NorESM3 aerosol development progression

Global aerosol properties across the NorESM3 development versions (pre-industrial control runs at ne16, one run per version tag), with NorESM2-LM as a reference. Each value is an area-weighted global mean over the last 10 complete model years of the run; the years are listed under each version tag and in the table of runs. Vertical lines in the figures mark three changes that affect the comparison: CMIP7 forcing and boundary files from beta14, dust and sea-salt settings with an energy-conservation fix in beta17 (no beta17 run, so the line sits before beta18), and native SE output from beta21.

Download all values (CSV)

Optical properties

Values

Run	AOD (0.44-0.63 µm)	Absorption AOD (0.44-0.63 µm)	Single-scattering albedo	Mass extinction efficiency (m²/g)
alpha03c	0.1463	0.002124	0.9855	2.885
beta01	0.1452	0.002142	0.9853	2.566
beta02	0.1446	0.002395	0.9834	2.305
beta03	0.1449	0.002353	0.9838	2.296
beta03a	0.1555	0.002356	0.9848	2.367
beta03b	0.1539	0.002318	0.9849	2.365
beta04	0.1547	0.00226	0.9854	2.407
beta06	0.1452	0.002072	0.9857	2.387
beta09	0.1447	0.0021	0.9855	2.466
beta10	0.1443	0.00208	0.9856	2.481
beta11	0.1449	0.002124	0.9853	2.451
beta12	0.1534	0.002074	0.9865	2.663
beta12a	0.1515	0.002035	0.9866	2.675
beta13a	0.1557	0.002129	0.9863	2.631
beta14	0.1532	0.002076	0.9864	2.728
beta15	0.1539	0.002115	0.9863	2.704
beta16	0.1477	0.0019	0.9871	2.816
beta18	0.1045	0.00173	0.9834	2.476
beta19	0.1207	0.002191	0.9818	2.271
beta20	0.1193	0.002144	0.982	2.315
beta21	0.1189	0.002176	0.9817	2.261
beta22	0.1213	0.002171	0.9821	2.301
beta23	0.1211	0.002174	0.982	2.307
beta24	0.1209	0.002181	0.982	2.29
beta25	0.1197	0.002165	0.9819	2.301
beta27	0.1193	0.00216	0.9819	2.313
NorESM2-LM	0.1485	0.001947	0.9869	3.563

Column burdens

Values

Run	BC burden (Tg)	OM burden (Tg)	Dust burden (Tg)	Sea salt burden (Tg)	Sulfate burden (Tg)	Sulfate (S) burden (Tg S)
alpha03c	0.03951	2.115	11.47	11.38	0.8505	–
beta01	0.03847	1.447	14.79	11.83	0.769	–
beta02	0.03951	1.559	17.94	11.66	0.8095	0.2551
beta03	0.04002	1.481	17.51	12.31	0.8329	0.2627
beta03a	0.04096	1.487	17.23	13.89	0.8617	0.2719
beta03b	0.04028	1.431	17.02	13.84	0.8576	0.2707
beta04	0.03964	1.433	16.42	14.06	0.8373	0.2643
beta06	0.0361	1.322	15.33	13.5	0.8327	0.2623
beta09	0.03788	1.684	13.85	13.62	0.7246	0.2294
beta10	0.03798	1.737	13.37	13.79	0.7399	0.2343
beta11	0.03809	1.738	13.96	13.7	0.729	0.2309
beta12	0.03781	1.738	13.2	13.68	0.7185	0.2275
beta12a	0.03784	1.719	12.8	13.61	0.7226	0.2287
beta13a	0.03842	1.729	13.93	13.75	0.7464	0.2365
beta14	0.03967	1.681	12.57	13.63	0.7137	0.2259
beta15	0.03983	1.682	13.04	13.56	0.71	0.2248
beta16	0.0398	1.489	10.89	13.63	0.7072	0.2238
beta18	0.03919	1.512	9.467	9.814	0.703	0.2225
beta19	0.03999	1.642	15.54	9.185	0.7044	0.2229
beta20	0.04013	1.633	14.76	9.155	0.7023	0.222
beta21	0.04018	1.598	15.4	9.082	0.7088	0.2239
beta22	0.04009	1.663	15.18	9.314	0.6864	0.2169
beta23	0.03966	1.667	15.22	9.149	0.6885	0.2176
beta24	0.03984	1.689	15.3	9.178	0.7043	–
beta25	0.03972	1.696	14.99	9.082	0.7233	–
beta27	0.03983	1.713	14.8	9.032	0.7257	–
NorESM2-LM	0.04228	2.084	8.742	9.795	0.5941	–

