significant

increasing linear trend of the average precipitation per

landfalling TC over mainland China as a whole (Fig. 2a)

with statistical significance over the 95% confidence

level. This means that the precipitation intensity per

landfalling TC increased significantly during 1980–2017,

especially in the southeastern coastal region over

mainland China (Fig. 2b). However, overHainan Island,

the precipitation per landfalling TC shows a significant

decreasing trend. We also analyzed the trend of the TC

precipitation per landfalling TC per day, which shows a

significant increasing trend over mainland China as a

whole as well (Fig. 3a). The trend also displays a spatial

distribution with the largest increasing trend in the

southeastern coastal area (Fig. 3b), which contributes to

the increase in the average precipitation per landfalling

TC in the region (Fig. 2b). The trend in annual TC

rainfall days (frequency) shows a clear transition near

248–258N—namely, an increasing trend over southeast-

ern China and a decreasing trend over southern China

(Fig. 3c). Therefore, both the annual precipitation fre-

quency and the average precipitation per TC per day

increased over southeastern China, leading to the large

increasing trend in total TC precipitation over south-

eastern China (Fig. 1c). The decreasing trend in the

frequency of landfalling TCs (Fig. 1d) offsets the in-

creasing trend of the average precipitation per TC per

day over southern China (Fig. 3a). This leads to the

decreasing trend in the total TC precipitation over

southern China as seen in Fig. 1c. Wu et al. (2005)

found a considerable decreasing trend of TCs in the

South China Sea, leading to fewer rainfall days of

landfalling TCs in the southern coastal area over main-

land China. In addition, the deceasing trends in both the

average precipitation per TC per day (Fig. 3b) and the

annual frequency of TC precipitation days (Fig. 3c) give



FIG. 1. (a) Spatial distribution of the landfalling TC-induced annual precipitation averaged during 1980–2017

over China (mmyr21). (b) Time series and trend of the landfalling TC-induced total annual precipitation averaged

over China during 1980–2017 (mmyr21). (c) Spatial distribution of trends in the landfalling TC-induced annual

precipitation over China during 1980–2017 (mmyr21). Also shown are time series and trend of the landfalling TC

frequency over (d) China mainland, (e) the southern area, and (f) the southeastern area during 1980–2017. The

dashed, solid, and blue curves in (b), (d), (e), and (f) indicate the raw data, 5-yr running mean, and the corre-

sponding linear trends, respectively. Regions with trends that are significant over 95% confidence level are shown

with dots in (c).



rise to a significant decrease in the total TC precipitation

over Hainan Island (Fig. 1c). This is consistent with the

results ofWu et al. (2007), who found that the number of

TCs impacting Hainan Island significantly decreased.

4. Characteristics of strong and weak TCprecipitation

We further classify landfalling TCs into strong TCs

(STCs; with sustained maximum wind speed$ 32m s21,

including typhoons, severe typhoons, and super-

typhoons) and weak TCs (WTCs; with sustained maxi-

mum wind speed , 32m s21, including tropical storms,

severe tropical storms, and tropical depressions) at

landfall. The TDs are included here because, on one

hand, TDs in the STI/CMA best-track dataset were, to

some extent, reliable based on the description of the

STI/CMA best-track data as mentioned in section 2; on

the other hand, the precipitation induced by TDs could

be very large when they interacted with some favor-

able weather systems. Thus, the precipitation induced

by TDs is also important. The spatial distributions of

precipitation induced by STCs andWTCs are shown in

Figs. 4a and 4b, respectively. Precipitation induced by

STCs is large in the southern coastal area, such as

Guangxi, Guangdong, and Hainan provinces (Fig. 4a),

and slightly south of the maximum in the total TC pre-

cipitation shown in Fig. 1a. Precipitation induced by

WTCs is generally large in the southern and southeastern

coastal area, including eastern Guangdong and Fujian

provinces (Fig. 4b) and is to the northeast of that induced

by STCs. Note that precipitation induced by WTCs is

generally weaker than that induced by STCs.

