The spatiotemporal patterns of sea ice in the Bohai Sea during the winter seasons of 2000–2016

Figures & data

Figure 1. Location of the Bohai Sea and distribution of automatic weather stations.

Table 1. The number of MODIS images in each winter.

Year	Numbers	Year	Numbers
2000–2001^a	13	2008–2009	54
2001–2002	19	2009–2010	50
2002–2003	49	2010–2011	52
2003–2004	52	2011–2012	46
2004–2005	46	2012–2013	40
2005–2006	46	2013–2014	44
2006–2007	59	2014–2015	51
2007–2008	52	2015–2016	49

^a2000–2001 denotes December 2000, January 2001, and February 2001. The remainder can be deduced by analogy. Before June 2003, only Terra MODIS data are available; after June 2003, MODIS data from both Terra and Aqua satellites are available.

Table 2. Coefficients used in the calculation of IST in the Northern Hemisphere (Riggs, Hall, and Salomonson 2006).

Temperature intervals	a	b	c	d
<240 K	−1.571	1.005	1.853	−0.791
240–260 K	−2.373	1.009	1.695	−0.205
>260 K	−4.295	1.015	1.950	0.197

Table 3. Estimated MODIS ice thickness (cm) results from this study, Zeng’s results, and in situ observations at the two offshore oil platforms in Liaodong Bay in the winter of 2009–2010.

			JZ9-3 Oil Platform			JZ20-2 Oil Platform
Index	Day of year (DOY)	Date	Our results	Zeng’s results	In situ data	Our results	Zeng’s results	In situ data
1	2009350	16-Dec-09	1.9	4	3.5	0	0	0
2	2009351	17-Dec-09	1.9	4	0	1.1	1	0
3	2009353	19-Dec-09	3.3	6	3.5	0	0	0
4	2009355	21-Dec-09	1.2	1	0	0	0	0
5	2009361	27-Dec-09	7.9	8	9.5	1.3	1	0
6	2010004	4-Jan-10	3.8	5	6	7.4	7	7.5
7	2010005	6-Jan-10	2.8	4	6	5.5	6	7.5
8	2010011	11-Jan-10	2.4	3	7	3.3	6	3
9	2010012	12-Jan-10	3.2	6	4.5	4.4	9	3
10	2010015	15-Jan-10	5	5	6	7.3	8	6.5
11	2010022	22-Jan-10	4.8	6	6.5	6.3	8	3
12	2010023	23-Jan-10	5.7	4	5	10.3	5	7.5
13	2010024	24-Jan-10	9	8	12.5	5.9	6	7.5
14	2010033	2-Feb-10	8.9	13	25	6.6	8	9
15	2010034	3-Feb-10	10.9	11	25	8.9	8	7.5
16	2010035	4-Feb-10	5.2	11	20	4.2	8	7.5
17	2010036	5-Feb-10	6	6	14	6	6	6
18	2010043	12-Feb-10	3.2	3	3.5	4.4	5	6
19	2010049	18-Feb-10	7.2	4	4	10.3	3	6
20	2010052	21-Feb-10	2.5	3	5.5	4.3	3	10

Table 4. Estimated MODIS ice thickness (in cm) results from this study, Shi’s results, and in situ observations at the two offshore oil platforms in Liaodong Bay in the winter of 2012–2013.

			JZ9-3 Oil Platform			JZ20-2 Oil Platform
Index	DOY	Date	Our results	Shi’s results	In situ data	Our results	Shi’s results	In situ data
1	2013003	3-Jan-13	5.3	5	4–7	6.9	8	8–15
2	2013007	7-Jan-13	8.7	4	5–9	16	11	15–25
3	2013009	9-Jan-13	8.5	7	5–9	10	13	15–30
4	2013018	18-Jan-13	4.6	2	4–9	4.8	2	8–20
5	2013025	25-Jan-13	5.6	3	3–7	7.8	5	3–8
6	2013035	4-Feb-13	2.0	7	15–30	1.3	5	5–10
7	2013043	15-Feb-13	13.0	4	12–15	6.4	5	8–15
8	2013047	19-Feb-13	6.9	7	3–22	9.8	9	8–15
9	2013050	22-Feb-13	/	/	/	13.2	2	8–15

Note: Slash represents no data on 22 February 2013 at JZ9-3 Oil Platform.

Figure 2. Retrieved ice thickness at the two oil platforms (JZ9-3 and JZ20-2) during the winter seasons of 2009–2010, based on Zeng’s result, our results (both are derived from MODIS data), and in situ observed ice thickness from Zeng et al. (2016). The index of the horizontal axis refers to time in Table 3.

