A sea fog prediction index extraction method and a sea fog prediction method thereof

Abstract

A sea fog forecast index extraction method and a sea fog forecast method thereof, comprising the following steps: screening historical sea fog cases of a target sea area; determining initial forecast index variables; determining forecast index variables and threshold values thereof; on the basis of obtaining the forecast index and the threshold value of the target sea area, obtaining numerical forecast products of the target sea area at a future time, extracting the determined forecast index variables therefrom, and if more than 80% of the forecast indexes meet the threshold value within the forecast validity, fog is predicted to occur in the target sea area. The present application innovatively proposes a sea fog forecast index extraction method under different complex weather conditions by using reanalysis data and visibility data of meteorological observation stations in the target sea area and the percentile method. In the business, the index variable value is read or calculated based on the real-time numerical model forecast product, and the target sea area sea fog is forecasted according to whether the threshold value is met, thereby providing a new index forecast method for sea fog forecast, so as to further improve the sea fog forecast level.

Description

Technical Field

[0001] This invention relates to a method for extracting sea fog forecasting indicators and a forecasting method thereof, belonging to the field of marine meteorological technology. Background Technology

[0002] Sea fog is a significant marine meteorological disaster. Influenced by the ocean, sea fog is a weather phenomenon that reduces horizontal visibility to less than 1 km at sea, near islands, or in target sea areas. When sea fog occurs, reduced horizontal visibility at sea or in target sea areas severely impacts maritime transportation, military activities, fisheries production, and agricultural production, and is also a major cause of various accidents at sea. Sea fog is frequent along my country's coastal waters, making sea fog forecasting particularly important given the increasing frequency of maritime activities such as shipping, fishing, and other production activities.

[0003] Sea fog often occurs behind high-pressure systems over the sea, under conditions of low pressure in the west and high pressure in the east, or under uniform pressure fields. Forecasters generally have a certain ability to predict this type of sea fog in daily operational forecasting. Besides common types of sea fog, it can also occur under suitable conditions in complex weather situations such as typhoons, cyclones, southerly winds, and the edge of subtropical highs. Currently, forecasters' ability to predict sea fog processes under complex weather conditions still needs improvement. Extracting sea fog forecasting indicators under complex weather backgrounds is beneficial for understanding the formation mechanism of sea fog, thereby improving the sea fog forecasting service capability under complex weather conditions and contributing to disaster prevention and mitigation efforts. Summary of the Invention

[0004] The purpose of this invention is to provide a method for extracting sea fog forecasting indicators and a sea fog forecasting method thereon, so as to improve the sea fog forecasting level of target sea areas under complex weather conditions.

[0005] A method for extracting sea fog forecasting indicators, characterized by including the following steps:

[0006] 1) Screen historical cases of sea fog in the target sea area;

[0007] 2) Determine the initial forecast indicators:

[0008] Acquire reanalysis data within the target sea area. For each meteorological observation station, read the meteorological elements at the grid point closest to the observation station, including surface meteorological elements and upper-air meteorological elements.

[0009] The surface meteorological elements include: air-sea temperature difference (°C), 2m temperature-dew point difference (°C), 2m relative humidity (%), wind speed (m / s) and wind direction (°) at 10m above the surface, 10m gust speed (m / s), 10m east-west wind speed (m / s), north-south wind speed (m / s), and north-south turbulent wind stress (N / m). 2 ), East-west turbulent wind stress (N / m) 2 ), heat flux (W / m2 Latent heat flux (W / m) 2 );

[0010] Upper-air meteorological elements include: 1000 hPa, 925 hPa, 850 hPa, relative humidity (%), specific humidity (g / kg), and water vapor flux divergence (g•hPa). -1 •cm -2 •s -1 ), wind direction (°) and wind speed (m / s), east-west wind speed (m / s), north-south wind speed (m / s), vertical velocity (Pa / s), and temperature advection (°C / s); air temperature at 975hPa, 950hPa, 925hPa, and 850hPa, and the temperature difference between each layer and the surface temperature (°C); and calculate the VIS index: VIS = (T s -T d ) / RH 1.67 T s T represents the surface temperature (K). d RH is the dew point temperature (K) 2m above the ground surface, and RH is the relative humidity (%) 2m above the ground surface.