Since the spatial distributions of STC and WTC pre-

cipitation are different, it is interesting to examine the

spatial pattern of their respective trends in the study pe-

riod. Figure 5 presents the time series and the trends of

average precipitation per STC and average precipitation

perWTC, respectively, during 1980–2017. Consistent with

the average precipitation per TC (Fig. 2a), STC precipi-

tation also shows a significant increasing trend with sta-

tistical significance over 95% confidence level (Fig. 5a),

indicating that precipitation induced by a STC increased

in the study period. The trends in STC precipitation are

positive over mainland China but negative over Hainan

Island (Fig. 5b). The most significant increase in STC

precipitation occurs in the southern coastal area (mainly

inGuangdong andGuangxi provinces), namely the region

with the maximum rainfall per STC shown in Fig. 4a. This

indicates that the precipitation induced by STCs signifi-

cantly increased over mainland China, especially in the

southern coastal area, but decreased over Hainan Island.

The average precipitation per WTC shows no signifi-

cant trend over mainland China (Fig. 5c). This is pri-

marily due to the cancellation of the decreasing trend in

the southern coastal area and the increasing trend in the

southeastern coastal area of mainland China (Fig. 5d). It

is interesting to note that significant increasing trends

primarily occurred in Fujian and Zhejiang provinces,

north of the peak WTC precipitation (Fig. 4b). This

means that WTC-induced precipitation shifted north-

ward in the study period, resulting in an increase inWTC

FIG. 2. (a) Time series and trend of precipitation (mmyr21) per landfalling TC averaged over China during 1980–

2017. (b) Spatial distribution of trend in total precipitation (mmyr21) per landfalling TC over China during 1980–

2017. The dashed, solid, and blue curves in (a) indicate the raw data, the 5-yr running mean, and the corresponding

linear trend, respectively. Regions with trends that are significant over 95% confidence level are shown with dots

in (b).



precipitation in the southeastern coastal area and a de-

crease in the southern coastal area (Fig. 5d). This is in

sharp contrast to the STC-induced precipitation, which

shows that the maximum increasing trend almost in the

region coincided with peak STC precipitation. This in-

dicates that the northward shift of total landfalling TC

precipitation over mainland China (Fig. 1c) is mainly

contributed by the northward shift of WTC-induced

precipitation.

To understand the possible mechanisms responsible for

the overall increasing trend in STC precipitation, we ex-

amined the large-scale environmental conditions and their

corresponding trends. It is found that in addition to some

other favorable dynamic and thermodynamic conditions

(not shown), the atmospheric moisture supply seems to

play a key role in enhancing STC precipitation. Figures 6a

and 6b display the average water vapor and vapor flux

vertically integrated between 1000 and 700hPa and their

trends during 1980–2017. The southern coastal area of

mainland China, where large STC precipitation occurred

(Fig. 4a), is perennially covered by high low-level water

vapor content and large moisture flux convergence be-

tween the southwesterly flow with high moisture content

from theBay of Bengal and southeasterly flowwith plenty

of water vapor from the western North Pacific. The area is

very conducive to precipitation induced by STCs. The

water vapor in this area increased significantly in the study

period (Fig. 6b), which favored the increase in STC-

induced precipitation. In addition, an increasing trend in

divergence in the upper troposphere occurred in the

southern area and neighboring seas (Fig. 6c) and an in-

creasing trend in ascending motion (Fig. 6d) appeared at

FIG. 3. (a) Time series and trend of precipitation (mm yr21) per landfalling TC per day averaged over China

during 1980–2017. (b) Spatial distribution of trend in averaged precipitation (mm yr21) per landfalling TC per

day over China during 1980–2017. (c) Trends in TC precipitation frequency (TC precipitation; days yr21). The

dashed, solid, and blue curves in (a) indicate the raw data, the 5-yr running mean, and the corresponding linear

trend, respectively. Regions with trends that are significant over 95% confidence level are shown with dots in

(b) and (c).



500hPa. Both are conducive to the maintenance of TC

intensity and thus contribute to the decrease in overland

intensity weakening rate and the increase in mean over-

land duration of landfalling TCs (e.g., Park et al. 2011).

Meanwhile, both the landfall intensity (Fig. 6e) and du-

ration after landfall (Fig. 6f) of STCs increased noticeably,

with statistical significance over the 90% confidence level.

This is also conducive to increasing precipitation of STCs.

Previous studies have suggested that there was some re-

lationship between TC-induced rainfall rate and TC in-

tensity (Rodgers et al. 2001; Lonfat et al. 2004; Jiang 2012;

Yu et al. 2017;M. Liu et al. 2019). Yu et al. (2017) analyzed

the rainfall distribution in TCs making landfall over

mainland China and revealed that, on average, axisym-

metric rainfall was closely related toTC intensity. Stronger

TCs produce more averaged total rainfall, larger averaged

rain areas, and higher averaged rain rates. M. Liu et al.

