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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