Figure 3. Retrieved ice thickness at the two oil platforms (JZ9-3 and JZ20-2) during the winter of 2012–2013, based on Shi’s result, our results (both are derived from MODIS data), and in situ observed ice thickness from Shi et al. (2016). Vertical bars represent the range of the in situ thickness measure.

Figure 4. Retrieved ice extent of the Bohai Sea based on MODIS data and previously published results during the winter of 2009–2010.

Figure 5. Median values of SIT in the Bohai Sea for six periods from 2000 to 2016.

Figure 6. SIT map of the Bohai Sea on the day when the maximum ice extent occurred in the six periods during the winter of 2009–2010.

Figure 7. SIT map of the Bohai Sea on the day when the median ice extent occurred in each year during 2000–2016.

Figure 8. SIE for six winter time periods during 2000–2016 in the Bohai Sea.

Figure 9. The evolution of negative accumulated temperature, SIE and SIT during 2000–2016.

Table 5. Ice thickness, ice extent, and average temperature in the Bohai Sea during the in six winter periods, averaged over years 2000–2016.

		D1	D2	J1	J2	F1	F2
Mean value	Ice thickness (cm)	4.77 ± 0.52	5.04 ± 0.69	5.23 ± 0.80	5.58 ± 0.86	4.85 ± 0.66	4.80 ± 0.82
	Ice extent (km^2)	5491 ± 1969	9146 ± 2756	14,113 ± 5567	20,745 ± 6226	22,996 ± 8048	14,812 ± 8907
Range (median value)	Ice thickness (cm)	3.80–5.90 (4.98)	3.77–6.43 (5.06)	3.61–6.19 (5.28)	3.72–7.42 (5.42)	3.55–6.09 (4.72)	3.46–6.35 (4.71)
	Ice extent (km^2)	2396–8503 (5592)	3136–12,571 (9503)	6289–26,845 (13,488)	11,546–31,430 (22,378)	9404–38,635 (23,666)	1015–30,361 (14,058)
Mean air temperature (°C)		−1.0	−3.6	−5.3	−5.4	−3.9	−1.9

Figure 10. Ratio of median SIE to area of each bay in F1 during 2000–2016.

Table 6. Area of sea ice cover (km²) with mean ice thickness ≥10 cm and <10 cm in the three bays connected to the Bohai Sea, for each one of the six periods within the winter season, averaged over the study period (from 2000 to 2016).

	Mean ice thickness ≥ 10 cm			Mean ice thickness < 10 cm
	Liaodong Bay	Bohai Bay	Laizhou Bay	Liaodong Bay	Bohai Bay	Laizhou Bay
D1	435	165	101	2372	1691	674
D2	687	343	207	4224	2454	1057
J1	1229	540	339	6986	3388	1579
J2	1866	791	369	11,272	4639	2159
F1	1570	638	354	13,777	4763	2171
F2	1001	442	230	10,016	2643	994

Table 7. Trends of air temperature increases (°C per decade) in the Bohai Sea, the three bays, and the NPA.

	1951–2016					1979–2016
	Winter	Spring	Summer	Autumn	annual	Winter	Spring	Summer	Autumn	annual
Bohai Sea	0.497	0.403	0.189	0.314	0.345	0.271*	0.324	0.209	0.341	0.277
Liaodong Bay	0.541	0.400	0.155	0.345	0.354	0.279	0.308	0.177	0.343	0.267
Bohai Bay	0.394	0.319	0.118	0.232	0.262	0.403	0.322	0.179	0.400	0.317
Laizhou Bay	0.382	0.351	0.201	0.243	0.287	0.192*	0.292	0.207	0.287	0.237
NPA	0.381	0.467	0.234	0.361	0.364	0.648	0.707	0.437	0.754	0.639

Note: Winter refers to December, January, and February; spring refers to March, April, and May; summer refers to June, July, and August; and autumn refers to September, October, and November.

*P < .05, for other data P < .001, P values of the trend values in NPA were not provided in Bekryaev’s paper but it has been stated that the trends are statistically significant.

Riggs, G. A., D. K. Hall, and V. V. Salomonson. 2006. “MODIS Sea Ice Products User Guide to Collection 5.” National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA.

 Google Scholar

Zeng, T., L. Shi, M. Makynen, B. Cheng, J. Zou, and Z. Zhang. 2016. “Sea Ice Thickness Analyses for the Bohai Sea Using MODIS Thermal Infrared Imagery.” Acta Oceanologica Sinica 35: 96–104. doi: 10.1007/s13131-016-0908-8

 Web of Science ®Google Scholar

Shi, L., T. Zeng, M. Makynen, and B. Cheng. 2016. “Sea Ice Thickness Retrieval with Modis Thermal Infrared Data over the Liaodong Bay During Winter 2012–2013”. Paper presented at the IGARSS 2016–2016 IEEE International Geoscience and Remote Sensing Symposium.

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