(2019) also showed that TCs with high intensity tended to

produce high rainfall rates, especially toward the storm

center. Therefore, the sufficient water vapor supply and

the increase in both duration after landfall and the increase

in storm intensity at landfall are all responsible for the

increasing trend in STC precipitation in the southern

coastal area ofmainlandChina except overHainan Island.

The northward shift of WTC precipitation is mainly

due to the northward shift of mean landfalling location

of WTCs (Fig. 7a) and changes in favorable environ-

mental conditions, including surface conditions and

low-level vertical wind shear. The average landfalling

latitude ofWTCs shows a clear increasing trend (Fig. 7a)

with statistical significance over 90% confidence level.

The average landfalling latitude increased from about

228N to about 248N in the study period. In addition to

the northward shift of the average landfalling location,

the average intensity of landfalling WTCs also shows a

significant increasing trend in the study period (Fig. 7b).

Therefore, nomatterwhether theywereSTCsorWTCs, the

intensity of TCs at landfall over mainland China increased

significantly in recent decades. This increasing trend is

consistent with the significant warming trend in SST in the

coastal oceans near East Asia, particularly offshore of

mainland China (Fig. 7c). The near-surface air temperature

(Fig. 7d) and soil moisture (Fig. 7e) also show increasing

trends, particularly in the southeastern coastal area of

mainland China, providing more favorable thermodynamic

conditions to slowdown theweakeningofTCsafter landfall.

Previous studies have demonstrated that the soil moisture

and temperature are critical for TC maintenance and TC

precipitation over land (Tuleya and Kurihara 1978; Tuleya

et al. 1984; Tuleya 1994; Shen et al. 2002; Zhang et al. 2011;

L. Liu et al. 2019). As shown in Tuleya (1994), warm land

surface and high soil moisture are favorable for surface

enthalpy flux and thus may slow down the weakening of a

TC after landfall. Zhang et al. (2011) conducted several

sensitivity numerical experiments and found that both the

latent and sensible heat flux sustained the landfalling TCs

and maintained the spiral structure of rainbands.

In addition, the low-level vertical wind shear between

850 and 1000hPa shows a significant decreasing trend over

southeastern China (Fig. 7f), which provides a favorable

dynamical environmental condition conducive to TC in-

tensification and maintenance. Note that the deep-layer

vertical wind shear between 850 and 200hPa was also an-

alyzed and the results showed a decreasing trend to the

north of approximately 338N over mainland China, but the

trend in the region affected by landfalling TCs was not

statistically significant (figure not shown). Wang et al.

(2015) compared the correlation between TC intensity

change and vertical wind shear in various vertical layers

over the WNP. They found that the low-level shear

FIG. 4. Spatial distributions of the averaged annual precipitation (mmyr21) induced by (a) strong landfalling TCs

and (b) weak landfalling TCs over China during 1980–2017 (see text for more details).



between 850 (or 700) and 1000hPa wasmore destructive to

TCs than the commonly used deep-layer vertical wind

shear between 200 and 850hPa in the active typhoon sea-

son over the WNP. As a result, the combination of the

northward shift of the average landfalling position ofWTCs

and the more favorable dynamic and thermodynamic

conditions led to the increasingWTC-induced precipitation

in the southeastern coastal area of mainland China. This

also explains why the increasing trend of WTC precipita-

tion occurred north of the maximum WTC precipitation

and the dominant contribution by WTCs to the northward

shift of the total landfalling TC precipitation.

5. Conclusions

In this study, the daily TC precipitation dataset pro-

duced using the OSAT method (Ren et al. 2006, 2007)

and the best-track TC data obtained from STI/CMA are

used to explore the characteristics of the landfalling TC-

induced precipitation and the precipitation per land-

falling TC after landfall over China during 1980–2017.

The total annual TC precipitation over China as a whole

shows a decreasing trend primarily due to the decreasing

trend in the frequency of landfalling TCs during 1980–

2017, which is consistent with the results of Ren et al.