[0011] 3) Determine forecast indicators:

[0012] Calculate the standard deviation and mean of each of the above preliminary forecast indicators. The ratio of standard deviation to mean, i.e., the coefficient of variation, measures the dispersion of the sample. The smaller the coefficient of variation, the more concentrated the values ​​of the preliminary forecast indicators are. Preliminary forecast indicators with a coefficient of variation of less than 30% are used as sea fog forecast indicators.

[0013] 4) Further determine the threshold values ​​for forecast indicators:

[0014] 4.1) Draw a box plot of the above sea fog forecast indicators. The corresponding data in the box plot are arranged from top to bottom in descending order, namely the maximum value, 75th percentile, 50th percentile (i.e., median), 25th percentile, and minimum value.

[0015] 4.2) The threshold for forecast indicators is determined based on the 75th or 25th percentile of the box plot of the forecast indicator. If the range of values ​​of the sample portion less than 25% in the box plot is greater than the range of values ​​of the sample portion greater than 75%, the value greater than 25% is selected as the threshold for the forecast indicator; conversely, if the range of values ​​of the sample portion less than 25% in the box plot is less than the range of values ​​of the sample portion greater than 75%, the value less than 75% is selected as the threshold for the forecast indicator.

[0016] Preferably, step 1 involves acquiring at least five years of historical data from meteorological observation stations within the target sea area and extracting visibility data from them, using visibility <1km as the standard for defining foggy days.

[0017] Step 1 is followed by screening four types of complex weather conditions for sea fog processes: Based on conventional surface weather maps, the weather conditions of the above fog days are determined, and four types of complex weather conditions for sea fog processes are screened out: cyclone type, typhoon type, southerly wind type, and subtropical high edge type.

[0018] Among them, cyclonic sea fog is defined as dense fog with visibility <1km when there is cyclonic activity in the target sea area (isobar interval 2.5hPa, at least one closed isobar); typhoon-type sea fog is dense fog that occurs in the first and fourth quadrants of the typhoon when the center of the typhoon is within 1000km of the target sea area; southerly wind-type sea fog is dense fog that occurs when the southerly wind speed in the coastal areas of the target sea area reaches 6m / s or more; and subtropical high edge-type sea fog is dense fog that occurs when the target sea area is within 200km of the 500hPa 588 line.

[0019] In step 2, the reanalysis data can be ERA5 reanalysis data or FNL reanalysis data.

[0020] The forecast indices and thresholds for sea fog in the Yellow Sea under four types of complex weather conditions determined using the above method are shown below:

[0021] For cyclonic weather backgrounds, there are seven forecast indicators: latent heat flux, sensible heat flux, 10-meter wind speed, north-south turbulent wind stress, east-west turbulent wind stress, 925 hPa temperature, and the temperature difference between surface temperature and 850 hPa. The thresholds for the seven indicators are: latent heat flux ~ less than 75th percentile, sensible heat flux ~ less than 75th percentile, 10-meter wind speed ~ less than 75th percentile, north-south turbulent wind stress ~ greater than 25th percentile, east-west turbulent wind stress ~ less than 75th percentile, 925 hPa temperature ~ greater than 25th percentile, and the temperature difference between surface temperature and 850 hPa ~ greater than 25th percentile.

[0022] For typhoon-type weather backgrounds, there are six forecast indicators: latent heat flux, 10-meter wind speed, 2-meter relative humidity, air-sea temperature difference, 925-hPa temperature advection, and surface temperature difference with 850-hPa. The thresholds for the six indicators are: latent heat flux ~>25th percentile, 10-meter wind speed ~>25th percentile, 2-meter relative humidity ~>25th percentile, air-sea temperature difference ~>25th percentile, 925-hPa temperature advection ~>25th percentile, and surface temperature difference with 850-hPa ~<75th percentile.

[0023] For a subtropical high-edge weather background, there are four forecast indicators: sensible heat flux, 2m relative humidity, 1000hPa relative humidity, and the temperature difference between the surface and 850hPa. The thresholds for these four indicators are: sensible heat flux ~ less than the 75th percentile, 2m relative humidity ~ greater than the 25th percentile, 1000hPa relative humidity ~ greater than the 25th percentile, and the temperature difference between the surface and 850hPa ~ greater than the 25th percentile.