Emissions

Values

Run	BC emission (Tg/yr)	OM emission (Tg/yr)	Dust emission (Tg/yr)	Sea salt emission (Tg/yr)	Sulfate emission (Tg/yr)	Sulfate (S) emission (Tg S/yr)	SO2 emission (Tg S/yr)	DMS emission (Tg S/yr)
alpha03c	2.569	61.31	1656	5247	1.418	0.4632	18.07	28.24
beta01	2.569	62.7	2103	5448	1.418	0.4632	18.07	24.25
beta02	2.569	60.89	2413	4918	1.418	0.4632	18.07	23.86
beta03	2.569	60.46	2394	4763	1.418	0.4632	18.07	24.15
beta03a	2.569	59.83	2283	4687	1.418	0.4632	18.07	24.15
beta03b	2.569	59.77	2207	4680	1.418	0.4632	18.07	23.73
beta04	2.568	60.24	2152	4774	1.418	0.4632	18.07	24.04
beta06	2.568	59.83	2139	4667	1.418	0.4632	18.07	23.9
beta09	2.568	59.5	1853	4648	1.417	0.4632	18.07	16.46
beta10	2.569	59.42	1805	4675	1.418	0.4632	18.07	16.53
beta11	2.569	59.51	1849	4660	1.418	0.4632	18.07	16.16
beta12	2.569	59.12	1741	4651	1.418	0.4632	18.07	16.04
beta12a	2.569	58.99	1719	4611	1.418	0.4632	18.07	16.12
beta13a	2.569	59.15	1847	4648	1.418	0.4632	18.07	16.44
beta14	2.828	60.55	1674	4633	1.305	0.4264	16.64	16.05
beta15	2.828	60.43	1711	4603	1.305	0.4264	16.64	15.99
beta16	2.828	60.66	1448	4647	1.305	0.4264	16.64	16.11
beta18	2.828	60.86	1541	3390	1.305	0.4264	16.64	16.28
beta19	2.828	60.15	2461	3210	1.305	0.4264	16.64	15.91
beta20	2.828	60.22	2280	3210	1.305	0.4264	16.64	16.22
beta21	2.841	60.35	2378	3171	1.288	0.4209	16.42	16.45
beta22	2.841	60.24	2362	3233	1.288	0.4209	16.42	15.89
beta23	2.841	60.47	2387	3231	1.288	0.4209	16.42	15.87
beta24	2.841	60.28	2370	3213	1.288	0.4209	16.42	15.75
beta25	2.841	60.32	2324	3207	1.288	0.4209	16.42	15.96
beta27	2.841	59.93	2302	3182	1.288	0.4209	16.42	15.89
NorESM2-LM	2.574	56.44	1692	3636	1.292	0.4223	16.48	19.53

Wet deposition

Values

Run	BC wet deposition (Tg/yr)	OM wet deposition (Tg/yr)	Dust wet deposition (Tg/yr)	Sea salt wet deposition (Tg/yr)	Sulfate wet deposition (Tg/yr)	Sulfate (S) wet deposition (Tg S/yr)
alpha03c	–	–	–	–	–	–
beta01	–	–	–	–	–	–
beta02	1.863	93.06	703.4	3962	60.46	17.56
beta03	1.878	87.88	742.5	3832	59.68	17.37
beta03a	1.872	83.63	709.5	3716	57.07	16.65
beta03b	1.87	82.41	667	3712	56.48	16.47
beta04	1.86	84.27	646.8	3784	55.8	16.29
beta06	1.874	82.41	668.2	3727	57.08	16.63
beta09	1.85	95.13	529.6	3661	44.27	12.99
beta10	1.859	96.73	524.7	3683	44.63	13.1
beta11	1.861	96.52	535.9	3673	44.07	12.93
beta12	1.862	96.51	502.8	3668	43.82	12.86
beta12a	1.859	95.38	515.4	3643	44.35	13.01
beta13a	1.857	95.74	537.7	3669	44.36	13.02
beta14	1.989	95.9	496	3659	43.78	12.87
beta15	1.988	95.87	496.8	3636	43.52	12.8
beta16	1.992	86.59	408.6	3676	43.93	12.91
beta18	2.002	88.73	365.8	2658	43.97	12.92
beta19	1.982	91.68	544.6	2515	44.22	12.98
beta20	1.982	90.73	522.6	2521	45.09	13.23
beta21	1.986	89.11	539.6	2493	45.73	13.41
beta22	1.985	92.3	541.9	2532	44.12	12.95
beta23	1.975	93.54	525.5	2529	44.34	13.01
beta24	1.977	93.99	522.6	2516	44	–
beta25	1.981	93.45	529.2	2519	45.13	–
beta27	1.976	93.04	522.5	2500	45.14	–
NorESM2-LM	1.906	121.4	285.6	2227	51.55	–