(2006). It is found that the total annual TC precipitation

shows a distinct spatial distribution with a significant

increasing trend in southeastern China but a decreasing

trend in southern China. This increasing to the north and

decreasing to the south are found to be related to the

increase in both the annual TC precipitation frequency

(annual average TC precipitation days) and the average

precipitation per TC per day, over southeastern China,

and to the decrease in the annual TC precipitation

FIG. 5. Time series and trends (mmyr21) of (a) strong TC–induced precipitation per TC and (c) weak TC–

induced precipitation per 1980–2017 averaged over China. Also shown are spatial distributions of trends (mmyr21)

of (b) STC precipitation per TC and (d) WTC precipitation per TC during 1980–2017. The dashed, solid, and blue

curves in (a) and (c) indicate the raw data, 5-yr running mean, and the corresponding linear trend, respectively.

Regions with trends that are significant over 95% confidence level are shown with dots in (b) and (d).



FIG. 6. Spatial distributions of (a) water vapor mixing ratio (shading; kg kg21) and vapor flux (vectors; kg

m kg21 s21) integrated from 1000 to 700 hPa, (b) trends in water vapor mixing ratio (shading; 1022 g kg21 yr21)

integrated from 1000 to 700 hPa, (c) upper-tropospheric divergence (1026 s21 yr21) at 200 hPa, and (d) vertical

motion at 500 hPa (Pa s21 yr21) during 1980–2017. Also shown are time series and trends of (e) averaged landfalling

intensity (m s21) and (f) duration after landfall (h) of STCs over China during 1980–2017. Regions with trends that

are significant over 90% confidence level are shown with dots in (b)–(d). The dashed, solid, and blue curves in

(e) and (f) indicate the raw data, the 5-yr running mean, and the corresponding linear trend, respectively.



FIG. 7. Time series and trends of (a) averaged landfalling latitude (8N) and (b) averaged landfalling intensity

(m s21) of WTCs over China during 1980–2017; spatial distributions of trends in (c) SST (K yr21), (d) air tem-

perature at 950 hPa (K yr21), (e) soil moisture (g kg21 yr21), and (f) vertical wind shear between 1000 and 850 hPa

(m s21 yr21) during 1980–2017. The dashed, solid, and blue curves in (a) and (b) indicate the raw data, the 5-yr

running mean, and the corresponding linear trend, respectively. Regions with trends that are significant over 90%

confidence level are shown with dots in (c)–(f).



frequency over southern China. In addition, a northward

shift in precipitation induced by landfalling TCs over

mainlandChina during recent decades has been identified.

Wehave further classified landfallingTCs into STCs and

WTCs to examine the differences in their precipitation

characteristics overmainlandChina. Some interesting new

findings include a noticeable northward shift in the average

landfalling location of WTCs and their associated precip-

itation, and an overall increasing trend in landfalling in-

tensity of both STCs and WTCs. It is shown that the

precipitation induced by STCs mainly concentrated in the

southern coastal area, slightly south of the maximum total

TCprecipitation, while the precipitation induced byWTCs

is mainly located in the southeastern coastal area over

mainland China, coinciding with the region of total TC

precipitation. Moreover, the STC precipitation shows an

increasing trend in most regions with large STC precipi-

tation over mainland China, especially in southern China.

The location of WTC-induced precipitation is east and

north of that of STC-induced precipitation and shows a

decreasing trend in the southern coastal area and an in-

creasing trend in the southeastern coastal area ofmainland

China. The most significant increasing trend occurred

north of the peak precipitation area induced by WTCs,

indicating a noticeable northward shift of the WTC-

induced precipitation in the study period. These results

demonstrate that the northward shift of total landfalling

TC precipitation is mainly contributed by the WTC pre-

cipitation primarily due to the northward shift of land-

falling location of WTCs.

Results from further analyses indicate that both the

intensity at landfall and the duration after landfall of

STCs increased noticeably. The region of STC pre-

cipitation is perennially located in the convergence

zone with high humidity in the lower troposphere.

Water vapor in the area increased significantly in the

study period, providing more water vapor supply for

TC intensification/maintenance and precipitation. In

contrast, WTCs show a significant increasing trend in

their average landfall latitude, leading to a northward

shift of WTC-induced precipitation. Moreover, the

increasing intensity of WTCs at landfall and the in-

creasing SST in the coastal oceans, the increase in land

surface soil moisture and temperature, and the de-

crease in low-level vertical wind shear over south-

eastern and eastern China provide more favorable

dynamic and thermodynamic conditions for WTCs to

survive longer after landfall, leading to the increase in

WTC precipitation.

Note that there was a remarkable decreasing trend

in landfallingTC-induced precipitation overHainan Island,

regardless of STCs or WTCs. We found that this is mainly

due to the significant decreasing trend in both the average

precipitation per TC and the annual frequency of TC

precipitation days over the past decades. Wu et al.