[0024] For a southerly windy weather background, there are four forecast indicators: north-south turbulent wind stress, 10-meter wind direction, 850 hPa wind speed, and 850 hPa temperature advection. The thresholds for the four indicators are: north-south turbulent wind stress ~ greater than 25 percentile, 10-meter wind direction ~ greater than 25 percentile, 850 hPa wind speed ~ greater than 25 percentile, and 850 hPa temperature advection ~ greater than 25 percentile.

[0025] As can be seen, a total of 14 preliminary forecast indicators were included in the forecast indicators under the four weather backgrounds, and their statistics are shown in Table 1:

[0026] Table 1. Sea fog forecasting indicators and their thresholds under four types of complex weather conditions.

[0027]

[0028] A sea fog forecasting method utilizing the aforementioned sea fog forecasting index extraction method, characterized by comprising the following steps:

[0029] 1) Obtain the forecast indicators and their thresholds for the target sea area using the methods described above;

[0030] 2) Obtain numerical weather prediction products for the target sea area at a future time, and extract the prediction indicators determined in the previous step from them; if the numerical weather prediction products do not provide sea surface heat flux, north-south turbulent wind stress, and east-west turbulent wind stress, then calculate these three indicators separately.

[0031] 3) If more than 80% of the forecast indicators meet the threshold within the forecast period, then the target sea area is predicted to be foggy.

[0032] The sea surface heat flux is calculated using the COARE 3.0 heat flux algorithm to measure the sensible and latent heat fluxes at the sea-air interface at a specified point; this algorithm is based on the bulk method.

[0033] ,

[0034] in H s For sensible heat flux, H l Latent heat flux; C The heat transfer coefficient is taken as 0.00115; SThe wind speed at sea surface is represented by a 10m wind speed. T s Sea surface temperature; q s The specific humidity at sea surface is replaced by the specific humidity at 2m; and q The specific humidity of air is replaced by the specific humidity of 1000 hPa. c pa The specific heat capacity of air is taken as 1004.67; θ Potential temperature, by definition, is obtained through air temperature. T air pressure p Compared to air humidity q calculate:

[0035] ,

[0036] ρ a For air density, use sea surface pressure. p and 2m temperature t Perform the calculation:

[0037] L e The Monin-Obukhov length is the sea surface length, using sea surface temperature. T s calculate:

[0038] .

[0039] The calculations for the north-south turbulent wind stress and the east-west turbulent wind stress are as follows:

[0040] If we approximate a 10m wind field as surface wind, then the turbulent wind stress can be calculated using an approximate formula:

[0041] ,

[0042] in, For surface wind stress, ρ air density, For surface wind, C s The surface drag coefficient is given by the empirical formula:

[0043] ,

[0044] in, V Wind speed;

[0045] When calculating east-west turbulent wind stress, the zonal wind component is used, while when calculating north-south turbulent wind stress, the meridional wind component is used.

[0046] This invention utilizes data from observation stations in the target sea area and its coastal regions, along with conventional surface weather maps, to identify historical cases of sea fog. Based on reanalysis of gridded data, preliminary indicators are preset according to the physical quantities affecting fog formation. The percentile method is then used to extract sea fog forecasting indicators for the target sea area under four types of complex weather conditions. Furthermore, indicators are read from real-time numerical weather prediction products, and real-time sea fog forecasts for the target sea area are generated based on threshold values, enabling practical application in operations.

[0047] The percentile method is frequently used in the study of environmental physical quantity indicators for severe convective weather such as short-duration heavy precipitation, thunderstorms, strong winds, and hail. This method is simple, intuitive, and effective for extracting forecast indicators. Based on the percentile method, sea fog forecast indicators were extracted for various complex weather conditions, including typhoons, cyclones, southerly winds, and the edge of the subtropical high, aiming to provide operational personnel with technical support for sea fog forecasting under complex weather backgrounds.

[0048] This invention innovatively proposes a method for extracting sea fog forecast indicators under different complex weather conditions by utilizing reanalysis data, visibility data from meteorological observation stations in the target sea area, and the percentile method. In operational use, the indicator values ​​are read or calculated based on real-time numerical model forecast products, and sea fog forecasts for the target sea area are made according to whether they meet the threshold. This provides a new indicator forecasting method for sea fog forecasting, thereby further improving the level of sea fog forecasting. Attached Figure Description

[0049] Figure 1 This is a flowchart of the sea fog forecast index extraction method of the present invention.