Dry deposition

Values

Run	BC dry deposition (Tg/yr)	OM dry deposition (Tg/yr)	Dust dry deposition (Tg/yr)	Sea salt dry deposition (Tg/yr)	Sulfate dry deposition (Tg/yr)	Sulfate (S) dry deposition (Tg S/yr)
alpha03c	–	–	–	–	–	–
beta01	–	–	–	–	–	–
beta02	0.7242	22.19	1715	1002	7.46	2.219
beta03	0.7078	20.8	1659	974.7	7.329	2.185
beta03a	0.714	20.3	1581	1012	7.439	2.226
beta03b	0.7167	19.93	1548	1009	7.407	2.218
beta04	0.7274	20.31	1515	1034	7.452	2.233
beta06	0.7129	19.56	1480	979.9	7.386	2.202
beta09	0.7366	24.05	1327	1029	6.236	1.881
beta10	0.7269	24.17	1282	1034	6.182	1.863
beta11	0.7257	24.11	1315	1029	6.146	1.853
beta12	0.7245	24.13	1240	1024	6.116	1.844
beta12a	0.7264	23.75	1207	1008	6.085	1.833
beta13a	0.73	23.96	1312	1021	6.178	1.865
beta14	0.8559	24.19	1180	1015	6.093	1.839
beta15	0.8571	24.19	1217	1008	6.062	1.831
beta16	0.8525	21.46	1044	1012	6.024	1.818
beta18	0.843	21.78	1179	763.4	6.061	1.83
beta19	0.8628	23.41	1923	723.7	6.119	1.844
beta20	0.8618	23.19	1765	716.1	6.155	1.853
beta21	0.8568	22.67	1851	705.8	6.245	1.878
beta22	0.8585	23.55	1833	731.2	6.156	1.855
beta23	0.8685	24.27	1875	731.4	6.176	1.859
beta24	0.8656	24.36	1860	725.3	6.184	–
beta25	0.8618	23.63	1807	716.8	6.123	–
beta27	0.8662	23.61	1792	710.9	6.127	–
NorESM2-LM	0.6655	22.74	1406	1411	6.408	–

Lifetime

Values

Run	BC lifetime (days)	OM lifetime (days)	Dust lifetime (days)	Sea salt lifetime (days)	Sulfate lifetime (days)
alpha03c	–	–	–	–	–
beta01	–	–	–	–	–
beta02	5.575	4.936	2.707	0.8575	4.35
beta03	5.648	4.975	2.662	0.9352	4.537
beta03a	5.78	5.221	2.746	1.072	4.875
beta03b	5.683	5.103	2.804	1.07	4.9
beta04	5.592	5.003	2.773	1.065	4.832
beta06	5.093	4.733	2.604	1.047	4.715
beta09	5.346	5.158	2.723	1.06	5.237
beta10	5.36	5.243	2.702	1.067	5.315
beta11	5.375	5.259	2.753	1.063	5.299
beta12	5.336	5.259	2.765	1.064	5.252
beta12a	5.342	5.266	2.711	1.068	5.229
beta13a	5.421	5.273	2.749	1.07	5.391
beta14	5.091	5.109	2.738	1.065	5.223
beta15	5.111	5.114	2.779	1.066	5.226
beta16	5.106	5.031	2.735	1.061	5.167
beta18	5.028	4.993	2.237	1.047	5.129
beta19	5.132	5.206	2.299	1.035	5.108
beta20	5.15	5.233	2.355	1.032	5.003
beta21	5.159	5.219	2.351	1.036	4.978
beta22	5.146	5.238	2.333	1.042	4.984
beta23	5.09	5.166	2.315	1.024	4.974
beta24	5.115	5.209	2.345	1.033	5.122
beta25	5.1	5.286	2.342	1.024	5.151
beta27	5.115	5.36	2.334	1.027	5.167
NorESM2-LM	6.001	5.278	1.886	0.9827	3.741