(2007) found that the number of TCs impacting Hainan

Island significantly decreased. Therefore, the decreas-

ing trend in landfalling induced precipitation over

Hainan Island is most likely a result of the decreasing

landfilling TC frequency. In addition, the decreasing

trend in the average precipitation per TC over Hainan

Island might be partially due to the decrease in TC

intensity at landfall and unfavorable environmental

conditions. For example, Wang et al. (2013) found that

due to the increase in the tropical Indian Ocean SST,

the lower-level anomalous anticyclone occurred over

South China Sea, which was unfavorable for TC genesis

and intensification over the South China Sea. This is ev-

ident by a trend of decreasing ascending motion in the

western South China Sea seen in Fig. 6d. Nevertheless,

because of the small area of the island and the sensitive

regional climate patterns over Hainan Island, a more

detailed analysis on the possible mechanism responsible

for the observed decreasing trend of landfalling TC-

induced precipitation over Hainan Island is reserved

for a future study.

Note that this study has focused on the analysis of long-

term trends in the observed precipitation induced by

landfalling TCs over mainland China based on data be-

tween 1980 and 2017. Because the limited period was an-

alyzed due to TC precipitation data quality, the northward

shift in TC precipitation could be partly contributed by the

decadal/interdecadal variations, which need further in-

vestigations. However, a recent study by Liu et al. (2020)

pointed out that the landfalling TC activity over mainland

China seems not to be significantly modulated by the

decadal/interdecadal variations because several in-

terdecadal shifts identified in other climate parameters

did not appear in landfalling TC characteristics over

mainland China. Nevertheless, results from this study im-

ply an increasing stress of potential landfalling TC-induced

precipitation in the populated southeastern coastal region

ofmainlandChina if the trend continues in the near future.

Acknowledgments. The authors thank three anony-

mous reviewers for helpful review comments and Dr.

Fumin Ren for providing the TC-induced precipitation

dataset over China in this study. This study has been

supported in part by the National Key R&D Program of

China under Grants 2017YFC1501602 and in part by

National Natural Science Foundation of China under

Grants 41675044, 41705027, 41730960, and 41875114.

The TC best-track data were obtained from STI/CMA

(http://tcdata.typhoon.org.cn). The ECMWF data used

in this study were obtained online (http://apps.ecmwf.int/

datasets/).The soil moisture dataset used in this study was



http://tcdata.typhoon.org.cn

http://apps.ecmwf.int/datasets/).The

http://apps.ecmwf.int/datasets/).The

obtained online (https://www.esrl.noaa.gov/psd/data/

gridded/data.cpcsoil.html). All figures were produced using

the NCAR Command Language (NCL).

REFERENCES

Dare, R. A., N. E. Davidson, and J. L. McBride, 2012: Tropical cy-

clone contribution to rainfall over Australia. Mon. Wea. Rev.,

140, 3606–3619, https://doi.org/10.1175/MWR-D-11-00340.1.

Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis:

Configuration and performance of the data assimilation sys-

tem.Quart. J. Roy. Meteor. Soc., 137, 553–597, https://doi.org/

10.1002/qj.828.

Emanuel, K., 2005: Increasing destructiveness of tropical cyclones

over the past 30 years. Nature, 436, 686–688, https://doi.org/

10.1038/nature03906.

Englehart, P. J., and A. V. Douglas, 2001: The role of eastern North

Pacific tropical storms in the rainfall climatology of westernMexico.

Int. J. Climatol., 21, 1357–1370, https://doi.org/10.1002/joc.637.

Groisman, P. Ya., R. W. Knight, D. R. Easterling, T. R. Karl, G. C.

Hegerl, and V. N. Razuvaev, 2005: Trends in intense precipi-

tation in the climate record. J. Climate, 18, 1326–1350, https://

doi.org/10.1175/JCLI3339.1.

Jiang, H., 2012: The relationship between tropical cyclone intensity

change and the strength of inner-core convection.Mon.Wea.Rev.,


Karl, T. R., and D. R. Easterling, 1999: Climate extremes: Selected

review and future research directions. Climatic Change, 42,

309–325, https://doi.org/10.1023/A:1005436904097.

Kim, J.-H., C.-H. Ho, M.-H. Lee, J.-H. Jeong, and D. Chen, 2006:

Large increase in heavy rainfall associated with tropical cy-

clone landfalls in Korea after the late 1970s. Geophys. Res.