[0050] Figure 2 These are box plots of some forecast indicators, where (a) is a box plot of the air-sea temperature difference and (b) is a box plot of the 10-wind direction. The percentages in the figures are the coefficients of variation.

[0051] Figure 3 This is a flowchart of the sea fog forecasting method of the present invention. Detailed Implementation

[0052] The implementation of the present invention will now be described in detail with reference to the accompanying drawings.

[0053] The purpose of this invention is to provide a method for extracting sea fog forecast indicators and a forecasting method thereof, so as to improve the sea fog forecasting level under complex weather conditions.

[0054] This invention uses data from automatic weather stations and buoy stations in the Yellow Sea from 2016 to 2022, as well as ERA5 reanalysis data and conventional surface weather maps. Based on the surface weather maps, sea fog processes occurring under four types of complex weather conditions were identified. Based on the reanalysis gridded data, forecast indicators were initially determined according to the physical quantities affecting fog formation. The percentile method was used to determine the sea fog forecast indicators for the target sea area under the four types of complex weather conditions, and sea fog forecasts for the target sea area were achieved based on real-time numerical weather prediction products.

[0055] A method for extracting sea fog forecasting indicators, such as Figure 1 As shown,

[0056] Step 1: Based on the visibility data obtained from the meteorological observation station in the target sea area, foggy days are defined with visibility <1km as the standard.

[0057] Based on conventional surface weather maps, the weather conditions of the aforementioned foggy days were determined, and four types of complex weather conditions for sea fog processes were further screened: cyclone-type, typhoon-type, southerly wind-type, and subtropical high-edge-type. Specifically, cyclone-type sea fog is defined as dense fog with visibility less than 1 km when there is cyclonic activity in the target sea area (isobars at intervals of 2.5 hPa, with at least one closed isobar); typhoon-type sea fog is dense fog occurring in the first or second quadrant of the typhoon when the typhoon center is within 1000 km of the target sea area; southerly wind-type sea fog is dense fog occurring when the southerly wind speed in the coastal areas of the target sea area reaches 6 m / s or higher; and subtropical high-edge-type sea fog is dense fog occurring when the target sea area is within 200 km of the 500 hPa 588 line. The sea fog forecast index extraction method of this invention will be described below using these four complex weather conditions as examples.

[0058] Step 2: For each observation station, the meteorological elements from the reanalysis data of the nearest grid point within the target sea area are used as initial forecast indicators. Surface meteorological elements include: air-sea temperature difference (°C), 2m temperature-dew point difference (°C), 2m relative humidity (%), wind speed (m / s) and direction (°) at 10m above the surface, 10m gust speed (m / s), 10m east-west wind speed (m / s), north-south wind speed (m / s), and north-south turbulent wind stress (N / m). 2 ), East-west turbulent wind stress (N / m) 2 ), heat flux (W / m 2 Latent heat flux (W / m) 2 Upper-air meteorological elements include: relative humidity (%), specific humidity (g / kg), and water vapor flux divergence (g•hPa) on isobaric surfaces of 1000hPa, 925hPa, and 850hPa. -1 •cm -2 •s -1), wind direction (°) and wind speed (m / s), east-west wind speed (m / s), north-south wind speed (m / s), vertical velocity (Pa / s), and temperature advection (°C / s); air temperature on isobaric surfaces at 975hPa, 950hPa, 925hPa, and 850hPa, and the temperature difference between each layer and the surface temperature (°C); and calculate the VIS index: VIS = (T s -T d ) / RH 1.67 T s T represents the surface temperature (K). d RH is the dew point temperature (K) 2m above the ground surface, and RH is the relative humidity (%) 2m above the ground surface.

[0059] Step 3: The selection of forecast indicators is based on the dispersion of the initial forecast indicators. The more concentrated the variable data values, the more reliable the variable is as a forecast indicator. The standard deviation and mean of each initial forecast indicator are calculated. The ratio of the standard deviation to the mean, i.e., the coefficient of variation, measures the dispersion of the sample, eliminating the influence of different variable units. The smaller the coefficient of variation, the more concentrated the values ​​of the initial forecast indicator. Variables with a coefficient of variation less than 30% are selected as forecast indicators for sea fog.