Wet-deposition fraction

Values

Run	BC wet-deposition fraction	OM wet-deposition fraction	Dust wet-deposition fraction	Sea salt wet-deposition fraction	Sulfate wet-deposition fraction
alpha03c	–	–	–	–	–
beta01	–	–	–	–	–
beta02	0.72	0.8074	0.2908	0.7981	0.8902
beta03	0.7263	0.8086	0.3092	0.7972	0.8906
beta03a	0.7239	0.8046	0.3097	0.786	0.8847
beta03b	0.723	0.8053	0.3011	0.7862	0.8841
beta04	0.7189	0.8058	0.2992	0.7853	0.8822
beta06	0.7244	0.8082	0.311	0.7918	0.8854
beta09	0.7152	0.7982	0.2852	0.7806	0.8765
beta10	0.7189	0.8001	0.2904	0.7807	0.8783
beta11	0.7194	0.8001	0.2895	0.7813	0.8776
beta12	0.7199	0.8	0.2885	0.7817	0.8775
beta12a	0.7191	0.8006	0.2992	0.7833	0.8794
beta13a	0.7178	0.7999	0.2907	0.7823	0.8777
beta14	0.6991	0.7986	0.296	0.7829	0.8778
beta15	0.6987	0.7985	0.2899	0.7829	0.8778
beta16	0.7004	0.8014	0.2812	0.7842	0.8794
beta18	0.7037	0.8029	0.2368	0.7769	0.8789
beta19	0.6967	0.7966	0.2207	0.7765	0.8784
beta20	0.697	0.7964	0.2285	0.7788	0.8799
beta21	0.6986	0.7972	0.2257	0.7794	0.8798
beta22	0.698	0.7967	0.2282	0.7759	0.8776
beta23	0.6946	0.794	0.2189	0.7757	0.8777
beta24	0.6955	0.7942	0.2193	0.7762	0.8768
beta25	0.6968	0.7981	0.2265	0.7785	0.8805
beta27	0.6952	0.7976	0.2257	0.7786	0.8805
NorESM2-LM	0.7412	0.8422	0.1688	0.6121	0.8894

Aerosol number, CCN and cloud droplets

Values

Run	Aerosol number at 850 hPa (cm⁻³)	CCN (S=0.2%) at 850 hPa (cm⁻³)	CCN (S=1.0%) at 850 hPa (cm⁻³)	In-cloud droplet number at 850 hPa (cm⁻³)	Cloud-top CCN (cm⁻³)	Column droplet number (m⁻²)
alpha03c	499.9	–	–	29.85	–	9.642e+09
beta01	429.6	–	–	29.34	–	9.31e+09
beta02	427.4	–	–	29.33	–	1.017e+10
beta03	427	–	–	30.24	–	9.816e+09
beta03a	449.9	–	–	30.96	–	9.59e+09
beta03b	445.7	–	–	30.77	–	9.451e+09
beta04	446.6	–	–	30.06	–	9.27e+09
beta06	420.4	–	–	30.83	–	9.74e+09
beta09	439.2	–	–	29.09	–	8.512e+09
beta10	438.5	–	–	29.16	–	8.562e+09
beta11	436.1	–	–	29.04	–	8.498e+09
beta12	435.8	–	–	29.16	–	8.453e+09
beta12a	433.8	–	–	29.36	–	8.554e+09
beta13a	439.8	–	–	29.31	–	8.412e+09
beta14	430.3	–	–	29.76	–	8.648e+09
beta15	430.7	–	–	29.61	–	8.549e+09
beta16	421.4	–	–	29.08	–	8.499e+09
beta18	436.8	–	–	26.27	–	8.047e+09
beta19	434.2	–	–	28.93	–	8.251e+09
beta20	430.8	–	–	29.36	–	8.398e+09
beta21	426.6	–	–	29.8	–	8.52e+09
beta22	434.4	–	–	28.52	23.03	8.219e+09
beta23	434.8	–	–	29.08	23.42	8.434e+09
beta24	437.7	87.27	426.6	29.04	23.38	–
beta25	427.3	85.16	415.5	29.19	23.56	–
beta27	428	85.53	416.2	29.29	23.67	–
NorESM2-LM	466.1	7.454	39.96	31.04	32.35	1.153e+10

