Table 2 Summary of the five selected episodic cases of nitrogenous aerosols and the average results during the whole measurement period (29th November 2020–28th February 2021).

Type

IN & ON

IN & ON

IN & ON

ON

ON

–

Time period

22:00, 19th –10:00, 22nd Dec 2020

22:00, 29th–2:00, 30th Dec 2020

4:00, 7th–20:00, 8th Jan 2021

0:00, 7th– 8:00, 9th Feb 2021

4:00–16:00, 18th Feb 2021

All

Influential factor

Secondary SO₄ & NO₃

SOA-1 (nighttime)

Secondary SO₄ & NO₃ (daytime)

SOA-1

Biomass burning

–

Important parameter

Wind

Wind, NO_x, levoglucosan, SOA tracers

Wind, O₃, SOA tracers

SOA tracers

Levoglucosan, mannosan

–

Duration (h)

60

4

40

56

12

–

TN (μgN/m³)

4.10

3.98

4.18

2.21

2.45

2.01

NO₃⁻-N (μgN/m³)

0.69

1.32

1.02

0.41

0.28

0.31

NH₄⁺-N (μgN/m³)

3.10

2.15

2.83

1.43

1.79

1.45

ON (μgN/m³)

0.32

0.44

0.33

0.36

0.38

0.26

ON/TN ratio (%)

7.8

13.1

7.9

16.3

15.5

12.9

RH (%)

56.2

72.3

59.9

79.6

57.5

69.3

T (°C)

14.6

19.8

10.2

18.1

17.6

16.9

WS (m/s)

5.0

4.0

5.8

3.0

3.9

3.1

O₃ (ppb)

38.3

30.1

27.1

59.8

45.4

44.9

NO_x (ppb)

9.0

25.6

10.1

4.7

4.7

7.8