Lett., 33, L18706, https://doi.org/10.1029/2006GL027430.

Klotzbach, P. J., 2006: Trends in global tropical cyclone activity

over the past twenty years (1986–2005). Geophys. Res. Lett.,

33, L10805, https://doi.org/10.1029/2006GL025881.

Knight, D. B., and R. E. Davis, 2009: Contribution of tropical cy-

clones to extreme rainfall events in the southeastern United

States. J. Geophys. Res., 114, D23102, https://doi.org/10.1029/

2009JD012511.

Knutson, T. R., and R. E. Tuleya, 2004: Impact of CO2-induced

warming on simulated hurricane intensity and precipitation:

Sensitivity to the choice of climate model and convective pa-

rameterization. J. Climate, 17, 3477–3495, https://doi.org/

10.1175/1520-0442(2004)017,3477:IOCWOS.2.0.CO;2.

——, J. J. Sirutis, S. T. Garner, I. M. Held, and R. E. Tuleya, 2007:

Simulation of the recent multidecadal increase of Atlantic

hurricane activity using an 18-km-grid regional model. Bull.

Amer. Meteor. Soc., 88, 1549–1565, https://doi.org/10.1175/

BAMS-88-10-1549.

——, and Coauthors, 2010: Tropical cyclones and climate change.

Nat. Geosci., 3, 157–163, https://doi.org/10.1038/ngeo779.

Kunkel, K. E., D. R. Easterling, D. A. Kristovich, B. Gleason,

L. Stoecker, and R. Smith, 2010: Recent increases in U.S. heavy

precipitation associated with tropical cyclones. Geophys. Res.


Liu, L., J. Xu, Y. Wang, and Y.-H. Duan, 2019: Contribution of re-

cycling of surface precipitation to landfalling tropical cyclone

rainfall: A modeling study for Typhoon Utor (2013). J. Geophys.

Res. Atmos., 124, 870–885, https://doi.org/10.1029/2018JD029380.

——, Y. Wang, R.-F. Zhan, J. Xu, and Y. Duan, 2020: Increasing

destructive potential of landfalling tropical cyclones overChina.

J. Climate, in press, https://doi.org/10.1175/JCLI-D-19-0451.

Liu,M., G. A. Vecchi, J. A. Smith, and T. R. Knutson, 2019: Causes

of large projected increases in hurricane precipitation rates

with global warming. npj Climate Atmos. Sci., 2, 38, https://

doi.org/10.1038/S41612-019-0095-3.

Lonfat, M., Jr., F. D. Marks, and S. S. Chen, 2004: Precipitation

distribution in tropical cyclones using the Tropical Rainfall

Measuring Mission (TRMM) Microwave Imager: A global

perspective. Mon. Wea. Rev., 132, 1645–1660, https://doi.org/

10.1175/1520-0493(2004)132,1645:PDITCU.2.0.CO;2.

Park,D.-S.R.,C.-H.Ho, J.-H.Kim, andH.-S.Kim, 2011: Strong landfall

typhoons in Korea and Japan in a recent decade. J. Geophys. Res.,

116, D07105, https://doi.org/10.1029/2010JD014801.

——, ——, and ——, 2014: Growing threat of intense tropical cy-

clones to East Asia over the period 1977–2010. Environ. Res.

Lett., 9, 014008, https://doi.org/10.1088/1748-9326/9/1/014008.Ren, F., G. Wu, W. Dong, X. Wang, Y. Wang, W. Ai, and W. Li, 2006:

Changes in tropical cyclone precipitation overChina.Geophys. Res.


——, Y. Wang, X. Wang, and W. Li, 2007: Estimating tropical

cyclone precipitation from station observations. Adv. Atmos.

Sci., 24, 700–711, https://doi.org/10.1007/s00376-007-0700-y.

Rodgers, E. B., R. F. Adler, and H. F. Pierce, 2001: Contribution of

tropical cyclones to the North Atlantic climatological rainfall as

observed from satellites. J. Appl. Meteor., 40, 1785–1800, https://

doi.org/10.1175/1520-0450(2001)040,1785:COTCTT.2.0.CO;2.

Shen,W., I. Ginis, and R. E. Tuleya, 2002: A numerical investigation

of land surface water on landfalling hurricanes. J. Atmos. Sci.,

59, 789–802, https://doi.org/10.1175/1520-0469(2002)059,0789:

ANIOLS.2.0.CO;2.