Budget imbalance (emission − deposition)

Values

Run	BC budget imbalance (Tg/yr)	BC relative budget imbalance	Dust budget imbalance (Tg/yr)	Dust relative budget imbalance	Sea salt budget imbalance (Tg/yr)	Sea salt relative budget imbalance
alpha03c	–	–	–	–	–	–
beta01	–	–	–	–	–	–
beta02	-0.01842	-0.00712	-5.805	-0.0024	-45.58	-0.009183
beta03	-0.01729	-0.006686	-6.807	-0.002835	-43.04	-0.008954
beta03a	-0.01774	-0.006859	-7.852	-0.003428	-41.73	-0.008825
beta03b	-0.01832	-0.007082	-7.899	-0.003566	-41.35	-0.008758
beta04	-0.01906	-0.007366	-9.695	-0.004485	-43.64	-0.009059
beta06	-0.01844	-0.007127	-10.11	-0.004703	-40.39	-0.008579
beta09	-0.01787	-0.006908	-3.471	-0.00187	-41.68	-0.008888
beta10	-0.01777	-0.006871	-2.225	-0.001232	-42.15	-0.008934
beta11	-0.01797	-0.006949	-2.337	-0.001262	-41.43	-0.008812
beta12	-0.01767	-0.006831	-1.861	-0.001068	-41.81	-0.008909
beta12a	-0.01716	-0.006637	-3.231	-0.001875	-40.75	-0.00876
beta13a	-0.01832	-0.007084	-2.27	-0.001227	-41.98	-0.008952
beta14	-0.01689	-0.005937	-2.32	-0.001384	-40.49	-0.008663
beta15	-0.01724	-0.006061	-2.315	-0.001351	-40.5	-0.008721
beta16	-0.01744	-0.006129	-4.662	-0.003208	-41.05	-0.008758
beta18	-0.01726	-0.006068	-3.938	-0.002549	-31.17	-0.009111
beta19	-0.01702	-0.005982	-6.824	-0.002765	-27.81	-0.008589
beta20	-0.01643	-0.005777	-7.32	-0.003201	-27.32	-0.00844
beta21	-0.001677	-0.0005897	-12.53	-0.005243	-27.63	-0.008636
beta22	-0.002077	-0.0007304	-12.85	-0.005409	-29.51	-0.009043
beta23	-0.002465	-0.0008669	-13.14	-0.005474	-29.04	-0.008907
beta24	-0.001516	-0.0005333	-13.04	-0.005474	-28.9	-0.008916
beta25	-0.001228	-0.0004321	-12.69	-0.005431	-28.56	-0.008827
beta27	-0.001099	-0.0003868	-12.48	-0.005392	-28.28	-0.00881
NorESM2-LM	0.00246	0.0009566	-0.3193	-0.0001887	-2.152	-0.0005914