[0060] Step 4.1: For the above sea fog forecast indicators, draw four types of box plots for cyclones, typhoons, the periphery of the subtropical high, and southerly winds. The box plots represent all data in the sample arranged from largest to smallest from top to bottom, namely the maximum value, 75th percentile, 50th percentile (median), 25th percentile, and minimum value.

[0061] Step 4.2: Determining the threshold of the forecast indicator. Based on the 75th or 25th percentile value of the box plot of the forecast indicator, if the range of sample values ​​less than 25% in the box plot is greater than the range of sample values ​​greater than 75%, the value greater than 25% is selected as the threshold of the forecast indicator; conversely, if the range of sample values ​​less than 25% in the box plot is less than the range of sample values ​​greater than 75%, the value less than 75% is selected as the threshold of the forecast indicator.

[0062] by Figure 2 Taking (a) and (b) as examples, the air-sea temperature difference has the smallest coefficient of variation of 25% in typhoon-type sea fog, which is used as the forecast indicator for typhoon-type sea fog. Similarly, the 10-meter wind direction has the smallest coefficient of variation of 7% in southerly gale-type sea fog, which is used as the forecast indicator for southerly gale-type sea fog. The threshold values ​​for the forecast indicators are determined based on the 75th or 25th percentile values ​​of the initial forecast indicator box plot. If the range of values ​​less than 25% in the box plot is greater than the range of values ​​greater than 75%, the value greater than 25% is selected as the threshold value for that forecast indicator; conversely, if the range of values ​​less than 25% in the box plot is less than the range of values ​​greater than 75%, the value less than 75% is selected as the threshold value for that forecast indicator. For example... Figure 2As shown in (a) and (b), the threshold for the air-sea temperature difference in forecasting indicators for typhoon-type sea fog is set at a value greater than the 25th percentile. Similarly, the threshold for the 10-meter wind direction in forecasting indicators for southerly gale-type sea fog is also set at a value greater than the 25th percentile. The threshold range includes 75% of the samples. The forecasting indicators and thresholds for the four complex types of sea fog are shown in Table 1.

[0063] Table 1. Sea fog forecasting indicators and their thresholds under four types of complex weather conditions.

[0064]

[0065] like Figure 3 After obtaining the sea forecast indicators under four types of complex weather conditions, further sea fog forecasting is carried out.

[0066] Step 5: Using numerical forecast products for a future time period of the target sea area, according to the forecast indicators for different types of complex weather conditions determined in Step 4.2, read the relevant meteorological elements at the designated point or calculate the current grid point indicator variable values. If 80% of the indicator values ​​calculated within the forecast period meet the threshold determined in Step 3.3, then fog is predicted in the target sea area.

[0067] In step 5, the sea surface heat flux is calculated using the COARE 3.0 heat flux algorithm to determine the sensible and latent heat fluxes at the sea-air interface at a specified point. This algorithm is based on the bulk method.

[0068] ,

[0069] in H s For sensible heat flux, H l Latent heat flux; C The heat transfer coefficient is taken as 0.00115; S The wind speed at sea surface is represented by a 10m wind speed. T s Sea surface temperature; q s The specific humidity at sea surface is replaced by the specific humidity at 2m; and q The specific humidity of air is replaced by the specific humidity of 1000 hPa. c pa The specific heat capacity of air is taken as 1004.67; θ Potential temperature, by definition, is obtained through air temperature. T air pressure p Compared to air humidity q calculate:

[0070] ,

[0071] ρ a For air density, use sea surface pressure.p and 2m temperature t Perform the calculation:

[0072] L e The Monin-Obukhov length is the sea surface length, using sea surface temperature. T s calculate:

[0073] .

[0074] In step 4, the 10m wind field is used as an approximation of surface wind. For east-west wind stress, the zonal wind component is used; for north-south surface wind stress, the meridional wind component is used. Surface wind stress is calculated using an approximate formula:

[0075] ,

[0076] in, For surface wind stress, ρ air density, For surface wind, C s The surface drag coefficient is given by the empirical formula:

[0077] ,

[0078] in, V Wind speed;

[0079] This invention innovatively proposes a sea fog forecasting index using reanalysis data, visibility data from meteorological observation stations in the target sea area, and the percentile method. In operational use, the index variable value is extracted or calculated based on numerical weather prediction products, and sea fog forecasts are made according to whether the threshold is met. This provides a new index forecasting method for sea fog forecasting under complex weather conditions in the target sea area, further improving the sea fog forecasting level.

