Masanori Konda (Kyoto University / JAMSTEC IORGC) Hiroshi Ichikawa, Hiroyuki Tomita, Akira Nagano

1. An observational analysis of the variability of the sea surface heat flux in the Kuroshio Extension region Masanori Konda (Kyoto University / JAMSTEC IORGC) Hiroshi Ichikawa, Hiroyuki Tomita, Akira Nagano (JAMSTEC IORGC) Meghan F. Cronin (NOAA PMEL) US CLIVAR WBC Workshop 15/Jan. 2009, Phoenix

2. outline • JKEO status • Surface turbulent heat flux pattern in the KE observed by KEO and JKEO (2007-2008 analysis) • Difference between the KEO and JKEO(one dimensional air-mass transformation)

3. the north side of the Kuroshio Extension (KEO in the other side) To measure the ocean meteorology, the radiation, water temperature and salinity The in situ observation for the validation of satellite-derived variables. JKEO (JAMSTEC Kuroshio Extension Observatory) JKEO 38.0 N 146.5 E JKEO1 -> K-TRITON KEO 32.4 N 144.6 E OCEAN SITES data format as well as ASCII real time and delayed data Visit http://www.jamstec.go.jp/iorgc/ocorp/ktsfg/data/jkeo/index.html And http://www.pmel.noaa.gov/keo/

4. Sensor arrangements of JKEO1 and K-TRITON (JKEO2)

5. The surface meteorology at JKEO1 and KEO 18 Feb-13 Mar 2007 • Wind is missed from Mar 13 to May 10. • Meteorological sensors (except for AT) are from Sep. 9 to Oct. 4. • All of meteorological sensors stop on Jan. 26 2008. • Mar 2009: JKEO1 is recovered and replaced by K-TRITON (JKEO2). • JKEO2 stopped on 28 May because of the vandalism (recovered on 5 Sep). • JKEO3 is deployed on 12 Nov. • Delayed mode data of JKEO1 is almost processed. • Real time mode data of JKEO2 and 3 data is under formatting. SST 4 Oct- 25 Jan. 2008 Ta RH(%) U

6. Temperature profile at JKEO (and KEO) Sensor failed at 15m on Feb.24, 20m on May 28, 10m on Jun. 8. The KE front Difference between the north and the south of the KE front with temporally high resolution

7. Satellite-derived and NNR latent heat fluxes 2000 January Consistent or not ? JKEO JKEO KEO KEO NNR1 satellite Generally large around the KE frontal region 2001 January JKEO JKEO KEO KEO

8. JKEO - KEO surface heat flux variation SST LHF Ta SHF DPT Individual parameters have a strong contrast across the KE front, whereas the resultant heat flux does not has it. Wind Feb. 19 (Deployment of JKEO) – Mar. 22 2007

9. Latent heat flux components Latent heat flux Suggesting a quick one dimensional adjustment of the atmosphere? Term i: bias Small north-south difference Term ii: Δq anomaly Advection of the atmospheric column ? Feb.24 Mar.1 Mar.15 Term iii: U anomaly Wind direction

10. Spatial anomaly analysis Spatial difference between JKEO and KEO (i): spatial difference (ii): Δq spatial anomaly (iii): U spatial anomaly (iv): ignored (ii) and (iii) are almost balanced during the strong north wind period. The wind is stronger in the north, while the air-sea humidity difference is largerin the south because of Clausius-Clapeyron relationship, suggesting the air-mass transfer LHF SHF

11. Spatial anomaly analysis Spatial difference between JKEO and KEO (i): spatial difference (ii): ΔT spatial anomaly (iii): U spatial anomaly (iv): ignored (ii) And (iii) are not balanced. The wind is stronger in the north, and the air-sea temperature difference is also larger in the north. The sensible heat fluxes change synchronously, but that in the north is larger. LHF SHF

12. Satellite snapshot complements the spatial pattern Feb.26 Latent heat flux Term i: bias KE front Term ii: mean U, Δq anomaly Latent heat flux Term iii: mean Δq, ,U anomaly • JKEO: behind the strong low •  Strong wind/small Δq • KEO ：behind the strong low • Warm condition / large Δq Increase of the latent heat flux at the KE front under the same stream line of the wind L Wind direction Bond and Cronin (2008)

13. Latent heat flux components 2007-2008 Latent heat flux Low pressure crossing Term i: bias Small north-south difference Term ii: Δq anomaly Dec 31 Jan. 13 Jan. 25 Term iii: U anomaly Wind direction

14. The KE Region : Anomalous heat loss and gain associated with ????? (Bond and Cronin 2008) L H • Differences between the anomalously heat loss and gain in the cold season is extracted from the NNR data set. • KEO is located on the flank of the region with large atmospheric anomaly. • The largest SST difference is centered on the JKEO region. • The difference between KEO and JKEO is quite large. H SLPA during anomalous heat loss SLPA during anomalous heat gain Difference in TA(850hPa) between anomalous heat loss and gain Difference in SST between anomalousheat loss and gain Fig. 8 in Bond and Cronin (2008)

15. Latent heat flux components in October 2007 Mixed layer is not evident -> SST is easily to decrease Latent heat flux Contribution of the mean field is almost the same Mixed layer is formed Term i: bias Variability of the sea-air (temperature and humidity) difference changes across the KE front. Spatial anomaly Term ii: Δq anomaly Synoptic scale disturbance might be weak Term iii: u anomaly Wind direction

16. summary • The north-south contrast of the air-sea coupling processes across the KE • Latent heat fluxes under the strong north wind are almost same, as the result of the quick one dimensional adjustment of the atmosphere (The KEO-JKEO gap may be too large to resolve it.) • Frequency of the typical wind pattern possibly may determine the anomalous flux distribution rather than the long-lasting bias. • The role of the SST front changes seasonally. • The winter time cross-frontal wind effect can change the ocean mixed layer rapidly. • Year-to-year variation needs longer observation. • On site measurements + satellite measurements + numerical model products can complement each other. • The scenario suggested here should be checked with satellite data and the numerical model result.

18. NCEP-Reanalysis 1 latent heat flux February-March 2007 January 2008 JKEO: 168.3 (121.4) W/m2 KEO : 237.0 (101.9) W/m2 JKEO: 177.5 (91.1) W/m2 KEO : 215.5 (93.6) W/m2