Runs

Tag	Case	Window (model years)	Output grid	aerotrack commit
alpha03c	n1850.ne16pg3_tn14.noresm3_0_alpha03c.blom_sra.20250619	71–80	lat/lon (regridded online)	199d96b
beta01	n1850.ne16pg3_tn14.nor3_b01.20250731	291–300	lat/lon (regridded online)	199d96b
beta02	n1850.ne16_tn14.noresm3_0_beta02-run2_yr001.ocnflx2.20250901	5–14	lat/lon (regridded online)	199d96b
beta03	n1850.ne16_tn14.nor3_b03-rc3_yr0031.20250928	61–70	lat/lon (regridded online)	199d96b
beta03a	n1850.ne16pg3_tn14.noresm3_0_beta03a.landAndCAMupdate.2025-10-16	231–240	lat/lon (regridded online)	199d96b
beta03b	n1850.ne16pg3_tn14.noresm3_0_beta03b.CPLHIST.2025-10-29	401–410	lat/lon (regridded online)	199d96b
beta04	n1850.ne16pg3_tn14.ppe_base_run.nor3_b04._202511105	401–410	lat/lon (regridded online)	199d96b
beta06	n1850.ne16pg3_tn14.noresm3_0_beta06.20251114	416–425	lat/lon (regridded online)	199d96b
beta09	n1850.ne16pg3_tn14.noresm3_0_beta09.Run5.2026-01-08	396–405	lat/lon (regridded online)	199d96b
beta10	n1850.ne16pg3_tn14.noresm3_0_beta10.Run7.2026-01-26	576–585	lat/lon (regridded online)	199d96b
beta11	n1850.ne16pg3_tn14.noresm3_0_beta11.Run8.2026-02-07	801–810	lat/lon (regridded online)	199d96b
beta12	n1850.ne16pg3_tn14.noresm3_0_beta12.Run9.2026-03-11	916–925	lat/lon (regridded online)	199d96b
beta12a	n1850.ne16pg3_tn14.noresm3_0_beta12a.Run10_hyb.2026-03-28	1121–1130	lat/lon (regridded online)	199d96b
beta13a	n1850.ne16pg3_tn14.noresm3_0_beta13a.Run11.OcnTune2026-04-19	1171–1180	lat/lon (regridded online)	199d96b
beta14	n1850.ne16pg3_tn14.noresm3_0_beta14.Run11.Olivia.2026-04-24	1221–1230	lat/lon (regridded online)	199d96b
beta15	n1850.ne16pg3_tn14.noresm3_0_beta15.Run12.Olivia.2026-05-05	1301–1310	lat/lon (regridded online)	199d96b
beta16	n1850.ne16pg3_tn14.noresm3_0_beta16.Run13.Olivia.2026-05-18	1501–1510	lat/lon (regridded online)	199d96b
beta18	n1850.ne16pg3_tn14.noresm3_0_beta18.Run14.Olivia.2026-05-28	1571–1580	lat/lon (regridded online)	199d96b
beta19	n1850.ne16pg3_tn14.noresm3_0_beta19.Run15-E.Olivia.2026-06-18	1741–1750	lat/lon (regridded online)	199d96b
beta20	n1850.ne16pg3_tn14.noresm3_0_beta20.470.ref461.20260626	1741–1750	lat/lon (regridded online)	199d96b
beta21	n1850.ne16pg3_tn14.noresm3_0_beta21.i478.2026-07-06	1136–1145	native SE	199d96b
beta22	n1850.ne16pg3_tn14.noresm3_0_beta22.bdmc2_1p2.20260730	1246–1255	native SE	199d96b
beta23	n1850.LM.n30b23.507.GAaxg_lnd_ic.20260820	1506–1515	native SE	199d96b
beta24	n1850GaxgGHG.LM.n30b24.516.20260909	1516–1525	native SE	199d96b
beta25	n1850GaxgGHG.LM.nor30b25.528.20260928	1716–1725	native SE	199d96b
beta27	n1850GHGGaxg.LM.nor30b27.002.20261016	116–125	native SE	199d96b
NorESM2-LM	N1850_f19_tn14_20190722	1891–1900	f19 lat/lon	599ab6c

Caveats

AOD includes the prescribed stratospheric volcanic background in all versions (CMIP6 file to beta13a, CMIP7 from beta14); it is not subtracted.
Output before beta21 was regridded online to lat/lon, which biases it; from beta21 the native SE output is used.
Cloud-top CCN is shown from beta22 only: the CCN_B diagnostic had a bug in earlier NorESM3 versions.
Emissions for alpha03c and beta01 are rebuilt from per-tracer fields; they match the combined fields to ~1e-10 where both exist.
Sulfate is in model mass unless marked (S); sulfate burden and deposition in S exist only for beta02–beta23. Sulfur emissions use the model's conversion factors.
Budget imbalances are emission minus deposition for BC, dust and sea salt, assuming steady state; deposition exceeds emission by up to ~0.9 % in NorESM3.
NorESM2-LM: AOD from AOD_VIS (all-time rather than daylight mean), deposition summed from per-tracer fields, 850 hPa pressure rebuilt from the hybrid coefficients (−0.2 to −0.4 % on 850 hPa values). Its CCN is not shown as a reference: it implies ~10× lower activation than NorESM3 at similar aerosol number.

Built 2026-10-30 with aerotrack (summaries from commit 199d96b, 599ab6c).