Claims

1. A method for extracting sea fog forecasting indicators, characterized in that, Includes the following steps: 1) Screen historical cases of sea fog in the target sea area; 2) Determine the initial forecast indicators: Acquire reanalysis data within the target sea area. For each meteorological observation station, read the meteorological elements at the grid point closest to the station, including surface meteorological elements and upper-air meteorological elements. 3) Determine forecast indicators: The standard deviation and mean of each preliminary forecast index were calculated. The ratio of the standard deviation to the mean, i.e. the coefficient of variation, was used to measure the dispersion of the sample. The smaller the coefficient of variation, the more concentrated the values ​​of the preliminary forecast index were. Preliminary forecast indices with a coefficient of variation of less than 30% were used as sea fog forecast indices. 4) Further determine the threshold values ​​for forecast indicators: 4.1) Draw a box plot of the above sea fog forecast indicators. The corresponding data in the box plot are arranged from top to bottom in descending order, namely the maximum value, 75th percentile, 50th percentile, 25th percentile, and minimum value. 4.2) The threshold for forecast indicators is determined based on the 75th or 25th percentile of the box plot of the forecast indicator. If the range of values ​​of the sample portion less than 25% in the box plot is greater than the range of values ​​of the sample portion greater than 75%, the value greater than 25% is selected as the threshold for the forecast indicator; conversely, if the range of values ​​of the sample portion less than 25% in the box plot is less than the range of values ​​of the sample portion greater than 75%, the value less than 75% is selected as the threshold for the forecast indicator.

2. The method for extracting sea fog forecast indicators as described in claim 1, characterized in that, When screening historical cases of sea fog in the target sea area in step 1, at least five years of historical data from meteorological observation stations in the target sea area are obtained and visibility data is extracted from them. Fog days are defined with visibility <1km as the standard.

3. The method for extracting sea fog forecast indicators as described in claim 1, characterized in that, In step 2, the reanalysis data includes: ERA5 reanalysis data or FNL reanalysis data.

4. The method for extracting sea fog forecast indicators as described in claim 1, characterized in that, In step 2, the surface meteorological elements include: air-sea temperature difference; 2m temperature-dew point difference; 2m relative humidity; 10m wind speed above the surface; wind direction; 10m gust wind speed; 10m east-west wind speed; north-south wind speed; north-south turbulent wind stress; east-west turbulent wind stress; sensible heat flux; latent heat flux. Upper-air meteorological elements include: relative humidity at 1000 hPa, 925 hPa, and 850 hPa; specific humidity; water vapor flux divergence; wind direction; wind speed; east-west wind speed; north-south wind speed; vertical velocity; temperature advection; air temperature at 975 hPa, 950 hPa, 925 hPa, and 850 hPa, and the temperature difference between each layer and the surface temperature; and the VIS index is calculated: VIS = (T s -T d ) / RH 1.67 T s T represents the surface temperature. d RH is the dew point temperature 2m above the ground surface; RH is the relative humidity 2m above the ground surface.

5. The sea fog forecast index extraction method as described in claim 4, characterized in that, Step 1 is followed by screening four types of complex weather conditions for sea fog processes: Based on conventional surface weather maps, the weather conditions of the above fog days are determined, and four types of complex weather conditions for sea fog processes are screened out: cyclone type, typhoon type, southerly wind type, and subtropical high edge type. Among them, cyclonic sea fog is defined as dense fog with visibility less than 1 km, where there is cyclonic activity in the target sea area, with isobars spaced at 2.5 hPa and at least one closed isobar. Typhoon-type sea fog is dense fog that occurs in the first and fourth quadrants of a typhoon when the center of the typhoon is within 1000 km of the target sea area. Southerly wind-type sea fog is dense fog that occurs when the southerly wind speed in the coastal areas of the target sea area reaches 6 m / s or more. Subtropical high edge-type sea fog is dense fog that occurs when the target sea area is within 200 km of the 500 hPa 588 line.

