| Summary: | In order to conduct real-time quantitative monitoring of dust storms, Ka-band millimeter wave radar (MMWR) was utilized for the consecutive detection of dust storms over the Taklimakan Desert from April to June 2018. The retrievals of the reflectivity factor, dust spectrum distribution and dust mass concentration were carried out with the power spectrum data detected by MMWR for three dust storm processes. The analysis shows that: The probability density distribution of dust conforms to the lognormal distribution. During the dust storm processes, the effective detection height of the reflectivity factor was within 2000 m and the range of the reflectivity factors was between <inline-formula> <math display="inline"> <semantics> <mrow> <mo>−</mo> <mn>25</mn> <mrow> <mtext> </mtext> <mi>dBZ</mi> </mrow> </mrow> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mrow> <mn>25</mn> <mrow> <mtext> </mtext> <mi>dBZ</mi> </mrow> </mrow> </semantics> </math> </inline-formula>. During the floating dust period, the effective height of the dust spectrum distribution was lower than 300 m and the values of dust mass concentration were less than 31.62 <inline-formula> <math display="inline"> <semantics> <mrow> <mrow> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>, at a height of 200 m. Furthermore, during the blowing sand stage, the effective height of the dust spectrum distribution was normally lower than 600 m and the values of dust mass concentration were mainly less than <inline-formula> <math display="inline"> <semantics> <mrow> <mn>316.23</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>, at a height of 200 m. During the dust storm period, the effective height of the dust spectrum distribution exceeded 1000 m; when the height was 100 m, the values of dust mass concentration were between <inline-formula> <math display="inline"> <semantics> <mrow> <mn>1220</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> <mrow> <mtext> </mtext> <mi>and</mi> <mtext> </mtext> </mrow> <mn>42,146</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> and the average mass concentration was <inline-formula> <math display="inline"> <semantics> <mrow> <mn>9287</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>; whereas, the values of dust mass concentration were between <inline-formula> <math display="inline"> <semantics> <mrow> <mn>2</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> <mrow> <mtext> </mtext> <mi>and</mi> <mtext> </mtext> </mrow> <mn>820</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> when the height was 1200 m and the average mass concentration was <inline-formula> <math display="inline"> <semantics> <mrow> <mn>24</mn> <mrow> <mtext> </mtext> <mi mathvariant="sans-serif">μ</mi> <mi mathvariant="normal">g</mi> </mrow> <mo>·</mo> <msup> <mi mathvariant="normal">m</mi> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>. The relationship between the reflectivity factor Z and the dust mass concentration M is defined as <inline-formula> <math display="inline"> <semantics> <mrow> <mi>Z</mi> <mo>=</mo> <mn>651.6</mn> <msup> <mi>M</mi> <mrow> <mn>0.796</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula>. Compared with the observational data from Grimm180 particle detector, the data of the retrieved dust mass concentration are basically accurate and this retrieved method proves to be feasible. Thus, the MMWR cans be used as a new device for quantitative monitoring of dust storms.
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