Shepherd, J. M., A. Grundstein, and T. L. Mote, 2007: Quantifying

the contribution of tropical cyclones to extreme rainfall along

the coastal southeastern United States. Geophys. Res. Lett.,

34, L23810, https://doi.org/10.1029/2007GL031694.

Tuleya, R. E., 1994: Tropical storm development and decay:

Sensitivity to surface boundary conditions. Mon. Wea. Rev.,

122, 291–304, https://doi.org/10.1175/1520-0493(1994)

122,0291:TSDADS.2.0.CO;2.

——, andY. Kurihara, 1978: A numerical simulation of the landfall

of tropical cyclones. J. Atmos. Sci., 35, 242–257, https://doi.org/

10.1175/1520-0469(1978)035,0242:ANSOTL.2.0.CO;2.

——, M. A. Bender, and Y. Kurihara, 1984: A simulation study of the

landfall of tropical cyclones.Mon.Wea. Rev., 112, 124–136, https://

doi.org/10.1175/1520-0493(1984)112,0124:ASSOTL.2.0.CO;2.

Wang, L., R. H. Huang, and R. Wu, 2013: Interdecadal variability in

tropical cyclone frequency over the South China Sea and its asso-

ciation with the Indian Ocean sea surface temperature. Geophys.

Res. Lett., 40, 768–771, https://doi.org/10.1002/grl.50171.

Wang, Y., Y. Rao, Z.-M. Tan, and D. Schönemann, 2015: A statistical

analysis of the effects of vertical wind shear on tropical cyclone

intensity change over the western North Pacific. Mon. Wea. Rev.,


Webster, P. J., G. J. Holland, J. A. Curry, and H. R. Chang, 2005:

Changes in tropical cyclone number, duration, and intensity

in a warming environment. Science, 309, 1844–1846, https://

doi.org/10.1126/science.1116448.

Wu, L., B.Wang, and S. Geng, 2005: Growing typhoon influence on

East Asia. Geophys. Res. Lett., 32, L18703, https://doi.org/

10.1029/2005GL022937.



