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Table. 1. Means, medians, and change rates for NO2, HCHO, and O3 concentrations in the lowest layer (altitude of 0–1 km) retrieved from MAX-DOAS observations at Chiba and Tsukuba, Japan, for 2013–2019. The change rates and determination coefficient (R2) were calculated by a linear least-squares fit. Statistics for the 8 months of March to October, when MAX-DOAS O3 data were available, are given. For NO2 and HCHO, statistics for 12 months are also given in brackets

From: Continuous multi-component MAX-DOAS observations for the planetary boundary layer ozone variation analysis at Chiba and Tsukuba, Japan, from 2013 to 2019

Species

Location

Mean (ppbv)

Median (ppbv)

Change rate (ppbv/year)

Change rate (%/year)

R2

NO2

Chiba

3.6

(4.1)

3.6

(4.1)

-0.2

(-0.3)

-6

(-7)

0.50

(0.76)

Tsukuba

1.6

(1.9)

1.5

(1.9)

-0.1

(-0.1)

-6

(-5)

0.48

(0.65)

HCHO

Chiba

2.0

(1.7)

2.2

(1.7)

-0.2

(-0.1)

-10

(-6)

0.83

(0.67)

Tsukuba

2.8

(2.2)

2.8

(2.1)

±0.0

(±0.0)

±0

(±0)

0.17

(0.03)

O3

Chiba

47

47

+0.5

+1

0.28

Tsukuba

49

50

-0.1

±0

0.37