{"title":"水下滑翔机温度微结构耗散测量","authors":"Algot K. Peterson, Ilker Fer","doi":"10.1016/j.mio.2014.05.002","DOIUrl":null,"url":null,"abstract":"<div><p>Microstructure measurements of temperature and current shear are made using an autonomous underwater glider. The glider is equipped with fast-response thermistors and airfoil shear probes, providing measurements of dissipation rate of temperature variance, <span><math><mi>χ</mi></math></span>, and of turbulent kinetic energy, <span><math><mi>ε</mi></math></span>, respectively. Furthermore, by fitting the temperature gradient variance spectra to a theoretical model, an independent measurement of <span><math><mi>ε</mi></math></span> is obtained. Both Batchelor (<span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>) and Kraichnan (<span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>K</mi></mrow></msub></math></span>) theoretical forms are used. Shear probe measurements are reported elsewhere; here, the thermistor-derived <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>K</mi></mrow></msub></math></span> are compared to the shear probe results, demonstrating the possibility of dissipation measurements using gliders equipped with thermistors only. A total of 152 dive and climb profiles are used, collected during a one-week mission in the Faroe Bank Channel, sampling the turbulent dense overflow plume and the ambient water above. Measurement of <span><math><mi>ε</mi></math></span> with thermistors using a glider requires careful consideration of data quality. Data are screened for glider flight properties, measurement noise, and the quality of fits to the theoretical models. Resulting dissipation rates from the two independent methods compare well for dissipation rates below 2×10<sup>−7</sup> W kg<sup>−1</sup>. For more energetic turbulence, thermistors underestimate dissipation rates significantly, caused primarily by increased uncertainty in the time response correction. Batchelor and Kraichnan spectral models give very similar results. Concurrent measurements of <span><math><mi>ε</mi></math></span> and <span><math><mi>χ</mi></math></span> are used to compute the dissipation flux coefficient <span><math><mi>Γ</mi></math></span> (or so-called apparent mixing efficiency). A wide range of values is found, with a mode value of <span><math><mi>Γ</mi><mo>≈</mo><mn>0.14</mn></math></span>, in agreement with previous studies. Gliders prove to be suitable platforms for ocean microstructure measurements, complementary to existing methods.</p></div>","PeriodicalId":100922,"journal":{"name":"Methods in Oceanography","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mio.2014.05.002","citationCount":"46","resultStr":"{\"title\":\"Dissipation measurements using temperature microstructure from an underwater glider\",\"authors\":\"Algot K. Peterson, Ilker Fer\",\"doi\":\"10.1016/j.mio.2014.05.002\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Microstructure measurements of temperature and current shear are made using an autonomous underwater glider. The glider is equipped with fast-response thermistors and airfoil shear probes, providing measurements of dissipation rate of temperature variance, <span><math><mi>χ</mi></math></span>, and of turbulent kinetic energy, <span><math><mi>ε</mi></math></span>, respectively. Furthermore, by fitting the temperature gradient variance spectra to a theoretical model, an independent measurement of <span><math><mi>ε</mi></math></span> is obtained. Both Batchelor (<span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>) and Kraichnan (<span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>K</mi></mrow></msub></math></span>) theoretical forms are used. Shear probe measurements are reported elsewhere; here, the thermistor-derived <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>K</mi></mrow></msub></math></span> are compared to the shear probe results, demonstrating the possibility of dissipation measurements using gliders equipped with thermistors only. A total of 152 dive and climb profiles are used, collected during a one-week mission in the Faroe Bank Channel, sampling the turbulent dense overflow plume and