6. The method for extracting sea fog forecast indicators as described in claim 5, characterized in that, The following are the forecast indices and thresholds for sea fog in the Yellow Sea under four types of complex weather conditions determined by this method: For cyclonic weather backgrounds, there are seven forecast indicators: latent heat flux, sensible heat flux, 10-meter wind speed, north-south turbulent wind stress, east-west turbulent wind stress, 925 hPa temperature, and the temperature difference between surface temperature and 850 hPa. The thresholds for the seven indicators are: latent heat flux ~ less than 75th percentile, sensible heat flux ~ less than 75th percentile, 10-meter wind speed ~ less than 75th percentile, north-south turbulent wind stress ~ greater than 25th percentile, east-west turbulent wind stress ~ less than 75th percentile, 925 hPa temperature ~ greater than 25th percentile, and the temperature difference between surface temperature and 850 hPa ~ greater than 25th percentile. For typhoon-type weather backgrounds, there are six forecast indicators: latent heat flux, 10-meter wind speed, 2-meter relative humidity, air-sea temperature difference, 925-hPa temperature advection, and surface temperature difference with 850-hPa. The thresholds for the six indicators are: latent heat flux ~>25th percentile, 10-meter wind speed ~>25th percentile, 2-meter relative humidity ~>25th percentile, air-sea temperature difference ~>25th percentile, 925-hPa temperature advection ~>25th percentile, and surface temperature difference with 850-hPa ~<75th percentile. For a subtropical high-edge weather background, there are four forecast indicators: sensible heat flux, 2m relative humidity, 1000hPa relative humidity, and the temperature difference between the surface and 850hPa. The thresholds for these four indicators are: sensible heat flux ~ less than the 75th percentile, 2m relative humidity ~ greater than the 25th percentile, 1000hPa relative humidity ~ greater than the 25th percentile, and the temperature difference between the surface and 850hPa ~ greater than the 25th percentile. For a southerly windy weather background, there are four forecast indicators: north-south turbulent wind stress, 10-meter wind direction, 850 hPa wind speed, and 850 hPa temperature advection. The thresholds for the four indicators are: north-south turbulent wind stress ~ greater than 25 percentile, 10-meter wind direction ~ greater than 25 percentile, 850 hPa wind speed ~ greater than 25 percentile, and 850 hPa temperature advection ~ greater than 25 percentile.

7. A sea fog forecasting method, characterized in that, Includes the following steps: 1) Obtain the forecast indicators and their thresholds for the target sea area according to the method described in claim 1; 2) Obtain numerical weather prediction products for the target sea area at a future time, and extract the prediction indicators determined in the previous step from them; if the numerical weather prediction products do not provide sea surface heat flux, north-south turbulent wind stress, and east-west turbulent wind stress, then calculate these three indicators separately. 3) If more than 80% of the forecast indicators meet the threshold within the forecast period, then the target sea area is predicted to be foggy.

8. The sea fog forecasting method as described in claim 7, characterized in that, The sea surface heat flux is calculated using the COARE 3.0 heat flux algorithm to measure the sensible and latent heat fluxes at the sea-air interface at a specified point; this algorithm is based on the bulk method. ， ， in For sensible heat flux, Latent heat flux; The heat transfer coefficient is taken as 0.00115; S represents the wind speed at the sea surface, represented by a 10m wind speed. Sea surface temperature; The specific humidity at sea surface is used as a substitute for the specific humidity at 2m. as well as q The specific humidity of air is replaced by the specific humidity of 1000 hPa. The specific heat capacity of air is taken as 1004.67; Potential temperature, by definition, is obtained through air temperature. air pressure Compared to air humidity calculate: ， For air density, use sea surface pressure. and 2m temperature Perform the calculation: ， The Monin-Obukhov length is the sea surface length, using sea surface temperature. calculate: 。 9. The sea fog forecasting method as described in claim 7, characterized in that, The calculations for the north-south turbulent wind stress and the east-west turbulent wind stress are as follows: If we approximate a 10m wind field as surface wind, then the turbulent wind stress can be calculated using an approximate formula: ， in, For surface wind stress, air density, For surface wind, The surface drag coefficient, The empirical formula is: ， in, V Wind speed; When calculating east-west turbulent wind stress, the zonal wind component is used, while when calculating north-south turbulent wind stress, the meridional wind component is used.

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