https://www.esrl.noaa.gov/psd/data/gridded/data.cpcsoil.html

https://www.esrl.noaa.gov/psd/data/gridded/data.cpcsoil.html

https://doi.org/10.1175/MWR-D-11-00340.1

https://doi.org/10.1002/qj.828

https://doi.org/10.1002/qj.828

https://doi.org/10.1038/nature03906

https://doi.org/10.1038/nature03906

https://doi.org/10.1002/joc.637

https://doi.org/10.1175/JCLI3339.1

https://doi.org/10.1175/JCLI3339.1


https://doi.org/10.1023/A:1005436904097

https://doi.org/10.1029/2006GL027430

https://doi.org/10.1029/2006GL025881

https://doi.org/10.1029/2009JD012511

https://doi.org/10.1029/2009JD012511

https://doi.org/10.1175/1520-0442(2004)017<3477:IOCWOS>2.0.CO;2

https://doi.org/10.1175/1520-0442(2004)017<3477:IOCWOS>2.0.CO;2

https://doi.org/10.1175/BAMS-88-10-1549

https://doi.org/10.1175/BAMS-88-10-1549

https://doi.org/10.1038/ngeo779

https://doi.org/10.1029/2010GL045164

https://doi.org/10.1029/2018JD029380

https://doi.org/10.1175/JCLI-D-19-0451

https://doi.org/10.1038/S41612-019-0095-3

https://doi.org/10.1038/S41612-019-0095-3

https://doi.org/10.1175/1520-0493(2004)132<1645:PDITCU>2.0.CO;2

https://doi.org/10.1175/1520-0493(2004)132<1645:PDITCU>2.0.CO;2

https://doi.org/10.1029/2010JD014801

https://doi.org/10.1088/1748-9326/9/1/014008

https://doi.org/10.1029/2006GL027951

https://doi.org/10.1007/s00376-007-0700-y

https://doi.org/10.1175/1520-0450(2001)040<1785:COTCTT>2.0.CO;2

https://doi.org/10.1175/1520-0450(2001)040<1785:COTCTT>2.0.CO;2

https://doi.org/10.1175/1520-0469(2002)059<0789:ANIOLS>2.0.CO;2

https://doi.org/10.1175/1520-0469(2002)059<0789:ANIOLS>2.0.CO;2

https://doi.org/10.1029/2007GL031694

https://doi.org/10.1175/1520-0493(1994)122<0291:TSDADS>2.0.CO;2

https://doi.org/10.1175/1520-0493(1994)122<0291:TSDADS>2.0.CO;2

https://doi.org/10.1175/1520-0469(1978)035<0242:ANSOTL>2.0.CO;2

https://doi.org/10.1175/1520-0469(1978)035<0242:ANSOTL>2.0.CO;2

https://doi.org/10.1175/1520-0493(1984)112<0124:ASSOTL>2.0.CO;2

https://doi.org/10.1175/1520-0493(1984)112<0124:ASSOTL>2.0.CO;2

https://doi.org/10.1002/grl.50171


https://doi.org/10.1126/science.1116448

https://doi.org/10.1126/science.1116448

https://doi.org/10.1029/2005GL022937

https://doi.org/10.1029/2005GL022937

Wu, Y., S. Wu, and P. Zhai, 2007: The impact of tropical cyclones

on Hainan Island’s extreme and total precipitation. Int.

J. Climatol., 27, 1059–1064, https://doi.org/10.1002/joc.1464.

Ying,M., B. Chen, andG.Wu, 2011a: Climate trends in tropical cyclone-

inducedwind andprecipitationovermainlandChina.Geophys.Res.


——, Y.-H. Yang, B.-D. Chen, and W. Zhang, 2011b: Climatic

variation of tropical cyclones affecting China during the past

50 years. Sci. China Earth Sci., 54, 1226–1237, https://doi.org/

10.1007/s11430-011-4213-2.

——,W.Zhang, H. Yu, X. Lu, J. Feng, Y. Fan, Y. Zhu, andD. Chen,

2014: An overview of the ChinaMeteorological Administration

tropical cyclone database. J. Atmos. Oceanic Technol., 31, 287–

301, https://doi.org/10.1175/JTECH-D-12-00119.1.

Yu, Z., Y. Wang, H. Xu, N. Davidson, Y. Chen, Y. Chen, and

H.Yu, 2017:On the relationship between intensity and rainfall

distribution in tropical cyclones making landfall over China.

J. Appl. Meteor. Climatol., 56, 2883–2901, https://doi.org/

10.1175/JAMC-D-16-0334.1.

Zhang, J., L. Wu, F. Ren, and X. Cui, 2013: Changes in tropical

cyclone rainfall in China. J. Meteor. Soc. Japan, 91, 585–595,

https://doi.org/10.2151/jmsj.2013-502.

Zhang, Q., L. Wu, and Q. Liu, 2009: Tropical cyclone damages in

China 1983–2006. Bull. Amer. Meteor. Soc., 90, 489–496,

https://doi.org/10.1175/2008BAMS2631.1.

Zhang, W., and Coauthors, 2016: Influences of natural variability and

anthropogenic forcing on the extreme 2015 accumulated cyclone

energy in the western north Pacific. Bull. Amer. Meteor. Soc., 97,

S131–S135, https://doi.org/10.1175/BAMS-D-16-0146.1.

——, G. Villarini, G. A. Vecchi, and H. Murakami, 2019: Rainfall from

tropical cyclones: High-resolution simulations and seasonal fore-

casts. Climate Dyn., 52, 5269–5289, https://doi.org/10.1007/s00382-

018-4446-2.

Zhang, Y., C. Cassardo, C. Ye, M. Galli, and N. Vela, 2011: The role of

the land surface processes in the rainfall generated by a landfall

typhoon: A simulation of the Typhoon Sepat (2007). Asia-Pac.

J. Atmos. Sci., 47, 63–77, https://doi.org/10.1007/s13143-011-1006-7.



https://doi.org/10.1002/joc.1464

https://doi.org/10.1029/2010GL045729

https://doi.org/10.1007/s11430-011-4213-2

https://doi.org/10.1007/s11430-011-4213-2

https://doi.org/10.1175/JTECH-D-12-00119.1

https://doi.org/10.1175/JAMC-D-16-0334.1

https://doi.org/10.1175/JAMC-D-16-0334.1

https://doi.org/10.2151/jmsj.2013-502

https://doi.org/10.1175/2008BAMS2631.1

https://doi.org/10.1175/BAMS-D-16-0146.1

https://doi.org/10.1007/s00382-018-4446-2

https://doi.org/10.1007/s00382-018-4446-2

https://doi.org/10.1007/s13143-011-1006-7

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