the ambient water above. Measurement of <span><math><mi>ε</mi></math></span> with thermistors using a glider requires careful consideration of data quality. Data are screened for glider flight properties, measurement noise, and the quality of fits to the theoretical models. Resulting dissipation rates from the two independent methods compare well for dissipation rates below 2×10<sup>−7</sup> W kg<sup>−1</sup>. For more energetic turbulence, thermistors underestimate dissipation rates significantly, caused primarily by increased uncertainty in the time response correction. Batchelor and Kraichnan spectral models give very similar results. Concurrent measurements of <span><math><mi>ε</mi></math></span> and <span><math><mi>χ</mi></math></span> are used to compute the dissipation flux coefficient <span><math><mi>Γ</mi></math></span> (or so-called apparent mixing efficiency). A wide range of values is found, with a mode value of <span><math><mi>Γ</mi><mo>≈</mo><mn>0.14</mn></math></span>, in agreement with previous studies. Gliders prove to be suitable platforms for ocean microstructure measurements, complementary to existing methods.</p></div>\",\"PeriodicalId\":100922,\"journal\":{\"name\":\"Methods in Oceanography\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2014-09-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/j.mio.2014.05.002\",\"citationCount\":\"46\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Methods in Oceanography\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2211122014000231\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Methods in Oceanography","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2211122014000231","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 46
摘要
显微结构测量温度和电流剪切使用自主水下滑翔机。该滑翔机配备了快速响应热敏电阻和翼型剪切探头,分别测量温度方差χ和湍流动能ε的耗散率。此外,通过将温度梯度方差谱拟合到理论模型中,得到了ε的独立测量值。采用了Batchelor (εB)和Kraichnan (εK)两种理论形式。剪切探头测量在其他地方也有报道;在这里,热敏电阻得到的εB和εK与剪切探头的结果进行了比较,证明了使用仅配备热敏电阻的滑翔机进行耗散测量的可能性。总共使用了152个潜水和爬升剖面,这些剖面是在法罗银行海峡为期一周的任务中收集的,对湍流密集的溢出羽流和上方的环境水进行了采样。使用滑翔机用热敏电阻测量ε需要仔细考虑数据质量。数据被筛选为滑翔机的飞行特性,测量噪声,和质量拟合的理论模型。在2×10−7 W kg−1以下的情况下,两种独立方法得到的耗散率比较好。对于能量更大的湍流,热敏电阻明显低估了耗散率,这主要是由于时间响应校正中的不确定性增加造成的。Batchelor和Kraichnan光谱模型给出了非常相似的结果。同时测量ε和χ用于计算耗散通量系数Γ(或所谓的表观混合效率)。该模型的取值范围很广,模态值为Γ≈0.14,与前人的研究结果一致。事实证明,滑翔机是海洋微观结构测量的合适平台,是现有方法的补充。
Dissipation measurements using temperature microstructure from an underwater glider
Microstructure measurements of temperature and current shear are made using an autonomous underwater glider. The glider is equipped with fast-response thermistors and airfoil shear probes, providing measurements of dissipation rate of temperature variance, , and of turbulent kinetic energy, , respectively. Furthermore, by fitting the temperature gradient variance spectra to a theoretical model, an independent measurement of is obtained. Both Batchelor () and Kraichnan () theoretical forms are used. Shear probe measurements are reported elsewhere; here, the thermistor-derived and are compared to the shear probe results, demonstrating the possibility of dissipation measurements using gliders equipped with thermistors only. A total of 152 dive and climb profiles are used, collected during a one-week mission in the Faroe Bank Channel, sampling the turbulent dense overflow plume and the ambient water above. Measurement of with thermistors using a glider requires careful consideration of data quality. Data are screened for glider flight properties, measurement noise, and the quality of fits to the theoretical models. Resulting dissipation rates from the two independent methods compare well for dissipation rates below 2×10−7 W kg−1. For more energetic turbulence, thermistors underestimate dissipation rates significantly, caused primarily by increased uncertainty in the time response correction. Batchelor and Kraichnan spectral models give very similar results. Concurrent measurements of and are used to compute the dissipation flux coefficient (or so-called apparent mixing efficiency). A wide range of values is found, with a mode value of , in agreement with previous studies. Gliders prove to be suitable platforms for ocean microstructure measurements, complementary to existing methods.